ß-Glucan Reverses the Epigenetic State of LPS-Induced Immunological Tolerance.

Innate immune memory is the phenomenon whereby innate immune cells such as monocytes or macrophages undergo functional reprogramming after exposure to microbial components such as lipopolysaccharide (LPS). We apply an integrated epigenomic approach to characterize the molecular events involved in LPS-induced tolerance in a time-dependent manner. Mechanistically, LPS-treated monocytes fail to accumulate active histone marks at promoter and enhancers of genes in the lipid metabolism and phagocytic pathways. Transcriptional inactivity in response to a second LPS exposure in tolerized macrophages is accompanied by failure to deposit active histone marks at promoters of tolerized genes. In contrast, ß-glucan partially reverses the LPS-induced tolerance in vitro. Importantly, ex vivo ß-glucan treatment of monocytes from volunteers with experimental endotoxemia re-instates their capacity for cytokine production. Tolerance is reversed at the level of distal element histone modification and transcriptional reactivation of otherwise unresponsive genes. VIDEO ABSTRACT.

Biosynthesis and export of bacterial lipopolysaccharides.

Lipopolysaccharide molecules represent a unique family of glycolipids based on a highly conserved lipid moiety known as lipid A. These molecules are produced by most gram-negative bacteria, in which they play important roles in the integrity of the outer-membrane permeability barrier and participate extensively in host-pathogen interplay. Few bacteria contain lipopolysaccharide molecules composed only of lipid A. In most forms, lipid A is glycosylated by addition of the core oligosaccharide that, in some bacteria, provides an attachment site for a long-chain O-antigenic polysaccharide. The complexity of lipopolysaccharide structures is reflected in the processes used for their biosynthesis and export. Rapid growth and cell division depend on the bacterial cell's capacity to synthesize and export lipopolysaccharide efficiently and in large amounts. We review recent advances in those processes, emphasizing the reactions that are essential for viability.

The ATP-Binding Cassette Gene ABCF1 Functions as an E2 Ubiquitin-Conjugating Enzyme Controlling Macrophage Polarization to Dampen Lethal Septic Shock.

Sepsis is a bi-phasic inflammatory disease that threatens approximately 30 million lives and claims over 14 million annually, yet little is known regarding the molecular switches and pathways that regulate this disease. Here, we have described ABCF1, an ATP-Binding Cassette (ABC) family member protein, which possesses an E2 ubiquitin enzyme activity, through which it controls the Lipopolysaccharide (LPS)- Toll-like Receptor-4 (TLR4) mediated gram-negative insult by targeting key proteins for K63-polyubiquitination. Ubiquitination by ABCF1 shifts the inflammatory profile from an early phase MyD88-dependent to a late phase TRIF-dependent signaling pathway, thereby regulating TLR4 endocytosis and modulating macrophage polarization from M1 to M2 phase. Physiologically, ABCF1 regulates the shift from the inflammatory phase of sepsis to the endotoxin tolerance phase, and modulates cytokine storm and interferon-ß (IFN-ß)-dependent production by the immunotherapeutic mediator, SIRT1. Consequently, ABCF1 controls sepsis induced mortality by repressing hypotension-induced renal circulatory dysfunction.

Chanzyme TRPM7 Mediates the Ca2+ Influx Essential for Lipopolysaccharide-Induced Toll-Like Receptor 4 Endocytosis and Macrophage Activation.

Toll-like receptors (TLRs) sense pathogen-associated molecular patterns to activate the production of inflammatory mediators. TLR4 recognizes lipopolysaccharide (LPS) and drives the secretion of inflammatory cytokines, often contributing to sepsis. We report that transient receptor potential melastatin-like 7 (TRPM7), a non-selective but Ca2+-conducting ion channel, mediates the cytosolic Ca2+ elevations essential for LPS-induced macrophage activation. LPS triggered TRPM7-dependent Ca2+ elevations essential for TLR4 endocytosis and the subsequent activation of the transcription factor IRF3. In a parallel pathway, the Ca2+ signaling initiated by TRPM7 was also essential for the nuclear translocation of NFκB. Consequently, TRPM7-deficient macrophages exhibited major deficits in the LPS-induced transcriptional programs in that they failed to produce IL-1ß and other key pro-inflammatory cytokines. In accord with these defects, mice with myeloid-specific deletion of Trpm7 are protected from LPS-induced peritonitis. Our study highlights the importance of Ca2+ signaling in macrophage activation and identifies the ion channel TRPM7 as a central component of TLR4 signaling.

Dicer Deficiency Differentially Impacts Microglia of the Developing and Adult Brain.

Microglia seed the embryonic neuro-epithelium, expand and actively sculpt neuronal circuits in the developing central nervous system, but eventually adopt relative quiescence and ramified morphology in the adult. Here, we probed the impact of post-transcriptional control by microRNAs (miRNAs) on microglial performance during development and adulthood by generating mice lacking microglial Dicer expression at these distinct stages. Conditional Dicer ablation in adult microglia revealed that miRNAs were required to limit microglial responses to challenge. After peripheral endotoxin exposure, Dicer-deficient microglia expressed more pro-inflammatory cytokines than wild-type microglia and thereby compromised hippocampal neuronal functions. In contrast, prenatal Dicer ablation resulted in spontaneous microglia activation and revealed a role for Dicer in DNA repair and preservation of genome integrity. Accordingly, Dicer deficiency rendered otherwise radio-resistant microglia sensitive to gamma irradiation. Collectively, the differential impact of the Dicer ablation on microglia of the developing and adult brain highlights the changes these cells undergo with time.

Clinical, experimental and pathophysiological effects of Yaq-001: a non-absorbable, gut-restricted adsorbent in models and patients with cirrhosis.

OBJECTIVE: Targeting bacterial translocation in cirrhosis is limited to antibiotics with risk of antimicrobial resistance. This study explored the therapeutic potential of a non-absorbable, gut-restricted, engineered carbon bead adsorbent, Yaq-001 in models of cirrhosis and acute-on-chronic liver failure (ACLF) and, its safety and tolerability in a clinical trial in cirrhosis. DESIGN: Performance of Yaq-001 was evaluated in vitro. Two-rat models of cirrhosis and ACLF, (4 weeks, bile duct ligation with or without lipopolysaccharide), receiving Yaq-001 for 2 weeks; and two-mouse models of cirrhosis (6-week and 12-week carbon tetrachloride (CCl4)) receiving Yaq-001 for 6 weeks were studied. Organ and immune function, gut permeability, transcriptomics, microbiome composition and metabolomics were analysed. The effect of faecal water on gut permeability from animal models was evaluated on intestinal organoids. A multicentre, double-blind, randomised, placebo-controlled clinical trial in 28 patients with cirrhosis, administered 4 gr/day Yaq-001 for 3 months was performed. RESULTS: Yaq-001 exhibited rapid adsorption kinetics for endotoxin. In vivo, Yaq-001 reduced liver injury, progression of fibrosis, portal hypertension, renal dysfunction and mortality of ACLF animals significantly. Significant impact on severity of endotoxaemia, hyperammonaemia, liver cell death, systemic inflammation and organ transcriptomics with variable modulation of inflammation, cell death and senescence in the liver, kidneys, brain and colon was observed. Yaq-001 reduced gut permeability in the organoids and impacted positively on the microbiome composition and metabolism. Yaq-001 regulated as a device met its primary endpoint of safety and tolerability in the clinical trial. CONCLUSIONS: This study provides strong preclinical rationale and safety in patients with cirrhosis to allow clinical translation. TRIAL REGISTRATION NUMBER: NCT03202498.

Signaling through the Salmonella PbgA-LapB regulatory complex activates LpxC proteolysis and limits lipopolysaccharide biogenesis during stationary-phase growth.

Salmonella enterica serovar Typhimurium (S. Typhimurium) controls lipopolysaccharide (LPS) biosynthesis by regulating proteolysis of LpxC, the rate-limiting enzyme and target of preclinical antibiotics. PbgA/YejM/LapC regulates LpxC levels and controls outer membrane (OM) LPS composition at the log-to-stationary phase transition. Suppressor substitutions in LPS assembly protein B (LapB/YciM) rescue the LPS and OM integrity defects of pbgA-mutant S. Typhimurium. We hypothesized that PbgA regulates LpxC proteolysis by controlling LapB's ability to bind LpxC as a function of the growth phase. According to existing models, when nutrients are abundant, PbgA binds and restricts LapB from interacting with LpxC and FtsH, which limits LpxC proteolysis. However, when nutrients are limited, there is debate whether LapB dissociates from PbgA to bind LpxC and FtsH to enhance degradation. We sought to examine these models and investigate how the structure of LapB enables salmonellae to control LpxC proteolysis and LPS biosynthesis. Salmonellae increase LapB levels during the stationary phase to promote LpxC degradation, which limits lipid A-core production and increases their survival. The deletion of lapB, resulting in unregulated lipid A-core production and LpxC overabundance, leads to bacterial growth retardation. Tetratricopeptide repeats near the cytosol-inner membrane interface are sufficient for LapB to bind LpxC, and remarkably, LapB and PbgA interact in both growth phases, yet LpxC only associates with LapB in the stationary phase. Our findings support that PbgA-LapB exists as a constitutive complex in S. Typhimurium, which differentially binds LpxC to control LpxC proteolysis and limit lipid A-core biosynthesis in response to changes in the environment.IMPORTANCEAntimicrobial resistance has been a costly setback for human health and agriculture. Continued pursuit of new antibiotics and targets is imperative, and an improved understanding of existing ones is necessary. LpxC is an essential target of preclinical trial antibiotics that can eliminate multidrug-resistant Gram-negative bacterial infections. LapB is a natural LpxC inhibitor that targets LpxC for degradation and limits lipopolysaccharide production in Enterobacteriaceae. Contrary to some studies, findings herein support that LapB remains in complex instead of dissociating from its presumed negative regulator, PbgA/YejM/LapC, under conditions where LpxC proteolysis is enhanced. Advanced comprehension of this critical protein-lipid signaling network will lead to future development and refinement of small molecules that can specifically interfere.

Mathematical models disentangle the role of IL-10 feedbacks in human monocytes upon proinflammatory activation.

Inflammation is one of the vital mechanisms through which the immune system responds to harmful stimuli. During inflammation, proinflammatory and anti-inflammatory cytokines interplay to orchestrate fine-tuned and dynamic immune responses. The cytokine interplay governs switches in the inflammatory response and dictates the propagation and development of the inflammatory response. Molecular pathways underlying the interplay are complex, and time-resolved monitoring of mediators and cytokines is necessary as a basis to study them in detail. Our understanding can be advanced by mathematical models that enable to analyze the system of interactions and their dynamical interplay in detail. We, therefore, used a mathematical modeling approach to study the interplay between prominent proinflammatory and anti-inflammatory cytokines with a focus on tumor necrosis factor and interleukin 10 (IL-10) in lipopolysaccharide-primed primary human monocytes. Relevant time-resolved data were generated by experimentally adding or blocking IL-10 at different time points. The model was successfully trained and could predict independent validation data and was further used to perform simulations to disentangle the role of IL-10 feedbacks during an acute inflammatory event. We used the insight to obtain a reduced predictive model including only the necessary IL-10-mediated feedbacks. Finally, the validated reduced model was used to predict early IL-10-tumor necrosis factor switches in the inflammatory response. Overall, we gained detailed insights into fine-tuning of inflammatory responses in human monocytes and present a model for further use in studying the complex and dynamic process of cytokine-regulated acute inflammation.

Conventional and unconventional T-cell responses contribute to the prediction of clinical outcome and causative bacterial pathogen in sepsis patients.

Sepsis is characterized by a dysfunctional host response to infection culminating in life-threatening organ failure that requires complex patient management and rapid intervention. Timely diagnosis of the underlying cause of sepsis is crucial, and identifying those at risk of complications and death is imperative for triaging treatment and resource allocation. Here, we explored the potential of explainable machine learning models to predict mortality and causative pathogen in sepsis patients. By using a modelling pipeline employing multiple feature selection algorithms, we demonstrate the feasibility of identifying integrative patterns from clinical parameters, plasma biomarkers, and extensive phenotyping of blood immune cells. While no single variable had sufficient predictive power, models that combined five and more features showed a macro area under the curve (AUC) of 0.85 to predict 90-day mortality after sepsis diagnosis, and a macro AUC of 0.86 to discriminate between Gram-positive and Gram-negative bacterial infections. Parameters associated with the cellular immune response contributed the most to models predictive of 90-day mortality, most notably, the proportion of T cells among PBMCs, together with expression of CXCR3 by CD4+ T cells and CD25 by mucosal-associated invariant T (MAIT) cells. Frequencies of Vδ2+ γδ T cells had the most profound impact on the prediction of Gram-negative infections, alongside other T-cell-related variables and total neutrophil count. Overall, our findings highlight the added value of measuring the proportion and activation patterns of conventional and unconventional T cells in the blood of sepsis patients in combination with other immunological, biochemical, and clinical parameters.

The Way It Was.

Mary Osborn was a native Californian. She was an undergraduate at the University of California, Berkeley, where she worked in the laboratory of I.L. Chaikoff. She received her PhD at the University of Washington, where her work on the role of folic acid coenzymes in one-carbon metabolism revealed the mechanism of action of methotrexate. After postdoctoral training with Bernard Horecker in the Department of Microbiology at New York University (NYU), she embarked on her research career as a faculty member in the NYU Department of Microbiology and in the Department of Molecular Biology at Albert Einstein College of Medicine. In 1968 she moved as one of the founding faculty of the new medical school of the University of Connecticut, where she remained until her retirement in 2014. Her research was focused on the biosynthesis of the endotoxin lipopolysaccharide (LPS) of gram-negative bacteria and on the assembly of the bacterial cell envelope. She made seminal contributions in these areas. She was the recipient of numerous honors and served as president of several important scientific organizations. Later in her career she served as chair of the National Research Council Committee on Space Biology and Medicine, advisory to the National Aeronautics and Space Administration (NASA), which produced an influential report that plotted the path for NASA's space biology research program in the first decade of the twenty-first century. Dr. Osborn died on Jan. 17, 2019.

The relevance of intestinal barrier dysfunction, antimicrobial proteins and bacterial endotoxin in metabolic dysfunction-associated steatotic liver disease.

BACKGROUND: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a leading cause of end-stage liver disease associated with increased mortality and cardiovascular disease. Obesity and diabetes are the most important risk factors of MASLD. It is well-established that obesity-associated insulin resistance leads to a situation of tissue lipotoxicity characterized by an accumulation of excess fat in non-fat tissues such as the liver, promoting the development of MASLD, and its progression into metabolic dysfunction-associated steatohepatitis. METHODS: Here, we aimed to review the impact of disrupted intestinal permeability, antimicrobial proteins and bacterial endotoxin in the development and progression of MASLD. RESULTS AND CONCLUSION: Recent studies demonstrated that obesity- and obesogenic diets-associated alterations of intestinal microbiota along with the disruption of intestinal barrier integrity, the alteration in antimicrobial proteins and, in consequence, an enhanced translocation of bacterial endotoxin into bloodstream might contribute to this pathological process through to impacting liver metabolism and inflammation.

Targeting transitioning lung monocytes/macrophages as treatment strategies in lung disease related to environmental exposures.

BACKGROUND: Environmental/occupational exposures cause significant lung diseases. Agricultural organic dust extracts (ODE) and bacterial component lipopolysaccharide (LPS) induce recruited, transitioning murine lung monocytes/macrophages, yet their cellular role remains unclear. METHODS: CCR2 RFP+ mice were intratracheally instilled with high concentration ODE (25%), LPS (10 µg), or gram-positive peptidoglycan (PGN, 100 µg) for monocyte/macrophage cell-trafficking studies. CCR2 knockout (KO) mice and administration of intravenous clodronate liposomes strategies were employed to reduce circulating monocytes available for lung recruitment following LPS exposure. Lung tissues and bronchoalveolar lavage fluid (BALF) were collected. Pro-inflammatory and/or pro-fibrotic cytokines, chemokines, and lung extracellular matrix mediators were quantitated by ELISA. Infiltrating lung cells including monocyte/macrophage subpopulations, neutrophils, and lymphocytes were characterized by flow cytometry. Lung histopathology, collagen content, vimentin, and post-translational protein citrullination and malondialdehyde acetaldehyde (MAA) modification were quantitated. Parametric statistical tests (one-way ANOVA, Tukey'smultiple comparison) and nonparametric statistical (Kruskal-Wallis, Dunn's multiple comparison) tests were used following Shapiro-Wilk testing for normality. RESULTS: Intratracheal instillation of ODE, LPS, or PGN robustly induced the recruitment of inflammatory CCR2+ CD11cintCD11bhi monocytes/macrophages and both CCR2+ and CCR2- CD11c-CD11bhi monocytes at 48 h. There were also increases in CCR2+ CD4+ and CD8+ T cells and NK cells. Despite reductions in LPS-induced lung infiltrating CD11cintCD11bhi cells (54% reduction), CCR2 knockout (KO) mice were not protected against LPS-induced inflammatory and pro-fibrotic consequences. Instead, compensatory increases in lung neutrophils and CCL2 and CCL7 release occurred. In contrast, the depletion of circulating monocytes through the administration of intravenous clodronate (vs. vehicle) liposomes 24 h prior to LPS exposure reduced LPS-induced infiltrating CD11cintCD11bhi monocyte-macrophage subpopulation by 59% without compensatory changes in other cell populations. Clodronate liposome pre-treatment significantly reduced LPS-induced IL-6 (66% reduction), matrix metalloproteinases (MMP)-3 (36%), MMP-8 (57%), tissue inhibitor of metalloproteinases (61%), fibronectin (38%), collagen content (22%), and vimentin (40%). LPS-induced lung protein citrullination and MAA modification, post-translational modifications implicated in lung disease, were reduced (39% and 48%) with clodronate vs. vehicle liposome. CONCLUSION: Highly concentrated environmental/occupational exposures induced the recruitment of CCR2+ and CCR2- transitioning monocyte-macrophage and monocyte subpopulations and targeting peripheral monocytes may reduce the adverse lung consequences resulting from exposures to LPS-enriched inhalants.

Acute experimental inflammation in healthy women attenuates empathy for psychological pain.

Administration of low-dose lipopolysaccharide (LPS) to healthy humans is a translational approach to analyze the effects of acute systemic inflammation and sickness behavior. Although studies documented that LPS-induced inflammation can alter social behavior, its impact on empathy remains poorly understood. In this double-blind, placebo-controlled study, 52 healthy female volunteers received an intravenous injection of either LPS (0.4 ng/kg body weight) or placebo and completed the Social Interaction Empathy Task (SIET) two hours after injection. Physiological responses (blood pressure, heart rate, body temperature, cytokines, cortisol) were analyzed along with sickness symptoms and mood before and after LPS or placebo administration. LPS application led to significant increases in plasma cytokines and sickness symptoms as well as low mood. Moreover, volunteers receiving LPS showed significantly less empathy for other's psychological pain than those who received placebo. Furthermore, LPS-injected volunteers with more severe sickness symptoms displayed higher pain ratings in the first-person perspective. Thus, low-grade inflammation reduces empathy for other's psychological pain which might reflect an adaptive strategy to save energy by not responding empathetically when sick oneself.

Characterization of differences in immune responses during bolus and continuous infusion endotoxin challenges using mathematical modelling.

Endotoxin administration is commonly used to study the inflammatory response, and though traditionally given as a bolus injection, it can be administered as a continuous infusion over multiple hours. Several studies hypothesize that the latter better represents the prolonged and pronounced inflammation observed in conditions like sepsis. Yet very few experimental studies have administered endotoxin using both strategies, leaving significant gaps in determining the underlying mechanisms responsible for their differing immune responses. We used mathematical modelling to analyse cytokine data from two studies administering a 2 ng kg-1 dose of endotoxin, one as a bolus and the other as a continuous infusion over 4 h. Using our model, we simulated the dynamics of mean and subject-specific cytokine responses as well as the response to long-term endotoxin administration. Cytokine measurements revealed that the bolus injection led to significantly higher peaks for interleukin (IL)-8, while IL-10 reaches higher peaks during continuous administration. Moreover, the peak timing of all measured cytokines occurred later with continuous infusion. We identified three model parameters that significantly differed between the two administration methods. Monocyte activation of IL-10 was greater during the continuous infusion, while tumour necrosis factor α $ {\alpha} $ and IL-8 recovery rates were faster for the bolus injection. This suggests that a continuous infusion elicits a stronger, longer-lasting systemic reaction through increased stimulation of monocyte anti-inflammatory mediator production and decreased recovery of pro-inflammatory catalysts. Furthermore, the continuous infusion model exhibited prolonged inflammation with recurrent peaks resolving within 2 days during long-term (20-32 h) endotoxin administration.

Nitric oxide and tumor necrosis factor-⍺ levels are negatively correlated in endotoxin tolerance recovery in vitro.

Endotoxin tolerance (ET) is the hyporesponsiveness to lipopolysaccharide (LPS) after prior exposure. It is characterized by the downregulation of pro-inflammatory cytokine levels. Although ET protects against inflammation, its abolishment or recovery is critical for immunity. Nitric oxide (NO) plays various roles in the development of ET; however, its specific role in ET recovery remains unknown. To induce ET, RAW264.7 cells (a murine macrophage cell line) were pre-exposed to LPS (LPS1, 100 ng/mL for 24 h) and subsequently re-stimulated with LPS (LPS2, 100 ng/mL for 24 h). Expression of cytokines, NO, nitrite and inducible NO synthase (iNOS) were measured after 0, 12, 24, and 36 h of resting after LPS1 treatment with or without the iNOS-specific inhibitor, 1400W. LPS2-induced tumor necrosis factor-⍺ (TNF-⍺) and interleukin-6 (IL-6) were downregulated after LPS1 treatment, confirming the development of ET. Notably, TNF-⍺ and IL-6 levels spontaneously rebounded after 12-24 h of resting following LPS1 treatment. In contrast, levles of NO, nitrite and iNOS increased during ET development and decreased during ET recovery. Moreover, 1400W inhibited ET development and blocked the early production of NO (<12 h) during ET recovery. Our findings suggest a negative correlation between iNOS-induced NO and cytokine levels in the abolishment of ET.

Immunology of gut microbiome and liver in non-alcoholic fatty liver disease (NAFLD): mechanisms, bacteria, and novel therapeutic targets.

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the world. Most important contributors to its development are diet and obesity. Gut microbiome's importance for immune system and inflammatory pathways more widely accepted as an important component in NAFLD and other liver diseases' pathogenesis. In this article we review potential mechanisms of microbiome alteration of local and systemic immune responses leading to NAFLD's development, and how can modulate them for the treatment. Our review mentions different immune system pathways and microorganisms regulating metabolism, liver inflammation and fibrosis. We specifically point out TLR-4 as a potential key immune pathway activated by bacterial lipopolysaccharides producing pro-inflammatory cytokines in NAFLD. Also, we discuss three endotoxin-producing strains (Enterobacter cloacae B29, Escherichia coli PY102, Klebsiella pneumoniae A7) that can promote NAFLD development via TLR4-dependent immune response activation in animal models and how they potentially contribute to disease progression in humans. Additionally, we discuss their other immune and non-immune mechanisms contributing to NAFLD pathogenesis. In the end we point out gut microbiome researches' future perspective in NAFLD as a potential new target for both diagnostic and treatment.

The expression of HIV-1 tat in Lactococcus lactis.

Efficient expression of functional proteins in heterologous hosts has become the pivotal focus of modern biotechnology and biomedical research. To this end, multiple alternatives to E. coli are being explored for recombinant protein expression. L. lactis, being a gram-positive organism, circumvents the need for an endotoxin removal step during protein purification. We report here the optimisation of the expression of HIV-1 Tat, a notoriously difficult protein, in Lactococcus lactis system. We evaluated five different promoters in two different Lactococcus lactis strains and examined the effect of pH, glucose, and induction time on the yield and purity of Tat. Finally, the recombinant Tat was functionally competent in transactivating the HIV-1 promoter in HLM-1 reporter cells. Our work provides a scaffold for future work on the expression of toxic proteins in Lactococcus lactis.

Applicability of mouse models for induction of severe acute lung injury.

Acute lung injury (ALI) is a significant clinical challenge associated with high morbidity and mortality. Worldwide, it affects approximately 200.000 individuals annually, with a staggering 40 % mortality rate in hospitalized cases and persistent complications in out-of-hospital cases. This review focuses on the key immunological pathways underlying bacterial ALI and the exploration of mouse models as tools for its induction. These models serve as indispensable platforms for unraveling the inflammatory cascades and biological responses inherent to ALI, while also facilitating the evaluation of novel therapeutic agents. However, their utility is not without challenges, mainly due to the stringent biosafety protocols required by the diverse bacterial virulence profiles. Simple and reproducible models of pulmonary bacterial infection are currently available, including intratracheal, intranasal, pleural and, intraperitoneal approaches. These models use endotoxins such as commercially available lipopolysaccharide (LPS) or live pathogens such as Pseudomonas aeruginosa, Mycobacterium tuberculosis, and Streptococcus pneumoniae, all of which are implicated in the pathogenesis of ALI. Combining murine models of bacterial lung infection with in-depth studies of the underlying immunological mechanisms is a cornerstone in advancing the therapeutic landscape for acute bacterial lung injury.

Differential tissue immune stimulation through immersion in bacterial and viral agonists in the Antarctic Notothenia rossii.

The genome evolution of Antarctic notothenioids has been modulated by their extreme environment over millennia and more recently by human-caused constraints such as overfishing and climate change. Here we investigated the characteristics of the immune system in Notothenia rossii and how it responds to 8 h immersion in viral (Poly I:C, polyinosinic: polycytidylic acid) and bacterial (LPS, lipopolysaccharide) proxies. Blood plasma antiprotease activity and haematocrit were reduced in Poly I:C-treated fish only, while plasma protein, lysozyme activity and cortisol were unchanged with both treatments. The skin and duodenum transcriptomes responded strongly to the treatments, unlike the liver and spleen which had a mild response. Furthermore, the skin transcriptome responded most to the bacterial proxy (cell adhesion, metabolism and immune response processes) and the duodenum (metabolism, response to stress, regulation of intracellular signal transduction, and immune system responses) to the viral proxy. The differential tissue response to the two proxy challenges is indicative of immune specialisation of the duodenum and the skin towards pathogens. NOD-like and C-type lectin receptors may be central in recognising LPS and Poly I:C. Other antimicrobial compounds such as iron and selenium-related genes are essential defence mechanisms to protect the host from sepsis. In conclusion, our study revealed a specific response of two immune barrier tissue, the skin and duodenum, in Notothenia rossii when exposed to pathogen proxies by immersion, and this may represent an adaptation to pathogen infective strategies.

There is no association between serum endotoxin levels and inflammation in asthma.

BACKROUND: Endotoxin, in lipopolysaccharide structure (LPS), is the main component of the outer membrane of gram negative bacteria. LPS levels were associated with inflammatory disease. Asthma is a chronic inflammatory disease involving many different cell types and cellular elements. The association between LPS serum levels and the asthma is not well known. The aim of this study was to investigate the association between the LPS serum levels and the severity of asthma, demographic data and laboratory parameters. METHODOLOGY: The study included 67 patients aged >18 years with a diagnosis of asthma, and 15 healthy volunteers with no history of chronic disease as a control group. The Asthma Control Test (ACT), Respiratory Function Tests (RFTs), fractional exhaled nitric oxide (FeNO), and endotoxin levels were measured and compared between the groups. The endotoxin measurements were performed using the ELISA method. RESULTS: The mild-moderate asthma group included 33 patients and the severe asthma group, 34 patients. The endotoxin level was measured as 17.78 (range 3.59 to 304.55) EU/ml in the patient group and 15 (range 4.01 to 74.06) EU/ml in the control group with no statistically significant difference determined between the groups. In the subgroups, the endotoxin level was measured as 15.21 (range 3.69 to 304.55) EU/ml in the mild-moderate group and 14.46 (range 3.59 to 278.86) EU/ml in the severe asthma group with no statistically significant difference determined between the groups. CONCLUSION: The results of this study showed no relationship between serum endotoxin level and asthma or asthma severity.