Resolvin D1, resolvin D2 and maresin 1 activate the GSK3β anti-inflammatory axis in TLR4-engaged human monocytes

Inverted U-Shaped Association of Plasma Resolvin D2 With Atherosclerotic Cardiovascular Disease and the Mediation Effects of Serum Cholesterol: A Chinese Community-Based Study

BACKGROUND

Resolvin D2 (RvD2) has been reported to protect against the development of atherosclerosis in animal models. The objective of this study was to examine the prospective association between plasma RvD2 and the risk of atherosclerotic cardiovascular disease (ASCVD) at the population level.

METHODS AND RESULTS

A cohort of 2633 community-dwelling individuals aged 35-60 years was followed for 8 years in this study. Adjusted hazard ratios and 95% CIs for ASCVD outcomes according to baseline RvD2 levels were calculated using Cox proportional hazards models. Mediation analysis was used to test the indirect effect of serum cholesterol indicators on the association between RvD2 and ASCVD probability. In total, 284 new cases of ASCVD were identified during follow-up. An inverted U-shaped association between natural log (ln)-transformed RvD2 and incident ASCVD was determined, and the threshold value for lnRvD2 was 3.87. Below the threshold, each unit increase in lnRvD2 was associated with a 2.05-fold increased risk of ASCVD (95% CI, 1.13-3.74; P=0.019). Above the threshold, each unit increase in lnRvD2 was associated with a 36% reduced risk of ASCVD (95% CI, 0.51-0.80; P<0.001). In addition, the association between RvD2 and ASCVD probability was partially mediated by high-density lipoprotein cholesterol (15.81%) when lnRvD2 <3.87, but by total cholesterol (30.23%) and low-density lipoprotein cholesterol (30.13%) when lnRvD2 ≥3.87.

CONCLUSIONS

Both lower and higher RvD2 levels are associated with a reduced risk of ASCVD, forming an inverted U-shaped relationship. Furthermore, this association is partially mediated by total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol.

Daqing formula ameliorated allergic asthma and airway dysbacteriosis in mice challenged with ovalbumin and ampicillin

ETHNOPHARMACOLOGICAL RELEVANCE

Asthma is a chronic airway inflammatory disease that can lead to several complications caused by bacterial infections. However, recurrent attacks of the disease require long-term use of antibiotics, resulting in lung dysbiosis and poor outcomes. Daqing Formula (DQF) is a well-known herbal medicine in Pharmacopoeia of China, which is widely used for various stimuli-induced lower respiratory diseases, including asthma, bronchitis, and pneumonia. Thus, it has been demonstrated to be a plant-derived broad-spectrum antibiotic for treating and preventing various acute and chronic respiratory diseases.

AIM OF THE STUDY

This study evaluated the efficacy and possible mechanism of DQF on allergic asthma and airway dysbiosis.

METHODS AND MATERIALS

The mice were co-challenged with ovalbumin and ampicillin to induce allergic asthma combined with airway dysbacteriosis. The populations of lung microbiota were detected by using 16s DNA sequencing. The levels of asthmatic markers in BALF were detected by ELISA. The levels of Th1/Th2 cytokines in splenic CD4+ cells of mice were analyzed by flow cytometry. The expressions of the GSK-3β signaling pathway in the lung tissues of asthmatic mice and eosinophils were detected by western blotting assay. The inhibition of DQF on the production of pro-inflammatory cytokines in eosinophils of asthmatic mice.

RESULTS

The results showed that treatment with DQF at 200-800 mg/kg doses significantly reduced the frequency of nasal rubbing and lung inflammation as well as the number of total cells, eosinophils, and macrophages in bronchoalveolar lavage fluid. It decreased the relative abundances of Streptococcus, Cuoriavidus, and Moraxella, increased Akkermansia and Prevotella_6 in lung tissues of asthmatic mice, and inhibited the growth of Staphylococcus aureus, Klebsiella pneumoniae, Streptococcus pneumoniae and their resistant strains in vitro. Furthermore, DQF reduced the levels of eotaxin, TSLP, IL-4, IL-5, IL-25, and IL-33, but enhanced IFN-γ and IL-12 in BALF. It elevated the population of Th1 cells, inhibited eosinophil activation, and downregulated the expressions of p-GSK-3β, p-p65, nuclear β-catenin, and p-STAT3 in the lung tissues of asthmatic mice.

CONCLUSIONS

The results revealed that DQF reduced airway inflammation, ameliorated lung dysbiosis, shifted the Th1/Th2 balance, and inhibited eosinophil activation in asthmatic mice, indicating its potential for severe asthma treatment.

The therapeutic potential of resolvins in pulmonary diseases

Uncontrolled inflammation leads to nonspecific destruction and remodeling of tissues and can contribute to many human pathologies, including pulmonary diseases. Stimulation of inflammatory resolution is considered an important process that protects against the progression of chronic inflammatory diseases. Resolvins generated from essential omega-3 polyunsaturated fatty acids have been demonstrated to be signaling molecules in inflammation with important pro-resolving and anti-inflammatory capabilities. By binding to specific receptors, resolvins can modulate inflammatory processes such as neutrophil migration, macrophage phagocytosis and the presence of pro-inflammatory mediators to reduce inflammatory pathologies. The discovery of these pro-resolving mediators has led to a shift in drug research from suppressing pro-inflammatory molecules to investigating compounds that promote resolution to treat inflammation. The exploration of inflammatory resolution also provided the opportunity to further understand the pathophysiology of pulmonary diseases. Alterations of resolution are now linked to both the development and exacerbation of diseases such as asthma, chronic obstructive pulmonary disease, cystic fibrosis, acute respiratory distress syndrome, cancer and COVID-19. These findings have resulted in the rise of novel design and testing of innovative resolution-based therapeutics to treat diseases. Hence, this paper reviews the generation and mechanistic actions of resolvins and investigates their role and therapeutic potential in several pulmonary diseases that may benefit from resolution-based pharmaceuticals.

Specialized pro-resolving mediators enhance the clearance of dead cells

The failure to resolve inflammation underpins to several prevalent diseases, like atherosclerosis, and so identifying ways to boost resolution is unmet clinical needs. The resolution of inflammation is governed by several factors such as specialized pro-resolving mediators (SPMs) that counter-regulate pro-inflammatory pathways and promote tissue repair without compromising host defense. A major function of nearly all SPMs is to enhance the clearance of dead cells or efferocytosis. As such, phagocytes, such as macrophages, are essential cellular players in the resolution of inflammation because of their ability to rapidly and efficiently clear dead cells. This review highlights the role of SPMs in the clearance of apoptotic and necroptotic cells and offers insights into how targeting efferocytosis may provide new treatments for non-resolving diseases, like atherosclerosis.

Maresin: Macrophage Mediator for Resolving Inflammation and Bridging Tissue Regeneration-A System-Based Preclinical Systematic Review

Maresins are lipid mediators derived from omega-3 fatty acids with anti-inflammatory and pro-resolving properties, capable of promoting tissue regeneration and potentially serving as a therapeutic agent for chronic inflammatory diseases. The aim of this review was to systematically investigate preclinical and clinical studies on maresin to inform translational research. Two independent reviewers performed comprehensive searches with the term "Maresin (NOT) Review" on PubMed. A total of 137 studies were included and categorized into 11 human organ systems. Data pertinent to clinical translation were specifically extracted, including delivery methods, optimal dose response, and specific functional efficacy. Maresins generally exhibit efficacy in treating inflammatory diseases, attenuating inflammation, protecting organs, and promoting tissue regeneration, mostly in rodent preclinical models. The nervous system has the highest number of original studies (n = 25), followed by the cardiovascular system, digestive system, and respiratory system, each having the second highest number of studies (n = 18) in the field. Most studies considered systemic delivery with an optimal dose response for mouse animal models ranging from 4 to 25 μg/kg or 2 to 200 ng via intraperitoneal or intravenous injection respectively, whereas human in vitro studies ranged between 1 and 10 nM. Although there has been no human interventional clinical trial yet, the levels of MaR1 in human tissue fluid can potentially serve as biomarkers, including salivary samples for predicting the occurrence of cardiovascular diseases and periodontal diseases; plasma and synovial fluid levels of MaR1 can be associated with treatment response and defining pathotypes of rheumatoid arthritis. Maresins exhibit great potency in resolving disease inflammation and bridging tissue regeneration in preclinical models, and future translational development is warranted.

Mesenchymal stromal cells and alpha-1 antitrypsin have a strong synergy in modulating inflammation and its resolution

Rationale: Trauma, surgery, and infection can cause severe inflammation. Both dysregulated inflammation intensity and duration can lead to significant tissue injuries, organ dysfunction, mortality, and morbidity. Anti-inflammatory drugs such as steroids and immunosuppressants can dampen inflammation intensity, but they derail inflammation resolution, compromise normal immunity, and have significant adverse effects. The natural inflammation regulator mesenchymal stromal cells (MSCs) have high therapeutic potential because of their unique capabilities to mitigate inflammation intensity, enhance normal immunity, and accelerate inflammation resolution and tissue healing. Furthermore, clinical studies have shown that MSCs are safe and effective. However, they are not potent enough, alone, to completely resolve severe inflammation and injuries. One approach to boost the potency of MSCs is to combine them with synergistic agents. We hypothesized that alpha-1 antitrypsin (A1AT), a plasma protein used clinically and has an excellent safety profile, was a promising candidate for synergism. Methods: This investigation examined the efficacy and synergy of MSCs and A1AT to mitigate inflammation and promote resolution, using in vitro inflammatory assay and in vivo mouse acute lung injury model. The in vitro assay measured cytokine releases, inflammatory pathways, reactive oxygen species (ROS), and neutrophil extracellular traps (NETs) production by neutrophils and phagocytosis in different immune cell lines. The in vivo model monitored inflammation resolution, tissue healing, and animal survival. Results: We found that the combination of MSCs and A1AT was much more effective than each component alone in i) modulating cytokine releases and inflammatory pathways, ii) inhibiting ROS and NETs production by neutrophils, iii) enhancing phagocytosis and, iv) promoting inflammation resolution, tissue healing, and animal survival. Conclusion: These results support the combined use of MSCs, and A1AT is a promising approach for managing severe, acute inflammation.

A multiscale hybrid model for exploring the effect of Resolvin D1 on macrophage polarization during acute inflammation

Dysregulated inflammation underlies various diseases. Specialized pro-resolving mediators (SPMs) like Resolvin D1 (RvD1) have been shown to resolve inflammation and halt disease progression. Macrophages, key immune cells that drive inflammation, respond to the presence of RvD1 by polarizing to an anti-inflammatory type (M₂). However, RvD1's mechanisms, roles, and utility are not fully understood. This paper introduces a gene-regulatory network (GRN) model that contains pathways for RvD1 and other SPMs and proinflammatory molecules like lipopolysaccharides. We couple this GRN model to a partial differential equation - agent-based hybrid model using a multiscale framework to simulate an acute inflammatory response with and without the presence of RvD1. We calibrate and validate the model using experimental data from two animal models. The model reproduces the dynamics of key immune components and the effects of RvD1 during acute inflammation. Our results suggest RvD1 can drive macrophage polarization through the G protein-coupled receptor 32 (GRP32) pathway. The presence of RvD1 leads to an earlier and increased M₂ polarization, reduced neutrophil recruitment, and faster apoptotic neutrophil clearance. These results support a body of literature that suggests that RvD1 is a promising candidate for promoting the resolution of acute inflammation. We conclude that once calibrated and validated on human data, the model can identify critical sources of uncertainty, which could be further elucidated in biological experiments and assessed for clinical use.

Resolvins Lipid Mediators: Potential Therapeutic Targets in Alzheimer and Parkinson Disease

Inflammation and resolution are highly programmed processes involving a plethora of immune cells. Lipid mediators synthesized from arachidonic acid metabolism play a pivotal role in orchestrating the signaling cascades in the game of inflammation. The majority of the studies carried out so far on inflammation were aimed at inhibiting the generation of inflammatory molecules, whereas recent research has shifted more towards understanding the resolution of inflammation. Owing to chronic inflammation as evident in neuropathophysiology, the resolution of inflammation together with the class of lipid mediators actively involved in its regulation has attracted the attention of the scientific community as therapeutic targets. Both omega-three polyunsaturated fatty acids, eicosapentaenoic acid and docosahexaenoic acid, orchestrate a vital regulatory role in inflammation development. Resolvins derived from these fatty acids comprise the D-and E-series resolvins. A growing body of evidence using in vitro and in vivo models has revealed the pro-resolving and anti-inflammatory potential of resolvins. This systematic review sheds light on the synthesis, specialized receptors, and resolution of inflammation mediated by resolvins in Alzheimer's and Parkinson's disease.

Resolvin D2 induces anti-microbial mechanisms in a model of infectious peritonitis and secondary lung infection

In severe bacterial infections, there is a pro-inflammatory response to promote bacterial clearance but this response can cause tissue injury. Later, the immune system becomes dysregulated and the host is unable to clear a secondary or a pre-existing infection. Specialized Pro-resolving Mediators (SPMs) such as resolvin D2 (RvD2) have been shown to be beneficial for inflammation/infection resolution in animal models of sepsis but in vivo mechanisms by which RvD2 may promote bacterial clearance and/or attenuate deleterious effects of a secondary infection have not been fully established. In this study, we used the 2-hit model of cecal ligation and puncture (CLP) induced infectious peritonitis and secondary lung infection with Pseudomonas aeruginosa to find possible antimicrobial and immunomodulatory mechanisms of RvD2. We show that RvD2 given as late as 48h after CLP surgery reduced blood bacterial load without altering plasma cytokines compared to mice given saline vehicle. RvD2 increased splenic neutrophil accumulation as well as average reactive oxygen species (ROS) production. There was also an increase in an immature leukocyte population the myeloid derived suppressor cells (MDSCs) in the spleen of RvD2 treated mice. RvD2 reduced lung lavage bacterial load 24h after P. aeruginosa administration and significantly decreased lung lavage levels of IL-23, a cytokine essential in the Th-17 inflammatory response. In addition, we show that RvD2 increased the number of non-inflammatory alveolar macrophages after P. aeruginosa administration compared to saline treated mice. The study uncovered an antimicrobial mechanism of RvD2 where RvD2 increases mature neutrophil and MDSC accumulation into the spleen to promote blood bacterial clearance. The study showed that in this 2-hit model, RvD2 promotes lung bacterial clearance, increased non-inflammatory alveolar macrophage number and inhibits an adaptive immune pathway providing evidence of its resolution mechanism in secondary pulmonary infection.

Enhanced silver nanoparticle-induced pulmonary inflammation in a metabolic syndrome mouse model and resolvin D1 treatment

BACKGROUND

Metabolic syndrome (MetS) exacerbates susceptibility to inhalation exposures such as particulate air pollution, however, the mechanisms responsible remain unelucidated. Previously, we determined a MetS mouse model exhibited exacerbated pulmonary inflammation 24 h following AgNP exposure compared to a healthy mouse model. This enhanced response corresponded with reduction of distinct resolution mediators. We hypothesized silver nanoparticle (AgNP) exposure in MetS results in sustained pulmonary inflammation. Further, we hypothesized treatment with resolvin D1 (RvD1) will reduce exacerbations in AgNP-induced inflammation due to MetS.

RESULTS

To evaluate these hypotheses, healthy and MetS mouse models were exposed to vehicle (control) or AgNPs and a day later, treated with resolvin D1 (RvD1) or vehicle (control) via oropharyngeal aspiration. Pulmonary lung toxicity was evaluated at 3-, 7-, 14-, and 21-days following AgNP exposure. MetS mice exposed to AgNPs and receiving vehicle treatment, demonstrated exacerbated pulmonary inflammatory responses compared to healthy mice. In the AgNP exposed mice receiving RvD1, pulmonary inflammatory response in MetS was reduced to levels comparable to healthy mice exposed to AgNPs. This included decreases in neutrophil influx and inflammatory cytokines, as well as elevated anti-inflammatory cytokines.

CONCLUSIONS

Inefficient resolution may contribute to enhancements in MetS susceptibility to AgNP exposure causing an increased pulmonary inflammatory response. Treatments utilizing specific resolution mediators may be beneficial to individuals suffering MetS following inhalation exposures.

Secreted phospholipase A2 modifies extracellular vesicles and accelerates B cell lymphoma

Extracellular vesicles (EVs) including exosomes act as intercellular communicators by transferring protein and microRNA cargoes, yet the role of EV lipids remains unclear. Here, we show that the pro-tumorigenic action of lymphoma-derived EVs is augmented via secreted phospholipase A₂ (sPLA₂)-driven lipid metabolism. Hydrolysis of EV phospholipids by group X sPLA₂, which was induced in macrophages of Epstein-Barr virus (EBV) lymphoma, increased the production of fatty acids, lysophospholipids, and their metabolites. sPLA₂-treated EVs were smaller and self-aggregated, showed better uptake, and increased cytokine expression and lipid mediator signaling in tumor-associated macrophages. Pharmacological inhibition of endogenous sPLA₂ suppressed lymphoma growth in EBV-infected humanized mice, while treatment with sPLA₂-modified EVs reversed this phenotype. Furthermore, sPLA₂ expression in human large B cell lymphomas inversely correlated with patient survival. Overall, the sPLA₂-mediated EV modification promotes tumor development, highlighting a non-canonical mechanistic action of EVs as an extracellular hydrolytic platform of sPLA₂.

Inflammatory Mediation of Heat Stress-Induced Growth Deficits in Livestock and Its Potential Role as a Target for Nutritional Interventions: A Review

Simple Summary

Heat stress is a persistent challenge for livestock producers. Molecular changes throughout the body that result from sustained heat stress slow muscle growth and thus are detrimental to carcass yield and value. Feedlot animals are at particularly high risk for heat stress because their confinement limits their ability to pursue shade and other natural cooling behaviors. Changes in infrastructure to reduce the impact of heat stress are often cost-prohibitive, but recent studies have revealed that anti-inflammatory therapies may help to improve growth deficits in heat-stressed animals. This review describes the conditions that cause heat stress and explains the role of inflammation in muscle growth impairment. Additionally, it discusses the potential for several natural anti-inflammatory dietary additives to improve muscle growth outcomes in heat-stressed livestock.

Abstract

Heat stress is detrimental to well-being and growth performance in livestock, and systemic inflammation arising during chronic heat stress contributes to these poor outcomes. Sustained exposure of muscle and other tissues to inflammation can impair the cellular processes that facilitate muscle growth and intramuscular fat deposition, thus reducing carcass quality and yield. Climate change is expected to produce more frequent extreme heat events, increasing the potential impact of heat stress on sustainable livestock production. Feedlot animals are at particularly high risk for heat stress, as confinement limits their ability to seek cooling from the shade, water, or breeze. Economically practical options to circumvent heat stress in feedlot animals are limited, but understanding the mechanistic role of inflammation in heat stress outcomes may provide the basis for treatment strategies to improve well-being and performance. Feedlot animals receive formulated diets daily, which provides an opportunity to administer oral nutraceuticals and other bioactive products to mitigate heat stress-induced inflammation. In this review, we examine the complex associations between heat stress, systemic inflammation, and dysregulated muscle growth in meat animals. We also present evidence for potential nutraceutical and dietary moderators of inflammation and how they might improve the unique pathophysiology of heat stress.

Aspirin-triggered resolvin D1 reduces parasitic cardiac load by decreasing inflammation in a murine model of early chronic Chagas disease

Background

Chagas disease, caused by the protozoan Trypanosoma cruzi, is endemic in Latin America and is widely distributed worldwide because of migration. In 30% of cases, after years of infection and in the absence of treatment, the disease progresses from an acute asymptomatic phase to a chronic inflammatory cardiomyopathy, leading to heart failure and death. An inadequate balance in the inflammatory response is involved in the progression of chronic Chagas cardiomyopathy. Current therapeutic strategies cannot prevent or reverse the heart damage caused by the parasite. Aspirin-triggered resolvin D1 (AT-RvD1) is a pro-resolving mediator of inflammation that acts through N-formyl peptide receptor 2 (FPR2). AT-RvD1 participates in the modification of cytokine production, inhibition of leukocyte recruitment and efferocytosis, macrophage switching to a nonphlogistic phenotype, and the promotion of healing, thus restoring organ function. In the present study, AT-RvD1 is proposed as a potential therapeutic agent to regulate the pro-inflammatory state during the early chronic phase of Chagas disease.

Methodology/Principal findings

C57BL/6 wild-type and FPR2 knock-out mice chronically infected with T. cruzi were treated for 20 days with 5 μg/kg/day AT-RvD1, 30 mg/kg/day benznidazole, or the combination of 5 μg/kg/day AT-RvD1 and 5 mg/kg/day benznidazole. At the end of treatment, changes in immune response, cardiac tissue damage, and parasite load were evaluated. The administration of AT-RvD1 in the early chronic phase of T. cruzi infection regulated the inflammatory response both at the systemic level and in the cardiac tissue, and it reduced cellular infiltrates, cardiomyocyte hypertrophy, fibrosis, and the parasite load in the heart tissue.

Conclusions/Significance

AT-RvD1 was shown to be an attractive therapeutic due to its regulatory effect on the inflammatory response at the cardiac level and its ability to reduce the parasite load during early chronic T. cruzi infection, thereby preventing the chronic cardiac damage induced by the parasite.

Chagas disease is prevalent in Latin America and is widely distributed worldwide due to migration. In 30% of patients, if the parasite is left untreated, the disease may progress from an acute symptomless phase to chronic myocardial inflammation, which can cause heart failure and death, years after the infection. Imbalances in the inflammatory response are related to this progression. Current treatments cannot prevent or reverse the cardiac damage inflicted by the parasite. Aspirin-triggered resolvin D1, also named AT-RvD1, can modify cellular and humoral inflammatory responses leading to the resolution of inflammation, thus promoting healing and restoring organ function. In this study, AT-RvD1, in an N-formyl peptide receptor 2 (FPR2)-dependent manner, was shown to regulate local and systemic inflammation and decrease cellular infiltration in the heart tissue of mice chronically infected with the parasite and reduce cardiac hypertrophy and fibrosis in the early stages of the chronic phase of the disease. Importantly, AT-RvD1 was able to decrease parasite load in the infected hearts. Thus, this research indicates that At-RvD1 treatment is a potential therapeutic strategy that offers an improvement on current drug therapies.

Resolvin D1, therapeutic target in acute respiratory distress syndrome

Acute lung injury (ALI), or its more severe form, acute respiratory distress syndrome (ARDS), is a disease with high mortality and is a serious challenge facing the World Health Organization because there is no specific treatment. The excessive and prolonged immune response is the hallmark of this disorder, so modulating and regulating inflammation plays an important role in its prevention and treatment. Resolvin D1 (RvD1) as a specialized pro-resolving mediator has the potential to suppress the expression of inflammatory cytokines and to facilitate the production of antioxidant proteins by stimulating lipoxin A4 receptor/formyl peptide receptor 2 (ALX/FPR2). These changes limit the invasion of immune cells into the lung tissue, inhibit coagulation, and enhance cell protection against oxidative stress (OS). In particular, this biomolecule reduces the generation of reactive oxygen species (ROS) by blocking the activation of inflammatory transcription factors, especially nuclear factor-κB (NF-κB), and accelerating the synthesis of antioxidant compounds such as heme oxygenase 1 (HO-1) and superoxide dismutase (SOD). Therefore, the destruction and dysfunction of important cell components such as cytoplasmic membrane, mitochondria, Na+/k + adenosine triphosphatase (ATPase) and proteins involved in the phagocytic activity of scavenger macrophages are attenuated. Numerous studies on the effect of RvD1 over inflammation using animal models revealed that Rvs have both anti-inflammatory and pro-resolving capabilities and therefore, might have potential therapeutic value in treating ALI. Here, we review the current knowledge on the classification, biosynthesis, receptors, mechanisms of action, and role of Rvs in ALI/ARDS.

A Novel Modified-Curcumin Promotes Resolvin-Like Activity and Reduces Bone Loss in Diabetes-Induced Experimental Periodontitis

PURPOSE

Clinically, it is challenging to manage diabetic patients with periodontitis. Biochemically, both involve a wide range of inflammatory/collagenolytic conditions which exacerbate each other in a "bi-directional manner." However, standard treatments for this type of periodontitis rely on reducing the bacterial burden and less on controlling hyper-inflammation/excessive-collagenolysis. Thus, there is a crucial need for new therapeutic strategies to modulate this excessive host response and to promote enhanced resolution of inflammation. The aim of the current study is to evaluate the impact of a novel chemically-modified curcumin 2.24 (CMC2.24) on host inflammatory response in diabetic rats.

METHODS

Type I diabetes was induced by streptozotocin injection; periodontal breakdown then results as a complication of uncontrolled hyperglycemia. Non-diabetic rats served as controls. CMC2.24, or the vehicle-alone, was administered by oral gavage daily for 3 weeks to the diabetics. Micro-CT was used to analyze morphometric changes and quantify bone loss. MMPs were analyzed by gelatin zymography. Cell function was examined by cell migration assay, and cytokines and resolvins were measured by ELISA.

RESULTS

In this severe inflammatory disease model, administration of the pleiotropic CMC2.24 was found to normalize the excessive accumulation and impaired chemotactic activity of macrophages in peritoneal exudates, significantly decrease MMP-9 and pro-inflammatory cytokines to near normal levels, and markedly increase resolvin D1 (RvD1) levels in the thioglycolate-elicited peritoneal exudates (tPE). Similar effects on MMPs and RvD1 were observed in the non-elicited resident peritoneal washes (rPW). Regarding clinical relevance, CMC2.24 significantly inhibited the loss of alveolar bone height, volume and mineral density (ie, diabetes-induced periodontitis and osteoporosis).

CONCLUSION

In conclusion, treating hyperglycemic diabetic rats with CMC2.24 (a tri-ketonic phenylaminocarbonyl curcumin) promotes the resolution of local and systemic inflammation, reduces bone loss, in addition to suppressing collagenolytic MMPs and pro-inflammatory cytokines, suggesting a novel therapeutic strategy for treating periodontitis complicated by other chronic diseases.

7S,15R-Dihydroxy-16S,17S-Epoxy-Docosapentaenoic Acid, a Novel DHA Epoxy Derivative, Inhibits Colorectal Cancer Stemness through Repolarization of Tumor-Associated Macrophage Functions and the ROS/STAT3 Signaling Pathway

Colorectal cancer is a highly malignant cancer that is inherently resistant to many chemotherapeutic drugs owing to the complicated tumor-supportive microenvironment (TME). Tumor-associated macrophages (TAM) are known to mediate colorectal cancer metastasis and relapse and are therefore a promising therapeutic target. In the current study, we first confirmed the anti-inflammatory effect of 7S,15R-dihydroxy-16S,17S-epoxy-docosapentaenoic acid (diHEP-DPA), a novel DHA dihydroxy derivative synthesized in our previous work. We found that diHEP-DPA significantly reduced lipopolysaccharide (LPS)-induced inflammatory cytokines secretion of THP1 macrophages, IL-6, and TNF-α. As expected, diHEP-DPA also modulated TAM polarization, as evidenced by decreased gene and protein expression of the TAM markers, CD206, CD163, VEGF, and TGF-β1. During the polarization process, diHEP-DPA treatment decreased the concentration of TGF-β1, IL-1β, IL-6, and TNF-α in culture supernatants via inhibiting the NF-κB pathway. Moreover, diHEP-DPA blocked immunosuppression by reducing the expression of SIRPα in TAMs and CD47 in colorectal cancer cells. Knowing that an inflammatory TME largely serves to support epithelial-mesenchymal transition (EMT) and cancer stemness, we tested whether diHEP-DPA acted through polarization of TAMs to regulate these processes. The intraperitoneally injected diHEP-DPA inhibited tumor growth when administered alone or in combination with 5-fluorouracil (5-FU) chemotherapy in vivo. We further found that diHEP-DPA effectively reversed TAM-conditioned medium (TCCM)-induced EMT and enhanced colorectal cancer stemness, as evidenced by its inhibition of colorectal cancer cell migration, invasion and expression of EMT markers, as well as cancer cell tumorspheres formation, without damaging colorectal cancer cells. DiHEP-DPA reduced the population of aldehyde dehydrogenase (ALDH)-positive cells and expression of colorectal stemness marker proteins (CD133, CD44, and Sox2) by modulating TAM polarization. Additionally, diHEP-DPA directly inhibited cancer stemness by inducing the production of reactive oxygen species (ROS), which, in turn, reduced the phosphorylation of nuclear signal transducer and activator of transcription 3 (STAT3). These data collectively suggest that diHEP-DPA has the potential for development as an anticancer agent against colorectal cancer.

Interaction Between Serum/Glucocorticoid-Regulated Kinase 1 and Interleukin-6 in Chronic Rhinosinusitis

PURPOSE

Serum/glucocorticoid-regulated kinase 1 (SGK1) has recently emerged as a critical regulator of inflammatory diseases. In this study, we examined SGK1 expression and its possible pathogenic roles in chronic rhinosinusitis (CRS).

METHODS

Immunohistochemistry, western blotting, Bio-Plex assay, enzyme-linked immunosorbent assays, and quantitative real-time polymerase chain reaction were performed to assess protein and gene expression levels. The mRNA expression levels of SGK1 and interleukin-6 (IL-6) were extracted from a CRS database to perform correlation analysis. Stable cell lines with SGK1 overexpression (16HBE) and knockdown (A549) were constructed to investigate the interaction between SGK1 and IL-6 in vitro.

RESULTS

SGK1 exhibited strong cytoplasmic and nuclear staining in the epithelial layers and the lamina propria of nasal polyps (NPs) and in the mucosal tissues of CRS without nasal polyps (CRSsNP). The mRNA and protein expression levels of SGK1 and IL-6 were significantly increased in NPs and CRSsNP tissues, compared to control tissues. SGK1 phosphorylation was significantly greater in NPs than in CRSsNP tissues (P < 0.01). The mRNA levels of SGK1 and IL-6 were significantly correlated (P < 0.001, r = 0.649). Exposure to IL-6 significantly increased SGK1 expression in cultured dispersed NP cells, 16HBE cells, and A549 cells. IL-6 expression was significantly down-regulated in SGK1-overexpressing 16HBE cells (P < 0.01) and significantly up-regulated in SGK1-knockdown A549 cells (P < 0.05). Administration of GSK650394, a SGK1 inhibitor, significantly increased IL-6 self-induced mRNA expression in cultured dispersed NP cells and 16HBE cells.

CONCLUSIONS

The interaction between SGK1 and IL-6 may play an anti-inflammatory role in IL-6-induced inflammation in the pathogenesis of CRS.

Molecular biochemical aspects of salt (sodium chloride) in inflammation and immune response with reference to hypertension and type 2 diabetes mellitus

Obesity, insulin resistance, type 2 diabetes mellitus (T2DM) and hypertension (HTN) are common that are associated with low-grade systemic inflammation. Diet, genetic factors, inflammation, and immunocytes and their cytokines play a role in their pathobiology. But the exact role of sodium, potassium, magnesium and other minerals, trace elements and vitamins in the pathogenesis of HTN and T2DM is not known. Recent studies showed that sodium and potassium can modulate oxidative stress, inflammation, alter the autonomic nervous system and induce dysfunction of the innate and adaptive immune responses in addition to their action on renin-angiotensin-aldosterone system. These actions of sodium, potassium and magnesium and other minerals, trace elements and vitamins are likely to be secondary to their action on pro-inflammatory cytokines IL-6, TNF-α and IL-17 and metabolism of essential fatty acids that may account for their involvement in the pathobiology of insulin resistance, T2DM, HTN and autoimmune diseases.

Pro-Resolving Ligands Orchestrate Phagocytosis

The resolution of inflammation is a tissue protective program that is governed by several factors including specialized pro-resolving mediators (SPMs), proteins, gasses and nucleotides. Pro-resolving mediators activate counterregulatory programs to quell inflammation and promote tissue repair in a manner that does not compromise host defense. Phagocytes like neutrophils and macrophages play key roles in the resolution of inflammation because of their ability to remove debris, microbes and dead cells through processes including phagocytosis and efferocytosis. Emerging evidence suggests that failed resolution of inflammation and defective phagocytosis or efferocytosis underpins several prevalent human diseases. Therefore, understanding factors and mechanisms associated with enhancing these processes is a critical need. SPMs enhance phagocytosis and efferocytosis and this review will highlight mechanisms associated with their actions.

Glycogen Synthase Kinase 3β Modulates the Inflammatory Response Activated by Bacteria, Viruses, and Parasites

Knowledge of glycogen synthase kinase 3β (GSK3β) activity and the molecules identified that regulate its function in infections caused by pathogenic microorganisms is crucial to understanding how the intensity of the inflammatory response can be controlled in the course of infections. In recent years many reports have described small molecular weight synthetic and natural compounds, proteins, and interference RNA with the potential to regulate the GSK3β activity and reduce the deleterious effects of the inflammatory response. Our goal in this review is to summarize the most recent advances on the role of GSK3β in the inflammatory response caused by bacteria, bacterial virulence factors (i.e. LPS and others), viruses, and parasites and how the regulation of its activity, mainly its inhibition by different type of molecules, modulates the inflammation.

SARS-CoV-2 journey to the brain with a focus on potential role of docosahexaenoic acid bioactive lipid mediators

Coronavirus Disease 2019 or COVID-19 have infected till day 82,579,768 confirmed cases including 1,818,849 deaths, reported by World Health Organization WHO. COVID-19, originated by Severe Acute respiratory syndrome Coronavirus 2 (SARS-CoV-2), contributes to respiratory distress in addition to neurological symptoms in some patients. In the current review, we focused on the neurological complications associated with COVID-19. We discussed different pathways followed by RNA-virus, especially Flaviviridae family in the brain and passage through the Blood-Brain-Barrier BBB. Then, we explored SARS-CoV-2 mechanisms responsible of neuroinvasion and BBB disruption as well as the immunopathogenesis of SARS-CoV-2 in the central nervous system CNS. Since SARS-CoV-2 is an enveloped virus, enclosed in a lipid bilayer and that lipids are essential cell components playing numerous biological roles in viral infection and replication, we investigated the lipid metabolism remodeling upon coronavirus replication. We also highlighted the anti-inflammatory and neuroprotective potential of an omega-3 polyunsaturated fatty acid, docosahexaenoic acid DHA, as well as several bioactive lipid mediators. Altogether, our data allow better understanding of SARS-CoV-2 neuroinvasion and could assist in drug targeting to decline the burden of short-term and long-term neurological manifestations of SARS-CoV-2.

Specialized Pro-Resolving Mediators as Potential Regulators of Inflammatory Macrophage Responses in COVID-19

The recent outbreak of SARS-CoV2 has emerged as one of the biggest pandemics of our century, with outrageous health, social and economic consequences globally. Macrophages may lay in the center of COVID-19 pathogenesis and lethality and treatment of the macrophage-induced cytokine storm has emerged as essential. Specialized pro-resolving mediators (SPMs) hold strong therapeutic potentials in the management of COVID-19 as they can regulate macrophage infiltration and cytokine production but also promote a pro-resolving macrophage phenotype. In this review, we discuss the homeostatic functions of SPMs acting directly on macrophages on various levels, towards the resolution of inflammation. Moreover, we address the molecular events that link the lipid mediators with COVID-19 severity and discuss the clinical potentials of SPMs in COVID-19 immunotherapeutics.

MAR1 suppresses inflammatory response in LPS-induced RAW 264.7 macrophages and human primary peripheral blood mononuclear cells via the SIRT1/PGC-1α/PPAR-γ pathway

Background

Sepsis is a complex syndrome characterized by a dysregulated inflammatory response to systemic infection and leads to shock, multiple organ failure and death especially if not recognized early and treated promptly. Previous studies have suggested Maresin 1 (MAR1) can alleviate systemic inflammation in sepsis, but its mechanism has not been clarified.

Methods

RAW 264.7 cells and human primary peripheral blood mononuclear cells (hPBMCs) were pretreated with LPS and MAR1. The mRNA expression and supernatant levels of pro-inflammatory cytokines, tumor necrosis factor (TNF-α), interleukin (IL)-1β and IL-6 were evaluated by RT-qPCR and ELISA, respectively. The expression levels of Sirtuin 1 (SIRT1), peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), and Peroxisome proliferator-activated receptor gamma (PPAR-γ) were determined by RT-qPCR and Western blot analysis, respectively.

Results

Our results show that LPS-induced inflammation increased the expression and secretion of proinflammatory cytokines TNF-α, IL-1β and IL-6 and induced suppression of SIRT1, PGC-1α, and PPAR-γ expression, which could be reversed by MAR1. And the effect of MAR1 was eliminated by repression of SIRT1/PPAR-γ and enhanced by PGC-1α overexpression.

Conclusions

MAR1 suppressed inflammatory response in LPS-induced RAW 264.7 macrophages and hPBMCs via the SIRT1/PGC-1α/PPAR-γ pathway.

Resolvin D1 and E1 promote resolution of inflammation in rat cardiac fibroblast in vitro

Cardiac fibroblasts (CFs) have a key role in the inflammatory response after cardiac injury and are necessary for wound healing. Resolvins are potent agonists that control the duration and magnitude of inflammation. They decrease mediators of pro-inflammatory expression, reduce neutrophil migration to inflammation sites, promote the removal of microbes and apoptotic cells, and reduce exudate. However, whether resolvins can prevent pro-inflammatory-dependent effects in CFs is unknown. Thus, the present work was addressed to study whether resolvin D1 and E1 (RvD1 and RvE1) can prevent pro-inflammatory effects on CFs after lipopolysaccharide (LPS) challenge. For this, CFs were stimulated with LPS, in the presence or absence of RvD1 or RvE1, to analyze its effects on intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion protein 1 (VCAM-1), monocyte adhesion and the cytokine levels of tumor necrosis factor alpha (TNF-α), interleukin-6(IL-6), interleukin-1beta (IL-1β), monocyte chemoattractant protein-1 (MCP-1) and interleukin-10 (IL-10). Our results showed that CFs are expressing ALX/FPR2 and ChemR23, RvD1 and RvE1 receptors, respectively. RvD1 and RvE1 prevent the increase of ICAM-1 and VCAM-1 protein levels and the adhesion of spleen mononuclear cells to CFs induced by LPS. Finally, RvD1, but not RvE1, prevents the LPS-induced increase of IL-6, MCP-1, TNF-α, and IL-10. In conclusion, our findings provide evidence that in CFs, RvD1 and RvE1 might actively participate in the prevention of inflammatory response triggered by LPS.

Maresin 1 attenuates pro-inflammatory activation induced by β-amyloid and stimulates its uptake

Alzheimer's disease (AD) is the most common dementia, characterized by pathological accumulation of β‐amyloid (Aβ) and hyperphosphorylation of tau protein, together with a damaging chronic inflammation. The lack of effective treatments urgently warrants new therapeutic strategies. Resolution of inflammation, associated with beneficial and regenerative activities, is mediated by specialized pro‐resolving lipid mediators (SPMs) including maresin 1 (MaR1). Decreased levels of MaR1 have been observed in AD brains. However, the pro‐resolving role of MaR1 in AD has not been fully investigated. In the present study, human monocyte‐derived microglia (MdM) and a differentiated human monocyte cell line (THP‐1 cells) exposed to Aβ were used as models of AD neuroinflammation. We have studied the potential of MaR1 to inhibit pro‐inflammatory activation of Aβ and assessed its ability to stimulate phagocytosis of Aβ₄₂. MaR1 inhibited the Aβ₄₂‐induced increase in cytokine secretion and stimulated the uptake of Aβ₄₂ in both MdM and differentiated THP‐1 cells. MaR1 was also found to decrease chemokine secretion and reduce the associated increase in the activation marker CD40. Activation of kinases involved in transduction of inflammation was not affected by MaR1, but the activity of nuclear factor (NF)‐κB was decreased. Our data show that MaR1 exerts effects that indicate a pro‐resolving role in the context of AD and thus presents itself as a potential therapeutic target for AD.

15-Lipoxygenase-1 biosynthesis of 7S,14S-diHDHA implicates 15-lipoxygenase-2 in biosynthesis of resolvin D5

The two oxylipins 7S,14S-dihydroxydocosahexaenoic acid (diHDHA) and 7S,17S-diHDHA [resolvin D5 (RvD5)] have been found in macrophages and infectious inflammatory exudates and are believed to function as specialized pro-resolving mediators (SPMs). Their biosynthesis is thought to proceed through sequential oxidations of DHA by lipoxygenase (LOX) enzymes, specifically, by human 5-LOX (h5-LOX) first to 7(S)-hydroxy-4Z,8E,10Z,13Z,16Z,19Z-DHA (7S-HDHA), followed by human platelet 12-LOX (h12-LOX) to form 7(S),14(S)-dihydroxy-4Z,8E,10Z,12E,16Z,19Z-DHA (7S,14S-diHDHA) or human reticulocyte 15-LOX-1 (h15-LOX-1) to form RvD5. In this work, we determined that oxidation of 7(S)-hydroperoxy-4Z,8E,10Z,13Z,16Z,19Z-DHA to 7S,14S-diHDHA is performed with similar kinetics by either h12-LOX or h15-LOX-1. The oxidation at C14 of DHA by h12-LOX was expected, but the noncanonical reaction of h15-LOX-1 to make over 80% 7S,14S-diHDHA was larger than expected. Results of computer modeling suggested that the alcohol on C7 of 7S-HDHA hydrogen bonds with the backbone carbonyl of Ile399, forcing the hydrogen abstraction from C12 to oxygenate on C14 but not C17. This result raised questions regarding the synthesis of RvD5. Strikingly, we found that h15-LOX-2 oxygenates 7S-HDHA almost exclusively at C17, forming RvD5 with faster kinetics than does h15-LOX-1. The presence of h15-LOX-2 in neutrophils and macrophages suggests that it may have a greater role in biosynthesizing SPMs than previously thought. We also determined that the reactions of h5-LOX with 14(S)-hydroperoxy-4Z,7Z,10Z,12E,16Z,19Z-DHA and 17(S)-hydroperoxy-4Z,7Z,10Z,13Z,15E,19Z-DHA are kinetically slow compared with DHA, suggesting that these reactions may be minor biosynthetic routes in vivo. Additionally, we show that 7S,14S-diHDHA and RvD5 have anti-aggregation properties with platelets at low micromolar potencies, which could directly regulate clot resolution.

Myeloid ALX/FPR2 regulates vascularization following tissue injury

Ischemic injury initiates a sterile inflammatory response that ultimately participates in the repair and recovery of tissue perfusion. Macrophages are required for perfusion recovery during ischemia, in part because they produce growth factors that aid in vascular remodeling. The input signals governing this pro-revascularization phenotype remain of interest. Here we found that hindlimb ischemia increases levels of resolvin D1 (RvD1), an inflammation-resolving lipid mediator that targets macrophages via its receptor, ALX/FPR2. Exogenous RvD1 enhances perfusion recovery during ischemia, and mice deficient in Alx/Fpr2 have an endogenous defect in this process. Mechanistically, RNA sequencing revealed that RvD1 induces a transcriptional program in macrophages characteristic of a pro-revascularization phenotype. Vascularization of ischemic skeletal muscle, as well as cutaneous wounds, is impaired in mice with myeloid-specific deficiency of Alx/Fpr2, and this is associated with altered expression of pro-revascularization genes in skeletal muscle and macrophages isolated from skeletal muscle. Collectively, these results uncover a role of ALX/FPR2 in revascularization that may be amenable to therapeutic targeting in diseases associated with altered tissue perfusion and repair.

Diet and cancer risk reduction: The role of diet-microbiota interactions and microbial metabolites

According to recent estimates, over one third of the human population will be diagnosed with cancer at some point in their lifetime. While genetic factors play a large part in cancer risk, as much as 50 % of cancers may be preventable through various lifestyle modifications. Nutrition is a major modifiable risk factor, both through its impacts on obesity as well as through dietary chemical exposures that can either increase or decrease cancer risk. However, specific associations and mechanistic links between diet and cancer risk are either inconsistent or elusive. New insights regarding the reciprocal interactions between diet and the gut microbiota, the trillions of organisms that reside in our intestines, may help clarify how diet impacts cancer. The gut microbiota is largely shaped by an individual's diet and has far-reaching effects on metabolism, the immune system, and inflammation- important factors in the development and progression of various cancers. Likewise, the microbiota modifies dietary components, and consequently, exposure to metabolites that can influence cancer. This review explores some of these diet-microbiota interactions in the context of their potential impacts on cancer prevention.

Resolvin D1 and D2 inhibit tumour growth and inflammation via modulating macrophage polarization

Plastic polarization of macrophage is involved in tumorigenesis. M1-polarized macrophage mediates rapid inflammation, entity clearance and may also cause inflammation-induced mutagenesis. M2-polarized macrophage inhibits rapid inflammation but can promote tumour aggravation. ω-3 long-chain polyunsaturated fatty acid (PUFA)-derived metabolites show a strong anti-inflammatory effect because they can skew macrophage polarization from M1 to M2. However, their role in tumour promotive M2 macrophage is still unknown. Resolvin D1 and D2 (RvD1 and RvD2) are docosahexaenoic acid (DHA)-derived docosanoids converted by 15-lipoxygenase then 5-lipoxygenase successively. We found that although dietary DHA can inhibit prostate cancer in vivo, neither DHA (10 μmol/L) nor RvD (100 nmol/L) can directly inhibit the proliferation of prostate cancer cells in vitro. Unexpectedly, in a cancer cell-macrophage co-culture system, both DHA and RvD significantly inhibited cancer cell proliferation. RvD1 and RvD2 inhibited tumour-associated macrophage (TAM or M2d) polarization. Meanwhile, RvD1 and RvD2 also exhibited anti-inflammatory effects by inhibiting LPS-interferon (IFN)-γ-induced M1 polarization as well as promoting interleukin-4 (IL-4)-mediated M2a polarization. These differential polarization processes were mediated, at least in part, by protein kinase A. These results suggest that regulation of macrophage polarization using RvDs may be a potential therapeutic approach in the management of prostate cancer.

Resolvin E1 is a pro-repair molecule that promotes intestinal epithelial wound healing

Resolution of intestinal inflammation and wound repair are active processes that mediate epithelial healing at mucosal surfaces. Lipid molecules referred to as specialized proresolving mediators (SPMs) play an important role in the restorative response. Resolvin E1 (RvE1), a SPM derived from omega-3 fatty acids, has been reported to dampen intestinal inflammation by promoting anti-inflammatory responses including increased neutrophil spherocytosis and macrophage production of IL-10. Despite these observations, a role for RvE1 in regulating intestinal epithelial cell migration and proliferation during mucosal wound repair has not been explored. Using an endoscopic biopsy-based wound healing model, we report that RvE1 is locally produced in response to intestinal mucosal injury. Exposure of intestinal epithelial cells to RvE1 promoted wound repair by increasing cellular proliferation and migration through activation of signaling pathways including CREB, mTOR, and Src-FAK. Additionally, RvE1-triggered activation of the small GTPase Rac1 led to increased intracellular reactive oxygen species (ROS) production, cell-matrix adhesion, and cellular protrusions at the leading edge of migrating cells. Furthermore, in situ administration of RvE1-encapsulated synthetic targeted polymeric nanoparticles into intestinal wounds promoted mucosal repair. Together, these findings demonstrate that RvE1 functions as a prorepair lipid mediator by increasing intestinal epithelial cell migration and proliferation, and highlight potential therapeutic applications for this SPM to promote mucosal healing in the intestine.

Specialized pro-resolving lipid mediators are differentially altered in peripheral blood of patients with multiple sclerosis and attenuate monocyte and blood-brain barrier dysfunction

Chronic inflammation is a key pathological hallmark of multiple sclerosis (MS) and suggests that resolution of inflammation, orchestrated by specialized pro-resolving lipid mediators (LM), is impaired. Here, through targeted-metabololipidomics in peripheral blood of patients with MS, we revealed that each disease form was associated with distinct LM profiles that significantly correlated with disease severity. In particular, relapsing and progressive MS patients were associated with high eicosanoids levels, whereas the majority of pro-resolving LM were significantly reduced or below limits of detection and correlated with disease progression. Furthermore, we found impaired expression of several pro-resolving LM biosynthetic enzymes and receptors in blood-derived leukocytes of MS patients. Mechanistically, differentially expressed mediators like LXA4, LXB4, RvD1 and PD1 reduced MS-derived monocyte activation and cytokine production, and inhibited inflammation-induced blood-brain barrier dysfunction and monocyte transendothelial migration. Altogether, these findings reveal peripheral defects in the resolution pathway in MS, suggesting pro-resolving LM as novel diagnostic biomarkers and potentially safe therapeutics.

Alteration of adipose tissue immune cell milieu towards the suppression of inflammation in high fat diet fed mice by flaxseed oil supplementation

The present study evaluates the effect of flaxseed oil (FXO) supplementation on adipose tissue macrophages (ATM’s), E and D series resolvin (Rv) levels and adipose tissue inflammation. Male C57BL/6J mice were divided into five groups (n = 5): lean group (given standard chow diet), HFD group given high fat diet (approx. 18 weeks) till they developed insulin resistance and 4, 8 or 16 mg/kg group (HFD group later orally supplemented with 4, 8 or 16 mg/kg body weight flaxseed oil) for 4 weeks.The present study showed that FXO supplementation led to enhanced DHA, EPA, RvE1-E2, RvD2, RvD5- D6, IL-4, IL-10 and arginase 1 levels in ATMs together with altered immune cell infiltration and reduced NF-κB expression. The FXO supplementation suppresses immune cell infiltration into adipose tissue and alters adipose tissue macrophage phenotype towards the anti-inflammatory state via enhancement of E and D series resolvins, arginase 1 expression and anti-inflammatory cytokines level (IL-4 and IL-10.) leading to amelioration of insulin resistance in flaxseed oil supplemented HFD mice.

Marijuana-Derived Cannabinoids Trigger a CB2/PI3K Axis of Suppression of the Innate Response to Oral Pathogens

Cannabis use is an emergent risk factor for periodontitis, a chronic bacterial-induced disease of the supporting structures of the teeth. However, the mechanisms by which marijuana exposure predisposes to periodontal tissue destruction have yet to be elucidated. Therefore, we examined the influence of physiologically relevant doses of major marijuana-derived phytocannabinoid subtypes (cannabidiol [CBD]; cannabinol [CBN]; and tetrahydrocannabinol [THC], 1.0 μg/ml) on the interactions of three ultrastructurally variant oral pathogens, Porphyromonas gingivalis, Filifactor alocis, and Treponema denticola with the immune system. CBD, CBN, and THC each suppressed P. gingivalis-induced IL-12 p40, IL-6, IL-8, and TNF release while enhancing the anti-inflammatory cytokine, IL-10, from human innate cells. Similar phenomena were observed in F. alocis- and T. denticola-exposed human monocytes and human gingival keratinocytes. Higher phytocannabinoid doses (≥5.0 μg/ml) compromised innate cell viability and inhibited the growth of P. gingivalis and F. alocis, relative to unexposed bacteria. T. denticola, however, was resistant to all cannabinoid doses tested (up to 10.0 μg/ml). Pharmaceutical inhibition and efficient gene silencing indicated that a common CB2/PI3K axis of immune suppression is triggered by phytocannabinoids in vitro. This pathway does not appear to perpetuate through the canonical GSK3β-dependent cholinergic anti-inflammatory pathway, the predominant endogenous inflammatory control system. In a repetitive, transient oral infection model, CBD also suppressed P. gingivalis-induced innate immune markers in wild-type mice, but not in CB2^−/− mice. If such phenomena occur in humans in situ, environmental cannabinoids may enhance periodontitis via direct toxic effects on specific oral bacteria; by compromising innate cell vitality; and/or through a suppressed innate response to periodontal pathogens involving a CB2/PI3K signaling lineage.

HMGB1-C1q complexes regulate macrophage function by switching between leukotriene and specialized proresolving mediator biosynthesis

Macrophage polarization is critical to inflammation and resolution of inflammation. We previously showed that high-mobility group box 1 (HMGB1) can engage receptor for advanced glycation end product (RAGE) to direct monocytes to a proinflammatory phenotype characterized by production of type 1 IFN and proinflammatory cytokines. In contrast, HMGB1 plus C1q form a tetramolecular complex cross-linking RAGE and LAIR-1 and directing monocytes to an antiinflammatory phenotype. Lipid mediators, as well as cytokines, help establish a milieu favoring either inflammation or resolution of inflammation. This study focuses on the induction of lipid mediators by HMGB1 and HMGB1 plus C1q and their regulation of IRF5, a transcription factor critical for the induction and maintenance of proinflammatory macrophages. Here, we show that HMGB1 induces leukotriene production through a RAGE-dependent pathway, while HMGB1 plus C1q induces specialized proresolving lipid mediators lipoxin A4, resolvin D1, and resolvin D2 through a RAGE- and LAIR-1-dependent pathway. Leukotriene exposure contributes to induction of IRF5 in a positive-feedback loop. In contrast, resolvins (at 20 nM) block IRF5 induction and prevent the differentiation of inflammatory macrophages. Finally, we have generated a molecular mimic of HMGB1 plus C1q, which cross-links RAGE and LAIR-1 and polarizes monocytes to an antiinflammatory phenotype. These findings may provide a mechanism to control nonresolving inflammation in many pathologic conditions.

Hyperglycaemia augments lipopolysaccharide-induced reduction in rat and human macrophage phagocytosis via the endoplasmic stress-C/EBP homologous protein pathway

BACKGROUND

Macrophage phagocytosis constitutes an essential part of the host defence against microbes and the resolution of inflammation. Hyperglycaemia during sepsis is reported to reduce macrophage function, and thus, potentiate inflammatory deterioration. We investigated whether high-glucose concentrations augment lipopolysaccharide-induced reduction in macrophage phagocytosis via the endoplasmic stress-C/EBP homologous protein (CHOP) pathway using animal and laboratory investigations.

METHODS

Peritoneal macrophages of artificially ventilated male Wistar rats, divided into four groups based on target blood glucose concentrations achieved by glucose administration with or without lipopolysaccharide, were obtained after 24 h. Human macrophages were also cultured in normal or high glucose with or without lipopolysaccharide exposure for 72 h. Changes in the phagocytic activity, intranuclear CHOP expression, and intracellular Akt phosphorylation status of macrophages were evaluated. These changes were also evaluated in human macrophages after genetic knock-down of CHOP by specific siRNA transfection or resolvin D2 treatment.

RESULTS

Lipopolysaccharide impaired phagocytosis, increased intranuclear expression of CHOP, and inhibited Akt phosphorylation in both rat peritoneal and human macrophages. Hyperglycaemic glucose concentrations augmented these changes. Genetic knock-down of CHOP restored phagocytic ability and Akt phosphorylation in human macrophages. Furthermore, resolvin D2 co-incubation restored the inhibited phagocytosis and Akt phosphorylation along with the inhibition of intranuclear CHOP expression in human macrophages.

CONCLUSIONS

These findings imply that controlling endoplasmic reticulum stress might provide new strategies for restoring reduced macrophage phagocytosis in sepsis-induced hyperglycaemia.

The specialised pro-resolving lipid mediator maresin 1 reduces inflammatory pain with a long-lasting analgesic effect

BACKGROUND AND PURPOSE

Maresin 1 (MaR1) is a specialised pro-resolving lipid mediator with anti-inflammatory and analgesic activities. In this study, we addressed the modulation of peripheral and spinal cord cells by MaR1 in the context of inflammatory pain.

EXPERIMENTAL APPROACH

Mice were treated with MaR1 before intraplantar injection of carrageenan or complete Freund's adjuvant (CFA). Mechanical hyperalgesia was assessed using the electronic von Frey and thermal hyperalgesia using a hot plate. Spinal cytokine production and NF-κB activation were determined by ELISA and astrocytes and microglia activation by RT-qPCR and immunofluorescence. CGRP release by dorsal root ganglia (DRG) neurons was determined by EIA. Neutrophil and macrophage recruitment were determined by immunofluorescence, flow cytometry, and colorimetric methods. Trpv1 and Nav1.8 expression and calcium imaging of DRG neurons were determined by RT-qPCR and Fluo-4AM respectively.

KEY RESULTS

MaR1 reduced carrageenan- and CFA-induced mechanical and thermal hyperalgesia and neutrophil and macrophage recruitment proximal to CGRP⁺ fibres in the paw skin. Moreover, MaR1 reduced NF-κB activation, IL-1β and TNF-α production, and spinal cord glial cells activation. In the DRG, MaR1 reduced CFA-induced Nav1.8 and Trpv1 mRNA expression and calcium influx and capsaicin-induced release of CGRP by DRG neurons.

CONCLUSIONS AND IMPLICATIONS

MaR1 reduced DRG neurons activation and CGRP release explaining, at least in part, its analgesic and anti-inflammatory effects. The enduring analgesic and anti-inflammatory effects and also post-treatment activity of MaR1 suggest that specialised pro-resolving lipid mediators have potential as a new class of drugs for the treatment of inflammatory pain.

In vitro and in vivo assessment of the proresolutive and antiresorptive actions of resolvin D1: relevance to arthritis

BACKGROUND

Resolvin D1 (RvD1), an important member of resolvins, exerts a wide spectrum of biological effects, including resolution of inflammation, tissue repair, and preservation of cell viability. The aim of the present study is to investigate the anti-arthritic potential and clarify the bone protective actions of RvD1 in vitro and in vivo.

METHODS

RAW264.7 cells were treated with 50 ng/ml LPS for 72 h in the presence or absence of RvD1 (0-500 nM). Primary human monocytes were treated with M-CSF + RANKL for 14 days ± RvD1 (0-500 nM) with or without siRNA against RvD1 receptor FPR2. Expressions of inflammatory mediators, degrading enzymes, osteoclasts (OC) formation, and bone resorption were analyzed. The therapeutic effect of RvD1 (0-1000 ng) was carried out in murine collagen antibody-induced arthritis. Arthritis scoring, joint histology, and inflammatory and bone turnover markers were measured.

RESULTS

RvD1 is not toxic and inhibits OC differentiation and activation. It decreases bone resorption, as assessed by the inhibition of TRAP and cathepsin K expression, hydroxyapatite matrix resorption, and bone loss. In addition, RvD1 reduces TNF-α, IL-1β, IFN-γ, PGE₂, and RANK and concurrently enhances IL-10 in OC. Moreover, in arthritic mice, RvD1 alleviates clinical score, paw inflammation, and bone and joint destructions. Besides, RvD1 reduces inflammatory mediators and markedly decreases serum markers of bone and cartilage turnover.

CONCLUSION

Our results provide additional evidence that RvD1 plays a key role in preventing bone resorption and other pathophysiological changes associated with arthritis. The study highlights the clinical relevance of RvD1 as a potential compound for the treatment of inflammatory arthritis and related bone disorders.

Omega-3 fatty acid-derived mediators that control inflammation and tissue homeostasis

Omega-3 polyunsaturated fatty acids (PUFAs), including eicosapentaenoic acid, docosapentaenoic acid and docosahexaenoic acid, display a wide range of beneficial effects in humans and animals. Many of the biological functions of PUFAs are mediated via bioactive metabolites produced by fatty acid oxygenases such as cyclooxygenases, lipoxygenases and cytochrome P450 monooxygenases. Liquid chromatography–tandem mass spectrometry-based mediator lipidomics revealed a series of novel bioactive lipid mediators derived from omega-3 PUFAs. Here, we describe recent advances on omega-3 PUFA-derived mediators, mainly focusing on their enzymatic oxygenation pathway, and their biological functions in controlling inflammation and tissue homeostasis.

Saving Problematic Mucosae: SPMs in Intestinal Mucosal Inflammation and Repair

The intestinal mucosa serves as a highly selective barrier that allows the absorption of nutrients and water while restricting microbiota access to tissues. This barrier is compromised in inflammatory conditions such as infectious colitis and inflammatory bowel disease (IBD). In response to mucosal injury, there is a temporal recruitment of leukocytes that crosstalk with epithelial cells to orchestrate repair. Specialized pro-resolving mediators (SPMs) play an important role in the resolution of inflammation and epithelial repair. SPMs actively promote resolution of inflammation by contributing to the clearance of neutrophils, stimulating efferocytosis, and promoting epithelial repair. SPMs have potential to serve as targeted therapeutic agents to be used in adjuvant therapy to promote resolution of inflammation and epithelial repair in chronic inflammatory diseases.

Specialized Proresolving Mediators in Innate and Adaptive Immune Responses in Airway Diseases

Airborne pathogens and environmental stimuli evoke immune responses in the lung. It is critical to health that these responses be controlled to prevent tissue damage and the compromise of organ function. Resolution of inflammation is a dynamic process that is coordinated by biochemical and cellular mechanisms. Recently, specialized proresolving mediators (SPMs) have been identified in resolution exudates. These molecules orchestrate anti-inflammatory and proresolving actions that are cell type specific. In this review, we highlight SPM biosynthesis, the influence of SPMs on the innate and adaptive immune responses in the lung, as well as recent insights from SPMs on inflammatory disease pathophysiology. Uncovering these mediators and cellular mechanisms for resolution is providing new windows into physiology and disease pathogenesis.

Omega-3 fatty acids in coronary heart disease: Recent updates and future perspectives

Incidence of coronary heart disease (CHD) increases worldwide with varying etiological factors. In addition to the control of risk factors, dietary modification has been recommended to reduce the prevalence. Omega-3 (ω-3) fatty acids (FAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), of fish oil are beneficial for the prevention of CHD. The effect can be ascribed to anti-inflammatory, vasodilating, antiarrhythmic, antihypertensive activities and lowering of triacyl glycerol level. The American Heart Association advises two fish meals per week in subjects without CHD or supplementation of 1 g of EPA plus DHA per day in subjects with CHD. Despite the beneficial effects of EPA/DHA reported in some of the clinical trials, results of many others were inconsistent that can be ascribed to short duration of studies, low doses of ω-3 FAs, variations in the EPA:DHA ratio, selection of patients with different risk factors or interaction of ω-3 FAs with drugs used in the therapy. Therefore, well designed clinical trials in various populations are warranted. This article discusses the current situation and future prospective of ω-3 FAs in CHD.

Metabololipidomic profiling of functional immunoresolvent clusters and eicosanoids in mammalian tissues

Metabolomics enables a systems approach to interrogate the bioactive mediators, their pathways and further metabolites involved in the physiology and pathophysiology of human and animal tissues. New metabololipidomic approaches with mass spectrometry presented in this brief review can now be utilized for the identification and profiling of lipid mediator networks that control inflammation-resolution in human blood and healthy and diseased solid tissues. Coagulation of blood is a protective response that prevents excessive bleeding on injury of blood vessels. Here, we review novel approaches to understand the relationship(s) between coagulation and resolution of inflammation and infection. To determine whether coagulation is involved in host-protective actions by lipid mediators, we used a metabololipidomic-based profiling approach with human whole blood (WB) during coagulation. We identified recently temporal clusters of endogenously produced pro-thrombotic and proinflammatory lipid mediators (eicosanoids), as well as specialized proresolving mediators (SPMs) in this vital process. In addition to the classic eicosanoids (prostaglandins, thromboxanes and leukotrienes), a specific SPM cluster was identified that consists of resolvin E1 (RvE1), RvD1, RvD5, lipoxin B₄, and maresin 1, each of which present at bioactive concentrations (0.1-1 nM). The removal of adenosine from coagulating blood samples significantly enhances SPM amounts and unleashes the biosynthesis of RvD3, RvD4, and RvD6 evident following rapid snap freezing with centrifugation before extraction and LC-MS-MS. The classic cyclooxygenase inhibitors, celecoxib and indomethacin, that block thromboxanes and prostanoids do not block production of the clot-driven SPM cluster. Unbiased mass cytometry analysis demonstrated that the SPM cluster produced in human blood targets leukocytes at the single-cell level, directly activating extracellular signaling in human neutrophils and monocytes. Human whole blood treated with the components of this SPM cluster enhanced both phagocytosis and killing of Escherichia coli by leukocytes. Thus, we identified a pro-resolving lipid mediator circuit and specific SPM cluster that promotes host defense. This new lipid mediator (LM)-SPM metabololipidomic approach now provides accessible metabolomic profiles in healthy and diseased human tissues, including cancer, for precision and personalized medicine.

Special pro-resolving mediator (SPM) actions in regulating gastro-intestinal inflammation and gut mucosal immune responses

Surfaces covered by epithelial cells, termed mucosal surfaces, serve special functions as selectively permeable barriers that partition the host and the outside world. Given its close association to microbial antigens, the intestinal mucosa has evolved creative mechanisms to maintain homeostasis, to prevent excessive inflammatory responses, and to promote rapid and full inflammatory resolution. In recent years, an active role for the epithelium has been attributed to the local generation of specialized pro-resolving mediators (SPMs) in the maintenance of immunological homeostasis. In this brief review, we highlight evidence that the epithelium actively contributes to coordination and resolution of inflammation, principally through the generation of SPMs. These autacoids are derived from omega-6 and omega-3 polyunsaturated fatty acids. Acting through widely expressed G-protein coupled receptors, SPMs are implicated in the resolution of acute inflammation that manifests specific, epithelial-directed actions focused on mucosal-homeostasis, including regulation of leukocyte trafficking, the generation of antimicrobial peptides, the dampening of endotoxin signaling, and the attenuation of mucosal cytokine responses.

A cluster of immunoresolvents links coagulation to innate host defense in human blood

Blood coagulation is a protective response that prevents excessive bleeding upon blood vessel injury. We investigated the relationship between coagulation and the resolution of inflammation and infection by lipid mediators (LMs) through metabololipidomics-based profiling of human whole blood (WB) during coagulation. We identified temporal clusters of endogenously produced prothrombotic and proinflammatory LMs (eicosanoids), as well as specialized proresolving mediators (SPMs). In addition to eicosanoids, a specific SPM cluster was identified that consisted of resolvin E1 (RvE1), RvD1, RvD5, lipoxin B₄, and maresin 1, each of which was present at bioactive concentrations (0.1 to 1 nM). Removal of adenosine from the coagulating blood markedly enhanced the amounts of SPMs produced and further increased the biosynthesis of RvD3, RvD4, and RvD6. The cyclooxygenase inhibitors celecoxib and indomethacin, which block the production of thromboxanes and prostanoids, did not block the production of clot-driven SPMs. Unbiased mass cytometry analysis demonstrated that the SPM cluster produced in human blood targeted leukocytes at the single-cell level, directly activating ERK and CREB signaling in neutrophils and CD14⁺ monocytes. Treatment of human WB with the components of this SPM cluster enhanced both the phagocytosis and killing of Escherichia coli by leukocytes. Together, these data identify a proresolving LM circuit, including endogenous molecular brakes and accelerators, which promoted host defense. These temporal LM-SPM clusters can provide accessible metabolomic profiles for precision and personalized medicine.