Resolvin D1 level during different trimesters of pregnancy for predicting the risk of fetal growth retardation in elderly pregnancy

Resolvin D1 (RvD1) is potentially associated with fetal growth retardation (FGR) through alleviating maternal inflammation and its linkage with several pregnancy complications. Thus, this study detected RvD1 levels at different trimesters of pregnancy, aiming to investigate its role in predicting FGR risk of elderly pregnant women. This prospective, observational cohort study enrolled 165 elderly pregnant women aged ≥35 years. Serum RvD1 was detected at 10-13 weeks (early pregnancy), 20-23 weeks (middle pregnancy), and 30-33 weeks (late pregnancy) of gestational week by enzyme-linked immunosorbent assay. RvD1 was varied among different trimesters of pregnancy in elderly pregnant women (p < 0.001). FGR occurred in 25 (15.2%) women in this study. RvD1 at early (p = 0.009), middle (p = 0.002), and late (p = 0.003) pregnancy was decreased in women with FGR versus those without. By multivariate analysis, RvD1 at middle pregnancy (odds ratio (OR): 0.477, p < 0.001), pre-pregnancy body mass index (OR: 0.763, p = 0.025), and gestational diabetes mellitus (yes versus no) (OR: 0.071, p = 0.031) were independently correlated with declined FGR risk. While age (OR: 1.382, p = 0.009) was independently associated with elevated risk of FGR. Furthermore, the combination of these independent factors as a predictive model exhibited a good potential for assessing FGR risk (area under the curve: 0.802, 95% confidence interval: 0.711-0.894). In conclusion, RvD1 at different trimesters of pregnancy is negatively linked with the risk of FGR, whose level at middle pregnancy serves as an independent factor for FGR risk in elderly pregnant women.

The relationship between serum resolvin D1, NLRP3, cytokine levels, and adolescents with first-episode medication-naïve major depressive disorder

BACKGROUND

Inflammation has become a critical pathological mechanism of Major Depressive Disorder (MDD). NLRP3 is a critical inflammatory pathway to maintain the immune balance. Recently, preclinical evidence showed that Resolvin D1 might potentially offer a new option for antidepressant treatment due to its protective effects through the inhibition of neuroinflammation. However, whether they have clinical value in the diagnosis and treatment evaluation of adolescent depression was unclear.

METHODS

Forty-eight untreated first-episode adolescent patients with moderate to severe major depressive disorder, as well as 30 healthy adolescents (HCs, age and gender-matched), were enrolled for this study. Their ages ranged from 13 to 18 (15.75 ± 1.36) years. The patients were treated with fluoxetine for 6-8 weeks. HDRS-17 was used to evaluate the severity of depressive symptoms. Venous blood samples were collected at baseline for the two groups and at the time-point of post-antidepressant treatment for the patients. Serum concentrations of RvD1, NLRP3, IL-1β, IL-18, and IL-4 were measured by enzyme-linked immunosorbent assays (ELISA) pre- and post-fluoxetine treatment.

RESULTS

Serum levels of RvD1 and anti-inflammatory cytokine IL-4 were significantly elevated in adolescents with MDD compared to healthy adolescents, but no significant difference in NLRP3, IL-1β, and IL-18 between the two groups. Meanwhile, RvD1 (positively) and IL-4 (negatively) were correlated with the severity of symptoms (HDRS-17 scores) after adjusting age, gender, and BMI. Interestingly, fluoxetine treatment significantly reduced the serum levels of RvD1, NLRP3, IL-1β, and IL-18 in MDD adolescents but increased the levels of IL-4 relative to baseline. Furthermore, we observed that serum levels of RvD1 might be an excellent distinguishing indicator for depression and healthy adolescents.

CONCLUSIONS

Our study is the first to compare RvD1 and NLRP3 between adolescent MDD and HCs. Our findings of reactive increase of RvD1 in adolescent MDD comprised a novel and critical contribution. Our results showed the presence of inflammation resolution unbalanced in adolescents with MDD and indicated that RvD1 might be an ideal biomarker for diagnosing and treating adolescent MDD.

Resolvin D1 alleviates apoptosis triggered by endoplasmic reticulum stress in IPEC-J2 cells

BACKGROUND

Resolvin D1 (RvD1), a specialized pro-resolving lipid mediator (SPM), is derived from docosahexaenoic acid (DHA). It plays a key role in actively resolving inflammatory responses, which further reduces small intestinal damage. However, its regulation of the apoptosis triggered by endoplasmic reticulum (ER) stress in intestinal epithelial cells is still poorly understood. The intestinal porcine epithelial cells (IPEC-J2) were stimulated with tunicamycin to screen an optimal stimulation time and concentration to establish an ER stress model. Meanwhile, RvD1 (0, 1, 10, 20, and 50 nM) cytotoxicity and its impact on cell viability and the effective concentration for reducing ER stress and apoptosis were determined. Finally, the effects of RvD1 on ER stress and associated apoptosis were furtherly explored by flow cytometry analysis, AO/EB staining, RT-qPCR, and western blotting.

RESULTS

The ER stress model of IPEC-J2 cells was successfully built by stimulating the cells with 1 µg/mL tunicamycin for 9 h. Certainly, the increased apoptosis and cell viability inhibition also appeared under the ER stress condition. RvD1 had no cytotoxicity, and its concentration of 1 nM significantly decreased cell viability inhibition (p= 0.0154) and the total apoptosis rate of the cells from 14.13 to 10.00% (p= 0.0000). RvD1 at the concentration of 1 nM also significantly reduced the expression of glucose-regulated protein 78 (GRP-78, an ER stress marker gene) (p= 0.0000) and pro-apoptotic gene Caspase-3 (p= 0.0368) and promoted the expression of B cell lymphoma 2 (Bcl-2, an anti-apoptotic gene)(p= 0.0008).

CONCLUSIONS

Collectively, the results shed light on the potential of RvD1 for alleviating apoptosis triggered by ER stress, which may indicate an essential role of RvD1 in maintaining intestinal health and homeostasis.

Development of New Resolvin D1 Analogues for Osteoarthritis Therapy: Acellular and Computational Approaches to Study Their Antioxidant Activities

In osteoarthritis (OA), oxidative stress plays a crucial role in maintaining and sustaining cartilage degradation. Current OA management requires a combination of pharmaceutical and non-pharmacological strategies, including intraarticular injections of hyaluronic acid (HA). However, several lines of evidence reported that HA oxidation by reactive oxygen species (ROS) is linked with HA cleavage and fragmentation, resulting in reduced HA viscosity. Resolvin D1 (RvD1) is a lipid mediator that is biosynthesized from omega-3 polyunsaturated fatty acids and is a good candidate with the potential to regulate a panoply of biological processes, including tissue repair, inflammation, oxidative stress, and cell death in OA. Herein, newly designed and synthesized imidazole-derived RvD1 analogues were introduced to compare their potential antioxidant properties with commercially available RvD1. Their antioxidant capacities were investigated by several in vitro chemical assays including oxygen radical absorbance capacity, 2,2-diphenyl-1-picrylhydrazyl radical scavenging, ferric ion reducing antioxidant power, hydroxyl radical scavenging, and HA fragmentation assay. All results proved that imidazole-derived RvD1 analogues showed excellent antioxidant performance compared to RvD1 due to their structural modifications. Interestingly, they scavenged the formed reactive oxygen species (ROS) and protected HA from degradation, as verified by agarose gel electrophoresis and gel permission chromatography. A computational study using Gaussian 09 with DFT calculations and a B3LYP/6-31 G (d, p) basis set was also employed to study the relationship between the antioxidant properties and chemical structures as well as calculation of the molecular structures, frontier orbital energy, molecular electrostatic potential, and bond length. The results showed that the antioxidant activity of our analogues was higher than that of RvD1. In conclusion, the findings suggest that imidazole-derived RvD1 analogues can be good candidates as antioxidant molecules for the treatment of oxidative stress-related diseases like OA. Therefore, they can prolong the longevity of HA in the knee and thus may improve the mobility of the articulation.

RvD1 improves resident alveolar macrophage self-renewal via the ALX/MAPK14/S100A8/A9 pathway in acute respiratory distress syndrome

INTRODUCTION

Acute respiratory distress syndrome (ARDS) is a pulmonary inflammatory process primarily caused by sepsis. The resolution of inflammation is an active process involving the endogenous biosynthesis of specialized pro-resolving mediators, including resolvin D1 (RvD1). Resident alveolar macrophages (RAMs) maintain pulmonary homeostasis and play a key role in the resolution phase. However, the role of RAMs in promoting the resolution of inflammation by RvD1 is unclear.

OBJECTIVES

Here, we investigated the mechanisms of RvD1 on regulating RAMs to promote the resolution of ARDS.

METHODS

Mice were administered lipopolysaccharide and/or Escherichia coli via aerosol inhalation to establish a self-limited ARDS model. Then, RvD1 was administered at the peak inflammatory response. RAMs self-renewal was measured by flow cytometry, RAM phagocytosis was measured by two-photon fluorescence imaging. In addition, plasma was collected from intensive care unit patients on days 0-2, 3-5, and 6-9 to measure RvD1 and S100A8/A9 levels using triple quadrupole/linear ion trap mass spectrometry.

RESULTS

RAMs were found to play a pivotal role in resolving inflammation during ARDS, and RvD1 enhanced RAM proliferation and phagocytosis, which was abrogated by a lipoxin A4 receptor (ALX, RvD1 receptor) inhibitor. Both primary RAMs transfected with rS100A8/A9 and/or S100A8/A9 siRNA and S100A9-/- mice (also deficient in S100A8 function) showed higher turnover and phagocytic function, indicating that RvD1 exerted its effects on RAMs by inhibiting S100A8/A9 production in the resolution phase. RvD1 reduced S100A8/A9 and its upstream MAPK14 levels in vivo and in vitro. Finally, in the patients, RvD1 levels were lower, but S100A8/A9 levels were higher.

CONCLUSIONS

We propose that RvD1 improved RAM self-renewal and phagocytosis via the ALX/MAPK14/S100A8/A9 signaling pathway. Plasma RvD1 and S100A8/A9 levels were negatively correlated, and associated with the outcome of sepsis-induced ARDS.

Promoting the proliferation of osteoarthritis chondrocytes by resolvin D1 regulating the NLRP3/caspase-1 signaling pathway

Osteoarthritis (OA) is a degenerative joint disease commonly found in middle-aged and older people. Chondrocytes are the only cells in joint cartilage that are difficult to heal after pyroptosis, and they will aggravate the wear and tear of joint cartilage and affect the progression of OA. Pyroptosis is a novel form of programmed cell death, and the classical pyroptosis pathway is a programmed cell death pattern mediated by inflammatory cysteine protease-1. Activation of NLRP3 leads to activation and cleavage of caspase-1 precursors, which in turn leads to activation and cleavage of GSDMD proteins and the release of proinflammatory factors. Resolvin D1 (RvD1) is a specialized pro-resolving mediator (SPM) derived from omega-3 unsaturated fatty acids that reduces inflammation and catabolic responses in OA chondrocytes. However, it is unclear whether RvD1 promotes OA chondrocyte proliferation and thus joint cartilage repair. Our results show that RvD1 regulates the NLRP3/caspase-1 signaling pathway by inhibiting the expression of caspase-1, promoting the proliferation of OA chondrocytes, promoting the repair of articular cartilage in rats and delaying the progression of osteoarthritis.

Resolvin D1 reprograms energy metabolism to promote microglia to phagocytize neutrophils after ischemic stroke

Neutrophil aggregation and clearance are important factors affecting neuroinflammatory injury during acute ischemic stroke. Emerging evidence suggests that energy metabolism is essential for microglial functions, especially microglial phagocytosis, which determines the degree of brain injury. Here, we demonstrate that Resolvin D1 (RvD1), a lipid mediator derived from docosahexaenic acid (DHA), promotes the phagocytosis of neutrophils by microglia, thereby reducing neutrophil accumulation in the brain and alleviating neuroinflammation in the ischemic brain. Further studies reveal that RvD1 reprograms energy metabolism from glycolysis to oxidative phosphorylation (OXPHOS), providing sufficient energy for microglial phagocytosis. Moreover, RvD1 enhances microglial glutamine uptake and stimulates glutaminolysis to support OXPHOS to boost ATP production depending on adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) activation. Overall, our results reveal that RvD1 reprograms energy metabolism to promote the microglial phagocytosis of neutrophils after ischemic stroke. These findings may guide perspectives for stroke therapy from modulating microglial immunometabolism.

Prognostic significance of serum resolvin D1 levels in patients with acute supratentorial intracerebral hemorrhage: a prospective longitudinal cohort study

OBJECTIVE

Resolvin D1 (RvD1) has anti-inflammatory properties and may be neuroprotective. This study was designed to assess usability of serum RvD1 as a prognostic biomarker after intracerebral hemorrhage (ICH).

METHODS

In this prospective, observational study of 135 patients and 135 controls, serum RvD1 levels were measured. Its relations to severity, early neurologic deterioration (END) and poststroke 6-month worse outcome (modified Rankin Scale scores of 3-6) were determined via multivariate analysis. Predictive effectiveness was evaluated based on area under receiver operating characteristic curve (AUC).

RESULTS

Patients had markedly lower serum RvD1 levels than controls (median, 0.69 ng/ml versus 2.15 ng/ml). Serum RvD1 levels were independently correlated with the National Institutes of Health Stroke Scale (NIHSS) [β, -0.036; 95% confidence interval (CI), -0.060--0.013; VIF, 2.633; t=-3.025; P=0.003] and hematoma volume (β, -0.019; 95% CI, -0.056--0.009; VIF, 1.688; t=-2.703; P=0.008). Serum RvD1 levels substantially discriminated risks of END and worse outcome with AUCs at 0.762 (95% CI, 0.681-0.831) and 0.783 (95% CI, 0.704-0.850) respectively. A RvD1 cut-off value of 0.85 ng/ml was effective in predicting END with a sensitivity of 95.0% and specificity of 48.4% and its levels <0.77 ng/ml distinguished patients at risk of worse outcome with a sensitivity of 84.5% and specificity of 63.6%. Under restricted cubic spline, serum RvD1 levels were linearly related to risk of END and worse outcome (both P>0.05). Serum RvD1 levels and NIHSS scores independently predicted END with odds ratio (OR) values of 0.082 (95% CI, 0.010-0.687) and 1.280 (95% CI, 1.084-1.513) respectively. Serum RvD1 levels (OR, 0.075; 95% CI, 0.011-0.521), hematoma volume (OR, 1.084; 95% CI, 1.035-1.135) and NIHSS scores (OR, 1.240; 95% CI, 1.060-1.452) were independently associated with worse outcome. END prediction model containing serum RvD1 levels and NIHSS scores, and prognostic prediction model containing serum RvD1 levels, hematoma volumes and NIHSS scores displayed efficient predictive ability with AUCs at 0.828 (95% CI, 0.754-0.888) and 0.873 (95% CI, 0.805-0.924) respectively. Such two models were visually shown via building two nomograms. Using Hosmer-Lemeshow test, calibration curve and decision curve, the models were comparatively stable and had clinical benefit.

CONCLUSION

There is a dramatical declination of serum RvD1 levels after ICH, which is tightly related to stroke severity and is independently predictive of poor clinical outcome, implying that serum RvD1 may be of clinical significance as a prognostic marker of ICH.

Chitosan 3D scaffolds with resolvin D1 for vertebral arthrodesis: a pilot study

PURPOSE

Over the last years, the number of vertebral arthrodesis has been steadily increasing. The use of iliac crest bone autograft remains the "gold standard" for bone graft substitute in these procedures. However, this solution has some side effects, such as the problem of donor site morbidity indicating that there is a real need for adequate alternatives. This pilot study aimed to evaluate the usefulness of chitosan (Ch) porous 3D scaffolds incorporated with resolvin D1 (RvD1) as an alternative implant to iliac bone autograft.

METHODS

We have performed bilateral posterolateral lumbar vertebral arthrodesis in a rat animal model. Three experimental groups were used: (i) non-operated animals; (ii) animals implanted with Ch scaffolds incorporated with RvD1 and (iii) animals implanted with iliac bone autograft.

RESULTS

The collagenous fibrous capsule formed around the Ch scaffolds with RvD1 is less dense when compared with the iliac bone autograft, suggesting an important anti-inflammatory effect of RvD1. Additionally, new bone formation was observed in the Ch scaffolds with RvD1.

CONCLUSION

These results demonstrate the potential of these scaffolds for bone tissue repair applications.

Resolvin D1 attenuates depressive-like behavior in LPS-challenged mice by promoting microglial autophagy

It has been proven that neuroinflammation triggered by microglial activation is the pathogenesis of depression associated with sepsis. An endogenous lipid mediator known as resolvin D1 (RvD1) is known to have anti-inflammatory effects in a sepsis model. However, it remains unknown if the effects of RvD1 on inflammatory responses are regulated by microglial autophagy. The current study investigated the role of RvD1-induced microglial autophagy in neuroinflammation. The findings showed that RvD1 reverses LPS-induced autophagy inhibition in microglia. RvD1 treatment significantly inhibits inflammatory responses by preventing NF-κB nuclear translocation and microglial M1 phenotypic transition. RvD1 exhibits an attenuation of neurotoxicity in both in vivo and in vitro models of sepsis. Following RvD1 injection, depressive-like behaviors in SAE mice were significantly improved. Notably, the aforesaid effects of RvD1 were eliminated by 3-MA, demonstrating that microglial autophagy was modulated. In conclusion, our findings shed new light on the involvement of microglial autophagy in SAE and emphasize the potential benefits of RvD1 as a promising therapeutic agent in the treatment of depression.

Mast cells contribute to the resolution of allergic inflammation by releasing resolvin D1

BACKGROUND

Mast cells are initiators and main effectors of allergic inflammation, together with eosinophils, with whom they can interact in a physical and soluble cross-talk with marked pro-inflammatory features, the Allergic Effector Unit. The pro-resolution role of mast cells, alone or in co-culture with eosinophils, has not been characterized yet.

OBJECTIVES

We aimed to investigate select pro-resolution pathways in mast cells in vitro and in vivo in allergic inflammation.

METHODS

In vitro, we employed human and murine mast cells and analyzed release of resolvin D1 and expression of 15-lipoxygenase after IgE-mediated activation. We performed co-culture of IgE-activated mast cells with peripheral blood eosinophils and investigated 15-lipoxygenase expression and Resolvin D1 release. In vivo, we performed Ovalbumin/Alum and Ovalbumin/S. aureus enterotoxin B allergic peritonitis model in Wild Type mice following a MC "overshoot" protocol.

RESULTS

We found that IgE-activated mast cells release significant amounts of resolvin D1 30 min after activation, while 15-lipoxygenase expression remained unchanged. Resolvin D1 release was found to be decreased in IgE-activated mast cells co-cultured with peripheral blood eosinophils for 30 min In vivo, mast cell-overshoot mice exhibited a trend of reduced inflammation, together with increased peritoneal resolvin D1 release.

CONCLUSIONS

Mast cells can actively contribute to resolution of allergic inflammation by releasing resolvin D1.

Resolvin D1 shows osseous-protection via RANK reduction on monocytes during orthodontic tooth movement

The study aimed to investigate the role of RvD1 in acute and prolonged sterile inflammation and bone remodeling. A mouse model of sterile inflammation that involves bone resorption was used to examine endogenous RvD1 kinetics during inflammation. Application of exogenous RvD1 significantly inhibited bone remodeling via osteoclast reduction, alongside an anti-inflammatory secretome shift, increased macrophages recruitment and reduction of T-cytotoxic cells. In vitro and in vivo, RvD1 led to significant reduction in RANK expression which reduce osteoclastogenesis in a dose-dependent manner. Taken together, the data shows a dual role for RvD1, as a potent immunoresolvent agent alongside an osteoresolvent role, showing a potential therapeutic agent in bone resorption associated inflammatory conditions.

Resolvin D1 Prevents Epithelial-to-Mesenchymal Transition and Reduces Collagen Deposition by Stimulating Autophagy in Intestinal Fibrosis

BACKGROUND

Intestinal fibrosis is the most common complication of inflammatory bowel disease; nevertheless, specific therapies are still unavailable. Resolvin D1 (RvD1), a typical endogenous ω-3 fatty acid-derived lipid mediator, has attracted wide attention due to its remarkable anti-fibrosis effects. However, the efficacy and mechanisms of RvD1 in intestinal fibrosis remain unclear.

AIM

To investigate the protective effect of RvD1 in a dextran sulfate sodium (DSS)-induced intestinal fibrosis model and explore the molecular mechanisms underlying its anti-fibrotic effect.

METHODS

A DSS-induced intestinal fibrosis model and intestinal epithelial-to-mesenchymal transition (EMT) model were used to observe the efficacy of RvD1, and fibroblasts were stimulated with conditioned medium with or without TGF-β1 to investigate the probable mechanisms of RvD1 in intestinal fibrosis disease.

RESULTS

Intestinal fibrosis was effectively alleviated by RvD1 in a DSS-induced model, both preventively and therapeutically, and autophagy inhibition-induced EMT in intestinal epithelial cells was significantly suppressed in vivo and in vitro. Furthermore, RvD1 reduced epithelial cell EMT paracrine signaling, which promoted the differentiation of local fibroblasts into myofibroblasts.

CONCLUSIONS

Our results suggested that RvD1 reduces autophagy-induced EMT in intestinal epithelial cells and ameliorates intestinal fibrosis by disrupting epithelial-fibroblast crosstalk.

Resolvin D1 protects against sepsis-associated encephalopathy in mice by inhibiting neuro-inflammation induced by microglia

OBJECTIVES

Neuro-inflammation induced by microglia is crucial in the pathogenesis of sepsis-associated encephalopathy (SAE). The endogenous lipid mediator, Resolvin D1 (RvD1), which is synthesized from docosahexaenoic acid, has been extensively reported to attenuate inflammation in various diseases by its anti-inflammation and pro-resolving functions. However, the effect of RvD1 on SAE remains unclear. In this study, we aimed to ex the function and mechanism of RvD1 on SAE mice.

METHODS

In our study, the SAE mice model was established by the method of cecal ligation and perforation (CLP). C57BL/6J mice were randomly divided into three groups: the Sham group, the CLP group and the CLP+RvD1 group. Cognitive impairment of the mice was assessed by Morris water maze. Iba1 immunohistochemistry was conducted to observe the activation of microglia in hippocampus of the mice from different groups. The production of cytokines, including TNF-α, IL-6 and IL-1β, and their mRNA levels were evaluated by ELISA and Q-PCR. The expression of the molecules from inflammatory signaling pathways was assessed by Western blot.

RESULTS

xaRvD1 treatment significantly improved the learning and cognitive ability of SAE mice. The activation of microglia and the production of inflammatory cytokines in hippocampal tissues were inhibited in CLP+RvD1 group. We also found that the inflammation of microglia was attenuated by RvD1 treatment both in vivo and in vitro. Moreover, the activation of NF-κB, MAPK and STAT signaling pathways were inhibited by RvD1 treatment, which partly explained the anti-inflammation function of RvD1 on SAE mice.

CONCLUSIONS

RvD1 could improve the learning and cognitive ability of SAE mice by inhibiting the systemic and local inflammation. It could attenuate the inflammation in microglia by inhibiting the activation of inflammatory signaling pathways and then decreasing the production of cytokines. These findings are helpful to better understand the pathophysiology of SAE, which also provide a novel therapeutic method in clinic.

Impact of Resolvin D1 on the inflammatory phenotype of periodontal ligament cell response to hypoxia

OBJECTIVE

Periodontal ligament cells (PDLCs) are critical for wound healing and regenerative capacity of periodontal diseases. Within an inflammatory periodontal pocket, a hypoxic environment can aggravate periodontal inflammation, where PDLCs response to the inflammation would change. Resolvin D1 (RvD1) is an endogenous lipid mediator, which can impact intracellular inflammatory pathways of periodontal/oral cells and periodontal regeneration. It is not clear how hypoxia and RvD1 impact the inflammatory responses of pro-inflammatory PDLCs phenotype. Therefore, this study aimed to test hypoxia could induce changes in pro-inflammatory phenotype of PDLCs and RvD1 could reverse it.

METHODS

Human PDLCs were cultured from periodontal tissues from eight healthy individuals and were characterized by immunofluorescence staining of vimentin and cytokeratin. Cell viability was examined by Methyl-thiazolyl-tetrazolium (MTT) assay. To examine the effects of hypoxia and RvD1 on the inflammatory responses of pro-inflammatory PDLCs phenotype, protein levels and gene expressions of inflammatory cytokines and signal transduction molecules were measured by enzyme-linked immunosorbent assay (ELISA), western blotting (WB), and real-time quantitative reverse transcription PCR (real-time qRT-PCR). Alizarin red S staining and real-time qRT-PCR were employed to study the effects of hypoxia and RvD1 on the osteogenic differentiation of pro-inflammatory PDLCs phenotype.

RESULTS

It was found that hypoxia increases the expression of inflammatory factors at the gene level (p < .05). RvD1 reduced the expression of IL-1β (p < .05) in PDLCs under hypoxia both at the protein and RNA levels. There were increases in the expression of p38 mitogen-activated protein kinase (p38 MAPK, p < .01) and protein kinase B (Akt, p < .05) in response to RvD1. Also, a significantly higher density of calcified nodules was observed after treatment with RvD1 for 21 days under hypoxia.

CONCLUSION

Our results indicate that hypoxia up-regulated the inflammatory level of PDLCs. RvD1 can reduce under-hypoxia-induced pro-inflammatory cytokines in the inflammatory phenotype of PDLCs. Moreover, RvD1 promotes the calcium nodules in PDLCs, possibly by affecting the p38 MAPK signaling pathway through Akt and HIF-1α.

Identifying the shared genes and KEGG pathways of Resolvin D1-targeted network and osteoarthritis using bioinformatics

Osteoarthritis (OA) is a common chronic degenerative disease characterized by the loss of articular cartilage, which causes loss of joint function and reduce quality of life. Resolvin D1 (RvD1) has shown interesting anti-inflammatory effects; however, the mechanism of action of RvD1 in OA remains unclear. The aim of this study was to investigate the potential mechanism of RvD1 in OA by bioinformatics and partial in vitro mechanisms. Here, 106 shared differentially expressed genes (DEGs) were identified based on the GSE82107, GSE55235, GSE55457 dataset; 700 DEGs were identified based on GSE169077. Enrichment analyses of these genes were then successively conducted. RvD1-targeted genes and KEGG pathways are identified by STITCH. 27 shared KEGG pathways were identified among RvD1-targeted pathways and OA. Furthermore, cell apoptosis assay, western blotting, real-time fluorescent quantitative PCR (qRT-PCR), enzyme linked immunosorbent assay (ELISA) were used to confirm the expression levels of the key genes of shared Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways between RvD1-targeted and OA in IL-1β treated rat knee chondrocytes. The results showed that RvD1-targeted pathways and the expression of nuclear p65, p53, and p-JNK were inhibited in the RvD1 group compared with the IL-1β group. Thus, the findings indicate that RvD1 may inhibit the development of OA through NF/kB, p53, MAPK/JNK, PI3K-AKT signaling pathways, and act as a treatment for OA.

The role of Resolvin D1 in liver diseases

The liver is a parenchymatous organ closely related to immunity, detoxification and metabolism of the three major nutrients. The inflammatory response is a protective mechanism of the body to eliminate harmful stimuli. However, continuous inflammatory stimulation leads to occurrence of many liver diseases and brings great social burden. Resolvin D1, a member of the specialized pro-resolving lipid mediators family, exerts anti-inflammatory, anti-oxidant stress, anti-fibrosis, anti-apoptotic, and anti-tumor effects by binding to ALX/FPR2 or GPR32. RvD1 plays an important role and has great therapeutic potential in liver diseases, which has been validated in multiple models of preclinical disease. This review will provide a detailed summary of the role of RvD1 in different liver diseases, including acute liver injury, liver ischemia/reperfusion injury, non-alcoholic fatty liver disease, liver fibrosis, and liver cancer, so as to help people have a more comprehensive understanding of RvD1 and promote its further research.

Resolvin D1 inhibits the proliferation of osteoarthritis fibroblast-like synoviocytes through the Hippo-YAP signaling pathway

Objective

Osteoarthritis (OA) is a disease characterized by cartilage degradation and structural destruction. Resolvin D1 (RvD1), a specialized proresolving mediator (SPM) derived from omega-3 fatty acids, has been preliminarily proven to show anti-inflammatory and antiapoptotic effects in OA. However, the mechanisms of RvD1 in osteoarthritis fibroblast-like synoviocytes (OA-FLSs) need to be clarified.

Methods

Synovial and fibroblast-like synoviocytes were obtained from OA patients and healthy individuals. MTT and EdU assays were performed to determine cell cytotoxicity and proliferation. The protein expression levels of cyclin D1, cyclin B1, PCNA, p53, MMP-13, YAP, p-YAP, and LATS1 were detected by western blot analysis. The release levels of IL-1β were detected by ELISA. The cell cycle was assessed by flow cytometry. Immunofluorescence was used to detect the levels of YAP in OA-FLSs.

Results

RvD1 inhibited OA-FLS proliferation and reduced MMP-13 and IL-1β secretion in the concentrations of 20 nM and 200 nM. Furthermore, RvD1 induced G2 cell cycle arrest in OA-FLSs via the Hippo-YAP signaling pathway and promoted YAP phosphorylation. However, RvD1 had no effects on normal FLSs.

Conclusions

RvD1 inhibits OA-FLS proliferation by promoting YAP phosphorylation and protects chondrocytes by inhibiting the secretion of MMP-13 and IL-1β, providing an experimental basis for RvD1 treatment of OA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05095-1.

Resolvin D1 ameliorates hepatic steatosis by remodeling the gut microbiota and restoring the intestinal barrier integrity in DSS-induced chronic colitis

BACKGROUND AND PURPOSE

The maintenance of intestinalmucosalbarrier function plays an important role in hepatic steatosis. Increasing evidence has shown that resolvin D1 (RVD1) exerts a potential effect on hepatic steatosis. The aims of this study were to explore the mechanisms of RVD1 on hepatic steatosis based on the gut-liver axis and intestinal barrier function.

EXPERIMENTAL APPROACH

We established a DSS-induced chronic colitis model to evaluate hepatic steatosis. RVD1 was administered i.p. during the last 4 weeks. The colon and liver samples were stained with hematoxylin and eosin for histopathological analysis. The expression levels of intestinal tight junction genes and inflammatory genes were determined by quantitative PCR. The serum levels of glucose, cholesterol, triglycerides and LPS were measured, and the gut microbiota was analyzed by 16S rRNA gene sequencing.

KEY RESULTS

RVD1 prevented weight loss, histopathological changes, and elevated levels of inflammatory cytokines. Moreover, RVD1 administration attenuated DSS-induced hepatic steatosis and inflammatory responses in mice. In addition, RVD1 improved intestinal barrier function by increasing levels of tight junction molecules and decreasing the plasma LPS levels. The RVD1-treated mice also showed a different gut microbiota composition compared with found in the mice belonging to the DSS group but similar to that in normal chow diet-fed mice.

CONCLUSIONS AND IMPLICATIONS

RVD1 treatment ameliorates DSS-induced hepatic steatosis by ameliorating gut inflammation, improving intestinal barrier function and modulating intestinal dysbiosis.

The Role of Serum Resolvin D1 Levels in Determining the Presence and Prognosis of ST-Segment Elevation Myocardial Infarction

BACKGROUND

Resolvin D1 (RvD1) can play a determining role in inflammatory cell migration and reduce the expression of inflammatory cytokines to enhance cardioprotection. The aim of this study was to compare serum RvD1 levels in patients with ST-segment elevation myocardial infarction (STEMI) and individuals with normal coronary arteries (NCAs) and to evaluate the association between serum RvD1 levels and prognostic markers of STEMI.

METHODS

140 subjects (88 patients diagnosed with the indication of STEMI and 52 healthy individuals with NCA) were studied.

RESULTS

Regression analysis revealed that RvD1 levels were independently associated with STEMI. While RvD1 levels were negatively correlated with high-sensitivity C-reactive protein, pro-brain natriuretic peptide, peak troponin, and Thrombolysis in Myocardial Infarction thrombus grade, they were positively correlated with left ventricular ejection fraction. An RvD1 cut-off value of 5.07 (ng/mL) was effective in predicting STEMI with a sensitivity of 79.5% and specificity of 96.2%.

CONCLUSION

Serum RvD1 levels were found to be lower in the group with STEMI compared to the control group. Levels of RvD1 at admission were associated with poor prognostic markers of STEMI.

Resolvin D1 attenuates acid-induced DNA damage in esophageal epithelial cells and rat models of acid reflux

The role of resolvin D1 (RvD1) in gastroesophageal reflux disease (GERD) remains largely unknown. Here, we investigated the potential role of RvD1 in acid-induced DNA damage in esophageal epithelial cells, patients with refractory GERD and a rat model of acid reflux. Weak acid exposure induced longer comet tails, reactive oxygen species (ROS) generation, oxidative DNA damage and DNA double-strand breaks (DSBs) in cells and RvD1 (0.1 μM) blocked all these effects. Mechanistic analyses showed that apart from ROS-reducing effects, RvD1 possessed a strong capacity to promote DNA damage repair, augmenting cell cycle checkpoint activity and DSB repair by modulating phosphatase and tensin homolog (PTEN) in cells. We also detected the surface expression of formyl peptide receptor 2 (FPR2), a receptor for RvD1, in the esophageal epithelial cells, and inhibition of FPR2 abrogated the protective effects of RvD1 on cells. Furthermore, a positive correlation between RvD1 and PTEN was observed predominantly in the esophageal epithelium from patients with refractory GERD (r = 0.67, P < 0.05). Additionally, RvD1 administration upregulated PTEN, suppressed DNA DSBs and alleviated microscopic damage in the rat model of gastric reflux. FPR2 gene silencing abolished the therapeutic effects of RvD1 on the rat model. Taken together, RvD1 binding to FPR2 protects the esophageal epithelium from acid reflux-induced DNA damage via a mechanism involving the inhibition of ROS production and facilitation of DSB repair. These findings support RvD1 as a promising approach that may be valuable for the treatment of GERD.

Low LXA4, RvD1 and RvE1 levels may be an indicator of the development of hypertension

Vascular structure and integrity are at the forefront of blood pressure regulation. However, there are many factors that affect the responses of the vessels. One of these is the inflammatory processes associated with high cholesterol and its modification. 15-lipoxygenase (15-LOX) is the critical enzyme in cholesterol oxidation, but this enzyme is also responsible for the synthesis of specialized proresoving lipid mediators (SPMs) called Lipoxin (Lxs) and Resolvin (Rvs). In this study, we determined serum LXA4, RvD1 and RvE1 levels in newly diagnosed hypertension (HT) and normotension (NT) cases. We evaluated how the presence of hypercholesterolemia (HC) in the follow-up changes the levels of these SPMs. We found that the three SPMs we measured decreased significantly in the presence of HC. In addition, we found a negative and significant correlation with systolic blood pressure and total cholesterol levels for the three SPMs. In conclusion, HT and HC are independent risk factors for cardiovascular death. However, the presence of HC may be an important factor for the development of HT. Increasing cholesterol levels may cause 15-LOX to shift towards LDL oxidation, thus leading to inflammation. This situation may negatively affect the vascular functions in the regulation of blood pressure. Serum LXA4, RvD1 and RvE1 measurements may provide clues that represent a shift of 15-LOX enzyme activity towards cholesterol.

Resolvin D1 reduces inflammation in co-cultures of primary human macrophages and adipocytes by triggering macrophages

Obesity leads to chronic inflammation of the adipose tissue which is tightly associated with the metabolic syndrome, type 2 diabetes and cardiovascular disease. Inflammation of the adipose tissue is mainly characterized by the presence of crown-like structures composed of inflammatory macrophages in the neighborhood of adipocytes. Resolvin D1 (RvD1), a potent anti-inflammatory and pro-resolving lipid mediator derived from the omega-3 fatty acid docosahexaenoic acid, has been shown to reduce the inflammatory tone of adipose tissue in animal models but the underlying mechanism is not clear. We investigated the effect of RvD1 on the inflammatory state of a human co-culture system of adipocytes and macrophages. For this, human mesenchymal stem cells were differentiated into mature adipocytes and overlaid with human primary macrophages. In this co-culture, 10-500 nM RvD1 dose-dependently reduced the secretion of the pro-inflammatory cytokine IL-6 (-21%) and its soluble receptor IL-6Rα (-22%), of the chemokine MCP-1 (-13%), and of the adipokine leptin (-22%). Similarly, we observed a reduction in secretion of the soluble receptor IL-6Rα (-20%), and TNF-α (-11%) when macrophages alone were treated with RvD1, while no change of cytokine secretion was observed when adipocytes were treated with RvD1. We conclude that RvD1 polarizes macrophages to an anti-inflammatory phenotype, which in turn modulates inflammation in adipocytes.

Resolvin D1 prevents cadmium chloride-induced memory loss and hippocampal damage in rats by activation/upregulation of PTEN-induced suppression of PI3K/Akt/mTOR signaling pathway

This study evaluated the protective effect of resolvin D1 (RVD1) against cadmium chloride (CdCl₂ )-induced hippocampal damage and memory loss in rats and investigated if such protection is mediated by modulating the PTEN/PI3K/Akt/mTOR pathway. Adult male Wistar rats (n = 18/group) were divided as control, control + RVD1, CdCl₂ , CdCl₂  + RVD1 and CdCl₂  + RVD1 + bpV(pic), a PTEN inhibitor. All treatments were conducted for 4 weeks. Resolvin D1 improved the memory function as measured by Morris water maze (MWM), preserved the structure of CA1 area of the hippocampus, and increased hippocampal levels of RVD1 in the CdCl₂ -treated rats. Resolvin D1 also suppressed the generation of reactive oxygen species (ROS), tumour necrosis factor-α and interleukine-6 (IL-6), inhibited nuclear factor κB (NF-κB) p65, stimulated levels of glutathione (GSH), manganese superoxide dismutase (MnSOD), and Bcl2 but reduced the expression of Bax and cleaved caspase 3 in hippocampi of CdCl₂ -treated rats. Concomitantly, it stimulated levels and activity of PTEN and reduced the phosphorylation (activation) of PI3K, Akt and mTOR in hippocampi of CdCl₂ -treated rats. In conclusion, RVD1 attenuates CdCl₂ -induced memory loss and hippocampal damage in rats mainly by activating PTEN-induced suppression of PI3K/Akt/mTOR, an effect that seems secondary to its' anti-oxidant and anti-inflammatory potential.

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

OBJECTIVES

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

DESIGN & METHODS

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

RESULTS

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

CONCLUSIONS

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

Resolvin D1 reduces expression and secretion of cytokines and monocyte adhesion triggered by Angiotensin II, in rat cardiac fibroblasts

Cardiac fibroblasts (CF) play an important role in the healing process and in pathological remodeling of cardiac tissue. As sentinel cells in the heart, they respond to inflammatory stimuli, expressing cytokines and cell adhesion proteins, which ultimately lead to increased recruitment of monocytes and enhancement of the inflammatory response. Angiotensin II (Ang II) triggers an inflammatory response, leading to cardiac tissue remodeling. On the other hand, RvD1 has been shown to contribute to the resolution of inflammation; however, its role in Ang II-treated CF has not been addressed until now. The present research aimed to study the effect of RvD1 on cytokine levels, cell adhesion proteins expression in a model of Ang II-triggered inflammatory response. CF from adult Sprague Dawley rats were used to study mRNA and protein levels of MCP-1, IL-6, TNF-a, IL-10, ICAM-1 and VCAM-1; and adhesion of spleen mononuclear cells to CF after Ang II stimulation. Our results show that Ang II increased IL-6, MCP-1 and TNF-a mRNA levels, but only increased IL-6 and MCP-1 protein levels. These effects were blocked by Losartan, but not by PD123369. Moreover, RvD1 was able to prevent all Ang II effects in CF. Additionally, RvD1 reduced the intracellular Ca²⁺ increase triggered by Ang II, indicating that RvD1 acts in an early manner to block Ang II signaling. Conclusion: our findings confirm the pro-resolutive effects of inflammation by RvD1, which at the cardiovascular level, could contribute to repair damaged cardiac tissue.

Possible protective effect of resolvin D1 on inflammation in atrial fibrillation: involvement of ER stress mediated the NLRP3 inflammasome pathway

Atrial fibrillation (AF) is the most common type of cardiac rhythm disturbance. At the cellular level, excessive ROS generation during AF is associated with ER stress, which induces an inflammatory response by activating the unfolded protein response (UPR) pathway and the nuclear factor-kappa B (NF-kB) signaling pathway. Activation of the NLR family pyrin domain containing 3 (NLRP3) inflammasome has been linked to the pathogenesis of AF through NF-kB activation and inflammatory cytokine secretion. It has been shown that NLRP3 inflammasome activation by endoplasmic reticulum (ER) stress is dependent on NF-kB activation. The anti-inflammatory role of resolvin D1 (RvD1), a pro-resolving mediator derived from omega-3 fatty acids, has demonstrated that the NF-κB/NLRP3 inflammasome pathway in different tissues is attenuated after treatment with RvD1. However, the mechanism of the anti-inflammatory activity of RvD1 in AF has not been clarified. This review suggests that RvD1 may inhibit ER stress-induced NLRP3 inflammasome through suppressing NF-κB in cardiac tissue and, thus ameliorate AF.

Resolvin D1 Improves the Treg/Th17 Imbalance in Systemic Lupus Erythematosus Through miR-30e-5p

Resolvin D1 (RvD1) prompts inflammation resolution and regulates immune responses. We explored the effect of RvD1 on systemic lupus erythematosus (SLE) and investigated the correlation between RvD1 and Treg/Th17 imbalance, which is one of the major factors contributing to the pathogenesis of disease. SLE patients and healthy controls were recruited to determine plasma RvD1 levels. MRL/lpr lupus model was used to verify rescue of the disease phenotype along with Treg/Th17 ratio. Purified naive CD4+ T cells were used to study the effect of RvD1 on Treg/Th17 differentiation in vitro. Furthermore, small RNA Sequencing and transfection were performed successively to investigate downstream microRNAs. The result showed that the RvD1 level was significantly lower in active SLE patients compared with inactive status and controls. Moreover, The SLE disease activity index (SLEDAI) score had a significant negative correlation with RvD1 level. As expected, RvD1 treatment ameliorated disease phenotype and inflammatory response, improved the imbalanced Treg/Th17 in MRL/lpr mice. In addition, RvD1 increased Treg while reduced Th17 differentiation in vitro. Furthermore, miR-30e-5p was verified to modulate the Treg/Th17 differentiation from naïve CD4+ T cells as RvD1 downstream microRNA. In conclusion, RvD1 effectively ameliorates SLE progression through up-regulating Treg and down-regulating Th17 cells via miR-30e-5p.

Resolvin D1 reduces cancer growth stimulating a protective neutrophil-dependent recruitment of anti-tumor monocytes

Background

Innovative therapies to target tumor-associated neutrophils (PMN) are of clinical interest, since these cells are centrally involved in cancer inflammation and tumor progression. Resolvin D1 (RvD1) is a lipid autacoid that promotes resolution of inflammation by regulating the activity of distinct immune and non-immune cells. Here, using human papilloma virus (HPV) tumorigenesis as a model, we investigated whether RvD1 modulates PMN to reduce tumor progression.

Methods

Growth-curve assays with multiple cell lines and in vivo grafting of two distinct HPV-positive cells in syngeneic mice were used to determine if RvD1 reduced cancer growth. To investigate if and how RvD1 modulates PMN activities, RNA sequencing and multiplex cytokine ELISA of human PMN in co-culture with HPV-positive cells, coupled with pharmacological depletion of PMN in vivo, were performed. The mouse intratumoral immune cell composition was evaluated through FACS analysis. Growth-curve assays and in vivo pharmacological depletion were used to evaluate anti-tumor activities of human and mouse monocytes, respectively. Bioinformatic analysis of The Cancer Genome Atlas (TCGA) database was exploited to validate experimental findings in patients.

Results

RvD1 decreased in vitro and in vivo proliferation of human and mouse HPV-positive cancer cells through stimulation of PMN anti-tumor activities. In addition, RvD1 stimulated a PMN-dependent recruitment of classical monocytes as key determinant to reduce tumor growth in vivo. In human in vitro systems, exposure of PMN to RvD1 increased the production of the monocyte chemoattractant protein-1 (MCP-1), and enhanced transmigration of classical monocytes, with potent anti-tumor actions, toward HPV-positive cancer cells. Consistently, mining of immune cells infiltration levels in cervical cancer patients from the TCGA database evidenced an enhanced immune reaction and better clinical outcomes in patients with higher intratumoral monocytes as compared to patients with higher PMN infiltration.

Conclusions

RvD1 reduces cancer growth by activating PMN anti-cancer activities and encouraging a protective PMN-dependent recruitment of anti-tumor monocytes. These findings demonstrate efficacy of RvD1 as an innovative therapeutic able to stimulate PMN reprogramming to an anti-cancer phenotype that restrains tumor growth.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01937-3.

Human neutrophil membrane-derived nanovesicles as a drug delivery platform for improved therapy of infectious diseases

Resolvins are a group of specialized proresolving lipid mediators (SPMs) enzymatically produced from omega-3 fatty acids during acute inflammation response to infections or tissue injury. Resolvin D1 (RvD1) is one of resolvins and is well studied in resolution of inflammation to treat inflammatory diseases. Resolution of inflammation includes the inhibition of polymorphonuclear leukocyte recruitment and reduced cytokine production. However, effective delivery of RvD1 to inflammatory tissues is challenging because of its lack of tissue targeting and poor physicochemical properties. Here, we proposed nanovesicles made from human neutrophil membrane which can specifically target inflamed tissues, and we loaded RvD1 on the surface of nanovesicles and antibiotic (ceftazidime, CEF) inside nanovesicles for improved treatment of bacterial infections. In a mouse model of bacterium-induced peritonitis, we demonstrated that human neutrophil cell membrane-formed vesicles (NMVs) enhanced inflammation resolution and bacterial killing after co-delivery of RvD1 and CEF. Our studies reveal that neutrophil nanovesicles may be critical for enhanced therapy to infectious diseases.

Role of resolvin D1 in psoriasis before and after narrowband ultraviolet B phototherapy: A case-control study

Resolvin D1 (RvD1) is an endogenous lipid mediator that originated from docosahexaenoic acid that stimulates a bimodal mechanism in the anti-inflammatory activity in addition to regulation of the inflammatory reaction. The study aimed at assessing the tissue level of RvD1 in psoriasis to study its role in the etiopathogenesis of psoriasis, studying the action of NB-UVB on the level of resolvin D1 in psoriasis, and raising the possibility of using resolvin D1 as a new therapy for psoriasis in the future. This case-control study included 20 psoriasis patients and 20 healthy controls. Patients took narrowband ultraviolet B (NB-UVB) for 36 sessions. Skin biopsies were taken before and after treatment from patients and from controls to assess the expression of RvD1 by a quantitative real-time polymerase chain reaction. Our findings revealed a statistically significant difference (P < .001) between psoriasis patients (either before or after treatment) and controls with lower levels of RvD1 in psoriasis patients. On comparing the RvD1 levels in psoriasis patients before and after treatment, a statistically significant increase was detected after treatment (P < .001). Tissue RvD1 levels in psoriasis patients were lower than healthy controls and increased after NB-UVB treatment in psoriasis patients. Thus, it is suggested that RvD1 might have a role in the etiopathogenesis of psoriasis. Moreover, the significantly up-regulated tissue levels of RvD1 in patients after treatment with NB-UVB highlighted a novel mechanism of phototherapy-mediated response in psoriasis by up-regulating RvD1 level.

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.

Resolvin D1 Attenuates Innate Immune Reactions in Experimental Subarachnoid Hemorrhage Rat Model

Excessive inflammation is a major cause contributing to early brain injury (EBI) and is associated with negative or catastrophic outcomes of subarachnoid hemorrhage (SAH). Resolvin D1 (RvD1) exerts strong anti-inflammatory and pro-resolving effects on either acute or chronic inflammation of various origin. Henceforth, we hypothesized that RvD1 potentially attenuates excessive inflammation in EBI following SAH. Therefore, we generated a filament perforation SAH model and administered 3 different doses (0.3, 0.6, and 1.2 nmol) of RvD1 after experimental SAH. Neurological scores, brain edema, and blood-brain barrier integrity were evaluated; besides, neutrophil infiltration, neuronal deaths, and microglial pro-inflammatory polarization were observed using histopathology or immunofluorescence staining, western blots, and qPCR. After confirming the effectiveness of RvD1 in SAH, we administered the FPR2-specific antagonist Trp-Arg-Trp-Trp-Trp-Trp-NH2 (WRW4) 30 min before SAH establishment to observe whether this compound could abolish the anti-inflammatory effect of RvD1. Altogether, our results showed that RvD1 exerted a strong anti-inflammatory effect and markedly reduced neutrophil infiltration and microglial pro-inflammatory activation, leading to remarkable improvements in neurological function and brain tissue restoration. After addition of WRW4, the anti-inflammatory effects of RvD1 were abolished. These results indicated that RvD1 could exert a good anti-inflammatory effect and alleviate EBI, which suggested that RvD1 might be a novel therapeutic alternative for SAH-induced injury.

Resolvin D1 attenuates the inflammatory process in mouse model of LPS-induced keratitis

The aim of this study was to investigate the effects of the lipid mediator Resolvin D1 in experimental keratitis. C57BL/6J mice were injected with lipopolysaccharide (2 µg/eye), and after 24 hours, the corneal damage was assessed. Clinical score was quantified, and corneal inflammatory biomarkers were detected by immunohistochemistry. A robust accumulation of sub‐epithelial macrophages and polymorphonuclear leucocytes, chemokine (C‐X‐C motif) ligand 1 (also known as keratinocyte‐derived chemokine), interleukin‐10 and promoters of apoptosis was also observed in lipopolysaccharide‐treated mice. Formyl peptide receptor 2 corneal expression was also assessed. The corneal stroma treated with lipopolysaccharide was characterized by presence of macrophages of M1‐like subtype and immature fibroblastic cells, marked with Ki67, not fully differentiated in fibroblasts. Indeed, the staining of the cornea with anti‐vimentin antibodies, a marker of differentiated myofibroblasts, was very faint. Resolvin D1 attenuated all the inflammatory parameters assessed in the present study, except for IL‐10. In conclusion, the data presented here seem to be consistent with the hypothesis that Resolvin D1 protected the cornea from the lipopolysaccharide‐induced keratitis by acting on several inflammatory components of this damage, pivoted by Formyl peptide receptor 2 (FPR2) activation and macrophages‐leucocytes activity.

Resolvin D1 mitigates non-alcoholic steatohepatitis by suppressing the TLR4-MyD88-mediated NF-κB and MAPK pathways and activating the Nrf2 pathway in mice

AIMS

Resolvin D1 (RvD1), a potent endogenous lipid mediator converted from docosahexaenoic acid (DHA), has exert anti-inflammatory and antioxidant effects in many preclinical disease models, but its potential role in non-alcoholic steatohepatitis (NASH) remains elusive. This study was performed to investigate the protective effects and mechanisms of RvD1 in NASH.

MAIN METHODS

In vivo, male C57BL/6 mice were fed an MCD diet for 4 weeks to induce NASH. RvD1 was added in the last 2 weeks of the feeding period. In vitro, lipopolysaccharide (LPS)-activated RAW264.7 macrophages were pretreated with increasing concentrations of RvD1. Serum liver functional markers and hepatic oxidative stress indicators were measured biochemically. Mouse liver tissue sections were stained with hematoxylin-eosin, oil red O, and Masson's trichrome to assess the severity of steatohepatitis, steatosis and fibrosis. The qRT-PCR, immunohistochemistry and Western blotting assays were applied to analyse mechanisms underlying RvD1 protection in NASH.

KEY FINDINGS

In vivo, RvD1 significantly attenuates steatohepatitis in MCD diet-fed mice by modulating key events, including steatosis, inflammation, oxidative stress and fibrosis in the progression of NASH. In vitro, RvD1 also represses LPS-induced inflammation in RAW264.7 cells. These effects may be mainly attributed to RvD1 markedly suppressing excessive inflammatory responses via the inhibition of the TLR4-MyD88-mediated NF-κB and MAPK signalling pathways as well as enhancing antioxidation capacity via the activation of the Nrf2 pathway.

SIGNIFICANCE

These results demonstrate that RvD1 is a promising hepatoprotective agent for the therapy of NASH.

Low levels of pro-resolving lipid mediators lipoxin-A4, resolvin-D1 and resolvin-E1 in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is a disease in which joint inflammation is at the forefront but the whole body is affected, and prevention of inflammation is the main treatment approach. Lipoxins (LXs) and resolvins (Rvs) are critical molecules in the resolution of inflammation. In this study, we aimed to investigate the role of LXs and Rvs in the RA pathogenesis. To this end, we measured the LXA 4, RvD 1, RvE 1 levels, and inflammatory cytokines and chemokines IL-6, IL-8, IL-10, IL-17a, IL-22 and MCP-1 in patients with RA and healthy individuals. We found that the LXA4, RvD1, RvE1 levels of the active RA cases were significantly lower than in remission RA and healthy individuals, but the levels of inflammatory cytokines and chemokines were significantly higher. The decreases in LXs and Rvs were independent of disease activity, suggesting that there might be an impairment of LX and Rvs synthesis or catabolism in patients with RA.

Functions of resolvin D1-ALX/FPR2 receptor interaction in the hemoglobin-induced microglial inflammatory response and neuronal injury

Background

Early brain injury (EBI) has been thought to be a key factor affecting the prognosis of subarachnoid hemorrhage (SAH). Many pathologies are involved in EBI, with inflammation and neuronal death being crucial to this process. Resolvin D1 (RvD1) has shown superior anti-inflammatory properties by interacting with lipoxin A4 receptor/formyl peptide receptor 2 (ALX/FPR2) in various diseases. However, it remains not well described about its role in the central nervous system (CNS). Thus, the goal of the present study was to elucidate the potential functions of the RvD1-ALX/FPR2 interaction in the brain after SAH.

Methods

We used an in vivo model of endovascular perforation and an in vitro model of hemoglobin (Hb) exposure as SAH models in the current study. RvD1 was used at a concentration of 25 nM in our experiments. Western blotting, quantitative polymerase chain reaction (qPCR), immunofluorescence, and other chemical-based assays were performed to assess the cellular localizations and time course fluctuations in ALX/FPR2 expression, evaluate the effects of RvD1 on Hb-induced primary microglial activation and neuronal damage, and confirm the role of ALX/FPR2 in the function of RvD1.

Results

ALX/FPR2 was expressed on both microglia and neurons, but not astrocytes. RvD1 exerted a good inhibitory effect in the microglial pro-inflammatory response induced by Hb, possibly by regulating the IRAK1/TRAF6/NF-κB or MAPK signaling pathways. RvD1 could also potentially attenuate Hb-induced neuronal oxidative damage and apoptosis. Finally, the mRNA expression of IRAK1/TRAF6 in microglia and GPx1/bcl-xL in neurons was reversed by the ALX/FPR2-specific antagonist Trp-Arg-Trp-Trp-Trp-Trp-NH2 (WRW4), indicating that ALX/FPR2 could mediate the neuroprotective effects of RvD1.

Conclusions

The results of the present study indicated that the RvD1-ALX/FPR2 interaction could potentially play dual roles in the CNS, as inhibiting Hb promoted microglial pro-inflammatory polarization and ameliorating Hb induced neuronal oxidant damage and death. These results shed light on a good therapeutic target (ALX/FPR2) and a potential effective drug (RvD1) for the treatment of SAH and other inflammation-associated brain diseases.

Intrathecal administration of Resolvin D1 and E1 decreases hyperalgesia in mice with bone cancer pain: Involvement of endocannabinoid signaling

Pain produced by bone cancer is often severe and difficult to treat. Here we examined effects of Resolvin D1 (RvD1) or E1 (RvE1), antinociceptive products of ω-3 polyunsaturated fatty acids, on cancer-induced mechanical allodynia and heat hyperalgesia. Experiments were performed using a mouse model of bone cancer produced by implantation of osteolytic ficrosarcoma into and around the calcaneus bone. Mechanical allodynia and heat hyperalgesia in the tumor-bearing paw were assessed by measuring withdrawal responses to a von Frey monofilament and to radiant heat applied on the plantar hind paw. RvD1, RvE1, and cannabinoid receptor antagonists were injected intrathecally. Spinal content of endocannabinoids was evaluated using UPLC-MS/MS analysis. RvD1 and RvE1 had similar antinociceptive potencies. ED_50s for RvD1 and RvE1 in reducing mechanical allodynia were 0.2 pg (0.53 fmol) and 0.6 pg (1.71 fmol), respectively, and were 0.3 pg (0.8 fmol) and 0.2 pg (0.57 fmol) for reducing heat hyperalgesia. Comparisons of dose-response relationships showed equal efficacy for reducing mechanical allodynia, however, efficacy for reducing heat hyperalgesia was greater for of RvD1. Using UPLC-MS/MS we determined that RvD1, but not RvE1, increased levels of the endocannabinoids Anandamide and 2-Arachidonoylglycerol in the spinal cord. Importantly, Resolvins did not alter acute nociception or motor function in naïve mice. Our data indicate, that RvD1 and RvE1 produce potent antiallodynia and antihyperalgesia in a model of bone cancer pain. RvD1 also triggers spinal upregulation of endocannabinoids that produce additional antinociception predominantly through CB2 receptors.

Resolvin D1 and D2 Inhibit Transient Receptor Potential Vanilloid 1 and Ankyrin 1 Ion Channel Activation on Sensory Neurons via Lipid Raft Modification

Transient Receptor Potential Vanilloid 1 and Ankyrin 1 (TRPV1, TRPA1) cation channels are expressed in nociceptive primary sensory neurons and regulate nociceptor and inflammatory functions. Resolvins are endogenous lipid mediators. Resolvin D1 (RvD1) is described as a selective inhibitor of TRPA1-related postoperative and inflammatory pain in mice acting on the G protein-coupled receptor DRV1/GPR32. Resolvin D2 (RvD2) is a very potent TRPV1 and TRPA1 inhibitor in DRG neurons, and decreases inflammatory pain in mice acting on the GPR18 receptor, via TRPV1/TRPA1-independent mechanisms. We provided evidence that resolvins inhibited neuropeptide release from the stimulated sensory nerve terminals by TRPV1 and TRPA1 activators capsaicin (CAPS) and allyl-isothiocyanate (AITC), respectively. We showed that RvD1 and RvD2 in nanomolar concentrations significantly decreased TRPV1 and TRPA1 activation on sensory neurons by fluorescent calcium imaging and inhibited the CAPS- and AITC-evoked ⁴⁵Ca-uptake on TRPV1- and TRPA1-expressing CHO cells. Since CHO cells are unlikely to express resolvin receptors, resolvins are suggested to inhibit channel opening through surrounding lipid raft disruption. Here, we proved the ability of resolvins to alter the membrane polarity related to cholesterol composition by fluorescence spectroscopy. It is concluded that targeting lipid raft integrity can open novel peripheral analgesic opportunities by decreasing the activation of nociceptors.

Resolvin D1 Ameliorates Nicotinamide-streptozotocin-induced Type 2 Diabetes Mellitus by its Anti-inflammatory Action and Modulating PI3K/Akt/mTOR Pathway in the Brain

OBJECTIVE

To study whether resolvin D1 (RvD1), a metabolite of docosahexaenoic acid (DHA), prevents NA-STZ-induced type 2 diabetes mellitus (type 2 DM) in vivo and if so, what could be the mechanism of this action.

MATERIAL AND METHODS

Single intra-peritoneal (i.p) injection of NA-STZ (175 mg/kg body weight of NA and 65 mg/kg of STZ) was injected simultaneously with RvD1 (60 ng/animal) (injected for 5 consecutive days) to Wistar rats. The effect of RvD1 on plasma glucose levels and apoptotic (Bcl2/Bax) and inflammatory (NF-κB/iNOS) protein expression, plasma lipoxin A4 and BDNF (brain-derived neurotrophic factor) were studied. Protein expressions of PI3k-Akt-mTOR pathway along with histopathological studies of brain were also evaluated.

RESULTS

NA-STZ-induced type 2 DM rats showed hyperglycemia, enhanced plasma IL-6/TNF-α (p ≤0.01), reduced plasma BDNF (p ≤0.01) and LXA4 (p ≤0.01) levels and low BDNF in pancreatic, hepatic and brain tissues (p <0.001), which were restored to near normal (p ≤0.01) in RvD1 treated group. RvD1 increased insulin sensitivity by suppressing inflammation (NF-κB/iNOS) (p ≤0.01) and decreasing apoptosis (Bcl2/Bax) and restoring BDNF and LXA4 levels to near normal. RvD1 treatment increased phosphorylation of Akt (Ser473), and subsequent activation (phosphorylation) of downstream signaling molecules of PI3K and mTOR indicating that RvD1 acts through PI3K/Akt/mTOR axis.

DISCUSSION

RvD1 is effective in preventing NA-STZ-induced type 2 DM in vivo by suppressing oxidative damage, enhancing the production of anti-inflammatory LXA4 and enhancing neuronal cell survival by augmenting the production of BDNF. Thus, RvD1 may be of benefit not only in preventing diabetes mellitus but also diabetes associated Alzheimer's disease and memory loss.

Resolvin D1 Prevents the Impairment in the Retention Memory and Hippocampal Damage in Rats Fed a Corn Oil-Based High Fat Diet by Upregulation of Nrf2 and Downregulation and Inactivation of p66Shc

This study investigated the effect of a high-fat diet rich in corn oil (CO-HFD) on the memory retention and hippocampal oxidative stress, inflammation, and apoptosis in rats, and examined if the underlying mechanisms involve modulating Resolvin D1 (RvD1) levels and activation of p⁶⁶Shc. Also, we tested if co-administration of RvD1 could prevent these neural adverse effects induced by CO-HFD. Adult male Wistar rats were divided into 4 groups (n = 18/each) as control fed standard diet (STD) (3.82 kcal/g), STD + RvD1 (0.2 µg/Kg, i.p/twice/week), CO-HFD (5.4 kcal/g), and CO-HFD + RvD1. All treatments were conducted for 8 weeks. With normal fasting glucose levels, CO-HFD induced hyperlipidemia, hyperinsulinemia, increased HOMA-IRI and reduced the rats' memory retention. In parallel, CO-HFD increased levels of reactive oxygen species (ROS), malondialdehyde (MDA), cytoplasmic cytochrome-c, and cleaved caspase-3 and significantly decreased levels of glutathione (GSH), Bcl-2, and manganese superoxide dismutase (MnSOD) in rats' hippocampi. Besides, CO-HFD significantly reduced hippocampal levels of docosahexaenoic acid (DHA) and RvD1, as well as total protein levels of Nrf2 and significantly increased nuclear protein levels of p-NF-κB. Concomitantly, CO-HFD increased hippocampal protein levels of p-JNK, p53, p⁶⁶Shc, p-p⁶⁶Shc, and NADPH oxidase. However, without altering plasma and serum levels of glucose, insulin, and lipids, co-administration of RvD1 to CO-HFD completely reversed all these events. It also resulted in similar effects in the STD fed-rats. In conclusion, CO-HFD impairs memory function and induces hippocampal damage by reducing levels of RvD1 and activation of JNK/p53/p⁶⁶Shc/NADPH oxidase, effects that are prevented by co-administration of RvD1.

Resolvin D1 Protects Against Ischemia/Reperfusion-Induced Acute Kidney Injury by Increasing Treg Percentages via the ALX/FPR2 Pathway

Aims

To evaluate whether Resolvin D1 attenuates ischemia/reperfusion-induced (IRI) acute kidney injury (AKI) via affecting Tregs.

Materials and Methods

The IRI-AKI mouse model was established, and RvD1 was injected into the mouse tail vein. Further, the renal function, histological changes, injury markers and serum cytokines were detected at 24 and 72 h after IRI. Flow cytometry was used to categorize regulatory T cells (Tregs) in the spleen and kidney. Treg cells were stripped with the anti-CD25 antibody blocker PC61 to assess its role in the protective effect of RvD1 on IRI mice. CD4⁺ T cells were obtained from spleen monocytes by magnetic bead sorting and differentiated into induced Treg (iTreg) cells. The effect of RvD1 on iTreg cell differentiation was observed in vitro. In addition, neutralizing antibodies against the orphan receptor G-protein-coupled receptor 32 (anti-GPR32) and LXA4 receptor (anti-ALX/FPR2), both RvD1 receptor blockers, were used to evaluate the effect of RvD1 on iTreg cell differentiation. Boc-1, an ALX/FPR2 receptor inhibitor, was administered via the tail vein to observe its effects on the ameliorative efficacy of RvD1 in IRI-AKI mice in vivo.

Results

In vivo, RvD1 increased Treg percentages, alleviated renal tubular injury and reduced the serum levels of IFN-γ, TNF-α and IL-6 in IRI-AKI mice, while PC61 depleted the number of Tregs and reversed the protective effects of RvD1. In vitro, RvD1 induced the generation of iTregs. Importantly, preincubation with anti-ALX/FPR2 neutralizing antibodies but not with anti-GPR32 neutralizing antibodies, abrogated the enhancement activity of RvD1 on iTregs. In addition, in vivo blockade of the receptor ALX/FPR2 by Boc-1 reversed the beneficial effects of RvD1 on the splenic and kidney Treg percentages, renal tubular injury and serum IFN-γ, TNF-α, and IL-6 levels.

Conclusion

Our study demonstrates that RvD1 protects against IRI-AKI by increasing the percentages of Tregs via the ALX/FPR2 pathway.

Resolvin D1 suppresses pannus formation via decreasing connective tissue growth factor caused by upregulation of miRNA-146a-5p in rheumatoid arthritis

Background

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by inflammation and joint stiffness, finally leading to tissue destruction. Connective tissue growth factor (CTGF) is a critical factor in RA progression, which promotes fibroblast-like synoviocyte (FLS) proliferation, pannus formation, and the damage of cartilage as well as bone. Resolvin D1 (RvD1) can promote inflammation resolution in acute inflammatory diseases, and recently, effects of RvD1 on chronic inflammatory diseases also attracted attention. This study aimed to examine the effect of RvD1 on pannus formation in RA and the underlying mechanism.

Methods

Serum levels of RvD1 and CTGF were determined in RA patients and healthy persons by UPLC-MS/MS and ELISA respectively. The levels of CTGF and inflammatory factors were assessed by qRT-PCR and ELISA. MicroRNA expression profile was determined by miRNA microarray. The effects of CTGF, RvD1, and miR-146a-5p on angiogenesis were evaluated with tube formation and chick chorioallantoic membrane (CAM) assays. Collagen-induced arthritis (CIA) mice were constructed to detect the effects of RvD1 and miR146a-5p on RA. STAT3 activation was determined by Western blotting.

Results

RvD1 levels decreased while CTGF levels increased in RA patients’ serum, and an inverse correlation of the concentrations of RvD1 and CTGF in the serum of RA patients was synchronously observed. In CIA mice, RvD1 suppressed angiopoiesis and decreased the expression of CTGF. Simultaneously, RvD1 significantly decreased CTGF and pro-inflammation cytokines levels in RA FLS. Furthermore, CTGF suppressed angiopoiesis and RvD1 inhibited the proliferation and migration of RA FLS and angiopoiesis. MiRNA microarray and qRT-PCR results showed that RvD1 upregulated miRNA-146a-5p. The transfection experiments demonstrated that miRNA-146a-5p could decrease inflammatory factors and CTGF levels. Moreover, miRNA-146a-5p decreased the proliferation of FLS and angiogenesis in vivo. MiRNA-146a-5p also suppressed angiogenesis and downregulated the expression of CTGF in CIA mice. Finally, Western blot results revealed that miRNA-146a-5p inhibited the activation of STAT3.

Conclusion

RvD1 is prone to alleviate RA progression through the upregulation of miRNA-146a-5p to suppress the expression of CTGF and inflammatory mediators, thereby decreasing pannus formation and cartilage damage.

Electronic supplementary material

The online version of this article (10.1186/s13075-020-2133-2) contains supplementary material, which is available to authorized users.

Resolvin D1 as a novel anti-inflammatory marker in manic, depressive and euthymic states of bipolar disorder

Background: Resolvin D1 (RvD1) is a soluble mediator, which is the metabolite of docosahexaenoic acid (DHA), an omega-3 fatty acid. It is thought that RvD1 may contribute to the etiology of bipolar disorder (BD) because of its anti-inflammatory and antidepressant effect. In this study, it was aimed to compare the serum RvD1 levels of patients with BD diagnosed manic-depressive-euthymic episodes with those of healthy subjects. The secondary objective of this study is to investigate the relationship between RvD1 measures and inflammatory markers.Methods: We included 121 male patients with BD type I, 44 in a mania, 35 in depression and 42 in euthymic state, and 41 healthy controls. Serum RvD1 levels and inflammation indicators (CRP, neutrophil, leukocyte, and albumin) were measured.Results: When the RvD1 values of patients were compared, the median (interquartile range) RvD1 value was 11.2 (5.2) for manic patients, 11.2 (6.6) for depressive patients, 9.6 (5.6) for euthymic patients and 8.4 (7.7) for the control group. There were statistically significant differences between the groups in terms of RvD1 values (p < .001). After adjustment for age and current state with ANCOVA, there were statistically significant differences between manic vs. control groups and depression vs. control groups (p < .001, p=.047). Also mean CRP measures (p=.029) and neutrophil counts (p=.009) were significantly correlated with log transformed RvD1 levels.Conclusions: Our results of increased anti-inflammatory RvD1 during manic and depressive states suggest RvD1 may serve as a delayed resolvent possibly improving inflammatory imbalance. Further research is needed to confirm our findings.

Oral Resolvin D1 attenuates early inflammation but not intimal hyperplasia in a rat carotid angioplasty model

Inflammation ensuing from vascular injury promotes intimal hyperplasia (IH) and restenosis. Resolvin D1 (RvD1) is a lipid mediator that attenuates IH in vivo when delivered locally to the vessel wall in animal models. We tested the hypothesis that peri-procedural oral administration of RvD1 could blunt the local inflammatory response to angioplasty, and attenuate downstream IH. Carotid angioplasty was performed on rats fed with either RvD1 or vehicle through oral gavage, starting one day prior to injury until post-operative day (POD) 3 or 14 when arteries were harvested. To study pharmacokinetics and bioactivity of oral RvD1, we measured plasma RvD1 by ELISA, whole blood phagocytosis activity using flow cytometry, and cAMP levels in the thoracic aorta by ELISA. Carotid arteries were harvested on POD3 for staining (anti-CD45, anti-Myeloperoxidase (MPO), anti-Ki67 or dihydroethidium (DHE) for reactive oxygen species), mRNA expression of target genes (quantitative RT-PCR), or on POD14 for morphometry (elastin stain). RvD1 plasma concentration peaked 3 h after gavage in rats, at which point we concurrently observed an increase in circulating monocyte phagocytosis activity and aortic cAMP levels in RvD1-treated rats vs. vehicle. Oral RvD1 attenuated local arterial inflammation after angioplasty by reducing CD45+, MPO+, Ki67+ cells, and DHE staining intensity. Oral RvD1 also reduced the expression of several pro-inflammatory genes within the injured vessels. However, oral RvD1 did not significantly reduce IH. Oral RvD1 attenuated acute inflammation within the arterial wall after angioplasty in rats, but did not significantly affect IH.

Inhibition of lung cancer growth and metastasis by DHA and its metabolite, RvD1, through miR-138-5p/FOXC1 pathway

BACKGROUND

Non small cell lung cancer (NSCLC) is one of the most common cancers in the world. DHA is known to be capable of suppressing NSCLC cell proliferation and metastasis. However, the mechanisms by which DHA exhibits its antitumor effects are unknown. Here we aimed to identify the effects and mechanisms of DHA and its metabolites on lung cancer cell growth and invasion.

METHODS

As measures of cell proliferation and invasion ability, the cell viability and transwell assays were used in vitro. Transgenic mfat-1 mice, which convert ω-6 PUFAs to ω-3 PUFAs, were used to detect the effect of endogenous DHA on tumor transplantation. An LC - MS/MS analysis identified the elevation of several eicosanoid metabolites of DHA. By using qPCR miRNA microarray, online prediction software, luciferase reporter assays and Western blot analysis, we further elucidated the mechanisms.

RESULTS

Addition of exogenous DHA inhibited the growth and invasion in NSCLC cells in vitro. Endogenously produced DHA attenuated LLC-derived tumor growth and metastasis in the transgenic mfat-1 mice. Among the elevation of DHA metabolites, resolvin D1 (RvD1) significantly contributed to the inhibition in cell growth and invasion. MiRNA microarray revealed that the level of miR-138-5p was significantly increased after RvD1 treatment. MiR-138-5p mimics decreased cell viability and invasion; while miR-138-5p inhibitor abolished RvD1-mediated suppression of cell viability and invasion. The expression of FOXC1 was significantly reduced upon overexpression of miR-138-5p while luciferase reporter assay showed that FOXC1 was a direct target of miR-138-5p. In vivo, endogenous DHA by the mfat-1 transgene enhanced miR-138-5p expression and decreased FOXC1 expression. Furthermore, overexpression of FOXC1 reversed the inhibition in cell viability and invasion induced by RvD1 treatment.

CONCLUSIONS

These data identified the RvD1/miR-138-5p/FOXC1 pathway as a novel mechanism by DHA and its metabolite, RvD1, and the potential of targeting such pathway as a therapeutic strategy in treating NSCLC.

Resolvin D1 suppresses inflammation-induced hyperexcitability of nociceptive trigeminal neurons associated with mechanical hyperalgesia

7S,8R,17S-trihydroxy-4Z,9E,11E,13Z,15E,19Z-docosahexaenoic acid (resolvin D1 [RvD1]) is biosynthesized from docosahexaenoic acid (DHA), and belongs to a novel family of lipid mediators showing remarkable anti-inflammatory effects; however, the effect of RvD1 on inflammation-induced hyperexcitability of nociceptive neurons under in vivo conditions remains to be determined. The present study, therefore, investigated whether under in vivo conditions, systemic administration of RvD1 could attenuate the inflammation-induced hyperexcitability of spinal trigeminal nucleus caudalis (SpVc) wide-dynamic range (WDR) neurons associated with hyperalgesia in rats. The threshold of escape from mechanical stimulation applied to the orofacial area in rats with complete Freund's adjuvant-induced inflammation was significantly lower than in naïve rats. The lowered mechanical threshold in rats with inflammation was returned to control levels following administration of RvD1 (3 ng/kg, i.p.) for 3 days. The mean discharge frequency of SpVc WDR neurons in rats with inflammation was significantly decreased after RvD1 administration for both non-noxious and noxious mechanical stimuli. Increased spontaneous discharge of SpVc WDR neurons in rats with inflammation was also significantly decreased after RvD1 administration. Noxious pinch-evoked afterdischarge frequency and occurrence in rats with inflammation was significantly diminished after RvD1 administration. Expansion of the receptive field in rats with inflammation also returned to control levels after RvD1 administration. These results suggest that administration of RvD1 attenuates inflammation-induced hyperexcitability of SpVc WDR neurons associated with inflammatory hyperalgesia. These findings support the idea that RvD1, derived from DHA, as well as DHA itself, are potential complementary or alternative therapeutic agents for the alleviation of inflammatory hyperalgesia.

ResolvinD1 attenuates high-mobility group box 1-induced epithelial-to-mesenchymal transition in nasopharyngeal carcinoma cells

Epithelial-to-mesenchymal transition (EMT) process is prevalent during the progression of tumors. Nasopharyngeal carcinoma (NPC) is no exception. High-mobility group box 1 (HMGB1) was reported to have the effect of inducing EMT in malignancy. However, the impact of HMGB1-induced EMT in NPC is unclear. Resolvin D1 (RvD1) was reported to regress the progression of inflammation and apoptosis of phagocytes. The effect of RvD1 in the EMT is largely unknown. The current research explored the role of RvD1 on HMGB1-induced EMT in NPC. EMT markers were investigated in 10 NPC and 10 nasopharyngitis (NPG) patients using immunohistochemistry and Western blot. In vitro, expression of EMT markers and HMGB1 in CNE1 and CNE2 cells was assessed with immunohistochemical, Western blot, and confocal microscopy after treatment with recombinant human HMGB1 (rhHMGB1) or HMGB1 gene silencing or RvD1. The invasion and migration of NPC cells were detected by scratch test and transwell assay. Overexpression and gene silencing of lipoxin A4 receptor/formyl peptide receptor 2 (ALX/FPR2) and G protein-coupled receptor 32 (GPR32) in CNE2 cells confirmed the effect of RvD1 using Western blots. N-cadherin, vimentin, and HMGB1 were found up-regulated in NPC samples compared with NPG samples, while ZO-1 and E-cadherin were down-regulated in NPC tissues. RhHMGB1-induced EMT in CNE1 and CNE2 cells in a dose-dependent way. CNE2 cell lines treated with rhHMGB1 possessed greater invasion and migration ability, which was confirmed by gene silencing. RvD1 suppressed HMGB1-induced EMT in NPC cells via ALX/FPR2 and GPR32 receptors. These results showed that EMT was obvious in NPC. HMGB1 played a key role in inducing EMT. RvD1 inhibited HMGB1-induced EMT and might have potential application in the area of NPC treatment.

Impact statement

Nasopharyngeal carcinoma has a high incidence in China. Discussing the molecular mechanism of nasopharyngeal carcinoma is important because of high recurrent rate and low quality of life after treatment. HMGB1, as an important inflammatory factor, promotes the process in many cancers. But little is known about how HMGB1 affects the progress of nasopharyngeal carcinoma cells. In our research, we assessed the role of HMGB1 on metastasis and invasion of nasopharyngeal carcinoma cells. The result of study indicates HMGB1-induced EMT in nasopharyngeal carcinoma cells. Furthermore, we observed that RvD1, which plays an actively protective role in many diseases, controls the migration and invasion of nasopharyngeal carcinoma cells by inhibiting the HMGB1-induced EMT. RvD1 can be further studied as a protective factor for nasopharyngeal carcinoma.

Resolvin D1 attenuates ventilator-induced lung injury by reducing HMGB1 release in a HO-1-dependent pathway

Mechanical ventilation (MV) is a major support for patients with severe clinical disease, surgery and anesthesia. However, complications of mechanical ventilation especially ventilator-induced lung injury(VILI) can make the course and prognosis worse. Resolvin D1(RvD1) is a class of endogenous polyunsaturated fatty acid derivative, which has protective effects on various pulmonary inflammatory diseases. However, the mechanism of RvD1 in the process of VILI has not been fully elucidated. Our study found that RvD1 does have a protective effect on VILI including inhibiting inflammatory responses, reducing tissue damage and improving pulmonary function. The protective effect of RvD1 is positively related to its dose. Our research suggested RvD1 plays a role that increases the expression of heme oxygenase‑1 (HO-1) and decreases the expression of the high mobility group chromosomal protein B1 (HMGB-1) in VILI. HO-1 can exert the protective effect of organism through multiple mechanisms such as anti-inflammatory, anti-oxidation, anti-apoptosis, etc. HMGB1 is a potent inflammatory response factor in the body, which can aggravate the inflammatory response of the body. Our study demonstrated that RvD1 can ameliorate lung inflammation and reduce pathological changes in lung tissue in a model of lung injury induced by mechanical ventilation. The protective role of RvD1 is closely linked to the increased expression of HO-1 and the decreased expression of HMGB1. Moreover, we found that RvD1 can increase the expression of Nrf2 and inhibit the expression of NF-κB. We found the specific inhibitor of HO-1, ZnPP, can significantly inhibit the protective role of RvD1 in VILI. When HO-1 is inhibited, pathological damage and inflammatory reaction in the lungs are considerably aggravated, and pulmonary function is significantly weakened. In addition, the expression of HMGB1 is drastically increased. This indicates that the HO-1-HMGB1 pathway plays an important role in the protective effect of RvD1 on mechanical ventilation lung injury.

RvD1binding with FPR2 attenuates inflammation via Rac1/NOX2 pathway after neonatal hypoxic-ischemic injury in rats

Neuroinflammation plays a crucial role in the pathological development after neonatal hypoxia-ischemia (HI). Resolvin D1 (RvD1), an agonist of formyl peptide receptor 2 (FPR2), has been shown to exert anti-inflammatory effects in many diseases. The objective of this study was to explore the protective role of RvD1 through reducing inflammation after HI and to study the contribution of Ras-related C3 botulinum toxin substrate 1 (Rac1)/nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) pathways in RvD1-mediated protection. Rat pups (10-day old) were subjected to HI or sham surgery. RvD1 was administrated by intraperitoneal injection 1 h after HI. FPR2 small interfering ribonucleic acid (siRNA) and Rac1 activation CRISPR were administered prior to RvD1 treatment to elucidate the possible mechanisms. Time course expression of FPR2 by Western blot and RvD1 by ELISA were conducted at 6 h, 12 h, 24 h, 48 h and 72 h post HI. Infarction area, short-term neurological deficits, immunofluorescent staining and Western blot were conducted at 24 h post HI. Long-term neurological behaviors were evaluated at 4 weeks post HI. Endogenous expression levels of RvD1 decreased in time dependent manner while the expression of FPR2 increased after HI, peaking at 24 h post HI. Activation of FPR2, with RvD1, reduced percent infarction area, and alleviated short- and long-term neurological deficits. Administration of RvD1 attenuated inflammation after HI, while, either inhibition of FPR2 with siRNA or activation of Rac1 with CRISPR reversed those effects. Our results showed that RvD1 attenuated neuroinflammation through FPR2, which then interacted with Rac1/NOX2 signaling pathway, thereby reducing infarction area and alleviating neurological deficits after HI in neonatal rat pups. RvD1 may be a potential therapeutic approach to reduce inflammation after HI.