Resolvin Research Articles

Abstract 2182: 15-lipoxygenase-1 modulation of colonic resolvin production to suppress colorectal carcinogenesis

Abstract Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are widely used dietary supplements and FDA-approved treatments. The reported impacts of fish oil, DHA, and EPA on colorectal carcinogenesis (CRC) have spurred debates, as certain studies suggest promotional effects while numerous others emphasize suppressive effects. Nevertheless, resolvins, oxidative metabolites of EPA and DHA, exhibit the ability to inhibit crucial pathways (such as TNF-α and IL-1β) that contribute to CRC. 15-lipoxygenase-1 (ALOX15) plays a crucial role in the oxidative metabolism of DHA and EPA, ultimately leading to the formation of resolvins. However, ALOX15 expression is commonly lost during human CRC. Whether loss of ALOX15 expression modulates the effects of DHA and EPA on CRC remains to be elucidated. We therefore conducted the experiments in preclinical CRC mouse models induced by Azoxymethane or Apc gene mutation to explore the hypothesis that ALOX15 expression in colonic epithelial cells regulates DHA and EPA metabolism to generate resolvins, subsequently influencing CRC outcomes. We found that 1) DHA and EPA exert differential effects on CRC, which can be further modified by factors such as their formulation (e.g., ethyl ester versus triglyceride); 2) targeted transgenic expression of ALOX15 in the intestines of mice (referred to as ALOX15-Gut mice) markedly augmented the production of resolvins and concurrently suppressed CRC; 3) the predominant products from the expressed ALOX15 enzymatic activity were identified as 17-HDHA and resolvin D5; and 4) the effects ALOX15 on increasing resolvin generation and suppressing CRC were consistent across various promoters used to drive ALOX15 transgenic expression in mice. These findings collectively underscore the profound importance of ALOX15 intestinal expression as a host-related factor in resolvin generation from EPA and DHA, which subsequently contributes to the suppression of CRC. Citation Format: Xiangsheng Zuo, Yoshiyuki Kiyasu, Yi Liu, Micheline Moussalli, Bo Wei, Peiying Yang, Imad Shureiqi. 15-lipoxygenase-1 modulation of colonic resolvin production to suppress colorectal carcinogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2182.

Abstract 7458: Inhibition of brain cancer progression via resolution of inflammation

Abstract While inflammation is a hallmark of cancer, the mechanisms that disrupt its resolution in cancer are not well understood. A paradigm shift is emerging in our understanding that the resolution of inflammation is an active process controlled by specialized pro-resolving mediators (SPMs), including protectins and resolvins, which are endogenous lipid autacoids present in multiple tissues including the brain and cerebrospinal fluid. SPMs counter-regulate pro-inflammatory cytokine production and stimulate phagocytosis of cellular debris (“pro-resolution”) without being immunosuppressive. We hypothesized treatment with pro-resolving agonists such as SPMs presents a novel debris-clearing and resolution-enhancing therapeutic approach to complement cytotoxic brain cancer therapies. Here, we demonstrate the failure of resolution of inflammation via dysregulated SPMs may be a critical risk factor for aggressive brain cancer growth. Moreover, chemotherapy and targeted therapy further disrupt inflammation resolution via a tumor cell death (“debris”)-induced cytokine storm by macrophages. The SPM receptors GPR37 (protectin D1), GPR18/DRV2 (resolvin (Rv) D2), GPR32 (RvD1), and ChemR23/ERV (RvE1) are expressed in tumor-infiltrating macrophages and endothelial cells in the brain tumor microenvironment. Plasma levels of SPMs were significantly reduced in the medulloblastoma-bearing mice, suggesting that brain cancer progression is associated with a failure of endogenous resolution of inflammation. To determine whether failed resolution in brain cancer can be rescued by lipid mediator agonists, we systemically administered SPMs to subcutaneous and orthotopic glioblastoma and medulloblastoma murine brain tumor models. Significantly, RvD1 and RvD2 each inhibited the growth of human glioblastoma tumors by 15-fold at nanogram concentrations without toxicity. Likewise, RvD2 inhibited the growth of human medulloblastoma tumors by 3-fold. Protectins, PDX and PD1n-3, each inhibited growth of human medulloblastoma in mice by approximately 5-fold. Systemic administration of PDX or RvD2 prolonged survival of mice injected with orthotopic human D556 medulloblastoma and also glioblastoma models. Flow cytometry analysis of orthotopic glioblastoma tumors revealed increased immune infiltration into the brain tumor microenvironment in the PCTR1-treatment group when compared to the tumor-bearing non-treated group. At nanogram per day doses, protectins and resolvins suppressed orthotopic debris-stimulated brain tumor growth by activating macrophage and microglial phagocytosis of tumor cell debris and counter-regulating pro-inflammatory cytokines, including TNF-α, CCL2, CXCL1, and CCL4. Thus, stimulating the resolution of inflammation via the clearance of cellular debris with pro-resolving agonists represents a novel therapeutic approach to brain cancer, including glioblastoma and medulloblastoma. Citation Format: Jacqueline Capuano, Kimberly Vasquez, Katherine Quinlivan, Rachel Bayer, Sarina Virani, Michael Gillespie, Mark Kieran, Charles Serhan, Diane Bielenberg, Dipak Panigrahy. Inhibition of brain cancer progression via resolution of inflammation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7458.

Resolvin D2 limits atherosclerosis progression via myeloid cell-GPR18.

Dysregulated inflammation-resolution programs are associated with atherosclerosis progression. Resolvins, in part, mediate inflammation-resolution programs. Indeed, Resolvin D2 (RvD2) activates GPR18, a G-protein-coupled receptor, and limits plaque progression, though the cellular targets of RvD2 remain unknown. Here, we developed a humanized GPR18 floxed ("fl/fl") and a myeloid (Lysozyme M Cre) GPR18 knockout (mKO) mouse. We functionally validated this model by assessing efferocytosis in bone marrow-derived macrophages (BMDMs) and found that RvD2 enhanced efferocytosis in the fl/fl, but not in the mKO BMDMs. To understand the functions of RvD2-GPR18 in atherosclerosis, we performed a bone marrow transfer of fl/fl or mKO bone marrow into Ldlr-/- recipients. For these experiments, we treated each genotype with either Vehicle/PBS or RvD2 (25 ng/mouse, 3 times/week for 3 weeks). Myeloid loss of GPR18 resulted in significantly more necrosis, increased cleaved caspase-3+ cells and decreased percentage of Arginase-1+ -Mac2+ cells without a change in overall Mac2+ plaque macrophages, compared with fl/fl➔Ldlr-/- transplanted mice. RvD2 treatment decreased plaque necrosis, the percent of cleaved caspase-3+ cells and increased the percent of Arginase-1+ -Mac2+ cells in fl/fl➔Ldlr-/- mice, but not in the mKO➔Ldlr-/- transplanted mice. These results suggest that GPR18 plays a causal role in limiting atherosclerosis progression and that RvD2's ability to limit plaque necrosis is in part dependent on myeloid GRP18.

Uncovering the Power of GPR18 Signalling: How RvD2 and Other Ligands Could Have the Potential to Modulate and Resolve Inflammation in Various Health Disorders.

The resolution of inflammation is the primary domain of specialised pro-resolving mediators (SPMs), which include resolvins, protectins, and their forms synthesised under the influence of aspirin and the maresins. The role of these SPMs has been discussed by many authors in the literature, with particular reference to neuroinflammation and significant neurological disorders. This review discusses the role of G protein-coupled receptor 18 (GPR18), resolvin D2 (RvD2) activity, and the GPR18-RvD2 signalling axis, as well as the role of small molecule ligands of GPR18 in inflammation in various health disorders (brain injuries, neuropathic pain, neurodegenerative/cardiometabolic/cardiovascular/gastrointestinal diseases, peritonitis, periodontitis, asthma and lung inflammation, Duchenne muscular dystrophy, SARS-CoV-2-induced inflammation, and placenta disorders. The idea of biological intervention through modulating GPR18 signalling is attracting growing attention because of its great therapeutic potential. With this paper, we aimed to present a comprehensive review of the most recent literature, perform a constructive view of data, and point out research gaps.

Anti-inflammatory actions of aspirin-triggered resolvin D1 (AT-RvD1) in bronchial epithelial cells stimulated by cigarette smoke extract

Smoking causes several diseases such as chronic obstructive pulmonary disease (COPD). Aspirin-triggered-resolvin D1 (AT-RvD1) is a lipid mediator produced during the resolution of inflammation and demonstrates anti-inflammatory and pro-resolution effects in several inflammatory experimental models including in the airways. Here we evaluated the role of AT-RvD1 (100 nM) in bronchial epithelial cells (BEAS-2B) stimulated by cigarette smoke extract (CSE; 1%; 1 cigarette) for 24 h. CSE induced the productions of IL-1β, TNF-α, IL-10, IL-4 and IFN-γ as well as the activations of NF-κB and STAT3 and the expression of ALX/FPR2 receptor. AT-RvD1 reduced the IL-1β and TNF-α production and increased the production of IFN-γ. These effects were reversed BOC2, an antagonist of ALX/FPR2 receptor for AT-RvD1. The production of IL-4 and IL-10 were not altered by AT-RvD1. In addition, AT-RvD1 reduced the phosphorylation of NF-κB and STAT3 when compared to CSE-stimulated BEAS-2B cells. No alteration of ALX/FPR2 expression was observed by AT-RvD1 when compared to CSE group. In the human monocytic leukemia cell line, the relative number of copies of IL-1β and IL-4 was significantly higher in CSE + AT-RvD1 group compared CSE group, however, the expression of M1 cytokine was more pronounced than M2 profile. AT-RvD1 could be an important target for the reduction of inflammation in the airways associated with smoking.

ATP citrate lyase (ACLY)-dependent immunometabolism in mucosal T cells drives experimental colitis in vivo

ObjectiveMucosal T cells play a major role in inflammatory bowel disease (IBD). However, their immunometabolism during intestinal inflammation is poorly understood. Due to its impact on cellular metabolism and proinflammatory...

Resolvin D1 suppresses macrophage senescence and splenic fibrosis in aged mice

Aging is associated with systemic, non-resolving inflammation and the accumulation of senescent cells. The resolution of inflammation (or inflammation-resolution) is in part mediated by the balance between specialized pro-resolving mediators (SPMs) and pro-inflammatory leukotrienes (LTs). Aged mice (i.e. 2 years of age) exhibit a significant decrease in the SPM:LT ratio in specific organs including the spleen, which suggests that this organ may exhibit heightened inflammation and may be particularly amenable to SPM therapy. Previous studies have shown that resolvin D1 (RvD1) is decreased in spleens of aged mice compared with young controls. Therefore, we asked whether treatment of RvD1 in aged mice would impact markers of cellular senescence in splenic macrophages, and downstream effects on splenic fibrosis, a hallmark of splenic aging. We found that in aged mice, both zymosan-elicited and splenic macrophages showed an increase in mRNA expression of inflammatory and eicosanoid biosynthesis genes and a dysregulation of genes involved in the cell cycle. Injections with RvD1 reversed these changes. Importantly, RvD1 also decreased splenic fibrosis, a hallmark of splenic aging. Our findings suggest that RvD1 treatment may limit several features of aging, including senescence and fibrosis in spleens from aged mice.SummaryAging is associated with systemic, low grade, non-resolving inflammation. The resolution of inflammation is in part mediated by the balance between specialized pro-resolving mediators (SPMs) and pro-inflammatory lipid mediators, like leukotrienes (LTs). A hallmark of aging is the accumulation of senescent cells that promote low grade inflammation by secreting pro-inflammatory cytokines and lipid mediators. Splenic macrophages contribute to systemic aging, and spleens of aged mice demonstrate decreased levels of the SPM called resolvin D1 (RvD1). Whether addition of RvD1 is protective in spleens of aged mice is unknown and is focus of this study. RvD1 treatment to aged mice led to decreased mRNA expression of markers of cellular senescence and inflammation in splenic macrophages compared with age-matched vehicle controls. Moreover, RvD1 decreased splenic fibrosis, which occurs due to persistent low-grade inflammation in aging. Promoting inflammation resolution with RvD1 thus limits macrophage senescence, pro-inflammatory signals and established splenic fibrosis in aging.

Cardiac Resolvin D2 ameliorates sepsis-induced cardiomyopathy via inhibiting Caspase-11/GSDMD dependent pyroptosis

BackgroundSepsis-induced cardiomyopathy (SICM) is common complication in septic patients with a high mortality and is characterized by an abnormal inflammation response, which was precisely regulated by endogenous specialized pro-resolving mediators (SPMs). However, the metabolic changes of cardiac SPMs during SICM and the roles of SPMs subset in the development of SICM remain unknown. MethodsIn this work, the SPMs concentration was assessed using ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) of SICM mice and SICM patients. The cardiac function was measured by echocardiography after the treatment of a SPMs subset, termed Resolvin D2 (RvD2). Caspase-11−/−, GSDMD−/− and double deficient (Caspase-11−/−GSDMD−/−) mice were used to clarify the mechanisms of RvD2 in SICM. ResultsWe found that endogenous cardiac SPMs were disorders and RvD2 was decreased significantly and correlated with left ventricular ejection fraction (LVEF) and β-BNP, cTnT in Lipopolysaccharide/Cecum ligation and puncture (CLP) induced SICM models. Treatment with RvD2 attenuated lethality, cardiac dysfunction and cardiomyocytes death during SICM. Mechanistically, RvD2 alleviated SICM via inhibiting Caspase-11/GSDMD-mediated cardiomyocytes pyroptosis. Finally, the plasma levels of RvD2 were also decreased and significantly correlated with IL-1β, β-BNP, cTnT and LVEF in patients with SICM. Of note, plasma RvD2 level is indicator of SICM patients from healthy controls or sepsis patients. ConclusionThese findings suggest that decreased cardiac RvD2 may involve in the pathogenesis of SICM. In addition, treatment with RvD2 represents a novel therapeutic strategy for SICM by inhibiting cardiomyocytes pyroptosis.

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

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. 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. 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.

Joint effects of one year of marine omega-3 fatty acid supplementation and participant dietary fish intake upon circulating lipid mediators of inflammation resolution in a randomized controlled trial

We assessed the joint effects of omega (n)-3 fatty acid supplementation and dietary fish intake on systemic lipid mediators of inflammation among adults. Within VITAL, a double-blind randomized controlled trial, adults were randomized to ω-3 fatty acids (460 mg EPA + 380 mg DHA/d) or placebo. We selected participants who reported low (<1 serving/mo) baseline dietary fish intake and matched them by age, sex, race, and trial arm to participants with self-reported highest fish intake (≥3.9 servings/wk). Baseline and 1-y plasma samples were tested for 9 ω-3 fatty acid-derived lipid mediators. Multivariable linear models assessed lipid mediator changes and joint effects of ω-3 fatty acid supplementation and dietary fish intake. Forty-eight participants with low baseline fish intake were matched to 48 with high fish intake. Mean age was 64.6 (±7.26), 50% were female, and 85% non-Hispanic white. One-year lipid mediator changes in expected directions were observed in those receiving ω-3 fatty acids versus placebo: reductions in proinflammatory mediators, PGD2, 5-HETE, and 12-HETE; increases in proresolving mediators, EPA and DHA. Larger 1-y lipid biomarker changes were seen in those with low baseline fish intake randomized to active ω-3 fatty acids for DHA, EPA, PGD2, Resolvin D1, and Resolvin D4 were observed, although no significant multiplicative interactions were detected. Beneficial changes in circulating proresolving and proinflammatory mediators were found with 1-y of ω-3 fatty acid supplementation versus placebo for all participants, with a trend toward larger effects among those with low baseline fish intake, although interactions were not significant.

Oral Clostridium butyricum on mice endometritis through uterine microbiome and metabolic alternations.

Endometritis occurs frequently in humans and animals, which can negatively affect fertility and cause preterm parturition syndrome. Orally administered Clostridium butyricum, a butyrate-producing gram-positive anaerobe, exhibits anti-inflammatory effects. However, the precise mechanism by which Clostridium butyricum attenuates endometritis remains unclear. This in vivo study evaluated the anti-inflammatory effects of orally administered Clostridium butyricum on uterine tissues. In addition, we conducted uterine microbiome and lipid metabolome analyses to determine the underlying mechanisms. Female Balb/c mice were divided into the following four groups (n = 5-20): (1) mock group, (2) only operation group (mice only underwent operation to exposed uterine horns from the side), (3) control group (mice underwent the same operation with the operation group + perfusion of lipopolysaccharide solution from uterine horns), and (4) Clostridium butyricum administration group (mice underwent the same operation with the control group + oral Clostridium butyricum administration from days 0 to 9). Clostridium butyricum was administered via oral gavage. On day 10, we investigated protein expression, uterine microbiome, and lipid metabolism in uterine tissues. Consequently, orally administered Clostridium butyricum altered the uterine microbiome and induced proliferation of Lactobacillus and Limosilactobacillus species. The effects can contribute to show the anti-inflammatory effect through the interferon-β upregulation in uterine tissues. Additionally, oral Clostridium butyricum administration resulted in the upregulations of some lipid metabolites, such as ω-3 polyunsaturated fatty acid resolvin D5, in uterine tissues, and resolvin D5 showed anti-inflammatory effects. However, the orally administered Clostridium butyricum induced anti-inflammatory effect was attenuated with the deletion of G protein-coupled receptor 120 and 15-lipooxgenase inhibition. In conclusion, Clostridium butyricum in the gut has anti-inflammatory effects on uterine tissues through alterations in the uterine microbiome and lipid metabolism. This study revealed a gut-uterus axis mechanism and provided insights into the treatment and prophylaxis of endometritis.

Adiposity associates with lower plasma resolvin E1 (Rve1): a population study

BackgroundInadequate inflammation resolution may contribute to persistent low-grade inflammation that accompanies many chronic conditions. Resolution of inflammation is an active process driven by Specialized Pro-resolving Mediators (SPM) that derive from long chain n-3 and n-6 fatty acids. This study examined plasma SPM in relation to sex differences, lifestyle and a broad range cardiovascular disease (CVD) risk factors in 978, 27-year olds from the Australian Raine Study.MethodsPlasma SPM pathway intermediates (18-HEPE, 17-HDHA and 14-HDHA), and SPM (E- and D-series resolvins, PD1, MaR1) and LTB4 were measured by liquid chromatography-tandem mass spectrometry (LCMSMS). Pearson correlations and multiple regression analyses assessed relationships between SPM and CVD risk factors. Unpaired t-tests or ANOVA assessed the effect of sex, smoking, unhealthy alcohol consumption and obesity on SPM.ResultsWomen had higher 17-HDHA (p = 0.01) and lower RvE1 (p < 0.0001) and RvD1 (p = 0.05) levels compared with men. In univariate analysis, obesity associated with lower RvE1 (p = 0.002), whereas smoking (p < 0.001) and higher alcohol consumption (p < 0.001) associated with increased RvE1. In multiple regression analysis, plasma RvE1 was negatively associated with a range of measures of adiposity including BMI, waist circumference, waist-to-height ratio, abdominal subcutaneous fat volume, and skinfold thicknesses in both men and women.ConclusionThis population study suggests that a deficiency in plasma RvE1 may occur in response to increasing adiposity. This observation could be relevant to ongoing inflammation that associates with CVD and other chronic diseases.

Resolvin D1 (Rvd1) Attenuates In Vitro LPS-Stimulated Inflammation Through Downregulation of miR-155, miR -146, miR -148 and Krupple Like Factor 5.

Chronic inflammation is associated with many inflammatory diseases. Specialized pro-resolving mediators (SPMs) are well known for their crucial role in promoting the resolution phase of inflammation and restoring tissue homeostasis. Resolvin D1 (RvD1) is an endogenous omega-3-derived lipid mediator with pro-resolving activity. This study aimed to evaluate the effect of Resolvin D1 (RvD1) on some inflammatory miRNAs (mir-155-5p, miR146a-5p and miR148-3p) and Krüppel-like factors 5 (KLF5) in an LPS-stimulated THP-1 preclinical model of inflammation. PMA-differentiated THP-1 cells (macrophages) were pre-incubated with or without various concentrations of RvD1 (10, 50, or 100 nM) for 2 h prior to stimulation by 1 μg/ml LPS. Un-stimulated PMA-differentiated THP-1 cells were as the control group. Then, the expression levels of target genes were evaluated by real-time PCR. Compared with untreated macrophages, stimulation with 1 µg/ml LPS increased mRNA expression levels of TNF-α, KLF5, miR-155-5p, miR-146-5p, and miR-148a-3p. When the cells were exposed to various concentrations (10, 50 and 100 nM) of RvD1 for 2 h prior to LPS stimulation, the TNF-α, KLF5, miR-155-5p, miR-146-5p, and miR-148a-3p mRNA expression levels were significantly downregulated in a dose-dependent manner, compared to the LPS group. The results demonstrate that RvD1 can attenuate inflammatory response in LPS-stimulated macrophages. Our data also showed that RvD1 may exert anti-inflammatory effects by inhibiting miR-155-5p, miR-146a-5p, and miR-148-3p.

Resolvins protect against diabetes-induced colonic oxidative stress, barrier dysfunction, and associated diarrhea via the HO-1 pathway.

Diabetes is associated with increased oxidative stress, leading to altered tight junction formation and increased apoptosis in colonic epithelial cells. These changes may lead to intestinal barrier dysfunction and corresponding gastrointestinal symptoms in patients with diabetes, including diarrhea. The aim of this study was to characterize the effect and mechanism of Resolvin D1 (RvD1) on diabetes-induced oxidative stress and barrier disruption in the colon. Mice with streptozotocin-induced diabetes were treated with RvD1 for 2 weeks, then evaluated for stool frequency, stool water content, gut permeability, and colonic transepithelial electrical resistance as well as production of reactive oxygen species (ROS), apoptosis, and expression of tight junction proteins Zonula Occludens 1 (ZO-1) and occludin. The same parameters were assessed in human colonoid cultures subjected to elevated glucose. We found that RvD1 treatment did not affect blood glucose, but normalized stool water content and prevented intestinal barrier dysfunction, epithelial oxidative stress, and apoptosis. RvD1 also restored ZO-1 and occludin expression in diabetic mice. RvD1 treatment increased phosphorylation of Akt and was accompanied by a 3.5-fold increase in heme oxygenase-1 (HO-1) expression in the epithelial cells. The protective effects of RvD1 were blocked by ZnPP, a competitive inhibitor of HO-1. Similar findings were observed in RvD1-treated human colonoid cultures subjected to elevated glucose. In conclusion, Oxidative stress in diabetes results in mucosal barrier dysfunction, contributing to the development of diabetic diarrhea. Resolvins prevent ROS-mediated mucosal injury and protect gut barrier function by intracellular PI3K/Akt activation and subsequent HO-1 upregulation in intestinal epithelial cells. These actions result in normalizing stool frequency and stool water content in diabetic mice, suggesting that resolvins may be useful in the treatment of diabetic diarrhea.

Resolvin D1 as a novel target in the management of hypertension.

Resolvin D1 as a novel target in the management of hypertension.

P168 Specialized pro-resolving lipid mediator Resolvin D1 and omega 6 dihomo-γ-linolenic acid are unable to solve inflammation in the creeping fat of patients with severe postoperative recurrence in Crohn's disease

Abstract Background The ω3 derivate resolvin D1 (RvD1), and the ω6 dihomo-γ-linolenic acid (DGLA) prevent collateral damage by overcoming inflammation and enhancing microbial clearance. In Crohn's disease, the mesenteric adipose tissue becomes inflamed and hyperplasies due to transmural lesions and bacterial translocation, developing the so-called creeping fat. This tissue is unable to clear inflammation and has been linked to severer intestinal inflammation and post-operative recurrence (POR). Recently, we have described the presence of DGLA and the increase in the ω6/ω3 ratio together with pro-inflammatory mediators in the creeping fat at surgery. Our aims were study the mechanisms within the inflammatory resolution related to polyunsaturated fatty acids depending on POR severity. Methods Creeping fat samples were obtained in the intestinal resection of Crohn's disease patients and endoscopic POR was evaluated according to the Rutgeerts score: non recurrence (i0+i1; n=18), mild recurrence (i2; n=14) and severe recurrence (i3+i4; n=10). Mesenteric adipose tissue was also collected from patients with colorectal cancer (n=10) and severe obesity (n=11) as reference groups. RvD1 was evaluated by C18/ELISA, lipoprotein lipase (LPL) and hormone-sensitive lipase (HSL) activity by radioassay, and the free fatty acid receptor 1 (FFAR1) expression by qRT-PCR. Results RvD1 was increased in the creeping fat in comparison to the mesenteric adipose tissues of the reference groups (Graphical abstract A) and correlated antagonistically with pro-inflammatory mediators in non-recurrence versus severe recurrence (B). Specifically, factors such as TNF-α, CD14 or IL-18 showed significant positive correlations with RvD1 in severe recurrence while negative in non recurrence. The LPL/HSL ratio indicated greater storage of fatty acids in severe recurrence creeping fats (C), and only in these patients, DGLA negatively correlated with HSL (D) and FFAR1 (E), a receptor that was only detected in Crohn's disease (F). At the same time, this receptor antagonistically correlated with pro-inflammatory mediators such as IL-8 in the creeping fat, positively in non-recurrence and negatively in severe recurrence (G). Conclusion The RvD1 increase suggests a greater production of this factor from ω3, but that would be insufficient to resolve inflammation in severe recurrent creeping fat at surgery time. In this phenotype, HSL activity is linked to a lower presence of DGLA, the only anti-inflammatory ω6. In contrast, the presence of this ligand in severe recurrents seems to reduce the expression of the FFAR1, which acts on the neutrophil function. Thus, immune-inflammation derived from lipid metabolism is antagonistic among the most disparate cases of POR in the creeping fat at surgery.

Specialized proresolving mediator resolvin E1 corrects the altered cystic fibrosis nasal epithelium cilia beating dynamics

In cystic fibrosis (CF), impaired mucociliary clearance leads to chronic infection and inflammation. However, cilia beating features in a CF altered environment, consisting of dehydrated airway surface liquid layer and abnormal mucus, have not been fully characterized. Furthermore, acute inflammation is normally followed by an active resolution phase requiring specialized proresolving lipid mediators (SPMs) and allowing return to homeostasis. However, altered SPMs biosynthesis has been reported in CF. Here, we explored cilia beating dynamics in CF airways primary cultures and its response to the SPMs, resolvin E1 (RvE1) and lipoxin B4 (LXB4). Human nasal epithelial cells (hNECs) from CF and non-CF donors were grown at air-liquid interface. The ciliary beat frequency, synchronization, orientation, and density were analyzed from high-speed video microscopy using a multiscale Differential Dynamic Microscopy algorithm and an in-house developed method. Mucins and ASL layer height were studied by qRT-PCR and confocal microscopy. Principal component analysis showed that CF and non-CF hNEC had distinct cilia beating phenotypes, which was mostly explained by differences in cilia beat organization rather than frequency. Exposure to RvE1 (10 nM) and to LXB4 (10 nM) restored a non-CF-like cilia beating phenotype. Furthermore, RvE1 increased the airway surface liquid (ASL) layer height and reduced the mucin MUC5AC thickness. The calcium-activated chloride channel, TMEM16A, was involved in the RvE1 effect on cilia beating, hydration, and mucus. Altogether, our results provide evidence for defective cilia beating in CF airway epithelium and a role of RvE1 and LXB4 to restore the main epithelial functions involved in the mucociliary clearance.

Lipid mediators obtained from docosahexaenoic acid by soybean lipoxygenase attenuate RANKL-induced osteoclast differentiation and rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic immune-mediated inflammatory disease characterized by persistent inflammation and joint destruction. A lipid mediator (LM, namely, 17S-monohydroxy docosahexaenoic acid, resolvin D5, and protectin DX in a ratio of 3:47:50) produced by soybean lipoxygenase from DHA, exhibits anti-inflammatory activity. In this study, we determined the effect of LM on collagen antibody-induced arthritis (CAIA) in mice and receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast formation in RAW264.7 cells. LM effectively downregulated the expression of tartrate-resistant acid phosphatase (TRAP) and cathepsin K, inhibited osteoclast formation, and suppressed the NF-κB signaling pathway in vitro. In vivo, LM at 10 μg/kg/day significantly decreased paw swelling and inhibited progression of arthritis in CAIA mice. Moreover, proinflammatory cytokine (tumor necrosis factor-α, interleukin (IL)-6, IL-1β, IL-17, and interferon-γ) levels in serum were decreased, whereas IL-10 levels were increased following LM treatment. Furthermore, LM alleviated joint inflammation, cartilage erosion, and bone destruction in the ankles, which may be related to matrix metalloproteinase and Janus kinase (JAK)–signal transducer and activators of transcription (STAT) signaling pathway. Our findings suggest that LM attenuates arthritis severity, restores serum imbalances, and modifies joint damage. Thus, LM represents a promising therapy for relieving RA symptoms.

Semaphorin3B promotes an anti-inflammatory and pro-resolving phenotype in macrophages from rheumatoid arthritis patients in a MerTK-dependent manner.

Previous works from our group show that Semaphorin3B (Sema3B) is reduced in RA and plays a protective role in a mouse arthritis model. In turn, MerTK plays a protective function in murine arthritis models, is expressed by synovial tissue macrophages and is linked to remission in patients with RA. In this study, we examined the role of Sema3B in the phenotypic characteristics of RA macrophages and the implication of MerTK. Peripheral blood monocytes from RA patients were differentiated into IFN-γ (RA MØIFN-γ) or M-CSF (RA MØM-CSF) macrophages and stimulated with LPS, Sema3B or their combination. Alternatively, RA fibroblast like synoviocytes (FLS) were stimulated with RA MØIFN-γ and RA MØM-CSF supernatants. Gene expression was determined by qPCR and protein expression and activation by flow cytometry, ELISA and western blot. Sema3B down-regulated the expression of pro-inflammatory mediators, in both RA MØIFN-γ and RA MØM-CSF. We observed a similar reduction in RA FLS stimulated with the supernatant of Sema3B-treated RA MØIFN-γ and RA MØM-CSF. Sema3B also modulated cell surface markers in macrophages towards an anti-inflammatory phenotype. Besides, MerTK expression and activation was up-regulated by Sema3B, just as GAS6 expression, Resolvin D1 secretion and the phagocytic activity of macrophages. Importantly, the inhibition of MerTK and neuropilins 1 and 2 abrogated the anti-inflammatory effect of Sema3B. Our data demonstrate that Sema3B modulates the macrophage characteristics in RA, inducing a skewing towards an anti-inflammatory/pro-resolving phenotype in a MerTK-dependant manner. Therefore, here we identify a new mechanism supporting the protective role of Sema3B in RA pathogenesis.

ChemR23 signaling ameliorates brain injury via inhibiting NLRP3 inflammasome-mediated neuronal pyroptosis in ischemic stroke

BackgroundInflammatory response has been recognized as a pivotal pathophysiological process during cerebral ischemia. ChemR23 signaling is involved in the pathophysiology of various inflammatory diseases. Nevertheless, the role of ChemR23 signaling in ischemic stroke remains largely unknown.MethodsPermanent ischemic stroke mouse model was accomplished by middle cerebral artery occlusion (MCAO). Resolvin E1 (RvE1) or chemerin-9 (C-9), the agonists of ChemR23, were administered by intracerebroventricular (i.c.v) injection before MCAO induction. Then, analysis of neurobehavioral deficits and brain sampling were done at Day 1 after MCAO. The brain samples were further analyzed by histological staining, immunofluorescence, RNA sequencing, ELISA, transmission electron microscope, and western blots. Furthermore, oxygen–glucose deprivation (OGD) was employed in SH-SY5Y to mimic MCAO in vitro, and ChemR23 signaling pathway was further studied by overexpression of ChemR23 or administration of related agonists or antagonists. Analysis of cell death and related pathway markers were performed.ResultsChemR23 expression was upregulated following MCAO. Under in vitro and in vivo ischemic conditions, ChemR23 deficiency or inhibition contributed to excessive NLRP3-mediated maturation and release of IL-1β and IL-18, as well as enhanced cleavage of GSDMD-N and neuronal pyroptosis. These influences ultimately aggravated brain injury and neuronal damage. On the other hand, ChemR23 activation by RvE1 or C-9 mitigated the above pathophysiological abnormalities in vivo and in vitro, and overexpression of ChemR23 in SH-SY5Y cells also rescued OGD-induced neuronal pyroptosis. Blockade of NLRP3 mimics the protective effects of ChemR23 activation in vitro.ConclusionOur data indicated that ChemR23 modulates NLRP3 inflammasome-mediated neuronal pyroptosis in ischemic stroke. Activation of ChemR23 may serve as a promising potential target for neuroprotection in cerebral ischemia.