Therapeutic Activity of Resolvin D1 (RvD1) in Murine MASH.

Background and Aims: Recent studies have highlighted the beneficial effect of resolvin D1 (RvD1), a DHA-derived specialized pro-resolving mediator, on metabolic dysfunction-associated steatohepatitis (MASH), but the underlying mechanisms are not well understood. Our study aims to determine the mechanism by which RvD1 protects against MASH progression. Methods: RvD1 was administered to mice with experimental MASH, followed by bulk and single-cell RNA sequencing analysis. Primary cells including bone marrow-derived macrophages (BMDMs), Kupffer cells, T cells, and primary hepatocytes were isolated to elucidate the effect of RvD1 on inflammation, cell death, and fibrosis regression genes. Results: Hepatic tissue levels of RvD1 were decreased in murine and human MASH, likely due to an expansion of pro-inflammatory M1-like macrophages with diminished ability to produce RvD1. Administering RvD1 reduced inflammation, cell death, and liver fibrosis. Mechanistically, RvD1 reduced inflammation by suppressing the Stat1-Cxcl10 signaling pathway in macrophages and prevented hepatocyte death by alleviating ER stress-mediated apoptosis. Moreover, RvD1 induced Mmp2 and decreased Acta2 expression in hepatic stellate cells (HSCs), and promoted Mmp9 and Mmp12 expression in macrophages, leading to fibrosis regression in MASH. Conclusions: RvD1 reduces Stat1-mediated inflammation, mitigates ER stress-induced apoptosis, and promotes MMP-mediated fibrosis regression in MASH. This study highlights the therapeutic potential of RvD1 to treat MASH.

Resolvin D1 Inhibits IL-6-Induced Epithelial-Mesenchymal Transition of Colorectal Cancer Cells by Targeting IL-6/STAT3 Signaling.

Colorectal cancer (CRC) has emerged as a prevalent malignancy worldwide, exhibiting the high morbidity and mortality rates. Resolvin D1 (RvD1) can exert anti-inflammation and anti-cancer effects on various diseases. This study is aimed to explore the role of RvD1 in CRC cells. HCT15 and SW480 cells were stimulated with IL-6 in our study. A series of assays such as CCK-8, colony formation, wound healing, Transwell, Western blotting, and immunofluorescence staining were designed and conducted to figure out the role of RvD1 in CRC cells. RvD1 suppressed IL-6-induced SW480 and HCT15 cell proliferation. In addition, RvD1 inhibited IL-6-induced SW480 and HCT15 cell migration, invasion, and EMT process. In mechanism, RvD1 inhibited the activation of IL-6/STAT3 signaling in SW480 and HCT15 cells. Angoline strengthened the inhibitive effect of RvD1 on cell malignancy. RvD1 inhibited cell growth, migration, invasion and EMT process by inactivating IL-6/STAT3 signaling in CRC.

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-1ß, 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-1ß 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-1ß 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.

Tissue factor targeting peptide enhances nanoparticle binding and delivery of a synthetic specialized pro-resolving lipid mediator to injured arteries.

Background: Specialized pro-resolving lipid mediators (SPM) such as resolvin D1 (RvD1) attenuate inflammation and exhibit vasculo-protective properties. Methods: We investigated poly-lactic-co-glycolic acid (PLGA)-based nanoparticles (NP), containing a peptide targeted to tissue factor (TF) for delivery of 17R-RvD1 and a synthetic analog 17-R/S-benzo-RvD1 (benzo-RvD1) using in vitro and in vivo models of acute vascular injury. NPs were characterized in vitro by size, drug loading, drug release, TF binding, and vascular smooth muscle cell migration assays. NPs were also characterized in a rat model of carotid angioplasty. Results: PLGA NPs based on a 75/25 lactic to glycolic acid ratio demonstrated optimal loading (507.3 pg 17R-RvD1/mg NP; P = ns) and release of RvD1 (153.1 pg 17R-RvD1/mg NP; P < .05). NPs incorporating the targeting peptide adhered to immobilized TF with greater avidity than NPs with scrambled peptide (50 nM: 41.6 ± 0.52 vs 32.66 ± 0.34; 100 nM: 35.67 ± 0.95 vs 23.5 ± 0.39; P < .05). NPs loaded with 17R-RvD1 resulted in a trend toward blunted vascular smooth muscle cell migration in a scratch assay. In a rat model of carotid angioplasty, 16-fold more NPs were present after treatment with TF-targeted NPs compared with scrambled NPs (P < .01), with a corresponding trend toward higher tissue levels of 17R-RvD1 (P = .06). Benzo-RvD1 was also detectable in arteries treated with targeted NP delivery and accumulated at 10 times higher levels than NP loaded with 17R-RvD1. There was a trend toward decreased CD45 immunostaining in vessels treated with NP containing benzo-RvD1 (0.76 ± 0.38 cells/mm2 vs 122.1 ± 22.26 cells/mm2; P = .06). There were no significant differences in early arterial inflammatory and cytokine gene expression by reverse transcription-polymerase chain reaction. Conclusions: TF-targeting peptides enhanced NP-mediated delivery of SPM to injured artery. TF-targeted delivery of SPMs may be a promising therapeutic approach to attenuate the vascular injury response.

Inflammation resolution and specialized pro-resolving lipid mediators in chronic rhinosinusitis.

INTRODUCTION: In chronic rhinosinusitis (CRS), a complex pathophysiology results from varied pro-inflammatory stimuli but is consistently characterized by classic cellular, molecular, and microbial alterations. Normally, endogenous specialized pro-resolving mediators (SPM) actively promote resolution of inflammation through numerous pathways, including those involved in host antimicrobial defense. However, these pathways appear to be disrupted in CRS. AREAS COVERED: This paper describes features of CRS in the context of chronic tissue inflammation, and potential mechanisms by which specialized pro-resolving mediators promote active resolution of tissue inflammation. EXPERT OPINION: Temporal phases of resolution must be tightly regulated to successfully resolve inflammation in CRS while preserving tissue functions such as barrier maintenance and special sensory function. Dysregulation of SPM enzymatic pathways has been recently shown in CRS and is associated with disease phenotypes and microbial colonization patterns. Current research in animal models and in vitro human cell culture, as well as human dietary studies, demonstrate relevant changes in cell signaling with lipid mediator bioavailability. Further clinical research may provide insight into the therapeutic value of this approach in CRS.

Addition of Resolvins D1 or E1 to Collagen Membranes Mitigates Their Resorption in Diabetic Rats.

Uncontrolled diabetes is characterized by aberrant inflammatory reactions and increased collagenolysis. We have reported that it accelerates the degradation of implanted collagen membranes (CM), thus compromising their function in regenerative procedures. In recent years, a group of physiological anti-inflammatory agents called specialized pro-resolving lipid mediators (SPMs) have been tested as a treatment for various inflammatory conditions, either systemically or locally, via medical devices. Yet, no study has tested their effect on the fate of the biodegradable material itself. Here, we measured the in vitro release over time of 100 or 800 ng resolvin D1 (RvD1) incorporated into CM discs. In vivo, diabetes was induced in rats with streptozotocin, while buffer-injected (normoglycemic) rats served as controls. Resolvins (100 or 800 ng of RvD1 or RvE1) were added to biotin-labeled CM discs, which were implanted sub-periosteally over the calvaria of rats. Membrane thickness, density, and uniformity were determined by quantitative histology after 3 weeks. In vitro, significant amounts of RvD1 were released over 1-8 days, depending on the amount loaded. In vivo, CMs from diabetic animals were thinner, more porous, and more variable in thickness and density. The addition of RvD1 or RvE1 improved their regularity, increased their density, and reduced their invasion by the host tissue significantly. We conclude that addition of resolvins to biodegradable medical devices can protect them from excessive degradation in systemic conditions characterized by high degree of collagenolysis.

Lung Inflammation Resolution by RvD1 and RvD2 in a Receptor-Dependent Manner.

Inflammation resolution is an active process via specialized pro-resolving mediators (SPMs) to fight invading microbes and repair tissue injury. RvD1 and RvD2 are SPMs produced from DHA during inflammation responses and show a benefit in treating inflammation disorders, but it is not completely understood how they act on vasculature and immune cells in the lung to promote inflammation resolution programs. Here, we studied how RvD1 and RvD2 regulated the interactions between endothelial cells and neutrophils in vitro and in vivo. In an acute lung inflammation (ALI) mouse model, we found that RvD1 and RvD2 resolved lung inflammation via their receptors (ALX/GPR32 or GPR18) and enhanced the macrophage phagocytosis of apoptotic neutrophils, which may be the molecular mechanism of lung inflammation resolution. Interestingly, we observed the higher potency of RvD1 over RvD2, which may be associated with unique downstream signaling pathways. Together, our studies suggest that the targeted delivery of these SPMs into inflammatory sites may be novel strategies with which to treat a wide range of inflammatory diseases.

Protective effects of resolvin D1 in Pseudomonas aeruginosa keratitis.

PURPOSE: Here, we explored the protective effects of resolvin D1 (RvD1) in Pseudomonas aeruginosa (PA) keratitis. METHODS: C57BL/6 (B6) mice were used as an animal model of PA keratitis. Plate counting and clinical scores were used to assess the severity of the infection and the therapeutic effects of RvD1 in the model. Myeloperoxidase assay was used to detect neutrophil infiltration and activity. Quantitative PCR (qPCR) was used to examine the expression of proflammatory and anti-inflammatory mediators. Immunofluorescence staining and qPCR were performed to identify macrophage polarization. RESULTS: RvD1 treatment alleviated PA keratitis severity by decreasing corneal bacterial load and inhibiting neutrophil infiltration in the mouse model. Furthermore, RvD1 treatment decreased mRNA levels of TNF-α, IFN-γ, IL-1ß, CXCL1, and S100A8/9 while increasing those of IL-1RA, IL-10, and TGF-ß1. RvD1 treatment also reduced the aggregation of M1 macrophages and increased that of M2 macrophages. RvD1 provided an auxiliary effect in gatifloxacin-treated mice with PA keratitis. CONCLUSION: Based on these findings, RvD1 may improve the prognosis of PA keratitis by inhibiting neutrophil recruitment and activity, dampening the inflammatory response, and promoting M2 macrophage polarization. Thus, RvD1 may be a potential complementary therapy for PA keratitis.

Aspirin-Triggered Resolvin D1 (AT-RvD1) Protects Mouse Skin against UVB-Induced Inflammation and Oxidative Stress.

Intense exposure to UVB radiation incites excessive production of reactive oxygen species (ROS) and inflammation. The resolution of inflammation is an active process orchestrated by a family of lipid molecules that includes AT-RvD1, a specialized proresolving lipid mediator (SPM). AT-RvD1 is derived from omega-3, which presents anti-inflammatory activity and reduces oxidative stress markers. The present work aims to investigate the protective effect of AT-RvD1 on UVB-induced inflammation and oxidative stress in hairless mice. Animals were first treated with 30, 100, and 300 pg/animal AT-RvD1 (i.v.) and then exposed to UVB (4.14 J/cm2). The results showed that 300 pg/animal of AT-RvD1 could restrict skin edema, neutrophil and mast cell infiltration, COX-2 mRNA expression, cytokine release, and MMP-9 activity and restore skin antioxidant capacity as per FRAP and ABTS assays and control O2•- production, lipoperoxidation, epidermal thickening, and sunburn cells development. AT-RvD1 could reverse the UVB-induced downregulation of Nrf2 and its downstream targets GSH, catalase, and NOQ-1. Our results suggest that by upregulating the Nrf2 pathway, AT-RvD1 promotes the expression of ARE genes, restoring the skin's natural antioxidant defense against UVB exposition to avoid oxidative stress, inflammation, and tissue damage.

Resolvin D1/N-formyl peptide receptor 2 ameliorates paclitaxel-induced neuropathic pain through the activation of IL-10/Nrf2/HO-1 pathway in mice.

Introduction: Paclitaxel is a chemotherapy drug that is commonly used to treat cancer, but it can cause paclitaxel-induced neuropathic pain (PINP) as a side effect. Resolvin D1 (RvD1) has been shown to be effective in promoting the resolution of inflammation and chronic pain. In this study, we evaluated the effects of RvD1 on PINP and its underlying mechanisms in mice. Methods: Behavioral analysis was used to assess the establishment of the PINP mouse model and to test the effects of RvD1 or other formulations on mouse pain behavior. Quantitative real-time polymerase chain reaction analysis was employed to detect the impact of RvD1 on 12/15 Lox, FPR2, and neuroinflammation in PTX-induced DRG neurons. Western blot analysis was used to examine the effects of RvD1 on FPR2, Nrf2, and HO-1 expression in DRG induced by PTX. TUNEL staining was used to detect the apoptosis of DRG neurons induced by BMDM conditioned medium. H2DCF-DA staining was used to detect the reactive oxygen species level of DRG neurons in the presence of PTX or RvD1+PTX treated BMDMs CM. Results: Expression of 12/15-Lox was decreased in the sciatic nerve and DRG of mice with PINP, suggesting a potential involvement of RvD1 in the resolution of PINP. Intraperitoneal injection of RvD1 promoted pain resolution of PINP in mice. Intrathecal injection of PTX-treated BMDMs induced mechanical pain hypersensitivity in naïve mice, while pretreatment of RvD1 in BMDMs prevented it. Macrophage infiltration increased in the DRGs of PINP mice, but it was not affected by RvD1 treatment. RvD1 increased IL-10 expression in the DRGs and macrophages, while IL-10 neutralizing antibody abolished the analgesic effect of RvD1 on PINP. The effects of RvD1 in promoting IL-10 production were also inhibited by N-formyl peptide receptor 2 (FPR2) antagonist. The primary cultured DRG neurons apoptosis increased after stimulation with condition medium of PTX-treated BMDMs, but decreased after pretreatment with RvD1 in BMDMs. Finally, Nrf2-HO1 signaling was additionally activated in DRG neurons after stimulation with condition medium of RvD1+PTX-treated BMDMs, but these effects were abolished by FPR2 blocker or IL-10 neutralizing antibody. Discussion: In conclusion, this study provides evidence that RvD1 may be a potential therapeutic strategy for the clinical treatment of PINP. RvD1/FPR2 upregulates IL-10 in macrophages under PINP condition, and then IL-10 activates the Nrf2- HO1 pathway in DRG neurons, relieve neuronal damage and PINP.

Resolvin D1 attenuates mechanical allodynia after burn injury: Involvement of spinal glia, p38 mitogen-activated protein kinase, and brain-derived neurotrophic factor/tropomyosin-related kinase B signaling.

Resolvin D1 (RvD1) suppresses inflammatory, postoperative, and neuropathic pain. The present study assessed the roles and mechanisms of RvD1 in mechanical allodynia after burn injury. A rat model of burn injury was established for analyses, and RvD1 was injected intraperitoneally. Pain behavior and the expression levels of spinal dorsal horn Iba-1 (microglia marker), GFAP (astrocyte marker), p-p38 mitogen-activated protein kinase (MAPK), brain-derived neurotrophic factor (BDNF), and tropomyosin-related kinase B (TrkB) were detected by behavioral and immunocytochemical assays. The results showed that RvD1 attenuated mechanical allodynia after burn injury, prevented microglial and astroglial activation, and downregulated p-p38 MAPK in microglia and BDNF/TrkB following burn injury. Similarly, inhibition of p38 MAPK and BDNF/TrkB signaling attenuated mechanical allodynia after burn injury. In addition, inhibition of p38 MAPK prevented spinal microglial activation and downregulated BDNF/TrkB following burn injury. Furthermore, inhibition of BDNF/TrkB signaling prevented spinal microglial activation and downregulated p-p38 MAPK within spinal microglia. Taken together, this study demonstrated that RvD1 might attenuate mechanical allodynia after burn injury by inhibiting spinal cord glial activation, microglial p38 MAPK, and BDNF/TrkB signaling in the spinal dorsal horn.

DHA, RvD1, RvD5, and MaR1 reduce human coronary arteries contractions induced by PGE2.

In patients with coronary artery disease (CAD), plasma levels of pro-inflammatory lipid mediators such as PGE2 and TxA2 are increased. They could increase vascular contraction while EPA and DHA could reduce it. Studies have been mostly conducted on animal vessels. Therefore, the aim of the study was to investigate if EPA, DHA, and DHA-derived metabolites: RvD1, RvD5 and MaR1 can modulate contraction of human coronary arteries (HCA) induced by PGE2 or TxA2 stable analogue (U46619). DHA and EPA relaxed HCA pre-contracted with PGE2. 18 h-incubation with DHA but not EPA reduced the PGE2-induced contractions. Pre-incubation with RvD1, RvD5 and MaR1 reduced the PGE2-induced contractions. Indomethacin did not significantly modify the PGE2 responses. L-NOARG (inhibitor of nitric oxide synthase), reduced only the PGE2-induced contractions in RvD1-treated rings. Finally, FPR2/ALX, GPR32 and LGR6 receptors are detected in HCA by immunofluorescence. Our results indicate that DHA and its metabolites could be beneficial for HCA blood flow and could be a therapeutic perspective for patients with CAD.

Resolvin D1 attenuates sepsis induced acute kidney injury targeting mitochondria and NF-κB signaling pathway.

Background: Acute kidney injury is a highly common and multifactorial renal disease resulting in significant morbidity and mortality, especially sepsis-induced acute kidney injury. There is no effective therapy available to treat or prevent sepsis-induced acute kidney injury. One of the specialized pro-resolving mediators, Resolvin D1 exhibits special anti-inflammatory effects in several inflammatory disease models, but there is little evidence about the effect and mechanism of Resolvin D1 in sepsis-induced acute kidney injury. Methods: We conducted experiments to explore the effect and mechanism of Resolvin D1 in sepsis-induced acute kidney injury. In vitro, human proximal tubular epithelial cells were used to test the apoptosis ratio, cell viability and reactive oxygen species level. In vivo, C57BL/6 mice were injected with lipopolysaccharide to establish a sepsis-induced acute kidney injury model. Renal function and structure, apoptosis ratio of kidney cells, mitochondrial structure and function and related protein and gene levels were assessed. Results: In vitro, the resolvin D1-treated group showed higher cell viability and lower reactive oxygen species levels and apoptosis ratios than the LPS group. In vivo, Resolvin D1 can not only improve renal function and mitochondrial function but also reduce the apoptosis ratio, while mediating mitochondrial dynamics and inhibiting NF-κB pathway. Conclusions: Resolvin D1 has a good renoprotective effect by maintaining mitochondrial dynamics and inhibiting the NF-κB pathway.

Resolvin D1: A key endogenous inhibitor of neuroinflammation.

After the initiation of inflammation, a series of processes start to resolve the inflammation. A group of endogenous lipid mediators, namely specialized pro-resolving lipid mediators is at the top list of inflammation resolution. Resolvin D1 (RvD1), is one of the lipid mediators with significant anti-inflammatory properties. It is produced from docosahexaenoic acid (omega-3 polyunsaturated fatty acid) in the body. In this article, we aimed to review the most recent findings concerning the pharmacological effects of RvD1 in the central nervous system with a focus on major neurological diseases and dysfunctions. A literature review of the past studies demonstrated that RvD1 plasma level changes during mania, depression, and Parkinson's disease. Furthermore, RVD1 and its epimer, aspirin-triggered RvD1 (AT-RvD1), have significant therapeutic effects on experimental models of ischemic and traumatic brain injuries, memory dysfunction, pain, depression, amyotrophic lateral sclerosis, and Alzheimer's and Parkinson's diseases. Interestingly, the beneficial effects of RvD1 and AT-RvD1 were mostly induced at nanomolar and micromolar concentrations implying the significant potency of these lipid mediators in treating diseases with inflammation.

Effect of Chlorogenic Acid via Upregulating Resolvin D1 Inhibiting the NF-κB Pathway on Chronic Restraint Stress-Induced Liver Inflammation.

Chronic stress can cause chronic inflammatory injury to the liver. Chlorogenic acid (CGA) is known to have a wide range of biological activities and anti-inflammatory effects. Resolvin D1 (RvD1) is a polyunsaturated fatty acid derivative that has inhibitory effects on a variety of inflammatory diseases. However, whether CGA can inhibit liver inflammation in chronic stress through RvD1 remains unclear. In this work, male rats were subjected to restraint stress for 6 h every day and built a chronic stress model for 21 days. CGA (100 mg/kg) was administered intragastrically 1 h before restraint, with intraperitoneal injection of RvD1 inhibitor WRW4 (antagonist of FPR2, 0.1 mg/kg) or WRW4 solution every 2 days for 30 min before CGA administration. CGA reduced hepatic hemorrhage and inflammatory cell infiltration, alleviated hepatic injury, decreased the activation of the NF-κB pathway and the expression of interleukin 1ß, interleukin 6, and tumor necrosis factor α in the liver, and increased RvD1 in the serum and liver. The therapeutic effect of CGA was blocked after WRW4 intervention. These results suggest that the protective effects of CGA mediate the NF-κB pathway by upregulating the generation of RvD1. Above all, this research demonstrates the liver protective effect of CGA and provides a potential treatment strategy for chronic inflammatory disease.

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

BACKGROUND: Metabolic syndrome (MetS) exacerbates susceptibility to inhalation exposures such as particulate air pollution, however, the mechanisms responsible remain unelucidated. Previously, we determined a MetS mouse model exhibited exacerbated pulmonary inflammation 24 h following AgNP exposure compared to a healthy mouse model. This enhanced response corresponded with reduction of distinct resolution mediators. We hypothesized silver nanoparticle (AgNP) exposure in MetS results in sustained pulmonary inflammation. Further, we hypothesized treatment with resolvin D1 (RvD1) will reduce exacerbations in AgNP-induced inflammation due to MetS. RESULTS: To evaluate these hypotheses, healthy and MetS mouse models were exposed to vehicle (control) or AgNPs and a day later, treated with resolvin D1 (RvD1) or vehicle (control) via oropharyngeal aspiration. Pulmonary lung toxicity was evaluated at 3-, 7-, 14-, and 21-days following AgNP exposure. MetS mice exposed to AgNPs and receiving vehicle treatment, demonstrated exacerbated pulmonary inflammatory responses compared to healthy mice. In the AgNP exposed mice receiving RvD1, pulmonary inflammatory response in MetS was reduced to levels comparable to healthy mice exposed to AgNPs. This included decreases in neutrophil influx and inflammatory cytokines, as well as elevated anti-inflammatory cytokines. CONCLUSIONS: Inefficient resolution may contribute to enhancements in MetS susceptibility to AgNP exposure causing an increased pulmonary inflammatory response. Treatments utilizing specific resolution mediators may be beneficial to individuals suffering MetS following inhalation exposures.

Effect of resolvin D1 on experimental bacterial keratitis to prevent corneal scar.

PURPOSE: The study aims to investigate the role of the lipid mediator resolvin D1 (RvD1) in bacterial keratitis in a murine model. METHODS: The effect of RvD1 on Pseudomonas aeruginosa-stimulated human corneal epithelial cells (HCECs) and mouse macrophages and dendritic cells (DCs) was assessed. C57BL/6 mouse corneas were abraded and treated with RvD1 after stimulation with P. aeruginosa, following which cytokine production level in the cornea and drainage lymph nodes was compared with that in controls. Corneal opacity and thickness were assessed using anterior segment photographs, and optical coherence tomography and corneal infiltrates were analyzed using immunohistochemistry for neutrophils. RESULTS: RvD1 significantly inhibited pro-inflammatory cytokine production in HCECs, mouse macrophages, and DCs. Corneal opacity and corneal thickness were reduced, and the development of corneal infiltrates, specifically neutrophils, was also significantly inhibited by RvD1 in response to stimulation with P. aeruginosa. CONCLUSIONS: RvD1 inhibits P. aeruginosa-induced corneal inflammation. This finding supports a potential therapeutic approach for patients with bacterial keratitis.

Resolvin D1 Alleviates Mechanical Allodynia via ALX/FPR2 Receptor Targeted Nod-like Receptor Protein 3/Extracellular Signal-Related Kinase Signaling in a Neuropathic Pain Model.

The current study aimed to investigate the role and underlying mechanism of Resolvin D1 (RvD1) alleviating spinal nerve ligation (SNL)-induced neuropathic pain (NP) and its interplay with regulatory cascades of Nod-like Receptor Protein 3 (NLRP3) inflammasome. Sprague-Dawley male rat models of SNL-stimulated NP were established, which were pre-treated with different doses of RvD1, WRW4 (ALX/FPR2 inhibitor) or U0126 (ERK inhibitor) for three successive days following the operation. Pain behavior was assessed by measuring changes in the mechanical sensitivity of the hind paws during an observation period of seven consecutive days. The spinal cord (SC) and dorsal root ganglions (DRGs) tissues were collected on postoperative day 7. Immunohistochemistry (IHC) and Western blot were performed to determine the expression levels of NLRP3 inflammasome complex, ALX/FPR2 receptor and extracellular signal-related kinase (ERK). The pro-inflammatory mediators (IL-1ß and IL-18) were measured by enzyme-linked immunosorbent assay (ELISA). The results showed that RvD1 could alleviate mechanical allodynia significantly in the SNL-induced NP rat models. Also, RvD1 inhibited the expression of p-ERK, the NLRP3 inflammasomes complex and its corresponding downstream pro-inflammatory mediators which were significantly enhanced in the SC and DRGs of the rat SNL models. While these changes were partially reversed by pre-administration of WRW4 and further strengthened by co-treated with U0126. Our results suggest that RvD1 dependent on ALX/FPR2 may have an analgesic and anti-inflammatory influence on SNL-induced NP driven by inhibiting NLRP3 inflammasome via ERK signaling pathway. These data also provide strong support for the recent modulation of neuro-inflammatory priming and highlight the potential for specialized pro-resolving mediators (SPMs) as novel therapeutic avenues for NP.

The inhibiting effect of Aspirin Triggered-Resolvin D1 in non-canonical pyroptosis in rats with acute keratitis.

PURPOSE: To investigate the effect of Aspirin Triggered-Resolvin D1 (AT-RvD1) as an anti-pyroptosis and anti-inflammatory agent on lipopolysaccharide (LPS) induced acute keratitis in Wistar rats. METHODS: Acute keratitis in rats were induced by LPS stromal injection. Inflammatory reaction was measured by clinical score and histological observations. The non-canonical pyroptosis, the role of AT-RvD1 and Docosahexaenoic Acid (DHA) on non-canonical pyroptosis, were verified by quantification real-time PCR (qRT-PCR) and Western-blot. Besides, Human corneal epithelial cells (HCECs) primed with LPS, were stimulated with Nigericin, AT-RvD1 and necrosulfonamide (NSA), a Gasdermin-D (GSDMD) inhibitor separately. CCK-8 tests and flow cytometry were conducted to evaluate the cell viability and death ratio. And the marker of non-canonical pyroptosis were verified by Western blot. RESULTS: AT-RvD1 and DHA both alleviated the inflammation of rat cornea through inhibiting the expression of Caspase-11 and p30 which was triggered by LPS. Meanwhile, the activation of Caspase-4 and p30 were also significantly suppressed by AT-RvD1 in vitro, which is consistent with the results in rats. CONCLUSIONS: The non-canonical pyroptosis signaling pathways played an important role in rats with acute keratitis. In addition, AT-RvD1 can exert as an anti-inflammatory activity by inhibiting the non-canonical pyroptosis. Hence, it may be a promising and safe agent in treating acute keratitis.

Fatty Acid Oxidation and Pro-Resolving Lipid Mediators Are Related to Male Infertility.

Specialized pro-resolving lipid mediators regulate the resolution of acute inflammation. They are formed by enzymatic oxygenation of polyunsaturated fatty acids and are divided into families including lipoxins, resolvins, protectins, and maresins. Resolvin D1 (RvD1), produced by docosahexaenoic acid, exerts anti-inflammatory and pro-resolving activities. This research aimed to investigate the implication of seminal RvD1 in human infertility. Infertile patients (n° 67) were grouped based on pathological reproductive conditions as idiopathic infertility, varicocele, and leukocytospermia; the fourth group was composed of fertile men (n° 18). Sperm characteristics were evaluated by light microscopy (WHO guidelines) and by transmission electron microscopy (TEM). The seminal levels of RvD1 and F2-isoprostane (F2-IsoPs) were dosed. In twenty men (6 fertile men, 8 with varicocele, 6 with leukocytospermia) seminal phospholipase A2, iron, cholesterol, transferrin, estradiol, ferritin, testosterone, and sperm membrane fatty acids were detected. The results indicated that: (i) RvD1 amount was positively correlated with F2-IsoPs and reduced sperm quality; (ii) RvD1 levels were significantly higher in patients with leukocytospermia, varicocele, and idiopathic infertility compared to fertile men; (iii) RvD1 increased along with other markers of oxidative stress and inflammation as fatty acids content and clinical biomarkers. This study suggests a panel of inflammatory markers and lipid mediators for a diagnosis of inflammatory status and a subsequent appropriate therapeutic approach.