Lipid mediators in immune dysfunction after severe inflammation

Sex differences in the lipid profiles of visceral adipose tissue with obesity and gonadectomy

In obesity, adipose tissue (AT) expansion is accompanied by chronic inflammation. Altered lipid composition in the visceral or gonadal white AT (GWAT) directly drive AT macrophage accumulation and activation to a proinflammatory phenotype. Sex steroid hormones modulate visceral versus subcutaneous lipid accumulation that correlates with metabolic syndrome, especially in men and postmenopausal women who are more prone to abdominal obesity. Prior studies demonstrated sex differences in GWAT lipid species in HFD-fed mice, but the role of sex hormones is still unclear. We hypothesized that sex hormone alterations with gonadectomy (GX) would further impact lipid composition in the obese GWAT. Untargeted lipidomics of obese GWAT identified sex differences in phospholipids, sphingolipids, sterols, fatty acyls, saccharolipids and prenol lipids. Males had significantly more precursor fatty acids (palmitic, oleic, linoleic, and arachidonic acid) than females and GX mice. Targeted lipidomics for fatty acids and oxylipins in the HFD-fed male and female GWAT stromal vascular fraction identified higher omega-6 to omega-3 free fatty acid profile in males and differences in PUFAs-derived prostaglandins, thromboxanes, and leukotrienes. Both obese male and female GWAT stromal vascular fraction showed increased levels of arachidonic acid-derived oxylipins compared to their lean counterparts. Bulk RNA-seq of sorted GWAT AT macrophages highlighted sex and diet differences in PUFA and oxylipin metabolism genes. These findings of sexual dimorphism in both stored lipid species and PUFA-derived mediators with diet and GX emphasize sex differences in lipid metabolism pathways that drive inflammation responses and metabolic disease risk in obesity.

Design, synthesis, in vitro and in vivo biological evaluation of pterostilbene derivatives for anti-inflammation therapy

Pterostilbene (PST) is a naturally derived stilbene compound in grapes, blueberries, and other fruits. It is also a natural dietary compound with a wide range of biological activities such as antioxidant, anti-inflammatory, antitumor, and so on. Structural modifications based on the chemical scaffold of the pterostilbene skeleton are of great importance for drug discovery. In this study, pterostilbene skeletons were used to design novel anti-inflammatory compounds with high activity and low toxicity. A total of 30 new were found and synthesised, and their anti-inflammatory activity and safety were screened. Among them, compound E2 was the most active (against NO: IC50 = 0.7 μM) than celecoxib. Further studies showed that compound E2 exerted anti-inflammatory activity by blocking LPS-induced NF-κB/MAPK signalling pathway activation. In vivo experiments revealed that compound E2 had a good alleviating effect on acute colitis in mice. In conclusion, compound E2 may be a promising anti-inflammatory lead compound.

The impact of trauma relevant concentrations of prostaglandin E2 on the anti-microbial activity of the innate immune system

Background

The mechanisms underlying the state of systemic immune suppression that develops following major trauma are poorly understood. A post-injury increase in circulating levels of prostaglandin E2 (PGE2) has been proposed as a contributory factor, yet few studies have addressed how trauma influences PGE2 biology.

Methods

Blood samples from 95 traumatically-injured patients (injury severity score ≥8) were collected across the pre-hospital (≤2 hours), acute (4-12 hours) and subacute (48-72 hours) post-injury settings. Alongside ex vivo assessments of lipopolysaccharide (LPS)-induced cytokine production by monocytes, neutrophil reactive oxygen species production and phagocytosis, serum concentrations of PGE2 and its scavenger albumin were measured, and the expression of enzymes and receptors involved in PGE2 synthesis and signalling analysed. Leukocytes from trauma patients were treated with cyclooxygenase (COX) inhibitors (indomethacin or NS-398), or the protein kinase A inhibitor H89, to determine whether injury-induced immune suppression could be reversed by targeting the PGE2 pathway. The effect that trauma relevant concentrations of PGE2 had on the anti-microbial functions of neutrophils, monocytes and monocyte-derived macrophages (MDMs) from healthy controls (HC) was examined, as was the effect of PGE2 on efferocytosis. To identify factors that may trigger PGE2 production post-trauma, leukocytes from HC were treated with mitochondrial-derived damage associated molecular patterns (mtDAMPs) and COX-2 expression and PGE2 generation measured.

Results

PGE2 concentrations peaked in blood samples acquired ≤2 hours post-injury and coincided with significantly reduced levels of albumin and impaired LPS-induced cytokine production by monocytes. Significantly higher COX-2 and phospholipase A2 expression was detected in neutrophils and/or peripheral blood mononuclear cells isolated from trauma patients. Treatment of patient leukocytes with indomethacin, NS-398 or H89 enhanced LPS-induced cytokine production and neutrophil extracellular trap generation. Exposure to physiological concentrations of PGE2 suppressed the anti-microbial activity of monocytes, neutrophils and MDMs of HC, but did not influence efferocytosis. In a formyl-peptide receptor-1 dependent manner, mtDAMP treatment significantly increased COX-2 protein expression in neutrophils and monocytes, which resulted in increased PGE2 production.

Conclusions

Physiological concentrations of PGE2 suppress the anti-microbial activities of neutrophils, monocytes and MDMs. Targeting the PGE2 pathway could be a therapeutic approach by which to enhance innate immune function post-injury.

Omega-3 long-chain polyunsaturated fatty acids and their bioactive lipids: A strategy to improve resistance to respiratory tract infectious diseases in the elderly?

Age-related changes in organ function, immune dysregulation, and the effects of senescence explain in large part the high prevalence of infections, including respiratory tract infections in older persons. Poor nutritional status in many older persons increases susceptibility to infection and worsens prognosis. Interestingly, there is an association between the amount of saturated fats in the diet and the rate of community-acquired pneumonia. Polyunsaturated fatty acids, particularly omega-3 long chain polyunsaturated fatty acids (ω-3 LC-PUFAs) including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have well-known anti-inflammatory, immunomodulatory, and antimicrobial effects, which may, in theory, be largely induced by PUFAs-derived lipids such as specialized pro-resolving mediators (SPMs). In adults, preliminary results of studies show that ω-3 LC-PUFAs supplementation can lead to SPM generation. SPMs have a crucial role in the resolution of inflammation, a factor relevant to survival from infection independent of the pathogen’s virulence. Moreover, the immune system of older adults appears to be more sensitive to ω-3 PUFAs. This review explores the effects of ω-3 LC-PUFAs, and PUFA bioactive lipid-derived SPMs in respiratory tract infections and the possible relevance of these data to infectious disease outcomes in the older population. The hypothesis that PUFAs have beneficial effects via SPM generation will need to be confirmed by animal experiments and patient-derived data.

Length and saturation of choline plasmalogens alter the aggregation rate of α-synuclein but not the toxicity of amyloid fibrils

Plasmalogens comprise a large fraction of the total phospholipids in plasma membranes. These molecules modulate membrane fluidity, produce inflammatory mediators mitigating effects of metabolic stresses. A growing body of evidence suggests that an onset of Parkinson's disease (PD), a severe neurodegenerative pathology, can be triggered by metabolic changes in plasma membranes. However, the role of plasmalogens in the aggregation of α-synuclein (α-syn), an expected molecular cause of PD, remains unclear. In this study we examine the effect of choline plasmalogens (CPs), unique phospholipids that have a vinyl ether linkage at the sn-1 position of glycerol, on the aggregation rate of α-syn. We found that the length and saturation of fatty acids (FAs) in CPs change rates of protein aggregation. We also found drastic changes in the morphology of α-syn fibrils formed in the presence of different CPs compared to α-syn fibrils grown in the lipid-free environment. At the same time, we did not observe substantial changes in the secondary structure and toxicity of α-syn fibrils formed in the presence of different CPs. These results indicate that the length and saturation of FAs in CPs present in the plasma membrane can alter α-syn stability and modulate its aggregation properties, which, in turn can accelerate or delay the onset of PD.

Occult hypoperfusion and changes of systemic lipid levels after severe trauma: an analysis in a standardized porcine polytrauma model

BACKGROUND

Occult hypoperfusion describes the absence of sufficient microcirculation despite normal vital signs. It is known to be associated with prolonged elevation of serum lactate and later complications in severely injured patients. We hypothesized that changes in circulating lipids are related to responsiveness to resuscitation. The purpose of this study is investigating the relation between responsiveness to resuscitation and lipidomic course after poly trauma.

METHODS

Twenty-five male pigs were exposed a combined injury of blunt chest trauma, liver laceration, controlled haemorrhagic shock, and femoral shaft fracture. After 1 h, animals received resuscitation and fracture stabilization. Venous blood was taken regularly and 233 specific lipids were analysed. Animals were divided into two groups based on serum lactate level at the end point as an indicator of responsiveness to resuscitation (<2 mmol/L: responder group (R group), ≧2 mmol/L: occult hypoperfusion group (OH group)).

RESULTS

Eighteen animals met criteria for the R group, four animals for the OH group, and three animals died. Acylcarnitines showed a significant increase at 1 h compared to baseline in both groups. Six lipid subgroups showed a significant increase only in R group at 2 h. There was no significant change at other time points.

CONCLUSIONS

Six lipid groups increased significantly only in the R group at 2 h, which may support the idea that they could serve as potential biomarkers to help us to detect the presence of occult hypoperfusion and insufficient resuscitation. We feel that further study is required to confirm the role and mechanism of lipid changes after trauma.

Exploring the causal correlations between 486 serum metabolites and systemic lupus erythematosus: a bidirectional Mendelian randomization study

Objective: The observational association between circulating metabolites and systemic lupus erythematosus (SLE) has been well documented. However, whether the association is causal remains unclear. In this study, bidirectional Mendelian randomization (MR) was introduced to analyse the causal relationships and possible mechanisms. Methods: We conducted a two-sample bidirectional MR study. A genome-wide association study (GWAS) with 7,824 participants provided data on 486 human blood metabolites. Outcome information was obtained from a large-scale GWAS summary, which contained 5,201 single nucleotide polymorphisms (SNPs) cases and 9,066 control cases of Europeans and yielded a total of 7,071,163 SNPs. The inverse variance weighted (IVW) model was recruited as the primary two-sample MR analysis approach, followed by sensitivity analyses such as the heterogeneity test, horizontal pleiotropy test, leave-one-out analysis, and linkage disequilibrium score (LDSC) regression. Results: In this study, we discovered that 24 metabolites belonging to the lipid, carbohydrate, xenobiotic and amino acid superpathways may increase the risk of SLE occurrence (p < 0.05). In addition, the metabolic disorders of 51 metabolites belonging to the amino acid, energy, xenobiotics, peptide and lipid superpathways were affected by SLE (p < 0.05). Palmitoleate belonging to the lipid superpathway and isobutyrylcarnitine and phenol sulfate belonging to the amino acid superpathway were factors with two-way causation. The metabolic enrichment pathway of bile acid biosynthesis was significant in the forward MR analysis (p = 0.0435). Linolenic acid and linoleic acid metabolism (p = 0.0260), betaine metabolism (p = 0.0314), and glycerolipid metabolism (p = 0.0435) were the significant metabolically enriched pathways in the reverse MR analysis. Conclusion: The levels of some specific metabolites may either contribute to the immune response inducing SLE, or they may be intermediates in the development and progression of SLE. These metabolites can be used as auxiliary diagnostic tools for SLE and for the evaluation of disease progression and therapeutic effects.

Plasma oxidative lipidomics reveals signatures for sepsis-associated acute kidney injury

BACKGROUND

Oxidized lipids are essential bioactive lipid mediators generated during infection that regulate oxidative stress and the inflammatory response, but their signatures in patients with sepsis-associated acute kidney injury (SA-AKI) are poorly understood. This study analyzed the oxidative lipidomics of plasma from patients with SA-AKI to reveal the underlying biomarkers and pathophysiological mechanisms involved in sepsis.

MATERIALS

A total of 67 patients with SA-AKI and 20 age- and sex-matched healthy controls (HCs) participated in this prospective cohort study. Among the patients with SA-AKI, 14 cases had stage I-II AKI and 53 cases had stage III AKI. Oxidative lipidomic analysis of plasma samples was conducted using ultra performance liquid chromatography coupled with tandem mass spectrometric (UPLC-MS /MS) detection.

RESULTS

Among 21 kinds of differentially oxidized lipids, 5(S),12(S)-DiHETE, 5-isoPGF2VI, 5,6-DiHETrE, 11,12-EET and 9,10-DiHOME showed the best performance. The prediction model incorporating them has shown highly sensitive and specific in distinguishing different stages of SA-AKI from HCs. The annotation of Kyoto Encyclopedia of Genes and Genomes illustrated that the overall downregulation of vascular smooth muscle contraction was closely related to the pathophysiological mechanism of SA-AKI.

CONCLUSION

This study revealed alterations in the characteristic oxidized lipids in the plasma of SA-AKI patients, and these lipids had high diagnostic efficiency and potential targeted intervention value for SA-AKI.

Statin and aspirin use in parasitic infections as a potential therapeutic strategy: A narrative review

Infections, including zoonoses, constitute a threat to human health due to the spread of resistant pathogens. These diseases generate an inflammatory response controlled by a resolving mechanism involving specialized membrane lipid-derived molecules called lipoxins, resolvins, maresins, and protectins. The production of some of these molecules can be triggered by aspirin or statins. Thus, it is proposed that modulation of the host response could be a useful therapeutic strategy, contributing to the management of resistance to antiparasitic agents or preventing drift to chronic, host-damaging courses. Therefore, the present work presents the state of the art on the use of statins or aspirin for the experimental management of parasitic infections such as Chagas disease, leishmaniasis, toxoplasmosis or malaria. The methodology used was a narrative review covering original articles from the last seven years, 38 of which met the inclusion criteria. Based on the publications consulted, modulation of the resolution of inflammation using statins may be feasible as an adjuvant in the therapy of parasitic diseases. However, there was no strong experimental evidence on the use of aspirin; therefore, further studies are needed to evaluate its role inflammation resolution process in infectious diseases.

Lipidomic signatures align with inflammatory patterns and outcomes in critical illness

Alterations in lipid metabolism have the potential to be markers as well as drivers of pathobiology of acute critical illness. Here, we took advantage of the temporal precision offered by trauma as a common cause of critical illness to identify the dynamic patterns in the circulating lipidome in critically ill humans. The major findings include an early loss of all classes of circulating lipids followed by a delayed and selective lipogenesis in patients destined to remain critically ill. The previously reported survival benefit of early thawed plasma administration was associated with preserved lipid levels that related to favorable changes in coagulation and inflammation biomarkers in causal modelling. Phosphatidylethanolamines (PE) were elevated in patients with persistent critical illness and PE levels were prognostic for worse outcomes not only in trauma but also severe COVID-19 patients. Here we show selective rise in systemic PE as a common prognostic feature of critical illness.

Absolute quantification and characterization of oxylipins in lupus nephritis and systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with multi-organ inflammation and defect, which is linked to many molecule mediators. Oxylipins as a class of lipid mediator have not been broadly investigated in SLE. Here, we applied targeted mass spectrometry analysis to screen the alteration of oxylipins in serum of 98 SLE patients and 106 healthy controls. The correlation of oxylipins to lupus nephritis (LN) and SLE disease activity, and the biomarkers for SLE classification, were analyzed. Among 128 oxylipins analyzed, 92 were absolutely quantified and 26 were significantly changed. They were mainly generated from the metabolism of several polyunsaturated fatty acids, including arachidonic acid (AA), linoleic acid (LA), docosahexanoic acid (DHA), eicosapentanoic acid (EPA) and dihomo-γ-linolenic acid (DGLA). Several oxylipins, especially those produced from AA, showed different abundance between patients with and without lupus nephritis (LN). The DGLA metabolic activity and DGLA generated PGE1, were significantly associated with SLE disease activity. Random forest-based machine learning identified a 5-oxylipin combination as potential biomarker for SLE classification with high accuracy. Seven individual oxylipin biomarkers were also identified with good performance in distinguishing SLE patients from healthy controls (individual AUC > 0.7). Interestingly, the biomarkers for differentiating SLE patients from healthy controls are distinct from the oxylipins differentially expressed in LN patients vs. non-LN patients. This study provides possibilities for the understanding of SLE characteristics and the development of new tools for SLE classification.

Lipids in Liver Failure Syndromes: A Focus on Eicosanoids, Specialized Pro-Resolving Lipid Mediators and Lysophospholipids

Lipids are organic compounds insoluble in water with a variety of metabolic and non-metabolic functions. They not only represent an efficient energy substrate but can also act as key inflammatory and anti-inflammatory molecules as part of a network of soluble mediators at the interface of metabolism and the immune system. The role of endogenous bioactive lipid mediators has been demonstrated in several inflammatory diseases (rheumatoid arthritis, inflammatory bowel disease, atherosclerosis, cancer). The liver is unique in providing balanced immunotolerance to the exposure of bacterial components from the gut transiting through the portal vein and the lymphatic system. This balance is abruptly deranged in liver failure syndromes such as acute liver failure and acute-on-chronic liver failure. In these syndromes, researchers have recently focused on bioactive lipid mediators by global metabonomic profiling and uncovered the pivotal role of these mediators in the immune dysfunction observed in liver failure syndromes explaining the high occurrence of sepsis and subsequent organ failure. Among endogenous bioactive lipids, the mechanistic actions of three classes (eicosanoids, pro-resolving lipid mediators and lysophospholipids) in the pathophysiological modulation of liver failure syndromes will be the topic of this narrative review. Furthermore, the therapeutic potential of lipid-immune pathways will be described.

Sex-Dependent Differential Expression of Lipidic Mediators Associated with Inflammation Resolution in Patients with Pulmonary Tuberculosis

There is a sex bias in tuberculosis’s severity, prevalence, and pathogenesis, and the rates are higher in men. Immunological and physiological factors are fundamental contributors to the development of the disease, and sex-related factors could play an essential role in making women more resistant to severe forms of the disease. In this study, we evaluated sex-dependent differences in inflammatory markers. Serum samples were collected from 34 patients diagnosed with pulmonary TB (19 male and 15 female) and 27 healthy controls (18 male and 9 female). Cytokines IL2, IL4, IL6, IL8, IL10, IFNγ, TNFα, and GM-CSF, and eicosanoids PGE2, LTB4, RvD1, and Mar1 were measured using commercially available immunoassays. The MDA, a product of lipidic peroxidation, was measured by detecting thiobarbituric-acid-reactive substances (TBARS). Differential inflammation patterns between men and women were observed. Men had higher levels of IL6, IL8, and TNFα than women. PGE2 and LTB4 levels were higher in patients than healthy controls, but there were no differences for RvD1 and Mar1. Women had higher RvD1/PGE2 and RvD1/LTB4 ratios among patients. RvD1 plays a vital role in resolving the inflammatory process of TB in women. Men are the major contributors to the typical pro-inflammatory profile observed in the serum of tuberculosis patients.

NSAIDs and Cancer Resolution: New Paradigms beyond Cyclooxygenase

Acute inflammation or resolved inflammation is an adaptive host defense mechanism and is self-limiting, which returns the body to a state of homeostasis. However, unresolved, uncontrolled, or chronic inflammation may lead to various maladies, including cancer. Important evidence that links inflammation and cancer is that nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin, reduce the risk and mortality from many cancers. The fact that NSAIDs inhibit the eicosanoid pathway prompted mechanistic drug developmental work focusing on cyclooxygenase (COX) and its products. The increased prostaglandin E2 levels and the overexpression of COX-2 in the colon and many other cancers provided the rationale for clinical trials with COX-2 inhibitors for cancer prevention or treatment. However, NSAIDs do not require the presence of COX-2 to prevent cancer. In this review, we highlight the effects of NSAIDs and selective COX-2 inhibitors (COXIBs) on targets beyond COX-2 that have shown to be important against many cancers. Finally, we hone in on specialized pro-resolving mediators (SPMs) that are biosynthesized locally and, in a time, -dependent manner to promote the resolution of inflammation and subsequent tissue healing. Different classes of SPMs are reviewed, highlighting aspirin's potential in triggering the production of these resolution-promoting mediators (resolvins, lipoxins, protectins, and maresins), which show promise in inhibiting cancer growth and metastasis.

Plasmalogens and Chronic Inflammatory Diseases

It is becoming widely acknowledged that lipids play key roles in cellular function, regulating a variety of biological processes. Lately, a subclass of glycerophospholipids, namely plasmalogens, has received increased attention due to their association with several degenerative and metabolic disorders as well as aging. All these pathophysiological conditions involve chronic inflammatory processes, which have been linked with decreased levels of plasmalogens. Currently, there is a lack of full understanding of the molecular mechanisms governing the association of plasmalogens with inflammation. However, it has been shown that in inflammatory processes, plasmalogens could trigger either an anti- or pro-inflammation response. While the anti-inflammatory response seems to be linked to the entire plasmalogen molecule, its pro-inflammatory response seems to be associated with plasmalogen hydrolysis, i.e., the release of arachidonic acid, which, in turn, serves as a precursor to produce pro-inflammatory lipid mediators. Moreover, as plasmalogens comprise a large fraction of the total lipids in humans, changes in their levels have been shown to change membrane properties and, therefore, signaling pathways involved in the inflammatory cascade. Restoring plasmalogen levels by use of plasmalogen replacement therapy has been shown to be a successful anti-inflammatory strategy as well as ameliorating several pathological hallmarks of these diseases. The purpose of this review is to highlight the emerging role of plasmalogens in chronic inflammatory disorders as well as the promising role of plasmalogen replacement therapy in the treatment of these pathologies.

Longitudinal assessment of leukotriene B4, lipoxin A4, and resolvin D1 plasma levels in pregnant women with risk factors for preeclampsia

OBJECTIVES

We carried out a longitudinal study to compare leukotriene B4 (LTB4), lipoxin A4 (LXA4), and resolvin D1 (RvD1) levels in pregnant women with risk factors for PE - who did (N = 11) or did not develop (N = 17) this clinical condition.

DESIGN & METHODS

For both groups, plasma levels of the lipid mediators were measured using immunoassays at 12-19, 20-29, and 30-34 weeks of gestation.

RESULTS

LTB4 tended to be upregulated throughout gestation in women who developed PE. Moreover, this increase was significant at 30-34 weeks. Although LXA4 levels also tended to be higher in the PE group, this difference was not significant for the evaluated gestational periods. Pregnant women with PE had lower RvD1 levels and a low RvD1/LTB4 ratio at 30-34 weeks, compared to those in the normotensive pregnant women. Contrarily, RvD1 levels increased at weeks 12-19 in pregnant women who developed PE. Particularly, LXA4 and RvD1 levels were higher at 30-34 weeks than those at 20-29 weeks considering both groups of women. We observed an interaction between the gestational outcome and the gestational period in case of RvD1.

CONCLUSIONS

The imbalance among LTB4, LXA4, and RvD1 levels in these preeclamptic women is consistent with the excessive inflammation that underlies the pathogenesis of PE. Although our data highlight the potential for the use of these lipid mediators as clinical markers for PE development, future longitudinal studies must be carried out to confirm these findings.

Qing-Luo-Yin Alleviated Monocytes/Macrophages-Mediated Inflammation in Rats with Adjuvant-Induced Arthritis by Disrupting Their Interaction with (Pre)-Adipocytes Through PPAR-γ Signaling

Background

The Chinese herbal formula Qing-Luo-Yin (QLY) has been successfully used in rheumatoid arthritis treatment for decades. It exhibits notable immune and metabolism regulatory properties. Thereby, we investigated its effects on the interplay between (pre)-adipocytes and monocytes/macrophages under adjuvant-induced arthritis (AIA) circumstances.

Methods

Fat reservoir and histological characteristics of white fat tissues (WAT) in AIA rats receiving QLY treatment were examined upon sacrifice. Metabolic parameters, clinical indicators, and oxidative stress levels were determined using corresponding kits, while mRNA/protein expression was investigated by PCR and immunoblotting methods. M1 macrophage distribution in WAT was assessed by flow cytometry. The effects of QLY on (pre)-adipocytes were further validated by experiments in vitro.

Results

Compared with normal healthy controls, body weight and circulating triglyceride were declined in AIA rats, but serological levels of free fatty acids and low-density lipoprotein cholesterol were increased. mRNA IL-1β and iNOS expression in white blood cells and rheumatoid factor, C-reactive protein, anti-cyclic citrullinated peptide antibody, MCP-1 and IL-1β production in serum/WAT were up-regulated. Obvious CD86⁺CD11b⁺ macrophages were enriched in WAT. Meanwhile, expression of PPAR-γ and SIRT1 and secretion of adiponectin and leptin in these AIA rats were impaired. QLY restored all these pathological changes. Of note, it significantly stimulated PPAR-γ expression in the treated AIA rats. Accordingly, QLY-containing serum promoted SCD-1, PPAR-γ, and SIRT1 expression in pre-adipocytes cultured in vitro. AIA rats-derived peripheral blood mononuclear cells suppressed PPAR-γ and SCD-1 expression in co-cultured pre-adipocytes, but serum from AIA rats receiving QLY treatment did not exhibit this potential. The changes on PPAR-γ expression eventually resulted in varied adipocyte differentiation statuses. PPAR-γ selective inhibitor T0070907 abrogated QLY-induced MCP-1 production decline in LPS-primed pre-adipocytes and reduced adiponectin secretion.

Conclusion

QLY was potent in promoting PPAR-γ expression and consequently disrupted inflammatory feedback in WAT by altering monocytes/macrophages polarization and adipocytes differentiation.

The Manipulation of the Lipid Mediator Metabolism as Adjunct Host-Directed Therapy in Tuberculosis

Host-directed therapies (HDTs) enhance the host response to tuberculosis (TB) infection to reduce disease severity. For instance, the manipulation of lipid mediator production diminishes the hyperactive immune response which is a known pathological feature of TB that generates lung tissue damage. Non-steroidal anti-inflammatory drugs (NSAIDs) and omega-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) are examples of such HDTs. In this mini-review, we recapitulate the literature available on the effects of NSAIDs and n-3 LCPUFA in TB as well as the immunological pathways underpinning these effects. Many NSAIDs have a great deal of data describing their effects and safety and in many jurisdictions are inexpensive, and sold over the counter in neighborhood convenience stores and supermarkets. The potential benefits of NSAIDs in TB are well-documented in pre-clinical studies. The reduction of pro-inflammatory lipid mediator production by inhibiting cyclooxygenase (COX) pathways with NSAIDs has been found to improve lung histopathology, bacterial control, and survival. Additionally, n-3 LCPUFA and its novel bioactive metabolites produced by COX and lipoxygenase (LOX) have been identified as safe and effective pro-resolving and antibacterial pharmaconutrients. Nevertheless, heterogeneous results have been reported in pre-clinical TB studies. Recently, the importance of the correct timing of NSAIDs and n-3 LCPUFA administration in TB has also been highlighted. This mini-review will provide a better understanding of the potential contribution of these therapies toward reducing inflammatory lung damage and improving bactericidal activity, especially during later stages of TB infection. It further highlights that clinical trials are required to confirm benefit and safety in TB patients.

Developments of specialized pro-resolving mediators in periodontitis

Resolution of inflammation plays an important part in maintaining homeostasis. It is an actively programmed progress involving multiple immune cells and mediators. Specialized pro-resolving mediators (SPMs) derived from Ω-3 polyunsaturated fatty acids include resolvins, protectins and maresins, and they exert abilities in the resolution of inflammation, host defense, organ protection, and tissue generation. Periodontitis is an inflammatory and destructive disease in the periodontal tissue initiated by dental plaque. Inadequate proinflammatory or proresolving responses, or the imbalance between the two, may contribute to the pathogenesis of the disease. Studies have shown that activating specialized receptors SPMs displayed multiple biological effects towards periodontitis, including resolution of inflammation, alveolar bone protection, periodontal tissue regeneration, and pathogen resistance. Thus, the relationship between SPM and periodontitis and the potentials and challenges in SPM application were reviewed.

Prominent Indomethacin-Induced Enteropathy in Fcgriib Defi-cient lupus Mice: An Impact of Macrophage Responses and Immune Deposition in Gut

A high dose of NSAIDs, a common analgesic, might induce lupus activity through several NSAIDs adverse effects including gastrointestinal permeability defect (gut leakage) and endotoxemia. Indomethacin (25 mg/day) was orally administered for 7 days in 24-wk-old Fc gamma receptor IIb deficient (FcgRIIb-/-) mice, an asymptomatic lupus model (increased anti-dsDNA without lupus nephritis), and age-matched wild-type (WT) mice. Severity of indomethacin-induced enteropathy in FcgRIIb-/- mice was higher than WT mice as demonstrated by survival analysis, intestinal injury (histology, immune-deposition, and intestinal cytokines), gut leakage (FITC-dextran assay and endotoxemia), serum cytokines, and lupus characteristics (anti-dsDNA, renal injury, and proteinuria). Prominent responses of FcgRIIb-/- macrophages toward lipopolysaccharide (LPS) compared to WT cells due to the expression of only activating-FcgRs without inhibitory-FcgRIIb were demonstrated. Extracellular flux analysis indicated the greater mitochondria activity (increased respiratory capacity and respiratory reserve) in FcgRIIb-/- macrophages with a concordant decrease in glycolysis activity when compared to WT cells. In conclusion, gut leakage-induced endotoxemia is more severe in indomethacin-administered FcgRIIb-/- mice than WT, possibly due to the enhanced indomethacin toxicity from lupus-induced intestinal immune-deposition. Due to a lack of inhibitory-FcgRIIb expression, mitochondrial function, and cytokine production of FcgRIIb-/- macrophages were more prominent than WT cells. Hence, lupus disease-activation from NSAIDs-enteropathy-induced gut leakage is possible.

Lipidomic Signatures Align with Inflammatory Patterns and Outcomes in Critical Illness

Alterations in lipid metabolism have the potential to be markers as well as drivers of the pathobiology of acute critical illness. Here, we took advantage of the temporal precision offered by trauma as a common cause of critical illness to identify the dynamic patterns in the circulating lipidome in critically ill humans. The major findings include an early loss of all classes of circulating lipids followed by a delayed and selective lipogenesis in patients destined to remain critically ill. Early in the clinical course, Fresh Frozen Plasma administration led to improved survival in association with preserved lipid levels that related to favorable changes in coagulation and inflammation biomarkers. Late over-representation of phosphatidylethanolamines with critical illness led to the validation of a Lipid Reprogramming Score that was prognostic not only in trauma but also severe COVID-19 patients. Our lipidomic findings provide a new paradigm for the lipid response underlying critical illness.

The effects of anti-inflammatory agents as host-directed adjunct treatment of tuberculosis in humans: a systematic review and meta-analysis

BACKGROUND

The potential role of adjunctive anti-inflammatory therapy to enhance tuberculosis (TB) treatment has recently received increasing interest. There is, therefore, a need to broadly examine current host-directed therapies (HDTs) that could accelerate treatment response and improve TB outcomes.

METHODS

This systematic review and meta-analysis included randomised controlled trials of vitamin D and other HDT agents in patients receiving antibiotic treatment for pulmonary TB. Sputum smear conversion rate at 4-8 weeks was the primary outcome. Secondary outcomes included blood indices associated with infectivity and inflammation, chest radiology and incidence of adverse events.

RESULTS

Fifty-five studies were screened for eligibility after the initial search, which yielded more than 1000 records. Of the 2540 participants in the 15 trials included in the meta-analysis, 1898 (74.7%) were male, and the age at entry ranged from 18 to 70 years. There was a 38% significantly (RR 1.38, 95% CI = 1.03-1.84) increased sputum smear negativity in patients administered with vitamin D in addition to standard TB treatment than those receiving only the TB treatment. Patients treated with other HDT anti-inflammatory agents in addition to TB treatment also had a 29% significantly increased sputum smear conversion rate (RR 1.29, 95% CI = 1.09-1.563). Lymphocyte to monocyte ratio was significantly higher in the vitamin D treatment groups compared to the controls (3.52 vs 2.70, 95% CI for difference 0.16-1.11, p = 0.009) and (adjusted mean difference 0.4, 95% CI 0.2 -- 0.6; p = 0.001); whilst tumour necrosis factor-alpha (TNF-α) showed a trend towards a reduction in prednisolone (p < 0.001) and pentoxifylline (p = 0.27) treatment groups. Vitamin D and N-acetylcysteine also accelerated radiographic resolution in treatment compared to placebo at 8 weeks. No differences were observed in the occurrence of adverse events among all HDT treatments.

CONCLUSIONS

Vitamin D and other anti-inflammatory HDT medications used as adjunct TB treatment may be well tolerated and effective. They significantly improved sputum smear conversion rate and chest radiological appearance, and also exhibited an inflammation resolution effect.

Lipidomic profiling of virus infection identifies mediators that resolve herpes simplex virus-induced corneal inflammatory lesions

Lipid mediators (LMs) play a pivotal role in the induction and resolution of inflammation. To identify and elucidate their involvement during virus infection, multiple reaction monitoring (MRM) based liquid chromatography-tandem mass spectrometry lipidomic profiling of 62 lipid species was performed in this study. Results show that RAW264.7 macrophages differentially produce specific LMs signals depending on difference in virus pathogenicity. Integration of large-scale lipidomics with targeted gene expression data revealed mediators, such as RVD3, 18-HEPE, 11(12)-EET etc. correlated with the pathogenic phase of the infection. The herpes simplex virus (HSV)-induced keratitis model demonstrates that 11(12)-EET treatment represents a novel alternative for treating viral infection.

Sphingolipids in neuroinflammation: a potential target for diagnosis and therapy

Sphingolipids are ubiquitous building blocks of eukaryotic cell membranes that function as signaling molecules for regulating a diverse range of cellular processes, including cell proliferation, growth, survival, immune-cell trafficking, vascular and epithelial integrity, and inflammation. Recently, several studies have highlighted the pivotal role of sphingolipids in neuroinflammatory regulation. Sphingolipids have multiple functions, including induction of the expression of various inflammatory mediators and regulation of neuroinflammation by directly effecting the cells of the central nervous system. Accumulating evidence points to sphingolipid engagement in neuroinflammatory disorders, including Alzheimer’s and Parkinson’s diseases. Abnormal sphingolipid alterations, which involves an increase in ceramide and a decrease in sphingosine kinase, are observed during neuroinflammatory disease. These trends are observed early during disease development, and thus highlight the potential of sphingolipids as a new therapeutic and diagnostic target for neuroinflammatory diseases.

Novel mediators and mechanisms in the resolution of infectious inflammation: evidence for vagus regulation

Excessive chronic inflammation is linked to many diseases and considered a stress factor in humans (Robbins Pathologic Basis of Disease. Philadelphia: W.B. Saunders Co., 1999, Proc Natl Acad Sci USA, 2008, 105: 17949, Immunity, 44, 2016, 44: 463, N Engl J Med, 2011, 364: 656). Today, the resolution of inflammation is widely recognized as a cellular biochemically active process involving biosynthesis of a novel superfamily of endogenous chemical signals coined specialized pro-resolving mediators (SPMs; Nature, 2014, 510:92). Herein, we review recent evidence, indicating a role for the vagus nerve and vagotomy in the regulation of lipid mediators. Vagotomy reduces pro-resolving mediators, including the lipoxins, resolvins, protectins and maresins, delaying resolution in mouse peritonitis. Vagotomy also delays resolution of Escherichia coli infection in mice. Specifically, right vagus regulates peritoneal Group 3 innate lymphoid cell (ILC-3) number and peritoneal macrophage responses with lipid mediator profile signatures with elevated pro-inflammatory eicosanoids and reduced resolvins, including the novel protective immunoresolvent agonist protectin conjugate in tissue regeneration1 (PCTR1). Acetylcholine upregulates PCTR biosynthesis, and administration of PCTR1 to vagotomized mice restores tissue resolution and host responses to E. coli infections. Results obtained with human vagus ex vivo indicate that vagus can produce both pro-inflammatory eicosanoids, such as prostaglandins and leukotrienes, as well as the SPM. Electrical stimulation of human vagus in vitro reduces both prostaglandins and leukotrienes and enhances resolvins and the other SPM. These results elucidate a host protective mechanism mediated by vagus stimulation of SPM that includes resolvins and PCTR1 to regulate myeloid antimicrobial functions and resolution of infection. Moreover, they define a new pro-resolution of inflammation reflex operative in mice and human tissue that involves a vagus SPM circuit.

Effects of a metabolic optimized fast track concept (MOFA) on bowel function and recovery after surgery in patients undergoing elective colon or liver resection: a randomized controlled trial

Background

Enhanced recovery after surgery programs (ERAS) using thoracic epidural anesthesia and perioperative patient conditioning with omega-3 fatty acids (n3FA), glucose control (GC) and on-demand fluid therapy, respectively, showed beneficial effects. In the MOFA- study these components were used together in patients undergoing colon or liver surgery. We hypothesized that the use of a perioperative MOFA program improves intestine function represented as time to the first postoperative bowel movement in adult patients compared to standard ERAS.

Methods

After BfArM and IRB approval 100 patients were enrolled in this prospective randomized controlled trial. All patients received ERAS therapy (control). In addition, the MOFA group received 0.2 g/kg fish oil (Omegaven®), preoperatively, followed by a 48 h continuous infusion of 0.2 g/kg/d n3FA; and GC was kept below < 8 mmol/L. Pre- and postoperatively energy drinks were administered.

Results

As compared to control group the MOFA concept resulted in an earlier onset of flatulence by 14 h (46.6 ± 25.7, 32.0 ± 17.9, p = 0.030, hours, control vs. MOFA, respectively). Effects on onset of bowel movement were not observed (74.5 ± 30.4, 66.4 ± 29.2, p = 0.163, hours, control vs. MOFA, respectively). The disease severity (SAPS II score; p = 0.720) as well as deployment of resources (TISS 28 score, p = 0.709) did not differ between groups. No statistic significant difference between MOFA and control group regarding inflammation, impairment of coagulation, length of hospital stay or incidence of postoperative surgical complications were observed.

Conclusions

The MOFA concept did not result in an improvement of intestine function or faster recovery after elective colon or liver surgery compared to standard ERAS therapy. Omega-3 fatty acids showed no impairment of coagulation or improved resolution of inflammation. Further trials in a larger patient collective are needed to investigate potential beneficial effects of omega-3 fatty acids in abdominal surgery.

Trial registration

This trial was prospectively registered at the European Union Clinical Trials Register (EuDraCT 2005–004814-33, date: 10-05-2005, https://www.clinicaltrialsregister.eu/ctr-search/search?query=2005-004814-33+).

Electronic supplementary material

The online version of this article (10.1186/s12871-019-0823-6) contains supplementary material, which is available to authorized users.

Characterization of supported liquid extraction as a sample pretreatment method for eicosanoids and related metabolites in biological fluids

Sample pretreatment is an important process in liquid chromatography-mass spectrometry-based quantitative lipidomics. Reversed-phase solid phase extraction (RP-SPE) has been widely used for analyzing various types of samples, including aqueous samples such as cell culture media, plasma, serum, urine, and other biological fluids. Because lipid mediators are often protein-bound, prior deproteinization is necessary for their effective recovery. Deproteinization is typically performed by the addition of organic solvents, which requires time-consuming evaporation-reconstitution, or dilution with aqueous solvents before RP-SPE; however, both of these approaches compromise the analytical performance. As a potential alternative, we attempted to utilize supported liquid extraction (SLE), an automation-compatible variant of liquid-liquid extraction, for the determination of eicosanoids and related metabolites in aqueous samples. We screened 81 different sample diluent-eluent conditions and found that the use of 0.1% formic acid-water as the diluent and 0.1% formic acid-methyl acetate as the eluent enabled the optimum recovery of a variety of eicosanoids, except for peptide leukotrienes. The optimized SLE method efficiently removed protein from human plasma, while phospholipids and neutral lipids were modestly recovered. Moreover, the proposed method exhibited a quantitative performance comparable to that of typical ordinary RP-SPE method in the analysis of human platelets stimulated with thrombin receptor-activating peptide 6. Thus, we propose SLE as an attractive option for rapid lipid mediator extraction from aqueous samples.

Genomic and epigenomic predictors of response to guadecitabine in relapsed/refractory acute myelogenous leukemia

Background

Guadecitabine is a novel DNA methyltransferase (DNMT) inhibitor with improved pharmacokinetics and clinical activity in a subset of patients with relapsed/refractory acute myeloid leukemia (r/r AML), but identification of this subset remains difficult.

Methods

To search for biomarkers of response, we measured genome-wide DNA methylation, mutations of 54 genes, and expression of a panel of 7 genes in pre-treatment samples from 128 patients treated at therapeutic doses in a phase I/II study.

Results

Response rate to guadecitabine was 17% (2 complete remission (CR), 3 CR with incomplete blood count recovery (CRi), or CR with incomplete platelets recovery (CRp)) in the phase I component and 23% (14 CR, 9 CRi/CRp) in phase II. There were no strong mutation or methylation predictors of response. Gene expression clustering defined a subset of patients (~ 20%) that had (i) high DNMT3B and low CDKN2B, CTCF, and CDA expression; (ii) enrichment for KRAS/NRAS mutations; (iii) frequent CpG island hypermethylation; (iv) low long interspersed nuclear element 1 (LINE-1) hypomethylation after treatment; and (v) resistance to guadecitabine in both phase I (response rate 0% vs. 33%, p = 0.07) and phase II components of the study (response rate 5% vs. 30%, p = 0.02). Multivariate analysis identified peripheral blood (PB) blasts and hemoglobin as predictors of response and cytogenetics, gene expression, RAS mutations, and hemoglobin as predictors of survival.

Conclusions

A subset of patients (~ 20%) with r/r AML is unlikely to benefit from guadecitabine as a single agent. In the remaining 80%, guadecitabine is a viable option with a median survival of 8 months and a 2-year survival rate of 21%.

Trial registration

NCT01261312.

Electronic supplementary material

The online version of this article (10.1186/s13148-019-0704-3) contains supplementary material, which is available to authorized users.

Pathological mechanisms and therapeutic outlooks for arthrofibrosis

Arthrofibrosis is a fibrotic joint disorder that begins with an inflammatory reaction to insults such as injury, surgery and infection. Excessive extracellular matrix and adhesions contract pouches, bursae and tendons, cause pain and prevent a normal range of joint motion, with devastating consequences for patient quality of life. Arthrofibrosis affects people of all ages, with published rates varying. The risk factors and best management strategies are largely unknown due to a poor understanding of the pathology and lack of diagnostic biomarkers. However, current research into the pathogenesis of fibrosis in organs now informs the understanding of arthrofibrosis. The process begins when stress signals stimulate immune cells. The resulting cascade of cytokines and mediators drives fibroblasts to differentiate into myofibroblasts, which secrete fibrillar collagens and transforming growth factor-β (TGF-β). Positive feedback networks then dysregulate processes that normally terminate healing processes. We propose two subtypes of arthrofibrosis occur: active arthrofibrosis and residual arthrofibrosis. In the latter the fibrogenic processes have resolved but the joint remains stiff. The best therapeutic approach for each subtype may differ significantly. Treatment typically involves surgery, however, a pharmacological approach to correct dysregulated cell signalling could be more effective. Recent research shows that myofibroblasts are capable of reversing differentiation, and understanding the mechanisms of pathogenesis and resolution will be essential for the development of cell-based treatments. Therapies with significant promise are currently available, with more in development, including those that inhibit TGF-β signalling and epigenetic modifications. This review focuses on pathogenesis of sterile arthrofibrosis and therapeutic treatments.

Chronic Critical Illness and Persistent Inflammation: What can we Learn from the Elderly, Injured, Septic, and Malnourished?

Patients in the intensive care unit (ICU) who develop chronic critical illness significantly stress the clinical capacity and financial resources of healthcare systems. Although vast improvements have been made in critical care management, outcomes for this ICU subset remain poor. A hallmark for patients who progress to chronic critical illness is the development of persistent inflammation and immunosuppression. The risk factors associated with the development of chronic critical illness include increased age, medical comorbidities, severe injury, septic shock, and malnutrition. Interestingly, each of these clinical states bears strikingly similar immune defects, often resulting in the activation of a persistent inflammatory state. Strategies aimed at the prevention or early recognition of this state of immune compromise may help improve outcomes for these individuals and minimize the number who progress to chronic critical illness. This review explores the current knowledge regarding the immune defects associated with the development of persistent inflammation, the ways in which it can manifest clinically, attempted therapeutic interventions to date, and future insights into improving outcomes for this patient population.

Burn-Related Dysregulation of Inflammation and Immunity in Experimental and Clinical Studies

The purpose of this study was to evaluate burn-related variations of inflammation and immunity. Fifty-five mice were divided randomly into sham burn and burn groups. Eighty-seven hospitalized burn patients were also reviewed. In mice, neutrophils and monocytes were elevated significantly on post burn day (PBD 1). Lymphocytes were reduced on PBDs 1 and 3. Levels of serum tumor necrosis factor-α and interleukin-6 were highest on PBD 1. Interleukin-1β levels were the highest on PBD 3. On PBD 3, CD4CD25T regulatory cells/CD4 cells in spleen were higher. On PBDs 1, 3, 7, and 14, percentage of splenic dendritic cells were significantly lower than the sham burn group. In patients, neutrophils and monocytes were significantly elevated on PBD 1. Levels declined but remained elevated at most days to PBD 7. Lymphocytes in burn groups 1 and 2 were reduced on PBDs 1 and 3, respectively. Our results exhibited that severe burn injury initiated a hyperinflammatory response and immunosuppression. PBDs 1 to 3 were important for changes in inflammation and immunosuppression.

Endogenous PGI2 signaling through IP inhibits neutrophilic lung inflammation in LPS-induced acute lung injury mice model

Endogenous prostaglandin I₂ (PGI₂) has inhibitory effects on immune responses against pathogens or allergens; however, the immunomodulatory activity of endogenous PGI₂ signaling in endotoxin-induced inflammation is unknown. To test the hypothesis that endogenous PGI₂ down-regulates endotoxin-induced lung inflammation, C57BL/6 wild type (WT) and PGI₂ receptor (IP) KO mice were challenged intranasally with LPS. Urine 6-keto-PGF_1α, a stable metabolite of PGI_2, was significantly increased following the LPS-challenge, suggesting that endogenous PGI₂ signaling modulates the host response to LPS-challenge. IPKO mice had a significant increase in neutrophils in the BAL fluid as well as increased proteins of KC, LIX, and TNF-α in lung homogenates compared with WT mice. In contrast, IL-10 was decreased in LPS-challenged IPKO mice compared with WT mice. The PGI₂ analog cicaprost significantly decreased LPS-induced KC, and TNF-α, but increased IL-10 and AREG in bone marrow-derived dendritic cells (BMDCs) and bone marrow-derived macrophages (BMMs) compared with vehicle-treatment. These results indicated that endogenous PGI₂ signaling attenuated neutrophilic lung inflammation through the reduced inflammatory cytokine and chemokine and enhanced IL-10.

Burns: Pathophysiology of Systemic Complications and Current Management

As a result of many years of research, the intricate cellular mechanisms of burn injury are slowly becoming clear. Yet, knowledge of these cellular mechanisms and a multitude of resulting studies have often failed to translate into improved clinical treatment for burn injuries. Perhaps the most valuable information to date is the years of clinical experience and observations in the management and treatment of patients, which has contributed to a gradual improvement in reported outcomes of mortality. This review provides a discussion of the cellular mechanisms and pathways involved in burn injury, resultant systemic effects on organ systems, current management and treatment, and potential therapies that we may see implemented in the future.

The Emerging Role of Vitamin B6 in Inflammation and Carcinogenesis

Vitamin B6 serves as a coenzyme catalyzing more than 150 enzymes regulating metabolism and synthesis of proteins, carbohydrates, lipids, heme, and important bioactive metabolites. For several years vitamin B6 and its vitamers (B6) were recognized as antioxidant and antiinflammatory and in modulating immunity and gene expression. During the last 10 years, there were growing reports implicating B6 in inflammation and inflammation-related chronic illnesses including cancer. It is unclear if the deficiency of B6 or additional intake of B6, above the current requirement, should be the focus. Whether the current recommended daily intake for B6 is adequate should be revisited, since B6 is important to human health beyond its role as a coenzyme and its status is affected by many factors including but not limited to age, obesity, and inflammation associated with chronic illnesses. A link between inflammation B6 status and carcinogenesis is not yet completely understood. B6-mediated synthesis of H₂S, a gasotransmitter, and taurine in health and disease, especially in maintaining mitochondrial integrity and biogenesis and inflammation, remains an important area to be explored. Recent developments in the molecular role of B6 and its direct interaction with inflammasomes, and nuclear receptor corepressor and coactivator, receptor-interacting protein 140, provide a strong impetus to further explore the multifaceted role of B6 in carcinogenesis and human health.

Different Lipid Regulation in Ovarian Cancer: Inhibition of the Immune System

Lipid metabolism is altered in several cancer settings leading to different ratios of intermediates. Ovarian cancer is the most lethal gynecological malignancy. Cancer cells disperse in the abdominal space and ascites occurs. T cells obtained from ascites are unable to proliferate after an antigenic stimulus. The proliferation of ascites-derived T cells can be restored after culturing the cells for ten days in normal culture medium. No pathway aberrancies were detected. The acellular fraction of ascites can inhibit the proliferation of autologous as well as allogeneic peripheral blood lymphocytes, indicating the presence of soluble factors that interfere with T cell functionality. Therefore, we analyzed 109 lipid mediators and found differentially regulated lipids in suppressive ascitic fluid compared to normal abdominal fluid. Our study indicates the presence of lipid intermediates in ascites of ovarian cancer patients, which coincidences with T cell dysfunctionality. Since the immune system in the abdominal cavity is compromised, this may explain the high seeding efficiency of disseminated tumor cells. Further research is needed to fully understand the correlation between the various lipids and T cell proliferation, which could lead to new treatment options.

Excessive Activation of TLR4/NF-κB Interactively Suppresses the Canonical Wnt/β-catenin Pathway and Induces SANFH in SD Rats

Nuclear factor-kappa B (NF-κB) interactively affects the Wnt/β-catenin pathway and is closely related to different diseases. However, such crosstalk effect in steroid-associated necrosis of femoral head (SANFH) has not been fully explored and evaluated. In this study, early-stage SANFH was induced by two doses of lipopolysaccharide (LPS, 2 mg/kg/day) and three doses of methylprednisolone (MPS, 40 mg/kg/day). LPS and pyrrolidine dithiocarbamate (PDTC) were administered to activate the TLR4/NF-κB pathway and selectively block the activation of NF-κB, respectively. Results showed that PDTC treatment significantly reduced NF-κB expression, diminished inflammation, and effectively decreased bone resorption processes (osteoclastogenesis, adipogenesis, and apoptosis), which were evidently reinforced after osteonecrosis induction. Moreover, PDTC remarkably increased the interfered Wnt/β-catenin pathway and elevated bone formation processes (osteogenesis and angiogenesis). Ultimately, PDTC treatment effectively reduced the incidence of SANFH. Therefore, the excessive activation of TLR4/NF-κB may interactively suppress the Wnt/β-catenin pathway and induce SANFH. Hence, we propose NF-κB-targeted treatment as a novel therapeutic strategy for SANFH.

Surgical and immune reconstitution murine models in bone marrow research: Potential for exploring mechanisms in sepsis, trauma and allergy

Bone marrow, the vital organ which maintains lifelong hemopoiesis, currently receives considerable attention, as a source of multiple cell types which may play important roles in repair at distant sites. This emerging function, distinct from, but closely related to, bone marrow roles in innate immunity and inflammation, has been characterized through a number of strategies. However, the use of surgical models in this endeavour has hitherto been limited. Surgical strategies allow the experimenter to predetermine the site, timing, severity and invasiveness of injury; to add or remove aggravating factors (such as infection and defects in immunity) in controlled ways; and to manipulate the context of repair, including reconstitution with selected immune cell subpopulations. This endows surgical models overall with great potential for exploring bone marrow responses to injury, inflammation and infection, and its roles in repair and regeneration. We review three different murine surgical models, which variously combine trauma with infection, antigenic stimulation, or immune reconstitution, thereby illuminating different aspects of the bone marrow response to systemic injury in sepsis, trauma and allergy. They are: (1) cecal ligation and puncture, a versatile model of polymicrobial sepsis; (2) egg white implant, an intriguing model of eosinophilia induced by a combination of trauma and sensitization to insoluble allergen; and (3) ectopic lung tissue transplantation, which allows us to dissect afferent and efferent mechanisms leading to accumulation of hemopoietic cells in the lungs. These models highlight the gain in analytical power provided by the association of surgical and immunological strategies.

Omega-3 Polyunsaturated Fatty Acids in Critical Illness: Anti-Inflammatory, Proresolving, or Both?

Prognosis and outcomes of critically ill patients are strictly related with inflammatory status. Inflammation involves a multitude of interactions between different cell types and chemical mediators. Omega-3 polyunsaturated fatty acids (PUFAs), mainly represented by eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are able to inhibit different pathways including leukocyte chemotaxis, adhesion molecule expression and interactions, and production of inflammatory cytokines, through the action of specialized proresolving mediators (SPMs). SPMs from omega-6 fatty acids, such as lipoxins, and from omega-3 fatty acids such as resolvins, protectins, and maresins, act in reducing/resolving the inflammatory process in critical diseases, stimulating the phases of resolution of inflammation. In this light, the resolution of inflammation is nowadays considered as an active process, instead of a passive process. In critical illness, SPMs regulate the excessive posttrauma inflammatory response, protecting organs from damage. This review focuses on the role of omega-3 PUFAs as pharma nutrition agents in acute inflammatory conditions, highlighting their effects as anti-inflammatory or proresolving agents.

Glutamine with probiotics attenuates intestinal inflammation and oxidative stress in a rat burn injury model through altered iNOS gene aberrant methylation

Severe burns may lead to intestinal inflammation and oxidative stress resulting in intestinal barrier damage and gut dysfunction. In the management of severe burns, therapies are needed to attenuate whole-body inflammatory responses and control the burden of oxidative stress. In this study, we evaluated the effects of oral glutamine (Gln) with probiotics on burn-induced intestinal inflammation and oxidative stress using a Wistar rat burn injury model. We then explored potential molecular mechanisms for the effects of glutamine and probiotics on intestinal tissue inflammation and oxidative stress. We found that glutamine and probiotics together significantly inhibited nitric oxide (NO) content; reduced levels of the inflammatory factors TNF-α, IL-6, and IL-8; and altered expression of oxidative stress factors including reactive oxygen species and superoxide dismutase. We found that the apoptotic proportion of intestinal epithelial cells in severely burned subjects was notably decreased following treatment with glutamine plus probiotics. We also found that glutamine and probiotics given together markedly reduced NO content by down-regulating the expression of iNOS in blood and intestinal tissue. These findings indicate that regulation of the iNOS gene plays a pivotal role in inflammation and oxidative stress in the response to severe burns in the Wistar rat. We then further investigated the mechanism by which combined therapy with glutamine and probiotics might reduce expression of iNOS and found that this treatment resulted in increased methylation of the iNOS gene. The methylation level of the iNOS gene was found to be regulated via differential expression of DNMT1 and Tet1. Collectively, our results suggest that combined therapy with glutamine and probiotics can markedly reduce the synthesis of NO, suppressing intestinal inflammation and oxidative stress in the Wistar rat burn injury model.

Ultra-weak photon emission as a dynamic tool for monitoring oxidative stress metabolism

In recent years, excessive oxidative metabolism has been reported as a critical determinant of pathogenicity in many diseases. The advent of a simple tool that can provide a physiological readout of oxidative stress would be a major step towards monitoring this dynamic process in biological systems, while also improving our understanding of this process. Ultra-weak photon emission (UPE) has been proposed as a potential tool for measuring oxidative processes due to the association between UPE and reactive oxygen species. Here, we used HL-60 cells as an in vitro model to test the potential of using UPE as readout for dynamically monitoring oxidative stress after inducing respiratory burst. In addition, to probe for possible changes in oxidative metabolism, we performed targeted metabolomics on cell extracts and culture medium. Lastly, we tested the effects of treating cells with the NADPH oxidase inhibitor diphenyleneiodonium chloride (DPI). Our results show that UPE can be used as readout for measuring oxidative stress metabolism and related processes.

Vagal Regulation of Group 3 Innate Lymphoid Cells and the Immunoresolvent PCTR1 Controls Infection Resolution

Uncovering mechanisms that control immune responses in the resolution of bacterial infections is critical for the development of new therapeutic strategies that resolve infectious inflammation without unwanted side effects. We found that disruption of the vagal system in mice delayed resolution of Escherichia coli infection. Dissection of the right vagus decreased peritoneal group 3 innate lymphoid cell (ILC3) numbers and altered peritoneal macrophage responses. Vagotomy resulted in an inflammatory peritoneal lipid mediator profile characterized by reduced concentrations of pro-resolving mediators, including the protective immunoresolvent PCTR1, along with elevated inflammation-initiating eicosanoids. We found that acetylcholine upregulated the PCTR biosynthetic pathway in ILC3s. Administration of PCTR1 or ILC3s to vagotomized mice restored tissue resolution tone and host responses to E. coli infections. Together these findings elucidate a host protective mechanism mediated by ILC3-derived pro-resolving circuit, including PCTR1, that is controlled by local neuronal output to regulate tissue resolution tone and myeloid cell responses.

Burn injury influences the T cell homeostasis in a butyrate-acid sphingomyelinase dependent manner

Following burn injury, a key factor for patients susceptible to opportunistic infections is immune suppression. Butyrate levels are important in maintaining a functional immune system and these levels can be altered after injury. The acid sphingomyelinase (Asm) lipid signaling system has been implicated in a T cell actions with some evidence of being influenced by butyrate. Here, we hypothesized that burn-injury changes in butyrate levels would mediate Asm activity and, consequently, T cell homeostasis. We demonstrate that burn injury temporally decreases butyrate levels. We further determined that T cell Asm activity is increased by butyrate and decreased after burn injury. We additionally observed decreased T cell numbers in Asm-deficient, burn-injured, and microbiota-depleted mice. Finally, we demonstrate that butyrate reduced T cell death in an Asm-dependent manner. These data suggest that restoration of butyrate after burn injury may ameliorate the T cell lost observed in burn-injured patients by Asm regulation.

Multifaceted effects of Francisella tularensis on human neutrophil function and lifespan

Francisella tularensis in an intracellular bacterial pathogen that causes a potentially lethal disease called tularemia. Studies performed nearly 100 years ago revealed that neutrophil accumulation in infected tissues correlates directly with the extent of necrotic damage during F. tularensis infection. However, the dynamics and details of bacteria-neutrophil interactions have only recently been studied in detail. Herein, we review current understanding regarding the mechanisms that recruit neutrophils to F. tularensis-infected lungs, opsonization and phagocytosis, evasion and inhibition of neutrophil defense mechanisms, as well as the ability of F. tularensis to prolong neutrophil lifespan. In addition, we discuss distinctive features of the bacterium, including its ability to act at a distance to alter overall neutrophil responsiveness to exogenous stimuli, and the evidence which suggests that macrophages and neutrophils play distinct roles in tularemia pathogenesis, such that macrophages are major vehicles for intracellular growth and dissemination, whereas neutrophils drive tissue destruction by dysregulation of the inflammatory response.

Unidirectional and sustained delivery of the proresolving lipid mediator resolvin D1 from a biodegradable thin film device

Resolvin D1 (RvD1) belongs to a family of endogenously derived proresolving lipid mediators that have been shown to attenuate inflammation, activate proresolution signaling, and promote homeostasis and recovery from tissue injury. In this study we present a poly(lactic-co-glycolic acid) (PLGA) based thin-film device composed of layers of varying ratios of lactic and glycolic acid that elutes RvD1 unidirectionally to target tissues. The device demonstrated sustained release in vitro for 56 days with an initial burst of release over 14 days. The asymmetric design of the device released 98% of RvD1 through the layer with the lowest molar ratio of lactic acid to glycolic acid, and the remainder through the opposite side. We validated structural integrity of RvD1 released from the device by mass spectrometry and investigated its bioactivity on human vascular endothelial (EC) and smooth muscle cells (VSMC). RvD1 released from the device attenuated VSMC migration, proliferation, and TNF-α induced NF-κB activation, without evidence of cytotoxicity. Delivery of RvD1 to blood vessels was demonstrated ex vivo in a flow chamber system using perfused rabbit aortas and in vivo in a rat carotid artery model, with the devices applied as an adventitial wrap. Our results demonstrate a novel approach for sustained, local delivery of Resolvin D1 to vascular tissue at therapeutically relevant levels. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 31-41, 2017.

Resolving Lipid Mediators Maresin 1 and Resolvin D2 Prevent Atheroprogression in Mice

RATIONALE

Atheroprogression is a consequence of nonresolved inflammation, and currently a comprehensive overview of the mechanisms preventing resolution is missing. However, in acute inflammation, resolution is known to be orchestrated by a switch from inflammatory to resolving lipid mediators. Therefore, we hypothesized that lesional lipid mediator imbalance favors atheroprogression.

OBJECTIVE

To understand the lipid mediator balance during atheroprogression and to establish an interventional strategy based on the delivery of resolving lipid mediators.

METHODS AND RESULTS

Aortic lipid mediator profiling of aortas from Apoe^-/- mice fed a high-fat diet for 4 weeks, 8 weeks, or 4 months revealed an expansion of inflammatory lipid mediators, Leukotriene B4 and Prostaglandin E2, and a concomitant decrease of resolving lipid mediators, Resolvin D2 (RvD2) and Maresin 1 (MaR1), during advanced atherosclerosis. Functionally, aortic Leukotriene B4 and Prostaglandin E2 levels correlated with traits of plaque instability, whereas RvD2 and MaR1 levels correlated with the signs of plaque stability. In a therapeutic context, repetitive RvD2 and MaR1 delivery prevented atheroprogression as characterized by halted expansion of the necrotic core and accumulation of macrophages along with increased fibrous cap thickness and smooth muscle cell numbers. Mechanistically, RvD2 and MaR1 induced a shift in macrophage profile toward a reparative phenotype, which secondarily stimulated collagen synthesis in smooth muscle cells.

CONCLUSIONS

We present evidence for the imbalance between inflammatory and resolving lipid mediators during atheroprogression. Delivery of RvD2 and MaR1 successfully prevented atheroprogression, suggesting that resolving lipid mediators potentially represent an innovative strategy to resolve arterial inflammation.

Intravenous Endotoxin Challenge in Healthy Humans: An Experimental Platform to Investigate and Modulate Systemic Inflammation

Activation of inflammatory pathways represents a central mechanism in multiple disease states both acute and chronic. Triggered via either pathogen or tissue damage-associated molecular motifs, common biochemical pathways lead to conserved yet variable physiological and immunological alterations. Dissection and delineation of the determinants and mechanisms underlying phenotypic variance in response is expected to yield novel therapeutic advances.

Intravenous (IV) administration of endotoxin (gram-negative bacterial lipopolysaccharide), a specific Toll-like receptor 4 agonist, represents an in vivo model of systemic inflammation in man. National Institutes for Health Clinical Center Reference Endotoxin (CCRE, Escherichia coli O:113:H10:K negative) is employed to reliably and reproducibly generate vascular, hematological, endocrine, immunological and organ-specific functional effects that parallel, to varying degrees, those seen in the early stages of pathological states. Alteration of dose (0.06 - 4 ng/kg) and time-scale of exposure (bolus vs. infusion) allows replication of either acute or chronic inflammation and a range of severity to be elicited, with higher doses (2 - 4 ng/kg) frequently being used to create a 'sepsis-like' state. Established and novel medicinal compounds may additionally be administered prior to or post endotoxin exposure to appreciate their effect on the inflammatory cascade. Despite limitations in scope and generalizability, human IV endotoxin challenge offers a unique platform to gain mechanistic insights into inducible physiological responses and inflammatory pathways. Rationally employed it may aid translation of this knowledge into therapeutic innovations.

Human milk proresolving mediators stimulate resolution of acute inflammation

Human milk contains nutrients and bioactive products relevant to infant development and immunological protection. Here, we investigated the proresolving properties of milk using human milk lipid mediator isolates (HLMIs) and determined their impact on resolution programs in vivo and with human macrophages. HLMIs reduced the maximum neutrophil numbers (14.6±1.2 × 10(6)-11.0±1.0 × 10(6) cells per exudate) and shortened the resolution interval (Ri; 50% neutrophil reduction) by 54% compared with peritonitis. Using rigorous liquid-chromatography tandem-mass spectrometry (LC-MS-MS)-based lipid mediator (LM) metabololipidomics, we demonstrated that human milk possesses a proresolving LM-specialized proresolving mediator (LM-SPM) signature profile, containing SPMs (e.g. resolvins (Rv), protectins (PDs), maresins (MaRs), and lipoxins (LXs)) at bioactive levels (pico-nanomolar concentrations) that enhanced human macrophage efferocytosis and bacterial containment. SPMs identified in human milk included D-series Rvs (e.g., RvD1, RvD2, RvD3, AT-RvD3, and RvD4), PD1, MaR1, E-series Rvs (e.g. RvE1, RvE2, and RvE3), and LXs (LXA4 and LXB4). Of the SPMs identified in human milk, RvD2 and MaR1 (50 ng per mouse) individually shortened Ri by ∼75%. Milk from mastitis gave higher leukotriene B4 and prostanoids and lower SPM levels. Taken together, these findings provide evidence that human milk has proresolving actions via comprehensive LM-SPM profiling, describing a potentially novel mechanism in maternal-infant biochemical imprinting.

Simvastatin and a Plant Galactolipid Protect Animals from Septic Shock by Regulating Oxylipin Mediator Dynamics through the MAPK-cPLA2 Signaling Pathway

Sepsis remains a major medical issue despite decades of research. Identification of important inflammatory cascades and key molecular mediators are crucial for developing intervention and prevention strategies. In this study, we conducted a comparative oxylipin metabolomics study to gain a comprehensive picture of lipid mediator dynamics during the initial hyperinflammatory phase of sepsis, and demonstrated, in parallel, the efficacy of simvastatin and plant galactolipid, 1,2-di-O-α-linolenoyl-3-O-β-galactopyranosyl-sn-glycerol (dLGG) in the homeostatic regulation of the oxylipin metabolome using a lipopolysaccharide (LPS)-induced sepsis C57BL/6J mouse model. LPS increased the systemic and organ levels of proinflammatory metabolites of linoleic acid including leukotoxin diols (9-,10-DHOME, 12-,13-DHOME) and octadecadienoic acids (9-HODE and 13-HODE) and arachidonic acid-derived prostanoid, PGE2, and hydroxyeicosatetraenoic acids (8-, 12- and 15-HETE). Treatment with either compound decreased the levels of proinflammatory metabolites and elevated proresolution lipoxin A₄, 5(6)-EET, 11(12)-EET and 15-deoxy-PGJ₂. dLGG and simvastatin ameliorated the effects of LPS-induced mitogen-activated protein kinase (MAPK)-dependent activation of cPLA₂, cyclooxygenase-2, lipoxygenase, cytochrome P450 and/or epoxide hydrolase lowered systemic TNF-α and IL-6 levels and aminotransferase activities and decreased organ-specific infiltration of inflammatory leukocytes and macrophages, and septic shock-induced multiple organ damage. Furthermore, both dLGG and simvastatin increased the survival rates in the cecal ligation and puncture (CLP) sepsis model. This study provides new insights into the role of oxylipins in sepsis pathogenesis and highlights the potential of simvastatin and dLGG in sepsis therapy and prevention.

Perivascular delivery of resolvin D1 inhibits neointimal hyperplasia in a rat model of arterial injury

OBJECTIVE

Lipid mediators derived from omega-3 polyunsaturated fatty acids such as resolvin D1 (RvD1) accelerate the resolution of inflammation and have potential as vascular therapeutics. The objective of this study was to evaluate local perivascular delivery of RvD1 as a means to attenuate neointimal hyperplasia in a rat model of arterial injury.

METHODS

Smooth muscle cells were harvested from rat aortas to study the effects of RvD1 on rat arterial vascular smooth muscle cell responses in vitro, with focus on inflammation, proliferation, migration, cytoskeletal changes, and cytotoxicity. The safety and efficacy of perivascular delivery of RvD1 through thin biodegradable three-layered poly(lactic-co-glycolic acid) wraps or 25% Pluronic F127 gels were studied in a rat model of carotid angioplasty. A total of 200 ng of RvD1 was loaded into each construct for perivascular delivery after injury. Morphometric and histologic analyses were performed 3 and 14 days after injury.

RESULTS

RvD1 attenuated rat arterial vascular smooth muscle cell inflammatory pathways, proliferation, migration, and mitogen-induced cytoskeletal changes in vitro, without evidence of cytotoxicity. RvD1-loaded wraps reduced neointimal formation after carotid angioplasty by 59% vs no-wrap controls (P = .001) and by 45% vs vehicle-wrap controls (P = .002). RvD1-loaded Pluronic gels similarly reduced neointimal formation by 49% vs no-gel controls (P = .02) and by 52% vs vehicle-gel controls (P = .02). No group was associated with infection, thrombosis, or negative vessel remodeling. Wraps were found to be easier to apply than gel constructs. Ki67 proliferation index was significantly lower in RvD1-loaded wrap-treated arteries compared with both no-wrap and vehicle-wrap controls at both 3 and 14 days after injury (65% vs no-wrap group and 70% vs vehicle-wrap group at day 3, 49% vs both control groups at day 14; P < .05). Similarly, oxidative stress (30% and 29%; P < .05) and nuclear factor κB activation (42% and 45%; P < .05) were significantly lower in the RvD1-loaded wrap group compared with both no-wrap and vehicle-wrap controls at 3 days after injury.

CONCLUSIONS

Local perivascular delivery of RvD1 attenuates formation of neointimal hyperplasia without associated toxicity in a rat model of carotid angioplasty. This effect is likely due to attenuation of inflammatory pathways as well as decreased arterial smooth muscle cell proliferation and migration.