Resolvin D1 Improves the Resolution of Inflammation via Activating NF-κB p50/p50-Mediated Cyclooxygenase-2 Expression in Acute Respiratory Distress Syndrome

LINC01270 Regulates the NF-κB-Mediated Pro-Inflammatory Response via the miR-326/LDOC1 Axis in THP-1 Cells

Long intergenic noncoding (LINC)01270 is a 2278 bp transcript belonging to the intergenic subset of long noncoding (lnc)RNAs. Despite increased reports of LINC01270's involvement in different diseases, evident research on its effects on inflammation is yet to be achieved. In the present study, we investigated the potential role of LINC01270 in modulating the inflammatory response in the human monocytic leukemia cell line THP-1. Lipopolysaccharide treatment upregulated LINC01270 expression, and siRNA-mediated suppression of LINC01270 enhanced NF-κB activity and the subsequent production of cytokines IL-6, IL-8, and MCP-1. Interestingly, the knockdown of LINC01270 downregulated expression of leucine zipper downregulated in cancer 1 (LDOC1), a novel NF-κB suppressor. An analysis of the LINC01270/micro-RNA (miRNA)/protein interactome profile identified miR-326 as a possible mediator. Synthetic RNA agents that perturb the interaction among LINC01270, miR-326, and LDOC1 mRNA mitigated the changes caused by LINC01270 knockdown in THP-1 cells. Additionally, a luciferase reporter assay in HEK293 cells further confirmed that LINC01270 knockdown enhances NF-κB activation, while its overexpression has the opposite effect. This study provides insight into LINC01270's role in modulating inflammatory responses to lipopolysaccharide stimulation in THP-1 cells via the miR-326/LDOC1 axis, which negatively regulates NF-κB activation.

Advances in the Chemistry and Biology of Specialised Pro-Resolving Mediators (SPMs)

This review article assembles key recent advances in the synthetic chemistry and biology of specialised pro-resolving mediators (SPMs). The major medicinal chemistry developments in the design, synthesis and biological evaluation of synthetic SPM analogues of lipoxins and resolvins have been discussed. These include variations in the top and bottom chains, as well as changes to the triene core, of lipoxins, all changes intended to enhance the metabolic stability whilst retaining or improving biological activity. Similar chemical modifications of resolvins are also discussed. The biological evaluation of these synthetic SPMs is also described in some detail. Original investigations into the biological activity of endogenous SPMs led to the pairing of these ligands with the FPR2/LX receptor, and these results have been challenged in more recent work, leading to conflicting results and views, which are again discussed.

Role of Resolvins in Inflammatory and Neuropathic Pain

Chronic pain is an unpleasant experience associated with actual or potential tissue damage. Inflammatory pain alerts the body to inflammation and promotes healing; however, unresolved inflammation can lead to chronic pain. Conversely, neuropathic pain, due to somatosensory damage, can be a disease in itself. However, inflammation plays a considerable role in the progression of both types of pain. Resolvins, derived from omega-3 fatty acids, actively suppress pro-inflammatory mediators and aid in the resolution of inflammation. Resolvins alleviate various inflammatory and neuropathic pain models by reducing hypersensitivity and regulating inflammatory cytokines and glial activation in the spinal cord and dorsal root ganglia. Thus, resolvins are a promising alternative for pain management with the potential to reduce the side effects associated with conventional medications. Continued research is crucial to unlock the therapeutic potential of resolvins and integrate them into effective clinical pain management strategies. This review aimed to evaluate the literature surrounding the resolvins in inflammatory and neuropathic pain.

Preventative and therapeutic potential of animal milk components against COVID-19: A comprehensive review

The global pandemic of COVID-19 is considered one of the most catastrophic events on earth. During the pandemic, food ingredients may play crucial roles in preventing infectious diseases and sustaining people's general health and well-being. Animal milk acts as a super food since it has the capacity to minimize the occurrence of viral infections due to inherent antiviral properties of its ingredients. SARS-CoV-2 virus infection can be prevented by immune-enhancing and antiviral properties of caseins, α-lactalbumin, β-lactoglobulin, mucin, lactoferrin, lysozyme, lactoperoxidase, oligosaccharides, glycosaminoglycans, and glycerol monolaurate. Some of the milk proteins (i.e., lactoferrin) may work synergistically with antiviral medications (e.g., remdesivir), and enhance the effectiveness of treatment in this disease. Cytokine storm during COVID-19 can be managed by casein hydrolyzates, lactoferrin, lysozyme, and lactoperoxidase. Thrombus formation can be prevented by casoplatelins as these can inhibit human platelet aggregation. Milk vitamins (i.e., A, D, E, and B complexes) and minerals (i.e., Ca, P, Mg, Zn, and Se) can have significantly positive effects on boosting the immunity and health status of individuals. In addition, certain vitamins and minerals can also act as antioxidants, anti-inflammatory, and antivirals. Thus, the overall effect of milk might be a result of synergistic antiviral effects and host immunomodulator activities from multiple components. Due to multiple overlapping functions of milk ingredients, they can play vital and synergistic roles in prevention as well as supportive agents during principle therapy of COVID-19.

Significance of Pulmonary Endothelial Injury and the Role of Cyclooxygenase-2 and Prostanoid Signaling

The endothelium plays a key role in the dynamic balance of hemodynamic, humoral and inflammatory processes in the human body. Its central importance and the resulting therapeutic concepts are the subject of ongoing research efforts and form the basis for the treatment of numerous diseases. The pulmonary endothelium is an essential component for the gas exchange in humans. Pulmonary endothelial dysfunction has serious consequences for the oxygenation and the gas exchange in humans with the potential of consecutive multiple organ failure. Therefore, in this review, the dysfunction of the pulmonary endothel due to viral, bacterial, and fungal infections, ventilator-related injury, and aspiration is presented in a medical context. Selected aspects of the interaction of endothelial cells with primarily alveolar macrophages are reviewed in more detail. Elucidation of underlying causes and mechanisms of damage and repair may lead to new therapeutic approaches. Specific emphasis is placed on the processes leading to the induction of cyclooxygenase-2 and downstream prostanoid-based signaling pathways associated with this enzyme.

Clinical response to EPA supplementation in patients with major depressive disorder is associated with higher plasma concentrations of pro-resolving lipid mediators

Chronic inflammation has been implicated in the pathophysiology of major depressive disorder (MDD). Activating the resolution of inflammation through ω-3 fatty acid supplementation may prove to be a successful therapeutic strategy for the treatment of MDD. Patients with MDD, body mass index >25 kg/m², and plasma high-sensitivity C-reactive protein ≥3 μg/mL (n = 61) were enrolled in a 12-week randomized trial consisting of 4 parallel arms: EPA 1, 2, and 4 g/d, and placebo. The supplement contained EPA and DHA in a 3.9:1 ratio. Depression symptoms were assessed using the IDS-C30 scale. Plasma fatty acids and pro-resolving lipid mediators (SPMs) were measured in 42 study completers at baseline and at the end of treatment by liquid chromatography/mass spectrometry. The response rate (≥50% reduction in IDS-30 score) was higher in the 4 g/d EPA arm than placebo (Cohen d = 0.53). In the 4 g/d EPA arm, responders had significantly greater increases in 18-hydroxyeicosapentaenoic acid (18-HEPE) and 13-hydroxydocosahexaenoic acid (13-HDHA) than non-responders (p < 0.05). Within the 4 g/d EPA arm, the increase in 18-HEPE was significantly associated with reductions in plasma hs-CRP concentrations (p < 0.05) and IDS-C30 scores (p < 0.01). In summary, response rates were greater among patients with MDD randomized to EPA 4 g/d supplementation and in those who showed a greater ability to activate the synthesis of 18-HEPE. The inverse association of 18-HEPE with both systemic inflammation and symptoms of depression highlights the activation of the resolution of inflammation as a likely mechanism in the treatment of MDD with ω-3 fatty acid supplementation.

Therapeutic Targeting of NF-κB in Acute Lung Injury: A Double-Edged Sword

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is a devastating disease that can be caused by a variety of conditions including pneumonia, sepsis, trauma, and most recently, COVID-19. Although our understanding of the mechanisms of ALI/ARDS pathogenesis and resolution has considerably increased in recent years, the mortality rate remains unacceptably high (~40%), primarily due to the lack of effective therapies for ALI/ARDS. Dysregulated inflammation, as characterized by massive infiltration of polymorphonuclear leukocytes (PMNs) into the airspace and the associated damage of the capillary-alveolar barrier leading to pulmonary edema and hypoxemia, is a major hallmark of ALI/ARDS. Endothelial cells (ECs), the inner lining of blood vessels, are important cellular orchestrators of PMN infiltration in the lung. Nuclear factor-kappa B (NF-κB) plays an essential role in rendering the endothelium permissive for PMN adhesion and transmigration to reach the inflammatory site. Thus, targeting NF-κB in the endothelium provides an attractive approach to mitigate PMN-mediated vascular injury, not only in ALI/ARDS, but in other inflammatory diseases as well in which EC dysfunction is a major pathogenic mechanism. This review discusses the role and regulation of NF-κB in the context of EC inflammation and evaluates the potential and problems of targeting it as a therapy for ALI/ARDS.

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.

Lipoxin alleviates oxidative stress: a state-of-the-art review

OBJECTIVE

This review aims to summarize the capability of lipoxin in regulating oxidative stress.

BACKGROUND

Oxidative stress is defined as an imbalance between the production of free radicals and the antioxidant system, and it is associated with the existence of a large number of oxidation products, such as reactive oxygen species (ROS) and reaction nitrogen species (RNS), causing damage to human tissues through immunoinflammatory responses. Therefore, reducing oxidative stress is vital to alleviate pathological damage. Lipoxin, an acronym for lipoxygenase interaction product, is a bioactive autacoid metabolite of arachidonic acid made by various cell types. Previous studies have shown that lipoxin is associated with a variety of biological functions, including anti-inflammatory, regulating immune responses, promoting the repair of damaged cells, etc. The deficiency of lipoxin is a critical pathological mechanism in different diseases. Moreover, the ability of lipoxin to attenuate oxidative stress is noteworthy, thereby protecting the human body from diverse diseases.

METHODS

We searched papers from PubMed database using search terms, such as lipoxin, lipoxin A4, oxidative stress, and other relevant terms.

RESULTS

A total of 103 articles published over the past 20 years were identified for inclusion. We summarized the capability of lipoxin in regulating oxidative stress and mechanism.

CONCLUSION

Lipoxin is provided with a protective role in attenuating oxidative stress.

Deciphering the immunoboosting potential of macro and micronutrients in COVID support therapy

The immune system protects human health from the effects of pathogenic organisms; however, its activity is affected when individuals become infected. These activities require a series of molecules, substrates, and energy sources that are derived from diets. The consumed nutrients from diets help to enhance the immunity of infected individuals as it relates to COVID-19 patients. This study aims to review and highlight requirement and role of macro- and micronutrients of COVID-19 patients in enhancing their immune systems. Series of studies were found to have demonstrated the enhancing potentials of macronutrients (carbohydrates, proteins, and fats) and micronutrients (vitamins, copper, zinc, iron, calcium, magnesium, and selenium) in supporting the immune system's fight against respiratory infections. Each of these nutrients performs a vital role as an antiviral defense in COVID-19 patients. Appropriate consumption or intake of dietary sources that yield these nutrients will help provide the daily requirement to support the immune system in its fight against pathogenic viruses such as COVID-19.

Protectin DX promotes the inflammatory resolution via activating COX-2/L-PGDS-PGD2 and DP1 receptor in acute respiratory distress syndrome

PURPOSE

Acute respiratory distress syndrome (ARDS) is characterized by uncontrollable inflammation. Cyclooxygenase-2(COX-2) and its metabolite prostaglandins are known to promote the inflammatory resolution of ARDS. Recently, a newly discovered endogenous lipid mediator, Protectin DX (PDX), was also shown to mediate the resolution of inflammation. However, the regulatory of PDX on the pro-resolving COX-2 in ARDS remains unknown.

MATERIAL AND METHODS

PDX (5 μg/kg) was injected into rats intravenously 12 h after the lipopolysaccharide (LPS, 3 mg/kg) challenge. Primary rat lung fibroblasts were incubated with LPS (1 μg/ml) and/or PDX (100 nM). Lung pathological changes examined using H&E staining. Protein levels of COX-2, PGDS and PGES were evaluated using western blot. Inflammatory cytokines were tested by qPCR, and the concentration of prostaglandins measured by using ELISA.

RESULTS

Our study revealed that, COX-2 and L-PGDS has biphasic activation characteristics that LPS could induce induced by LPS both in vivo and in vitro.. The secondary peak of COX-2, L-PGDS-PGD2 promoted the inflammatory resolution in ARDS model with the DP1 receptor being activated and PDX up-regulated the inflammatory resolutionvia enhancing the secondary peak of COX-2/L-PGDS-PGD2 and activating the DP1 receptor.

CONCLUSION

PDX promoted the resolution of inflammation of ARDS model via enhancing the expression of secondary peak of COX-2/L-PGDS-PGD2 and activating the DP1 receptor. PDX shows promising therapeutic potential in the clinical management of ARDS.

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

Background

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

Methodology/Principal findings

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

Conclusions/Significance

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

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

Chia oil prevents chemical and immune-mediated inflammatory responses in mice: Evidence for the underlying mechanisms

Chia (Salvia hispanica L.) is an herbaceous plant used as omega-3 polyunsaturated fatty acid (ω-3 PUFA) source that presents a range of beneficial effects on human health. Herein, it was used a chia oil containing over than 62% of α-linolenic acid (ALA), a compound widely related to anti-inflammatory actions. Chia oil effect was tested using paw edema and mechanical hyperalgesia induced by carrageenan, and ear edema induced by croton oil, histamine, and capsaicin. Croton oil was used in both preventive and therapeutic treatment schedules of chia oil while histamine and capsaicin were used only in preventive treatment schedule. Chia oil mechanism of action was investigated using nociception and paw edema response induced by intraplantar injection of acidified saline (ASIC activator), PGE₂ (prostaglandin pathway), cinnamaldehyde (TRPA1 activator), bradykinin (BK pathway), menthol (TRPM8 activator), and capsaicin (TRPV1 activator). Further, RT-PCR for inflammatory mediators (TRPA1, NF-κB, PPAR-γ, COX-2, IL-6, TNF, FPR2, FAAH, MAGL, and IL-12A) induced by carrageenan, NLRP3 inflammasome activation, and the cell viability were then accessed. Later, chia oil actions were evaluated in the experimental autoimmune encephalomyelitis (EAE), a multiple sclerosis (MS) model. Chia oil showed anti-edematogenic and anti-hyperalgesic effects when administered 1 h before pro-inflammatory stimulus - particularly carrageenan and croton oil. Moreover, chia oil upregulated the mRNA levels of COX-2 and formyl peptide receptor 2 (FPR2) while reduced IL-6 expression in the spinal cord of mice submitted to i.pl. injection of carrageenan. Interestingly, chia oil mediates antinociceptive effects in mice decreasing the nociceptive response induced by acidified saline, PGE₂, and cinnamaldehyde, but not by bradykinin, menthol, and capsaicin. On the EAE model, chia oil preventively administered attenuated EAE-induced motor deficits and mechanical hyperalgesia in mice, suggesting a valuable effect of chia oil supplementation in regulating inflammatory responses and some immune functions during immune-mediated inflammatory disorders (IMID). Nonetheless, additional reports will need to assess the effect of chia oil in well-controlled clinical trials performed in MS patients.

A γ-PGA/KGM-based injectable hydrogel as immunoactive and antibacterial wound dressing for skin wound repair

Injectable hydrogels, of which the cover area and volume can be flexibly adjusted according to the shape and depth of the wound, are considered to be an ideal material for wound dressing. Konjac glucomannan (KGM) is a natural polysaccharide with immunomodulatory capability, while γ-polyglutamic acid (γ-PGA) is a single chain polyamino acid with moisturizing, water-retention and antibacterial properties. This work intended to combine the advantages of the two materials to prepare an injectable hydrogel (P-OK) by mixing the adipic acid dihydrazide (ADH) modified γ-PGA with oxidized KGM. The chemical structures, the physical and chemical properties, and the biological properties of the P-OK hydrogel were evaluated. The optimal conditions to form the P-OK hydrogel were fixed, and the cytotoxicity, qPCR, antibacterial and animal experiments were performed. Results showed that the P-OK hydrogel had a fast gelation time, good water-retention rate, little cytotoxicity, good immunomodulating and antibacterial capabilities, and could shorten the healing period in the rat full-thickness defect model, which makes it a potential candidate for wound repair dressing.

Can N-3 polyunsaturated fatty acids be considered a potential adjuvant therapy for COVID-19-associated cardiovascular complications?

Coronavirus disease 2019 (COVID-19), caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), has currently led to a global pandemic with millions of confirmed and increasing cases around the world. The novel SARS-CoV-2 not only affects the lungs causing severe acute respiratory dysfunction but also leads to significant dysfunction in multiple organs and physiological systems including the cardiovascular system. A plethora of studies have shown the viral infection triggers an exaggerated immune response, hypercoagulation and oxidative stress, which contribute significantly to poor cardiovascular outcomes observed in COVID-19 patients. To date, there are no approved vaccines or therapies for COVID-19. Accordingly, cardiovascular protective and supportive therapies are urgent and necessary to the overall prognosis of COVID-19 patients. Accumulating literature has demonstrated the beneficial effects of n-3 polyunsaturated fatty acids (n-3 PUFA) toward the cardiovascular system, which include ameliorating uncontrolled inflammatory reactions, reduced oxidative stress and mitigating coagulopathy. Moreover, it has been demonstrated the n-3 PUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are precursors to a group of potent bioactive lipid mediators, generated endogenously, which mediate many of the beneficial effects attributed to their parent compounds. Considering the favorable safety profile for n-3 PUFAs and their metabolites, it is reasonable to consider n-3 PUFAs as potential adjuvant therapies for the clinical management of COVID-19 patients. In this article, we provide an overview of the pathogenesis of cardiovascular complications secondary to COVID-19 and focus on the mechanisms that may contribute to the likely benefits of n-3 PUFAs and their metabolites.

GRK2 levels in myeloid cells modulate adipose-liver crosstalk in high fat diet-induced obesity

Macrophages are key effector cells in obesity-associated inflammation. G protein-coupled receptor kinase 2 (GRK2) is highly expressed in different immune cell types. Using LysM-GRK2+/- mice, we uncover that a reduction of GRK2 levels in myeloid cells prevents the development of glucose intolerance and hyperglycemia after a high fat diet (HFD) through modulation of the macrophage pro-inflammatory profile. Low levels of myeloid GRK2 confer protection against hepatic insulin resistance, steatosis and inflammation. In adipose tissue, pro-inflammatory cytokines are reduced and insulin signaling is preserved. Macrophages from LysM-GRK2+/- mice secrete less pro-inflammatory cytokines when stimulated with lipopolysaccharide (LPS) and their conditioned media has a reduced pathological influence in cultured adipocytes or naïve bone marrow-derived macrophages. Our data indicate that reducing GRK2 levels in myeloid cells, by attenuating pro-inflammatory features of macrophages, has a relevant impact in adipose-liver crosstalk, thus preventing high fat diet-induced metabolic alterations.

The pathophysiology of SARS-CoV-2: A suggested model and therapeutic approach

In this paper, a model is proposed of the pathophysiological processes of COVID-19 starting from the infection of human type II alveolar epithelial cells (pneumocytes) by SARS-CoV-2 and culminating in the development of ARDS. The innate immune response to infection of type II alveolar epithelial cells leads both to their death by apoptosis and pyroptosis and to alveolar macrophage activation. Activated macrophages secrete proinflammatory cytokines and chemokines and tend to polarise into the inflammatory M1 phenotype. These changes are associated with activation of vascular endothelial cells and thence the recruitment of highly toxic neutrophils and inflammatory activated platelets into the alveolar space. Activated vascular endothelial cells become a source of proinflammatory cytokines and reactive oxygen species (ROS) and contribute to the development of coagulopathy, systemic sepsis, a cytokine storm and ARDS. Pulmonary activated platelets are also an important source of proinflammatory cytokines and ROS, as well as exacerbating pulmonary neutrophil-mediated inflammatory responses and contributing to systemic sepsis by binding to neutrophils to form platelet-neutrophil complexes (PNCs). PNC formation increases neutrophil recruitment, activation priming and extraversion of these immune cells into inflamed pulmonary tissue, thereby contributing to ARDS. Sequestered PNCs cause the development of a procoagulant and proinflammatory environment. The contribution to ARDS of increased extracellular histone levels, circulating mitochondrial DNA, the chromatin protein HMGB1, decreased neutrophil apoptosis, impaired macrophage efferocytosis, the cytokine storm, the toll-like receptor radical cycle, pyroptosis, necroinflammation, lymphopenia and a high Th17 to regulatory T lymphocyte ratio are detailed.

Formyl peptide receptors in the mucosal immune system

Formyl peptide receptors (FPRs) belong to the G protein-coupled receptor (GPCR) family and are well known as chemotactic receptors and pattern recognition receptors (PRRs) that recognize bacterial and mitochondria-derived formylated peptides. FPRs are also known to detect a wide range of ligands, including host-derived peptides and lipids. FPRs are highly expressed not only in phagocytes such as neutrophils, monocytes, and macrophages but also in nonhematopoietic cells such as epithelial cells and endothelial cells. Mucosal surfaces, including the gastrointestinal tract, the respiratory tract, the oral cavity, the eye, and the reproductive tract, separate the external environment from the host system. In mucosal surfaces, the interaction between the microbiota and host cells needs to be strictly regulated to maintain homeostasis. By sharing the same FPRs, immune cells and epithelial cells may coordinate pathophysiological responses to various stimuli, including microbial molecules derived from the normal flora. Accumulating evidence shows that FPRs play important roles in maintaining mucosal homeostasis. In this review, we summarize the roles of FPRs at mucosal surfaces.

Transcription factor-mediated signaling pathways' contribution to the pathology of acute lung injury and acute respiratory distress syndrome

The 2019 novel coronavirus (2019-nCoV) is still spreading rapidly around the world, and one cause of lethality for patients infected with 2019-nCoV is acute respiratory distress syndrome (ARDS). ARDS is a severe syndrome of acute lung injury (ALI) that is predominantly triggered by inflammation and results in a sudden loss of, or damage to, kidney function. Emerging studies reveal that multiple transcription factor-associated signaling pathways are activated in the pathology of ALI/ARDS. Of these pathways, the activation of NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells), AP-1 (activator protein 1), IRFs (interferon regulatory factors), STATs (signal transducer and activator of transcription), Wnt/β-catenin-TCF/LEF (T-cell factor/lymphoid enhancer-binding factor), and CtBP2 (C-Terminal binding protein 2)-associated transcriptional complex contributes to ALI/ARDS pathology through diverse mechanisms, such as inducing proinflammatory cytokine levels and mediating macrophage polarization. In this review, we present an updated summary of the mechanisms underlying these signaling activations and regulations, as well as their contribution to the pathogenesis of ALI/ARDS. We aim to develop a better understanding of how ALI/ARDS occurs and improve ALI/ARDS therapy.

Potential benefits and risks of omega-3 fatty acids supplementation to patients with COVID-19

Studies have shown that infection, excessive coagulation, cytokine storm, leukopenia, lymphopenia, hypoxemia and oxidative stress have also been observed in critically ill Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) patients in addition to the onset symptoms. There are still no approved drugs or vaccines. Dietary supplements could possibly improve the patient's recovery. Omega-3 fatty acids, specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), present an anti-inflammatory effect that could ameliorate some patients need for intensive care unit (ICU) admission. EPA and DHA replace arachidonic acid (ARA) in the phospholipid membranes. When oxidized by enzymes, EPA and DHA contribute to the synthesis of less inflammatory eicosanoids and specialized pro-resolving lipid mediators (SPMs), such as resolvins, maresins and protectins. This reduces inflammation. In contrast, some studies have reported that EPA and DHA can make cell membranes more susceptible to non-enzymatic oxidation mediated by reactive oxygen species, leading to the formation of potentially toxic oxidation products and increasing the oxidative stress. Although the inflammatory resolution improved by EPA and DHA could contribute to the recovery of patients infected with SARS-CoV-2, Omega-3 fatty acids supplementation cannot be recommended before randomized and controlled trials are carried out.

PCTR1 ameliorates lipopolysaccharide-induced acute inflammation and multiple organ damage via regulation of linoleic acid metabolism by promoting FADS1/FASDS2/ELOV2 expression and reducing PLA2 expression

Gram-negative bacterial infection causes an excessive inflammatory response and acute organ damage or dysfunction due to its outer membrane component, lipopolysaccharide (LPS). Protectin conjugates in tissue regeneration 1 (PCTR1), an endogenous lipid mediator, exerts fundamental anti-inflammation and pro-resolution during infection. In the present study, we examined the properties of PCTR1 on the systemic inflammatory response, organic morphological damage and dysfunction, and serum metabolic biomarkers in an LPS-induced acute inflammatory mouse model. The results show that PCTR1 reduced serum inflammatory factors and ameliorated morphological damage and dysfunction of the lung, liver, kidney, and ultimately improved the survival rate of LPS-induced acute inflammation in mice. In addition, metabolomics analysis and high performance liquid chromatography-mass spectrometry revealed that LPS-stimulated serum linoleic acid (LA), arachidonic acid (AA), and prostaglandin E2 (PGE2) levels were significantly altered by PCTR1. Moreover, PCTR1 upregulated LPS-inhibited fatty acid desaturase 1 (FADS1), fatty acid desaturase 2 (FADS2), and elongase of very long chain fatty acids 2 (ELOVL2) expression, and downregulated LPS-stimulated phospholipase A2 (PLA2) expression to increase the intrahepatic content of AA. However, these effects of PCTR1 were partially abrogated by a lipoxin A4 receptor (ALX) antagonist (BOC-2). In summary, via the activation of ALX, PCTR1 promotes the conversion of LA to AA through upregulation of FADS1, FADS2, and ELOVL2 expression, and inhibits the conversion of bound AA into free AA through downregulation of PLA2 expression to decrease the serum AA and PGE2 levels.

Optimal Nutritional Status for a Well-Functioning Immune System Is an Important Factor to Protect against Viral Infections

Public health practices including handwashing and vaccinations help reduce the spread and impact of infections. Nevertheless, the global burden of infection is high, and additional measures are necessary. Acute respiratory tract infections, for example, were responsible for approximately 2.38 million deaths worldwide in 2016. The role nutrition plays in supporting the immune system is well-established. A wealth of mechanistic and clinical data show that vitamins, including vitamins A, B6, B12, C, D, E, and folate; trace elements, including zinc, iron, selenium, magnesium, and copper; and the omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid play important and complementary roles in supporting the immune system. Inadequate intake and status of these nutrients are widespread, leading to a decrease in resistance to infections and as a consequence an increase in disease burden. Against this background the following conclusions are made: (1) supplementation with the above micronutrients and omega-3 fatty acids is a safe, effective, and low-cost strategy to help support optimal immune function; (2) supplementation above the Recommended Dietary Allowance (RDA), but within recommended upper safety limits, for specific nutrients such as vitamins C and D is warranted; and (3) public health officials are encouraged to include nutritional strategies in their recommendations to improve public health.

The Anti-inflammatory Mediator Resolvin E1 Protects Mice Against Lipopolysaccharide-Induced Heart Injury

Background

Sepsis-induced cardiomyopathy (SIC) is a common severe complication of sepsis that contributes to mortality. SIC is closely associated with excessive inflammatory responses, failed inflammation resolution, and apoptotic damage. Resolvin E1 (RvE1), an omega-3 polyunsaturated fatty acid (PUFA)-derived metabolite, has been reported to exert anti-inflammatory or proresolving activity in multiple animal models of inflammatory disease. However, the therapeutic potential of RvE1 in SIC remains undetermined, which was, therefore, the aim of the present study.

Methods

C57BL/6J mice were randomly divided into three groups: control, lipopolysaccharide (LPS), and LPS + RvE1. Echocardiography, Western blotting (WB), quantitative real-time (QRT)-PCR, histological analyses, and flow cytometry were used to evaluate cardiac function, myocardial inflammation, and the underlying mechanisms.

Results

The RvE1-injected group showed improved left ventricular (LV) function and reduced serum lactate dehydrogenase (LDH) and creatine kinase myocardial bound (CK-MB) levels. Compared to LPS treatment alone, RvE1 treatment inhibited the infiltration of neutrophils and macrophages into the heart and spleen and suppressed the secretion of pro-inflammatory cytokines, including interleukin (IL)-1β, IL-6, and monocyte chemoattractant protein (MCP)-1, in the heart. We also observed that the activation of the mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-κB signaling pathways was blocked by RvE1 treatment, and this inhibition contributed to the improvement in the inflammatory response induced by LPS. RvE1 inhibited LPS-induced M1 macrophage polarization and promoted macrophage polarization toward the M2-like phenotype in both the heart and spleen. In addition, LPS administration dysregulated cyclooxygenase (COX) and lipoxygenase (LOX) in the heart, which were rectified by RvE1 treatment. RvE1 also reduced myocardial apoptosis rate in response to LPS-induced heart injury.

Conclusion

RvE1 protects the heart against SIC possibly through the inhibition of the MAPK and NF-κB inflammatory signaling pathways, modulation of macrophage polarization, and reduction in myocardial apoptosis. RvE1 may be a novel lipid mediator for the treatment of SIC.

Maresin-1 Inhibits Oxidative Stress and Inflammation and Promotes Apoptosis in a Mouse Model of Caerulein-Induced Acute Pancreatitis

Background

This study aimed to investigate the effects of maresin-1 (MaR1) in a mouse model of caerulein-induced acute pancreatitis (AP).

Material/Methods

Fifty C57BL/6 mice with caerulein-induced AP were divided into the untreated control group (N=10), the untreated AP model group (N=10), the MaR1-treated (low-dose, 0.1 μg) AP model group (N=10), the MaR1-treated (middle-dose, 0.5 μg) AP model group (N=10), and the MaR1-treated (high-dose, 1 μg) AP model group (N=10). Enzyme-linked immunoassay (ELISA) measured serum levels of amylase, lipase, tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and IL-6 and mRNA was measured by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Malondialdehyde (MDA), protein carbonyls, superoxide dismutase (SOD), and the ratio of reduced glutathione/oxidized glutathione (GSH/GSSG) were measured. Histology of the pancreas included measurement of acinar cell apoptosis using the terminal-deoxynucleotidyl transferase-mediated nick end-labeling (TUNEL) assay. Western blot measured Toll-like receptor 4 (TLR4), MyD88, and phospho-NF-κB p65, and apoptosis-associated proteins Bcl-2, Bax, cleaved caspase-3, and cleaved caspase-9.

Results

Following treatment with MaR1, serum levels of amylase, lipase, TNF-α, IL-1β, and IL-6 decreased, MDA and protein carbonyl levels decreased, SOD and the GSH/GSSG ratio increased in a dose-dependent manner. In the MaR1-treated AP mice, inflammation of the pancreas and the expression of inflammatory cytokines, pancreatic acinar cell apoptosis, Bcl-2 expression, and expression of TLR4, MyD88, and p-NF-κB p65 were reduced, but Bax, cleaved caspase-3, and cleaved caspase-9 expression increased.

Conclusions

In a mouse model of caerulein-induced AP, treatment with MaR1 reduced oxidative stress and inflammation and reduced apoptosis.

Protective effect of nimesulide on acute lung injury in mice with severe acute pancreatitis

The study was designed to investigate the effect of Nimesulide (NIM) on acute lung injury (ALI) in mice with severe acute pancreatitis (SAP). In our study, caerulein and LPS were employed to establish the ALI mice model induced by SAP. All animals were divided into four groups randomly: control, model (SAP), NIM low and high dosages groups. Following treatment with NIM, histopathology observation of pancreatic tissues and lung tissues were detected by hematoxylin and eosin (H&E) staining. The levels of serum amylase, lipase, tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β) and IL-6 were measured by ELISA. The ratio of wet lung to dry lung (W/D) was calculated. In addition, the expression levels of TNF-α, IL-1β and IL-6 were measured by Western blotting. Moreover, the expression of cyclooxygenase-2 (COX-2) was detected using Immunohistochemistry analysis. The results revealed that NIM markedly improved pancreatic histological injury and decreased the levels of serum amylase, lipase, TNF-α, IL-1β and IL-6 in a dose-dependent after NIM treatment. For ALI induced by SAP, pulmonary edema were significantly alleviated compared with the mice in SAP group. In addition, the decreased ratio of W/D were observed after NIM intervene. The expression levels of TNF-α, IL-1β and IL-6 proteins were downregulated following NIM treatment. More, NIM inhibited the expression of COX2 in lung tissues. Taken together, our study demonstrated that NIM was able to protect against ALI induced by SAP via inhibiting inflammation, which will be of novel therapeutic strategies for the clinical treatment of ALI.

Anti-inflammatory effects of resolvins in diabetic nephropathy: Mechanistic pathways

The incidence of diabetes mellitus is growing rapidly. The exact pathophysiology of diabetes is unclear, but there is increasing evidence of the role of the inflammatory response in both developing diabetes as well as its complications. Resolvins are naturally occurring polyunsaturated fatty acids that are found in fish oil and sea food that have been shown to possess anti-inflammatory actions in several tissues including the kidneys. The pathways by which resolvins exert this anti-inflammatory effect are unclear. In this review we discuss the evidence showing that resolvins can suppress inflammatory responses via at least five molecular mechanisms through inhibition of the nucleotide-binding oligomerization domain protein 3 inflammasome, inhibition of nuclear factor κB molecular pathways, improvement of oxidative stress, modulation of nitric oxide synthesis/release and prevention of local and systemic leukocytosis. Complete understanding of these molecular pathways is important as this may lead to the development of new effective therapeutic strategies for diabetes and diabetic nephropathy.

Maresin 1 mitigates renal ischemia/reperfusion injury in mice via inhibition of the TLR4/MAPK/NF-κB pathways and activation of the Nrf2 pathway

BACKGROUND

Inflammation and oxidative stress play a crucial role in the pathogenesis of renal ischemia/reperfusion injury (IRI). Maresin 1 (MaR1), which has shown strong anti-inflammatory and antioxidant effects, was recently reported to have protective properties in several different animal models.

AIM

The objectives of our study were to determine whether MaR1 alleviates renal IRI and to identify the underlying mechanisms.

MATERIALS AND METHODS

The mouse model in this study was induced by ischemia of the left kidney for 45 minutes and by nephrectomy of the right kidney. All mice were intravenously injected with a vehicle or MaR1. Renal histopathologic changes, function, proinflammatory cytokines, and oxidative stress were assessed. The expression of proteins was measured by Western blot.

RESULTS

The results indicated that MaR1 markedly protected against renal IRI. The protective effects were accompanied by the reduction of histologic changes and reduction of renal dysfunction. Meanwhile, MaR1 remarkably mitigated renal IRI-induced inflammation and oxidative stress. In addition, our results showed that MaR1 significantly inhibited the expression of TLR4 and the expression of phosphorylated Erk, JNK, and P38. Furthermore, MaR1 decreased the nuclear translocation of NF-κB and increased the nuclear translocation of Nrf2.

CONCLUSION

MaR1 protects against renal IRI by inhibiting the TLR4/MAPK/NF-κB pathways, which mediate anti-inflammation, and by activating the Nrf2 pathway, which mediates antioxidation.

Neutrophils in the initiation and resolution of acute pulmonary inflammation: understanding biological function and therapeutic potential

Acute respiratory distress syndrome (ARDS) is the often fatal sequelae of a broad range of precipitating conditions. Despite decades of intensive research and clinical trials there remain no therapies in routine clinical practice that target the dysregulated and overwhelming inflammatory response that characterises ARDS. Neutrophils play a central role in the initiation, propagation and resolution of this complex inflammatory environment by migrating into the lung and executing a variety of pro-inflammatory functions. These include degranulation with liberation of bactericidal proteins, release of cytokines and reactive oxygen species as well as production of neutrophil extracellular traps. Although these functions are advantageous in clearing bacterial infection, the consequence of associated tissue damage, the contribution to worsening acute inflammation and prolonged neutrophil lifespan at sites of inflammation are deleterious. In this review, the importance of the neutrophil will be considered, together with discussion of recent advances in understanding neutrophil function and the factors that influence them throughout the phases of inflammation in ARDS. From a better understanding of neutrophils in this context, potential therapeutic targets are identified and discussed. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Arachidonic acid and other unsaturated fatty acids and some of their metabolites function as endogenous antimicrobial molecules: A review

Our body is endowed with several endogenous anti-microbial compounds such as interferon, cytokines, free radicals, etc. However, little attention has been paid to the possibility that lipids could function as antimicrobial compounds. In this short review, the antimicrobial actions of various polyunsaturated fatty acids (PUFAs, mainly free acids) and their putative mechanisms of action are described. In general, PUFAs kill microbes by their direct action on microbial cell membranes, enhancing generation of free radicals, augmenting the formation of lipid peroxides that are cytotoxic, and by increasing the formation of their bioactive metabolites, such as prostaglandins, lipoxins, resolvins, protectins and maresins that enhance the phagocytic action of leukocytes and macrophages. Higher intakes of α-linolenic and cis-linoleic acids (ALA and LA respectively) and fish (a rich source of eicosapentaenoic acid and docosahexaenoic acid) might reduce the risk pneumonia. Previously, it was suggested that polyunsaturated fatty acids (PUFAs): linoleic, α-linolenic, γ-linolenic (GLA), dihomo-GLA (DGLA), arachidonic (AA), eicosapentaenoic (EPA), and docosahexaenoic acids (DHA) function as endogenous anti-bacterial, anti-fungal, anti-viral, anti-parasitic, and immunomodulating agents. A variety of bacteria are sensitive to the growth inhibitory actions of LA and ALA in vitro. Hydrolyzed linseed oil can kill methicillin-resistant Staphylococcus aureus. Both LA and AA have the ability to inactivate herpes, influenza, Sendai, and Sindbis virus within minutes of contact. AA, EPA, and DHA induce death of Plasmodium falciparum both in vitro and in vivo. Prostaglandin E1 (PGE1) and prostaglandin A (PGA), derived from DGLA, AA, and EPA inhibit viral replication and show anti-viral activity. Oral mucosa, epidermal cells, lymphocytes and macrophages contain and release significant amounts of PUFAs on stimulation. PUFAs stimulate NADPH-dependent superoxide production by macrophages, neutrophils and lymphocytes to kill the invading microorganisms. Cytokines induce the release of PUFAs from cell membrane lipid pool, a potential mechanism for their antimicrobial action. AA, EPA, and DHA give rise to lipoxins (LXs), resolvins, protectins, and maresins that limit and resolve inflammation and have antimicrobial actions. Thus, PUFAs and their metabolites have broad antimicrobial actions.