Inflammation resolution and specialized pro-resolving lipid mediators in CNS diseases

Maresin1 restrains chronic inflammation and Aβ production to ameliorate Alzheimer's disease via modulating ADAM10/17 and its associated neuroprotective signal pathways: A pilot study

Chronic inflammation is an important pathogenetic factor that leads to the progression of Alzheimer's disease (AD), and specialized pro-resolving lipid mediators (SPMs) play critical role in regulating inflammatory responses during AD pathogenesis. Maresin1 (MaR1) is the latest discovered SPMs, and it is found that MaR1 improves AD cognitive impairment by regulating neurotrophic pathways to protect AD synapses and reduce Aβ production, which made MaR1 as candidate agent for AD treatment. Unfortunately, the underlying mechanisms are still largely known. In this study, the AD mice and cellular models were subjected to MaR1 treatment, and we found that MaR1 reduced Aβ production to ameliorate AD-related symptoms and increased the expression levels of ADAM10/17, sAPPα and sAPPβ to exert its anti-inflammatory role. In addition, as it was determined by Western Blot analysis, we observed that MaR1 could affected the neuroprotective signal pathways. Specifically, MaR1 downregulated p57NTR and upregulated TrkA to activate the p75NTR/TrkA signal pathway, and it could increase the expression levels of p-PI3K and p-Akt, and downregulated p-mTOR to activate the PI3K/AKT/ERK/mTOR pathway. Finally, we verified the role of ADAM10/17 in regulating AD progression, and we found that silencing of ADAM10/17 inactivated the above neuroprotective signal pathways to aggravate AD pathogenesis. In conclusion, MaR1 is verified as potential therapeutic agent for AD by eliminating Aβ production, upregulating ADAM10/17, sAPPα and sAPPβ, and activating the neuroprotective p75NTR/TrkA pathway and the PI3K/AKT/ERK/mTOR pathway.

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

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

Crosstalk among N6-methyladenosine modification and RNAs in central nervous system injuries

Central nervous system (CNS) injuries, including traumatic brain injury (TBI), intracerebral hemorrhage (ICH) and ischemic stroke, are the most common cause of death and disability around the world. As the most common modification on ribonucleic acids (RNAs), N6-methyladenosine (m6A) modification has recently attracted great attentions due to its functions in determining the fate of RNAs through changes in splicing, translation, degradation and stability. A large number of studies have suggested that m6A modification played an important role in brain development and involved in many neurological disorders, particularly in CNS injuries. It has been proposed that m6A modification could improve neurological impairment, inhibit apoptosis, suppress inflammation, reduce pyroptosis and attenuate ferroptosis in CNS injuries via different molecules including phosphatase and tensin homolog (PTEN), NLR family pyrin domain containing 3 (NLRP3), B-cell lymphoma 2 (Bcl-2), glutathione peroxidase 4 (GPX4), and long non-coding RNA (lncRNA). Therefore, m6A modification showed great promise as potential targets in CNS injuries. In this article, we present a review highlighting the role of m6A modification in CNS injuries. Hence, on the basis of these properties and effects, m6A modification may be developed as therapeutic agents for CNS injury patients.

Specialized Pro-Resolving Mediators in Neuroinflammation: Overview of Studies and Perspectives of Clinical Applications

Specialized pro-resolving mediators (SPMs) are lipid mediators derived from poly-unsaturated fatty acids (PUFAs) which have been demonstrated to have an important role in the inflammation environment, preventing an overreaction of the organism and promoting the resolution of inflammation. Our purpose was to point out the current evidence for specialized pro-resolving mediators, focusing on their role in neuroinflammation and in major neurological diseases.

Personalized Nutrition in the Management of Female Infertility: New Insights on Chronic Low-Grade Inflammation

Increasing evidence on the significance of nutrition in reproduction is emerging from both animal and human studies, suggesting a mutual association between nutrition and female fertility. Different “fertile” dietary patterns have been studied; however, in humans, conflicting results or weak correlations are often reported, probably because of the individual variations in genome, proteome, metabolome, and microbiome and the extent of exposure to different environmental conditions. In this scenario, “precision nutrition”, namely personalized dietary patterns based on deep phenotyping and on metabolomics, microbiome, and nutrigenetics of each case, might be more efficient for infertile patients than applying a generic nutritional approach. In this review, we report on new insights into the nutritional management of infertile patients, discussing the main nutrigenetic, nutrigenomic, and microbiomic aspects that should be investigated to achieve effective personalized nutritional interventions. Specifically, we will focus on the management of low-grade chronic inflammation, which is associated with several infertility-related diseases.

Pursuing Multiple Biomarkers for Early Idiopathic Parkinson's Disease Diagnosis

Parkinson's disease (PD) ranks first in the world as a neurodegenerative movement disorder and occurs most commonly in an idiopathic form. PD patients may have motor symptoms, non-motor symptoms, including cognitive and behavioral changes, and symptoms related to autonomic nervous system (ANS) failures, such as gastrointestinal, urinary, and cardiovascular symptoms. Unfortunately, the diagnostic accuracy of PD by general neurologists is relatively low. Currently, there is no objective molecular or biochemical test for PD; its diagnosis is based on clinical criteria, mainly by cardinal motor symptoms, which manifest when patients have lost about 60-80% of dopaminergic neurons. Therefore, it is urgent to establish a panel of biomarkers for the early and accurate diagnosis of PD. Once the disease is accurately diagnosed, it may be easier to unravel idiopathic PD's pathogenesis, and ultimately, finding a cure. This review discusses several biomarkers' potential to set a panel for early idiopathic PD diagnosis and future directions.

Neurorepair and Regeneration of the Brain: A Decade of Bioscaffolds and Engineered Microtissue

Repairing the human brain remains a challenge, despite the advances in the knowledge of inflammatory response to injuries and the discovery of adult neurogenesis. After brain injury, the hostile microenvironment and the lack of structural support for neural cell repopulation, anchoring, and synapse formation reduce successful repair chances. In the past decade, we witnessed the rise of studies regarding bioscaffolds’ use as support for neuro repair. A variety of natural and synthetic materials is available and have been used to replace damaged tissue. Bioscaffolds can assume different shapes and may or may not carry a diversity of content, such as stem cells, growth factors, exosomes, and si/miRNA that promote specific therapeutic effects and stimulate brain repair. The use of these external bioscaffolds and the creation of cell platforms provide the basis for tissue engineering. More recently, researchers were able to engineer brain organoids, neural networks, and even 3D printed neural tissue. The challenge in neural tissue engineering remains in the fabrication of scaffolds with precisely controlled topography and biochemical cues capable of directing and controlling neuronal cell fate. The purpose of this review is to highlight the existing research in the growing field of bioscaffolds’ development and neural tissue engineering. Moreover, this review also draws attention to emerging possibilities and prospects in this field.

The Role of Sphingolipids and Specialized Pro-Resolving Mediators in Alzheimer's Disease

Alzheimer’s disease (AD) is the leading cause of dementia worldwide giving rise to devastating forms of cognitive decline, which impacts patients’ lives and that of their proxies. Pathologically, AD is characterized by extracellular amyloid deposition, neurofibrillary tangles and chronic neuroinflammation. To date, there is no cure that prevents progression of AD. In this review, we elaborate on how bioactive lipids, including sphingolipids (SL) and specialized pro-resolving lipid mediators (SPM), affect ongoing neuroinflammatory processes during AD and how we may exploit them for the development of new biomarker panels and/or therapies. In particular, we here describe how SPM and SL metabolism, ranging from ω-3/6 polyunsaturated fatty acids and their metabolites to ceramides and sphingosine-1-phosphate, initiates pro- and anti-inflammatory signaling cascades in the central nervous system (CNS) and what changes occur therein during AD pathology. Finally, we discuss novel therapeutic approaches to resolve chronic neuroinflammation in AD by modulating the SPM and SL pathways.

Cytokine Storm and Failed Resolution in COVID-19: Taking a Cue from Multiple Sclerosis

INTRODUCTION

Excessive inflammatory responses and failed resolution are major common causes of tissue injury and organ dysfunction in a variety of diseases, including multiple sclerosis (MS), diabetes, and most recently, COVID-19, despite the distinct pathoetiology of the diseases. The promotion of the natural process of inflammatory resolution has been long recognized to improve functional recovery and disease outcomes effectively. To mitigate the excessive inflammation in MS, scientific investigations identified a group of derivatives of omega fatty acids, known as specialized pro-resolving lipid mediators (SPM) that have been significantly effective in treating preclinical disease models of MS.

METHODS

This chapter is based on our observations from MS. It is being increasingly deliberated that the ongoing COVID-19 infection induces severe cytokine storm that ultimately triggers rampant inflammation. The impact of infection and associated mortality is much higher in patients with co-morbid diseases. Also, reports suggest a better outcome in diabetic patients with reasonable glycemic control, which certainly hints towards a hidden role of anti-hyperglycemic drugs such as metformin in alleviating disease pathology through its anti-inflammatory feature. Notably, SPM and metformin share common therapeutic features in exerting a broad-spectrum anti-inflammatory activity in human patients with a superior safety profile.

RESULTS

When there is an immediate need to encounter the fast-rampant infection of COVID-19 and control the viral-infection associated morbid inflammatory cytokine storm causing severe organ damage, SPM and metformin should be seriously considered as a potential adjunctive treatment.

CONCLUSION

Given the fact that current treatment for COVID-19 is only supportive, global research is aimed at developing safe and effective therapeutic options that can result in a better clinical course in patients with comorbid conditions. Accordingly, taking a cue from our experiences in controlling robust inflammatory response in MS and diabetes by simultaneously inhibiting inflammatory process and stimulating its resolution, combinatorial therapy of metformin and SPM in COVID-19 holds significant promise in treating this global health crisis.

Neuroinflammation, oxidative stress and their interplay in neuropathic pain: Focus on specialized pro-resolving mediators and NADPH oxidase inhibitors as potential therapeutic strategies

Neuropathic pain (NP) is a chronic condition that results from a lesion or disease of the nervous system, greatly impacting patients' quality of life. Current pharmacotherapy options deliver inadequate and/or insufficient responses and thus a significant unmet clinical need remains for alternative treatments in NP. Neuroinflammation, oxidative stress and their reciprocal relationship are critically involved in NP pathophysiology. In this context, new pharmacological approaches, aiming at enhancing the resolution phase of inflammation and/or restoring redox balance by targeting specific reactive oxygen species (ROS) sources, are emerging as potential therapeutic strategies for NP, with improved efficacy and safety profiles. Several reports have demonstrated that administration of exogenous specialized pro-resolving mediators (SPMs) ameliorates NP pathophysiology. Likewise, deletion or inhibition of the ROS-generating enzyme NADPH oxidase (NOX), particularly its isoforms 2 and 4, results in beneficial effects in NP models. Notably, SPMs also modulate oxidative stress and NOX also regulates neuroinflammation. By targeting neuroinflammatory and oxidative pathways, both SPMs analogues and isoform-specific NOX inhibitors are promising therapeutic strategies for NP.

Structural considerations on lipoxygenase function, inhibition and crosstalk with nitric oxide pathways

Lipoxygenases (LOX) are non-heme iron-containing enzymes that catalyze regio- and stereo-selective dioxygenation of polyunsaturated fatty acids (PUFA). Mammalian LOXs participate in the eicosanoid cascade during the inflammatory response, using preferentially arachidonic acid (AA) as substrate, for the synthesis of leukotrienes (LT) and other oxidized-lipid intermediaries. This review focus on lipoxygenases (LOX) structural and kinetic implications on both catalysis selectivity, as well as the basic and clinical implications of inhibition and interactions with nitric oxide (^•NO) and nitroalkenes pathways. During inflammation ^•NO levels are increasingly favoring the formation of reactive nitrogen species (RNS). ^•NO may act itself as an inhibitor of LOX-mediated lipid oxidation by reacting with lipid peroxyl radicals. Besides, ^•NO may act as an O₂ competitor in the LOX active site, thus displaying a protective role on lipid-peroxidation. Moreover, RNS such as nitrogen dioxide (^•NO₂) may react with lipid-derived species formed during LOX reaction, yielding nitroalkenes (NO₂FA). NO₂FA represents electrophilic compounds that could exert anti-inflammatory actions through the interaction with critical LOX nucleophilic amino acids. We will discuss how nitro-oxidative conditions may limit the availability of common LOX substrates, favoring alternative routes of PUFA metabolization to anti-inflammatory or pro-resolutive pathways.

Resolvin D1 protects against sepsis-induced cardiac injury in mice

Increased inflammation is the key mechanism that mediates sepsis induced cardiac injury. Resolvin D1 (RvD1), a bioactive lipid mediator synthesized from docosahexaenoic acid, can attenuate the severity of many inflammation-related diseases through anti-inflammatory and pro-resolving properties. However, the protective role of RvD1 in sepsis induced cardiac injury remains unclear. Mice were randomly divided into three groups: the control group, LPS group and RvD1 + LPS group. LPS (10 mg/kg, i.p.) was used to establish a sepsis-induced cardiac injury model. RvD1 (5 ug/kg, i.p.) was injected 30 min before LPS injection. RvD1 treatment significantly attenuated the deteriorated cardiac function and cardiac injury induced by LPS, as evidenced by the improved left ventricular ejection fraction, serum levels of cardiac injury markers and severity of cardiomyocyte apoptosis. In addition, RvD1 treatment significantly attenuated the infiltration of pro-inflammatory M1 macrophages and expression of inflammatory cytokines in the heart. Mechanistically, the attenuated activation of NK-κB and MAPK signaling mediated the anti-inflammatory and antiapoptotic effects of RvD1. In addition, LPS-induced infiltration of neutrophils and M1 macrophages in the spleen was significantly attenuated by the RvD1 treatment. Results of the present study suggest that RvD1 protects the heart against LPS-induced injuries by attenuating the local and systemic inflammatory response, highlighting the therapeutic effects of RvD1 in sepsis-induced cardiac injury.

Specialized Pro-Resolving Lipid Mediators: Emerging Therapeutic Candidates for Multiple Sclerosis

Multiple sclerosis (MS) is a neuroinflammatory disease in which unresolved and uncontrolled inflammation disrupts normal cellular homeostasis and leads to a pathological disease state. It has long been recognized that endogenously derived metabolic by-products of omega fatty acids, known as specialized pro-resolving lipid mediators (SPMs), are instrumental in resolving the pathologic inflammation. However, there is minimal data available on the functional status of SPMs in MS, despite the fact that MS presents a classical model of chronic inflammation. Studies to date indicate that dysfunction of the SPM biosynthetic pathway is responsible for their altered levels in patient-derived biofluids, which contributes to heightened inflammation and disease severity. Collectively, current findings suggest the contentious role of SPMs in MS due to variable outcomes in biological matrices across studies conducted so far, which could, in part, also be attributed to differences in population characteristics. It seems that SPMs have neuroprotective action on MS by exerting proresolving effects on brain microglia in its preclinical model; however, there are no reports demonstrating the direct effect of SPMs on oligodendrocytes or neurons. This reveals that "one size does not fit all" notion holds significance for MS in terms of the status of SPMs in other inflammatory conditions. The lack of clarity served as the impetus for this review, which is the first of its kind to summarize the relevant data regarding the role of SPMs in MS and the potential to target them for biomarker development and future alternative therapies for this disease. Understanding the mechanisms behind biological actions of SPMs as resolution mediators may prevent or even cure MS and other neurodegenerative pathologies.

Role of Resolvins in the Inflammatory Resolution of Neurological Diseases

The occurrence of neurological diseases including neurodegenerative disorders, neuroimmune diseases, and cerebrovascular disorders is closely related to neuroinflammation. Inflammation is a response against infection or injury. Genetic abnormalities, the aging process, or environmental factors can lead to dysregulation of the inflammatory response. Our immune system can cause massive damage when the inflammatory response becomes dysregulated. Inflammatory resolution is an effective process that terminates the inflammatory response to maintain health. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are omega-three polyunsaturated fatty acids that play a crucial regulatory role in the development of inflammation. Resolvins (Rvs) derived from EPA and DHA constitute the Rvs E and Rvs D series, respectively. Numerous studies on the effect of Rvs over inflammation using animal models reveal that they have both anti-inflammatory and pro-resolving capabilities. Here, we review the current knowledge on the classification, biosynthesis, receptors, mechanisms of action, and role of Rvs in neurological diseases.