Proresolving lipid mediators resolvin D1, resolvin D2, and maresin 1 are critical in modulating T cell responses

The ω-3 Polyunsaturated Fatty Acid Docosahexaenoic Acid Enhances NK-Cell Antitumor Effector Functions

ω-3 polyunsaturated fatty acids (PUFA) are known to directly repress tumor development and progression. In this study, we explored whether docosahexaenoic acid (DHA), a type of ω-3 PUFA, had an immunomodulatory role in inhibiting tumor growth in immunocompetent mice. The number of natural killer (NK) cells but not the number of T or B cells was decreased by DHA supplementation in various tissues under physiologic conditions. Although the frequency and number of NK cells were comparable, IFNγ production by NK cells in both the spleen and lung was increased in DHA-supplemented mice in the mouse B16F10 melanoma tumor model. Single-cell RNA sequencing revealed that DHA promoted effector function and oxidative phosphorylation in NK cells but had no obvious effects on other immune cells. Using Rag2-/- mice and NK-cell depletion by PK136 antibody injection, we demonstrated that the suppression of B16F10 melanoma tumor growth in the lung by DHA supplementation was dependent mainly on NK cells. In vitro experiments showed that DHA directly enhanced IFNγ production, CD107a expression, and mitochondrial oxidative phosphorylation (OXPHOS) activity and slightly increased proliferator-activated receptor gamma coactivator-1α (PGC-1α) protein expression in NK cells. The PGC-1α inhibitor SR-18292 in vitro and NK cell-specific knockout of PGC-1α in mice reversed the antitumor effects of DHA. In summary, our findings broaden the current knowledge on how DHA supplementation protects against cancer growth from the perspective of immunomodulation by upregulating PGC-1α signaling-mediated mitochondrial OXPHOS activity in NK cells.

The endocannabinoid anandamide activates pro-resolving pathways in human primary macrophages by engaging both CB2 and GPR18 receptors

Resolution of inflammation is the cellular and molecular process that protects from widespread and uncontrolled inflammation and restores tissue function in the aftermath of acute immune events. This process is orchestrated by specialized pro-resolving mediators (SPM), a class of bioactive lipids able to reduce immune activation and promote removal of tissue debris and apoptotic cells by macrophages. Although SPMs are the lipid class that has been best studied for its role in facilitating the resolution of self-limited inflammation, a number of other lipid signals, including endocannabinoids, also exert protective immunomodulatory effects on immune cells, including macrophages. These observations suggest that endocannabinoids may also display pro-resolving actions. Interestingly, the endocannabinoid anandamide (AEA) is not only known to bind canonical type 1 and type 2 cannabinoid receptors (CB1 and CB2) but also to engage SPM-binding receptors such as GPR18. This suggests that AEA may also contribute to the governing of resolution processes. In order to interrogate this hypothesis, we investigated the ability of AEA to induce pro-resolving responses by classically-activated primary human monocyte-derived macrophages (MoDM). We found that AEA, at nanomolar concentration, enhances efferocytosis in MoDMs in a CB2- and GPR18-dependent manner. Using lipid mediator profiling, we also observed that AEA modulates SPM profiles in these cells, including levels of resolvin (Rv)D1, RvD6, maresin (MaR)2, and RvE1 in a CB2-dependent manner. AEA treatment also modulated the gene expression of SPM enzymes involved in both the formation and further metabolism of SPM such as 5-lipoxygenase and 15-Prostaglandin dehydrogenase. Our findings show, for the first time, a direct effect of AEA on the regulation of pro-resolving pathways in human macrophages. They also provide new insights into the complex interactions between different lipid pathways in activation of pro-resolving responses contributing to the reestablishment of homeostasis in the aftermath of acute inflammation.

Crosstalk between efferocytic myeloid cells and T-cells and its relevance to atherosclerosis

The interplay between myeloid cells and T-lymphocytes is critical to the regulation of host defense and inflammation resolution. Dysregulation of this interaction can contribute to the development of chronic inflammatory diseases. Important among these diseases is atherosclerosis, which refers to focal lesions in the arterial intima driven by elevated apolipoprotein B-containing lipoproteins, notably low-density lipoprotein (LDL), and characterized by the formation of a plaque composed of inflammatory immune cells, a collection of dead cells and lipids called the necrotic core, and a fibrous cap. As the disease progresses, the necrotic core expands, and the fibrous cap becomes thin, which increases the risk of plaque rupture or erosion. Plaque rupture leads to a rapid thrombotic response that can give rise to heart attack, stroke, or sudden death. With marked lowering of circulating LDL, however, plaques become more stable and cardiac risk is lowered-a process known as atherosclerosis regression. A critical aspect of both atherosclerosis progression and regression is the crosstalk between innate (myeloid cells) and adaptive (T-lymphocytes) immune cells. Myeloid cells are specialized at clearing apoptotic cells by a process called efferocytosis, which is necessary for inflammation resolution. In advanced disease, efferocytosis is impaired, leading to secondary necrosis of apoptotic cells, inflammation, and, most importantly, defective tissue resolution. In regression, efferocytosis is reawakened aiding in inflammation resolution and plaque stabilization. Here, we will explore how efferocytosing myeloid cells could affect T-cell function and vice versa through antigen presentation, secreted factors, and cell-cell contacts and how this cellular crosstalk may contribute to the progression or regression of atherosclerosis.

Pathological and pharmacological functions of the metabolites of polyunsaturated fatty acids mediated by cyclooxygenases, lipoxygenases, and cytochrome P450s in cancers

Oxylipins have garnered increasing attention because they were consistently shown to play pathological and/or pharmacological roles in the development of multiple cancers. Oxylipins are the metabolites of polyunsaturated fatty acids via both enzymatic and nonenzymatic pathways. The enzymes mediating the metabolism of PUFAs include but not limited to lipoxygenases (LOXs), cyclooxygenases (COXs), and cytochrome P450s (CYPs) pathways, as well as the down-stream enzymes. Here, we systematically summarized the pleiotropic effects of oxylipins in different cancers through pathological and pharmacological aspects, with specific reference to the enzyme-mediated oxylipins. We discussed the specific roles of oxylipins on cancer onset, growth, invasion, and metastasis, as well as the expression changes in the associated metabolic enzymes and the associated underlying mechanisms. In addition, we also discussed the clinical application and potential of oxylipins and related metabolic enzymes as the targets for cancer prevention and treatment. We found the specific function of most oxylipins in cancers, especially the underlying mechanisms and clinic applications, deserves and needs further investigation. We believe that research on oxylipins will provide not only more therapeutic targets for various cancers but also dietary guidance for both cancer patients and healthy humans.

Inflammation, lipid dysregulation, and transient receptor potential cation channel subfamily V member 4 signaling perpetuate chronic vulvar pain

ABSTRACT

Localized provoked vulvodynia is characterized by chronic vulvar pain that disrupts every aspect of the patient's life. Pain is localized to the vulvar vestibule, a specialized ring of tissue immediately surrounding the vaginal opening involved in immune defense. In this article, we show inflammation is the critical first step necessary for the generation of pain signals in the vulva. Inflammatory stimuli alone or combined with the transient receptor potential cation channel subfamily V member 4 (TRPV4) agonist 4α-phorbol 12,13-didecanoate stimulate calcium flux into vulvar fibroblast cells. Activity is blocked by the TRPV4 antagonist HC067047, denoting specificity to TRPV4. Using lipidomics, we found pro-resolving lipids in the vulvar vestibule were dysregulated, characterized by a reduction in pro-resolving mediators and heightened production of inflammatory mediators. We demonstrate specialized pro-resolving mediators represent a potential new therapy for vulvar pain, acting on 2 key parts of the disease mechanism by limiting inflammation and acutely inhibiting TRPV4 signaling.

Maresin 1 Activates LGR6 to Alleviate Neuroinflammation via the CREB/JMJD3/IRF4 Pathway in a Rat Model of Subarachnoid Hemorrhage

Neuroinflammation is an early event of brain injury after subarachnoid hemorrhage (SAH). Whether the macrophage mediators in resolving inflammation 1 (MaR1) is involved in SAH pathogenesis is unknown. In this study, 205 male Sprague-Dawley rats were subjected to SAH via endovascular perforation in the experimental and control groups. MaR1 was dosed intranasally at 1 h after SAH, with LGR6 siRNA and KG-501, GSK-J4 administered to determine the signaling pathway. Neurobehavioral, histological and biochemical data were obtained from the animal groups with designated treatments. The results showed: (i) The leucine-rich repeat containing G protein-coupled receptor 6 (LGR6) was decreased after SAH and reached to the lowest level at 24 h after SAH. Jumonji d3 (JMJD3) protein levels tended to increase and peaked at 24 h after SAH. LGR6 and JMJD3 expression were co-localized with microglia. (ii) MaR1 administration mitigated short-term neurological deficits, brain edema and long-term neurobehavioral performance after SAH, and attenuated microglial activation and neutrophil infiltration. (iii) Knockdown of LGR6, inhibition of CREB phosphorylation or JMJD3 activity abolished the anti-neuroinflammatory effect of MaR1 on the expression of CREB, CBP, JMJD3, IRF4, IRF5, IL-1β, IL-6 and IL-10, thus prevented microglial activation and neutrophil infiltration. Together, the results show that MaR1 can activate LGR6 and affect CREB/JMJD3/IRF4 signaling to attenuate neuroinflammation after SAH, pointing to a potential pharmacological utility in this disorder.

Canine T zone lymphoma is a tumor of mature, previously activated αβ T cells

T cell lymphomas are a diverse group of tumors found in both dogs and humans, originating from various normal T cell types. Identifying the origin of neoplastic lymphocytes can offer valuable insights into the pathogenesis and clinical behavior of these tumors. T zone lymphoma (TZL) in dogs is characterized by the absence of CD45 expression, a strong breed predilection, and its association with adult-onset demodicosis-a condition believed to be linked to immunosuppression. In this study, our aim was to employ transcriptomic and functional data to determine the normal counterpart of TZL. Identifying the normal counterpart may help us understand both how these tumors arise and explain their clinical behavior. Gene expression profiling using NanoString and RNA seq was used to compare the transcriptome between neoplastic T zone cells, normal canine T cells and publicly available gene sets using Gene Set Enrichment Analysis. Mitogen, anti-CD3 stimulation and PMA/ionomycin stimulation were used to assess T cell proliferation in vitro, and intracellular cytokine production was measured by flow cytometry. Gene expression profiling revealed that TZL is most likely derived from an activated or memory alpha-beta T cell but the cells do not fall cleanly into an effector subtype. TZL cells express CD4-specific transcription factors GATA3 and THPOK, even though TZL cells more commonly express CD8, or neither CD4 nor CD8. TZL cells produce high levels of interferon gamma and tumor necrosis factor alpha when stimulated, further supporting the hypothesis that they are derived from an antigen experienced T cell. TZL cells do not proliferate when stimulated through the T cell receptor but will divide when the T cell receptor is bypassed with PMA and ionomycin. The observation that these cells are derived from a mature, previously activated T cell is the first step in understanding the genesis of this unique T cell tumor.

Immune system and gut microbiota senescence in elderly IBD patients

In inflammatory bowel disease (IBD), the loss of immune tolerance against gut microbiota causes chronic inflammation and the progressive accumulation of organ damage in genetically susceptible individuals. In the elderly, IBD is often characterized by a different disease behavior when compared with pediatric and young adult disease. Besides disease behavior, another aspect of the multifaceted impact of age on elderly IBD course is increased susceptibility to infections. In this context, age-of-onset-dependent IBD behavior and clinical course are two major contributors to immune system senescence and change of gut microbiota in older subjects. Here, we review the available literature linking immunosenescence and age-dependent changes in the gut microbiota composition to IBD pathogenesis speculating on their possible implications in disease expression in this age class.

Scd-1 deficiency promotes the differentiation of CD8+ T effector

The impact of various fatty acid types on adaptive immunity remains uncertain, and their roles remain unelucidated. Stearoyl-CoA desaturase (Scd) is a Δ-9 desaturase, which is a key rate-limiting enzyme for the conversion of saturated fatty acids (SFA) to monounsaturated fatty acids (MUFA) in the fatty acid de novo synthesis. Scd-1 converts stearic acid (SA) and palmitic acid (PA) to oleic acid (OA) and palmitoleic acid (PO), respectively. In this study, through a series of experiments, we showed that Scd-1 and its resulting compound, OA, have a substantial impact on the transformation of CD8+ naïve T cells into effector T cells. Inactivation of Scd-1 triggers the specialization of CD8+ T cells into the Teff subset, enhancing the effector function and mitochondrial metabolism of Teff cells, and OA can partially counteract this. A deeper understanding of lipid metabolism in immune cells and its impact on cell function can lead to new therapeutic approaches for controlling the immune response and improving prognosis.

Insights Into Inflammatory Bowel Disease and Effects of Dietary Fatty Acid Intake With a Focus on Polyunsaturated Fatty Acids Using Preclinical Models

While the aetiology of inflammatory bowel disease (IBD) has been linked to genetic susceptibility coupled with environmental factors, the underlying molecular mechanisms remain unclear. Among the environmental factors, diet and the gut microbiota have been implicated as drivers of immune dysregulation in IBD. Indeed, epidemiologic studies have highlighted that the increase in incidence of IBD parallels the increase in dietary intake of omega-6 (n-6) polyunsaturated fatty acids (PUFAs) and the change in balance of intake of n-6 to n-3 fatty acids. Experimental evidence suggests that the increase in n-6 PUFA intake increases cell membrane arachidonic acid, which is accompanied by the production of pro-inflammatory mediators as well as increased oxidative stress; together, this contributes to the development of chronic inflammation. However, it is also increasingly clear that some of the n-6 PUFA-derived mediators exert beneficial effects depending on the settings and timing of ingestion. In contrast to n-6, when n-3 PUFA eicosapentaenoic acid and docosahexaenoic acid are incorporated into the cell membrane and are metabolized into less pro-inflammatory eicosanoids, as well as strong specialized pro-resolving mediators, which play a role in inflammation cessation. With a focus on preclinical models, we explore the relationship between dietary lipid, the gut microbiome, and intestinal inflammation.

Novel UV-B Phototherapy With a Light-Emitting Diode Device Prevents Atherosclerosis by Augmenting Regulatory T-Cell Responses in Mice

BACKGROUND

Ultraviolet B (UV-B) irradiation is an effective treatment for human cutaneous disorders and was shown to reduce experimental atherosclerosis by attenuating immunoinflammatory responses. The aim of this study was to clarify the effect of specific wavelengths of UV-B on atherosclerosis and the underlying mechanisms focusing on immunoinflammatory responses.

METHODS AND RESULTS

Based on light-emitting diode technology, we developed novel devices that can emit 282 nm UV-B, which we do not receive from natural sunlight, 301 nm UV-B, and clinically available 312 nm UV-B. We irradiated 6-week-old male atherosclerosis-prone Apoe-/- (apolipoprotein E-deficient) mice with specific wavelengths of UV-B and evaluated atherosclerosis and immunoinflammatory responses by performing histological analysis, flow cytometry, biochemical assays, and liquid chromatography/mass spectrometry-based lipidomics. Irradiation of 282 nm UV-B but not 301 or 312 nm UV-B significantly reduced the development of aortic root atherosclerotic plaques and plaque inflammation. This atheroprotection was associated with specifically augmented immune responses of anti-inflammatory CD4+ Foxp3 (forkhead box P3)+ regulatory T cells in lymphoid tissues, whereas responses of other immune cells were not substantially affected. Analysis of various lipid mediators revealed that 282 nm UV-B markedly increased the ratio of proresolving to proinflammatory lipid mediators in the skin.

CONCLUSIONS

We demonstrated that 282 nm UV-B irradiation effectively reduces aortic inflammation and the development of atherosclerosis by systemically augmenting regulatory T-cell responses and modulating the balance between proresolving and proinflammatory lipid mediators in the skin. Our findings indicate that a novel 282 nm UV-B phototherapy could be an attractive approach to treat atherosclerosis.

RNA m6A modifications regulate crosstalk between tumor metabolism and immunity

In recent years, m6A modifications in RNA transcripts have arisen as a hot topic in cancer research. Indeed, a number of independent studies have elaborated that the m6A modification impacts the behavior of tumor cells and tumor-infiltrating immune cells, altering tumor cell metabolism along with the differentiation and functional activity of immune cells. This review elaborates on the links between RNA m6A modifications, tumor cell metabolism, and immune cell behavior, discussing this topic from the viewpoint of reciprocal regulation through "RNA m6A-tumor cell metabolism-immune cell behavior" and "RNA m6A-immune cell behavior-tumor cell metabolism" axes. In addition, we discuss the various factors affecting RNA m6A modifications in the tumor microenvironment, particularly the effects of hypoxia associated with cancer cell metabolism along with immune cell-secreted cytokines. Our analysis proposes the conclusion that RNA m6A modifications support widespread interactions between tumor metabolism and tumor immunity. With the current viewpoint that long-term cancer control must tackle cancer cell malignant behavior while strengthening anti-tumor immunity, the recognition of RNA m6A modifications as a key factor provides a new direction for the targeted therapy of tumors. This article is categorized under: RNA Processing > RNA Editing and Modification RNA in Disease and Development > RNA in Disease RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.

Pro-resolving and anti-inflammatory effects of resolvins and protectins in rheumatoid arthritis

Rheumatoid arthritis (RA) is typified by persistent joint inflammation, which leads to the deterioration of bone and cartilage and a reduction in overall quality of life. The global prevalence of pain as a primary symptom in RA is influenced by the interplay between inflammation and its resolution. The identification of a family of lipid mediators known as specialized pro-resolving mediators (SPM)s has contributed to the progress of our comprehension of inflammatory conditions. SPMs have been observed to trigger the process of inflammation resolution, thereby reinstating the homeostasis of the inflammatory response. Autacoids are synthesized through the stereo-selective transformation of essential fatty acids, resulting in molecules dynamically modulated during inflammation and possessing strong immunoregulatory properties. This review delves into the available evidence that supports the involvement of certain SPM as protective lipids, biomarkers with potential, and therapeutic targets in the context of RA.

The therapeutic potential of resolvins in pulmonary diseases

Uncontrolled inflammation leads to nonspecific destruction and remodeling of tissues and can contribute to many human pathologies, including pulmonary diseases. Stimulation of inflammatory resolution is considered an important process that protects against the progression of chronic inflammatory diseases. Resolvins generated from essential omega-3 polyunsaturated fatty acids have been demonstrated to be signaling molecules in inflammation with important pro-resolving and anti-inflammatory capabilities. By binding to specific receptors, resolvins can modulate inflammatory processes such as neutrophil migration, macrophage phagocytosis and the presence of pro-inflammatory mediators to reduce inflammatory pathologies. The discovery of these pro-resolving mediators has led to a shift in drug research from suppressing pro-inflammatory molecules to investigating compounds that promote resolution to treat inflammation. The exploration of inflammatory resolution also provided the opportunity to further understand the pathophysiology of pulmonary diseases. Alterations of resolution are now linked to both the development and exacerbation of diseases such as asthma, chronic obstructive pulmonary disease, cystic fibrosis, acute respiratory distress syndrome, cancer and COVID-19. These findings have resulted in the rise of novel design and testing of innovative resolution-based therapeutics to treat diseases. Hence, this paper reviews the generation and mechanistic actions of resolvins and investigates their role and therapeutic potential in several pulmonary diseases that may benefit from resolution-based pharmaceuticals.

Lipoxin-mediated signaling: ALX/FPR2 interaction and beyond

In the aftermath of tissue injury or infection, an efficient resolution mechanism is crucial to allow tissue healing and preserve appropriate organ functioning. Pro-resolving bioactive lipids prevent uncontrolled inflammation and its consequences. Among these mediators, lipoxins were the first described and their pro-resolving actions have been mainly described in immune cells. They exert their actions mostly through formyl-peptide receptor 2 (ALX/FPR2 receptor), a G-protein-coupled receptor whose biological function is tremendously complex, primarily due to its capacity to mediate variable cellular responses. Moreover, lipoxins can also interact with alternative receptors like the cytoplasmic aryl hydrocarbon receptor, the cysteinyl-leukotrienes receptors or GPR32, triggering different intracellular signaling pathways. The available information about this complex response mediated by lipoxins is addressed in this review, going over the different mechanisms used by these molecules to stop the inflammatory reaction and avoid the development of dysregulated and chronic pathologies.

Risk of cardiac rupture among elderly patients with diabetes presenting with first acute myocardial infarction

Objective

We aimed to analyze the risk of cardiac rupture (CR) in aged diabetic patients with acute ST-segment elevated myocardial infarction (STEMI) who were followed up for one month, and analyze its independent risk factors.

Methods

A total of 3063 aged patients with first onset STEMI admitted to Beijing Anzhen Hospital from January 2001 to December 2020 were retrospectively included. There were 2020 patients without diabetes mellitus (DM) and 1043 patients with DM. We used propensity scores matching (PSM) method to balance baseline exposure factors between patients with or without DM, and all were divided the DM group (1043 cases) and the non-DM group (1043 cases) after the PSM. The primary outcome was CR (the composite rate of papillary muscle rupture, ventricular septum perforation, free wall rupture), which was diagnosed based on clinical manifestations and/or echocardiographic findings. Kaplan-meier survival analyses and log-rank test was used to evaluate the risk of CR between the two groups, and Cox regression analysis was used to evaluate the independent risk factors for CR.

Results

After PSM, the baseline clinical data were similar between the DM and non-DM group (all P>0.05). However, level of glycated hemoglobin was significantly higher in the DM group (P<0.05). During 1 month of follow-up, there were 55 (2.64%) cases of CR, most occurred within 48h after admission (40 cases). Among the 55 cases, 11(0.53%) had papillary muscle rupture, 18(0.86%) had ventricular septum perforation, and 26(1.25%) had free wall rupture. Kaplan-meier survival analyses detected that the DM group was associated with significantly increased risk of CR (3.36% vs. 1.92%, HR=1.532, 95% CI: 1.054-2.346, P=0.030), ventricular septum perforation (1.05% vs. 0.67%, HR=1.464, 95% CI: 1.021-2.099, P=0.038) and free wall rupture (1.63% vs. 0.86%, HR=1.861, 95% CI: 1.074-3.225, P=0.027) than those in the non-DM group. Among the 2031 aged STEMI patients without CR, 144 cases (6.90%, 144/2086) died; and among the 55 patients with CR, 37 cases (1.77%, 37/2086) died due to CR. Therefore, twenty percent (20.44%, 37/181) of death was due to CR. Multivariate Cox regression analysis indicated that DM (HR=1.532, 95%CI: 1.054-2.346), age (HR=1.390, 95%CI: 1.079-1.791), female (HR=1.183, 95%CI: 1.049-1.334), troponin I (HR=1.364, 95%CI: 1.108-1.679), brain natriuretic peptide (HR=1.512, 95%CI: 1.069-2.139), revascularization (HR=0.827, 95%CI: 0.731-0.936) and β-receptor blocker (HR=0.849, 95%CI: 0.760-0.948) were independent risk factors of CR (all P<0.05).

Conclusion

DM as well as a few other factors, are independent determinants of CR. CR is not a rare event among the aged STEMI patients and twenty percent of deaths are due to CR. However, large sample-sized studies are warranted to confirm these findings.

Modifiable risk factors linked to the development of rheumatoid arthritis: evidence, immunological mechanisms and prevention

Rheumatoid Arthritis (RA) is a common autoimmune disease that targets the synovial joints leading to arthritis. Although the etiology of RA remains largely unknown, it is clear that numerous modifiable risk factors confer increased risk to developing RA. Of these risk factors, cigarette smoking, nutrition, obesity, occupational exposures and periodontal disease all incrementally increase RA risk. However, the precise immunological mechanisms by which these risk factors lead to RA are not well understood. Basic and translational studies have provided key insights into the relationship between inflammation, antibody production and the influence in other key cellular events such as T cell polarization in RA risk. Improving our general understanding of the mechanisms which lead to RA will help identify targets for prevention trials, which are underway in at-risk populations. Herein, we review the modifiable risk factors that are linked to RA development and describe immune mechanisms that may be involved. We highlight the few studies that have sought to understand if modification of these risk factors reduces RA risk. Finally, we speculate that modification of risk factors may be an appealing avenue for prevention for some at-risk individuals, specifically those who prefer lifestyle interventions due to safety and economic reasons.

Herring roe oil in treatment of psoriasis - influence on immune cells and cytokine network

Background

Psoriasis is a chronic immune-mediated skin disease with systemic inflammation and comorbidities. Although the disease severity may vary over time, many patients suffer from mild to moderate disease. Often local treatment will be sufficient to control the symptoms, but they may have several side effects. ω-3 polyunsaturated fatty acids have shown promising results in clinical trials with mild-to-moderate psoriasis.

Methods

We explored the impact of phospholipid bound docosahexaenoic acid and eicosapentaenoic acid in a 3:1 ratio on immune cells and cytokine networks in peripheral blood of patients with psoriasis. We investigated the inter-relation of plasma cytokine levels and disease severity in 58 patients, and explored the status of circulating immune cell activity in 18 patients with non-severe psoriasis before and during herring roe oil supplementation. Plasma concentration of 22 cytokines was measured by Luminex technology and circulating immune cells were analyzed by multicolor flow cytometry.

Results

CCL2 levels decreased over time, and IFN-γR1 increased, possibly related to the action of ω-3 polyunsaturated fatty acids. We observed a shift from naïve to effector CD4+ T cells and decreases of CD38 expression on CD4+ and CD8+ T cells, CD56bright NK cells and CD14+CD16- classical monocytes.

Conclusions

These findings support the beneficial effect of herring roe oil supplementation.

Resolvin D2 and its receptor GPR18 in cardiovascular and metabolic diseases: A promising biomarker and therapeutic target

Accumulating evidence suggests that inflammation plays an important role in the pathophysiology of the initiation and progression of cardiovascular and metabolic diseases (CVMDs). Anti-inflammation strategies and those that promote inflammation resolution have gradually become potential therapeutic approaches for CVMDs. Resolvin D2 (RvD2), a specialized pro-resolving mediator, exerts anti-inflammatory and pro-resolution effects through its receptor GPR18, a G protein-coupled receptor. Recently, the RvD2/GPR18 axis has received more attention due to its protective role in CVMDs, including atherosclerosis, hypertension, ischaemiareperfusion, and diabetes. Here, we introduce basic information about RvD2 and GPR18, summarize their roles in different immune cells, and review the therapeutic potential of the RvD2/GPR18 axis in CVMDs. In summary, RvD2 and its receptor GPR18 play an important role in the occurrence and development of CVMDs and are potential biomarkers and therapeutic targets.

Polyunsaturated Fatty Acid-Derived Lipid Mediators as Potential Biomarkers for Leprosy Among Individuals with Asymptomatic Mycobacterium leprae Infection

Intra-household contacts (HCs) of leprosy patients are at increased risk of infection by Mycobacterium leprae and about ∼5-10% will develop active disease. A prognostic tool to identify HCs with the greatest risk of progressing to active disease would enhance early leprosy diagnosis and optimize prophylactic intervention. Previous metabolomics studies suggest that host lipid mediators derived from ω-3 and ω-6 polyunsaturated fatty acids (PUFAs) are potential biomarkers for leprosy. In this study, we investigated retrospective sera of leprosy HCs by liquid chromatography-mass spectrometry and enzyme-linked immunoassay to determine whether circulating levels of ω-3 and ω-6 PUFA metabolites were altered in HCs that developed leprosy (HCDL) in comparison to those that did not (HCNDL). Sera were collected from HCs at the time of index case diagnosis and before clinical signs/symptoms of leprosy. Our findings showed that HCDL sera exhibited a distinct metabolic profile in comparison to HCDNL. Specifically, arachidonic acid, leukotriene B4, 11-hydroxyeicosatetraenoic acid, prostaglandin D2, and lipoxin A4 were elevated in HCDL. In contrast, prostaglandin E2 levels were reduced in HCDL. The ω-3 PUFAs, docosahexaenoic acid, eicosapentaenoic acid, and the docosahexaenoic acid-derived resolvin D1 and maresin-1 were also elevated in HCDL individuals compared to HCNDL. Principal component analyses provided further evidence that lipid mediators could serve as an early biomarker for progression to active leprosy. A logistic model identified resolvin D1 and D2, and prostaglandin D2 as having the greatest potential for early detection of HCs that will manifest leprosy.

Inflammation, lipids, and pain in vulvar disease

Localized provoked vulvodynia (LPV) affects ∼14 million people in the US (9% of women), destroying lives and relationships. LPV is characterized by chronic pain (>3 months) upon touch to the vulvar vestibule, which surrounds the vaginal opening. Many patients go months or years without a diagnosis. Once diagnosed, the treatments available only manage the symptoms of disease and do not correct the underlying problem. We have focused on elucidating the underlying mechanisms of chronic vulvar pain to speed diagnosis and improve intervention and management. We determined the inflammatory response to microorganisms, even members of the resident microflora, sets off a chain of events that culminates in chronic pain. This agrees with findings from several other groups, which show inflammation is altered in the painful vestibule. The vestibule of patients is acutely sensitive to inflammatory stimuli to the point of being deleterious. Rather than protect against vaginal infection, it causes heightened inflammation that does not resolve, which coincides with alterations in lipid metabolism that favor production of proinflammatory lipids and not pro-resolving lipids. Lipid dysbiosis in turn triggers pain signaling through the transient receptor potential vanilloid subtype 4 receptor (TRPV4). Treatment with specialized pro-resolving mediators (SPMs) that foster resolution reduces inflammation in fibroblasts and mice and vulvar sensitivity in mice. SPMs, specifically maresin 1, act on more than one part of the vulvodynia mechanism by limiting inflammation and acutely inhibiting TRPV4 signaling. Therefore, SPMs or other agents that target inflammation and/or TRPV4 signaling could prove effective as new vulvodynia therapies.

Insight of a lipid metabolism prognostic model to identify immune landscape and potential target for retroperitoneal liposarcoma

Introduction

The exploration of lipid metabolism dysregulation may provide novel perspectives for retroperitoneal liposarcoma (RPLS). In our study, we aimed to investigate potential targets and facilitate further understanding of immune landscape in RPLS, through lipid metabolism-associated genes (LMAGs) based prognostic model.

Methods

Gene expression profiles and corresponding clinical information of 234 cases were enrolled from two public databases and the largest retroperitoneal tumor research center of East China, including cohort-TCGA (n=58), cohort-GSE30929 (n=92), cohort-FD (n=50), cohort-scRNA-seq (n=4) and cohort-validation (n=30). Consensus clustering analysis was performed to identify lipid metabolism-associated molecular subtypes (LMSs). A prognostic risk model containing 13 LMAGs was established using LASSO algorithm and multivariate Cox analysis in cohort-TCGA. ESTIMATE, CIBERSORT, XCELL and MCP analyses were performed to visualize the immune landscape. WGCNA was used to identify three hub genes among the 13 model LMAGs, and preliminarily validated in both cohort-GSE30929 and cohort-FD. Moreover, TIMER was used to visualize the correlation between antigen-presenting cells and potential targets. Finally, single-cell RNA-sequencing (scRNA-seq) analysis of four RPLS and multiplexed immunohistochemistry (mIHC) were performed in cohort-validation to validate the discoveries of bioinformatics analysis.

Results

LMS1 and LMS2 were characterized as immune-infiltrated and -excluded tumors, with significant differences in molecular features and clinical prognosis, respectively. Elongation of very long chain fatty acids protein 2 (ELOVL2), the enzyme that catalyzed the elongation of long chain fatty acids, involved in the maintenance of lipid metabolism and cellular homeostasis in normal cells, was identified and negatively correlated with antigen-presenting cells and identified as a potential target in RPLS. Furthermore, ELOVL2 was enriched in LMS2 with significantly lower immunoscore and unfavorable prognosis. Finally, a high-resolution dissection through scRNA-seq was performed in four RPLS, revealing the entire tumor ecosystem and validated previous findings.

Discussion

The LMS subgroups and risk model based on LMAGs proposed in our study were both promising prognostic classifications for RPLS. ELOVL2 is a potential target linking lipid metabolism to immune regulations against RPLS, specifically for patients with LMS2 tumors.

Lipidomics in pathogenesis, progression and treatment of nonalcoholic steatohepatitis (NASH): Recent advances

Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease affecting up to 30% of the general adult population. NAFLD encompasses a histological spectrum ranging from pure steatosis to non-alcoholic steatohepatitis (NASH). NASH can progress to cirrhosis and is becoming the most common indication for liver transplantation, as a result of increasing disease prevalence and of the absence of approved treatments. Lipidomic readouts of liver blood and urine samples from experimental models and from NASH patients disclosed an abnormal lipid composition and metabolism. Collectively, these changes impair organelle function and promote cell damage, necro-inflammation and fibrosis, a condition termed lipotoxicity. We will discuss the lipid species and metabolic pathways leading to NASH development and progression to cirrhosis, as well as and those species that can contribute to inflammation resolution and fibrosis regression. We will also focus on emerging lipid-based therapeutic opportunities, including specialized proresolving lipid molecules and macrovesicles contributing to cell-to-cell communication and NASH pathophysiology.

Characteristic fragmentation of polyunsaturated fatty acids with allylic vicinal diols in positive-ion LC/ESI-MS/MS

A characteristic fragmentation was observed for PUFAs that contain allylic vicinal diol groups (resolvin D1, D2, D4, E3, lipoxin A4, B4, and maresin 2), which were derivatized with N,N-dimethylethylenediamine (DMED), in positive-ion ESI-MS/MS. The findings indicate that when these compounds contain an allylic hydroxyl group that is located distal to the terminal DMED moiety in the case of resolvin D1, D4, and lipoxin A4, an aldehyde (-CH=O) is predominately formed, which arises from the breakdown in between vicinal diols, whereas, in the case of an allylic hydroxyl group that is located proximal to the DMED moiety, as in resolvin D2, E3, lipoxin B4, and maresin 2, an allylic carbene (-CH=CH-CH:) is formed. These specific fragmentations could be used as diagnostic ions for characterizing the above seven PUFAs. As a result, it was possible to detect resolvin D1, D2, E3, lipoxin A4, and B4 in sera (20 μl) obtained from healthy volunteers by multiple-reaction monitoring using LC/ESI-MS/MS.

Differential impact of environmental factors on systemic and localized autoimmunity

The influence of environmental factors on the development of autoimmune disease is being broadly investigated to better understand the multifactorial nature of autoimmune pathogenesis and to identify potential areas of intervention. Areas of particular interest include the influence of lifestyle, nutrition, and vitamin deficiencies on autoimmunity and chronic inflammation. In this review, we discuss how particular lifestyles and dietary patterns may contribute to or modulate autoimmunity. We explored this concept through a spectrum of several autoimmune diseases including Multiple Sclerosis (MS), Systemic Lupus Erythematosus (SLE) and Alopecia Areata (AA) affecting the central nervous system, whole body, and the hair follicles, respectively. A clear commonality between the autoimmune conditions of interest here is low Vitamin D, a well-researched hormone in the context of autoimmunity with pleiotropic immunomodulatory and anti-inflammatory effects. While low levels are often correlated with disease activity and progression in MS and AA, the relationship is less clear in SLE. Despite strong associations with autoimmunity, we lack conclusive evidence which elucidates its role in contributing to pathogenesis or simply as a result of chronic inflammation. In a similar vein, other vitamins impacting the development and course of these diseases are explored in this review, and overall diet and lifestyle. Recent work exploring the effects of dietary interventions on MS showed that a balanced diet was linked to improvement in clinical parameters, comorbid conditions, and overall quality of life for patients. In patients with MS, SLE and AA, certain diets and supplements are linked to lower incidence and improved symptoms. Conversely, obesity during adolescence was linked with higher incidence of MS while in SLE it was associated with organ damage. Autoimmunity is thought to emerge from the complex interplay between environmental factors and genetic background. Although the scope of this review focuses on environmental factors, it is imperative to elaborate the interaction between genetic susceptibility and environment due to the multifactorial origin of these disease. Here, we offer a comprehensive review about the influence of recent environmental and lifestyle factors on these autoimmune diseases and potential translation into therapeutic interventions.

Maresin1: A multifunctional regulator in inflammatory bone diseases

Inflammation plays a crucial role in the physical response to danger signals, the elimination of toxic stimuli, and the restoration of homeostasis. However, dysregulated inflammatory responses lead to tissue damage, and chronic inflammation can disrupt osteogenic-osteoclastic homeostasis, ultimately leading to bone loss. Maresin1 (MaR1), a member of the specialized pro-resolving mediators (SPMs) family, has been found to possess significant anti-inflammatory, anti-allergic, pro-hemolytic, pro-healing, and pain-relieving properties. MaR1 is synthesized by macrophages (Mφs) and omega-3 fatty acids, and it may have the potential to promote bone homeostasis and treat inflammatory bone diseases. MaR1 has been found to stimulate osteoblast proliferation through leucine-rich repeat G protein-coupled receptor 6 (LGR6). It also activates Mφ phagocytosis and M2-type polarization, which helps to control the immune system. MaR1 can regulate T cells to exert anti-inflammatory effects and inhibit neutrophil infiltration and recruitment. In addition, MaR1 is involved in antioxidant signaling, including nuclear factor erythroid 2-related factor 2 (NRF2). It has also been found to promote the autophagic behavior of periodontal ligament stem cells, stimulate Mφs against pathogenic bacteria, and regulate tissue regeneration and repair. In summary, this review provides new information and a comprehensive overview of the critical roles of MaR1 in inflammatory bone diseases, indicating its potential as a therapeutic approach for managing skeletal metabolism and inflammatory bone diseases.

Differential effects of high dose omega-3 fatty acids on metabolism and inflammation in patients with obesity: eicosapentaenoic and docosahexaenoic acid supplementation

Background

Obesity is complicated by low-grade chronic inflammation characterised by increases in inflammatory proteins and cells in peripheral blood. It has been known that omega-3 fatty acids (FA) like eicosapentaenoic (EPA) and docosahexaenoic (DHA) could modulate the inflammatory process and improve metabolic markers.

Objective

This study aimed to determine the effect of high-dose omega-3 FA on metabolic and inflammatory markers among patients with obesity and healthy volunteers.

Methods

This prospective study included 12 women with obesity (body mass index [BMI] ≥ 35.0 kg/m²) and 12 healthy women (BMI < 24.0 kg/m²) who were supplemented with a dose of 4.8 g/day (3.2 g EPA plus 1.6 g DHA) for 3 months followed by no treatment for 1 month. Plasma metabolic and inflammatory markers and levels of mRNA transcripts of CD4⁺ T lymphocyte subsets were determined monthly.

Results

None of the participants exhibited changes in weight or body composition after study completion. EPA and DHA supplementation improved metabolic (insulin, Homeostatic Model Assessment of Insulin Resistance [HOMA-IR], triglyceride [TG]/ high-density lipoprotein [HDL] ratio, TG, and arachidonic acid [AA]/EPA ratio) and tumor necrosis factor-alpha (TNF-α). Moreover, the levels of mRNA transcripts of T CD4⁺ lymphocyte subsets (TBX21, IFNG, GATA-3, interleukin [IL]-4, FOXP3, IL-10 IL-6, and TNF-α), were down-regulated during the intervention phase. After 1 month without supplementation, only insulin, HOMA-IR and the mRNA transcripts remained low, whereas all other markers returned to their levels before supplementation.

Conclusion

Supplementation with high-dose omega-3 FAs could modulate metabolism and inflammation in patients with obesity without weight loss or changes in body composition. However, these modulatory effects were ephemeral and with clear differential effects: short-duration on metabolism and long-lasting on inflammation.

Lipid metabolism in tumor immunology and immunotherapy

Lipids are a diverse class of biomolecules that have been implicated in cancer pathophysiology and in an array of immune responses, making them potential targets for improving immune responsiveness. Lipid and lipid oxidation also can affect tumor progression and response to treatment. Although their importance in cellular functions and their potential as cancer biomarkers have been explored, lipids have yet to be extensively investigated as a possible form of cancer therapy. This review explores the role of lipids in cancer pathophysiology and describes how further understanding of these macromolecules could prompt novel treatments for cancer.

Fatty acid desaturation by stearoyl-CoA desaturase-1 controls regulatory T cell differentiation and autoimmunity

The imbalance between pathogenic and protective T cell subsets is a cardinal feature of autoimmune disorders such as multiple sclerosis (MS). Emerging evidence indicates that endogenous and dietary-induced changes in fatty acid metabolism have a major impact on both T cell fate and autoimmunity. To date, however, the molecular mechanisms that underlie the impact of fatty acid metabolism on T cell physiology and autoimmunity remain poorly understood. Here, we report that stearoyl-CoA desaturase-1 (SCD1), an enzyme essential for the desaturation of fatty acids and highly regulated by dietary factors, acts as an endogenous brake on regulatory T-cell (Treg) differentiation and augments autoimmunity in an animal model of MS in a T cell-dependent manner. Guided by RNA sequencing and lipidomics analysis, we found that the absence of Scd1 in T cells promotes the hydrolysis of triglycerides and phosphatidylcholine through adipose triglyceride lipase (ATGL). ATGL-dependent release of docosahexaenoic acid enhanced Treg differentiation by activating the nuclear receptor peroxisome proliferator-activated receptor gamma. Our findings identify fatty acid desaturation by SCD1 as an essential determinant of Treg differentiation and autoimmunity, with potentially broad implications for the development of novel therapeutic strategies and dietary interventions for autoimmune disorders such as MS.

The Roles of sPLA2s in Skin Homeostasis and Disease

Among the phospholipase A₂ (PLA₂) family, the secreted PLA₂ (sPLA₂) family in mammals contains 11 members that exhibit unique tissue or cellular distributions and enzymatic properties. Current studies using knockout and/or transgenic mice for a nearly full set of sPLA₂s, in combination with comprehensive lipidomics, have revealed the diverse pathophysiological roles of sPLA₂s in various biological events. Individual sPLA₂s exert specific functions within tissue microenvironments, likely through the hydrolysis of extracellular phospholipids. Lipids are an essential biological component for skin homeostasis, and disturbance of lipid metabolism by deletion or overexpression of lipid-metabolizing enzymes or lipid-sensing receptors often leads to skin abnormalities that are easily visible on the outside. Over the past decades, our studies using knockout and transgenic mice for various sPLA₂s have uncovered several new aspects of these enzymes as modulators of skin homeostasis and disease. This article summarizes the roles of several sPLA₂s in skin pathophysiology, providing additional insight into the research fields of sPLA₂s, lipids, and skin biology.

Maresin1 can be a potential therapeutic target for nerve injury

Nerve injury significantly affects human motor and sensory function due to destruction of the integrity of nerve structure. In the wake of nerve injury, glial cells are activated, and synaptic integrity is destroyed, causing inflammation and pain hypersensitivity. Maresin1, an omega-3 fatty acid, is a derivative of docosahexaenoic acid. It has showed beneficial effects in several animal models of central and peripheral nerve injuries. In this review, we summarize the anti-inflammatory, neuroprotective and pain hypersensitivity effects of maresin1 in nerve injury and provide a theoretical basis for the clinical treatment of nerve injury using maresin1.

An update on animal models of intervertebral disc degeneration and low back pain: Exploring the potential of artificial intelligence to improve research analysis and development of prospective therapeutics

Animal models have been invaluable in the identification of molecular events occurring in and contributing to intervertebral disc (IVD) degeneration and important therapeutic targets have been identified. Some outstanding animal models (murine, ovine, chondrodystrophoid canine) have been identified with their own strengths and weaknesses. The llama/alpaca, horse and kangaroo have emerged as new large species for IVD studies, and only time will tell if they will surpass the utility of existing models. The complexity of IVD degeneration poses difficulties in the selection of the most appropriate molecular target of many potential candidates, to focus on in the formulation of strategies to effect disc repair and regeneration. It may well be that many therapeutic objectives should be targeted simultaneously to effect a favorable outcome in human IVD degeneration. Use of animal models in isolation will not allow resolution of this complex issue and a paradigm shift and adoption of new methodologies is required to provide the next step forward in the determination of an effective repairative strategy for the IVD. AI has improved the accuracy and assessment of spinal imaging supporting clinical diagnostics and research efforts to better understand IVD degeneration and its treatment. Implementation of AI in the evaluation of histology data has improved the usefulness of a popular murine IVD model and could also be used in an ovine histopathological grading scheme that has been used to quantify degenerative IVD changes and stem cell mediated regeneration. These models are also attractive candidates for the evaluation of novel anti-oxidant compounds that counter inflammatory conditions in degenerate IVDs and promote IVD regeneration. Some of these compounds also have pain-relieving properties. AI has facilitated development of facial recognition pain assessment in animal IVD models offering the possibility of correlating the potential pain alleviating properties of some of these compounds with IVD regeneration.

Current experimental methods to investigate the impact of specialized pro-resolving lipid mediators on Sjögren's syndrome

Sjögren's syndrome is a chronic inflammatory autoimmune disease characterized by diminished secretory function of the exocrine glands. Although extensive investigation has been done to understand Sjögren's syndrome, the causes of the disease are as yet unknown and treatments remain largely ineffective, with established therapeutic interventions being limited to use of saliva substitutes with modest effectiveness. A primary feature of Sjögren's syndrome is uncontrolled inflammation of exocrine tissues and previous studies have demonstrated that lipid-based specialized pro-resolving mediators reduce inflammation and restores tissue integrity in salivary glands. However, these studies are limited to a single specialized pro-resolving lipid mediator's family member resolvin D1 or RvD1 and its aspirin-triggered epimer, AT-RvD1. Consequently, additional studies are needed to explore the potential benefits of other members of the specialized pro-resolving lipid mediator's family and related molecules (e.g., additional resolvin subtypes as well as lipoxins, maresins and protectins). In support of this goal, the current review aims to briefly describe the range of current experimental methods to investigate the impact of specialized pro-resolving lipid mediators on Sjögren's syndrome, including both strengths and weaknesses of each approach where this information is known. With this article, the possibilities presented by specialized pro-resolving lipid mediators will be introduced to a wider audience in immunology and practical advice is given to researchers who may wish to take up this work.

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.

Role of omega-3 endocannabinoids in the modulation of T-cell activity in a multiple sclerosis experimental autoimmune encephalomyelitis (EAE) model

Epidemiological studies show that omega-3 fatty acid consumption is associated with improved conditions in neurodegenerative diseases such as multiple sclerosis (MS). However, the mechanism of this association is not well understood. Emerging evidence suggests that parent molecules such as docosahexaenoic acid are converted into downstream metabolites that are capable of directly modulating immune responses. In vitro, we found that docosahexaenoyl ethanolamide (DHEA), another dietary component and its epoxide metabolite, reduced the polarization of naïve T-cells toward proinflammatory Th1 and Th17 phenotypes. Furthermore, we identified that DHEA and related endocannabinoids are changing during the disease progression in mice undergoing relapse-remitting experimental autoimmune encephalomyelitis (RR-EAE). In addition, daily administration of DHEA to mice delayed the onset of disease, the rate of relapse, and the severity of clinical scores at relapse in RR-EAE, an animal model of MS. Collectively, these data indicate that DHEA and their downstream metabolites reduce the disease severity in the RR-EAE model of MS and can be potential dietary adjuvants to existing MS therapeutics.

Haemophilus ducreyi Infection Induces Oxidative Stress, Central Metabolic Changes, and a Mixed Pro- and Anti-inflammatory Environment in the Human Host

Few studies have investigated host-bacterial interactions at sites of infection in humans using transcriptomics and metabolomics. Haemophilus ducreyi causes cutaneous ulcers in children and the genital ulcer disease chancroid in adults. We developed a human challenge model in which healthy adult volunteers are infected with H. ducreyi on the upper arm until they develop pustules. Here, we characterized host-pathogen interactions in pustules using transcriptomics and metabolomics and examined interactions between the host transcriptome and metabolome using integrated omics. In a previous pilot study, we determined the human and H. ducreyi transcriptomes and the metabolome of pustule and wounded sites of 4 volunteers (B. Griesenauer, T. M. Tran, K. R. Fortney, D. M. Janowicz, et al., mBio 10:e01193-19, 2019, https://doi.org/10.1128/mBio.01193-19). While we could form provisional transcriptional networks between the host and H. ducreyi, the study was underpowered to integrate the metabolome with the host transcriptome. To better define and integrate the transcriptomes and metabolome, we used samples from both the pilot study (n = 4) and new volunteers (n = 8) to identify 5,495 human differentially expressed genes (DEGs), 123 H. ducreyi DEGs, 205 differentially abundant positive ions, and 198 differentially abundant negative ions. We identified 42 positively correlated and 29 negatively correlated human-H. ducreyi transcriptome clusters. In addition, we defined human transcriptome-metabolome networks consisting of 9 total clusters, which highlighted changes in fatty acid metabolism and mitigation of oxidative damage. Taken together, the data suggest a mixed pro- and anti-inflammatory environment and rewired central metabolism in the host that provides a hostile, nutrient-limited environment for H. ducreyi. IMPORTANCE Interactions between the host and bacteria at sites of infection in humans are poorly understood. We inoculated human volunteers on the upper arm with the skin pathogen H. ducreyi or a buffer control and biopsied the resulting infected and sham-inoculated sites. We performed dual transcriptome sequencing (RNA-seq) and metabolic analysis on the biopsy samples. Network analyses between the host and bacterial transcriptomes and the host transcriptome-metabolome network were used to identify molecules that may be important for the virulence of H. ducreyi in the human host. Our results suggest that the pustule is highly oxidative, contains both pro- and anti-inflammatory components, and causes metabolic shifts in the host, to which H. ducreyi adapts to survive. To our knowledge, this is the first study to integrate transcriptomic and metabolomic responses to a single bacterial pathogen in the human host.

Resolution Potential of Necrotic Cell Death Pathways

During tissue damage caused by infection or sterile inflammation, not only damage-associated molecular patterns (DAMPs), but also resolution-associated molecular patterns (RAMPs) can be activated. These dying cell-associated factors stimulate immune cells localized in the tissue environment and induce the production of inflammatory mediators or specialized proresolving mediators (SPMs). Within the current prospect of science, apoptotic cell death is considered the main initiator of resolution. However, more RAMPs are likely to be released during necrotic cell death than during apoptosis, similar to what has been observed for DAMPs. The inflammatory potential of many regulated forms of necrotic cell death modalities, such as pyroptosis, necroptosis, ferroptosis, netosis, and parthanatos, have been widely studied in necroinflammation, but their possible role in resolution is less considered. In this review, we aim to summarize the relationship between necrotic cell death and resolution, as well as present the current available data regarding the involvement of certain forms of regulated necrotic cell death in necroresolution.

Mechanisms and Therapeutic Modulation of Neutrophil-Mediated Inflammation

Neutrophils are abundant, short-lived myeloid cells that are readily recruitable to sites of inflammation, where they serve as first-line defense against infection and other types of insult to the host. In recent years, there has been increased understanding on the involvement of neutrophils in chronic inflammatory diseases, where they may act as direct effectors of destructive inflammation. However, destructive tissue inflammation is also instigated in settings of neutrophil paucity, suggesting that neutrophils also mediate critical homeostatic functions. The activity of neutrophils is regulated by a variety of local tissue factors. In addition, systemic metabolic conditions, such as hypercholesterolemia and hyperglycemia, affect the production and mobilization of neutrophils from the bone marrow. Moreover, according to the recently emerged concept of innate immune memory, the functions of neutrophils can be enhanced through the process of trained granulopoiesis. This process may have both beneficial and potentially destructive effects, depending on context, that is, protective against infections and tumors, while destructive in the context of chronic inflammatory conditions. Although we are far from a complete understanding of the mechanisms underlying the regulation and function of neutrophils, current insights enable the development of targeted therapeutic interventions that can restrain neutrophil-mediated inflammation in chronic inflammatory diseases, such as periodontitis.

Resolvin D2 induces anti-microbial mechanisms in a model of infectious peritonitis and secondary lung infection

In severe bacterial infections, there is a pro-inflammatory response to promote bacterial clearance but this response can cause tissue injury. Later, the immune system becomes dysregulated and the host is unable to clear a secondary or a pre-existing infection. Specialized Pro-resolving Mediators (SPMs) such as resolvin D2 (RvD2) have been shown to be beneficial for inflammation/infection resolution in animal models of sepsis but in vivo mechanisms by which RvD2 may promote bacterial clearance and/or attenuate deleterious effects of a secondary infection have not been fully established. In this study, we used the 2-hit model of cecal ligation and puncture (CLP) induced infectious peritonitis and secondary lung infection with Pseudomonas aeruginosa to find possible antimicrobial and immunomodulatory mechanisms of RvD2. We show that RvD2 given as late as 48h after CLP surgery reduced blood bacterial load without altering plasma cytokines compared to mice given saline vehicle. RvD2 increased splenic neutrophil accumulation as well as average reactive oxygen species (ROS) production. There was also an increase in an immature leukocyte population the myeloid derived suppressor cells (MDSCs) in the spleen of RvD2 treated mice. RvD2 reduced lung lavage bacterial load 24h after P. aeruginosa administration and significantly decreased lung lavage levels of IL-23, a cytokine essential in the Th-17 inflammatory response. In addition, we show that RvD2 increased the number of non-inflammatory alveolar macrophages after P. aeruginosa administration compared to saline treated mice. The study uncovered an antimicrobial mechanism of RvD2 where RvD2 increases mature neutrophil and MDSC accumulation into the spleen to promote blood bacterial clearance. The study showed that in this 2-hit model, RvD2 promotes lung bacterial clearance, increased non-inflammatory alveolar macrophage number and inhibits an adaptive immune pathway providing evidence of its resolution mechanism in secondary pulmonary infection.

Targeting NRF2-KEAP1 axis by Omega-3 fatty acids and their derivatives: Emerging opportunities against aging and diseases

The transcription factor NRF2 and its endogenous inhibitor KEAP1 play a crucial role in the maintenance of cellular redox homeostasis by regulating the gene expression of diverse networks of antioxidant, anti-inflammatory, and detoxification enzymes. Therefore, activation of NRF2 provides cytoprotection against numerous pathologies, including age-related diseases. An age-associated loss of NRF2 function may be a key driving force behind the aging phenotype. Recently, numerous NRF2 inducers have been identified and some of them are promising candidates to restore NRF2 transcriptional activity during aging. Emerging evidence indicates that omega-3 (n-3) polyunsaturated fatty acids (PUFAs) and their electrophilic derivatives may trigger a protective response via NRF2 activation, rescuing or maintaining cellular redox homeostasis. In this review, we provide an overview of the NRF2-KEAP1 system and its dysregulation in aging cells. We also summarize current studies on the modulatory role of n-3 PUFAs as potential agents to prevent multiple chronic diseases and restore the age-related impairment of NRF2 function.

The effect of resolvin D1 on bone regeneration in a rat calvarial defect model

Resolvin D1 (RvD1) is a pro-resolving lipid mediator of inflammation, endogenously synthesized from omega-3 docosahexaenoic acid. The purpose of this study was to investigate the effect of RvD1 on bone regeneration using a rat calvarial defect model. Collagen 3D nanopore scaffold (COL) and Pluronic F127 hydrogel (F127) incorporated with RvD1 (RvD1-COL-F127 group) or COL and F127 (COL-F127 group) were implanted in symmetrical calvarial defects. After implantation, RvD1 was administrated subcutaneously every 7 days for 4 weeks. The rats were sacrificed at weeks 1 and 8 post-implantation. Tissue samples were analyzed by real-time reverse transcriptase-polymerase chain reaction and histology at week 1. Radiographical and histological analyses were done at week 8. At week 1, calvarial defects treated with RvD1 exhibited decreased numbers of inflammatory cells and tartrate-resistant acid phosphatase (TRAP) positive cells, greater numbers of newly formed blood vessels, upregulated gene expression of vascular endothelial growth factor and alkaline phosphatase, and downregulated gene expression of receptor activator of nuclear factor-κB ligand, interleukin-1β and tumor necrosis factor-α. At week 8, the radiographical results showed that osteoid area fraction of the RvD1-COL-F127 group was higher than that of the COL-F127 group, and histological examination exhibited enhanced osteoid formation and newly formed blood vessels in the RvD1-COL-F127 group. In conclusion, this study showed that RvD1 enhanced bone formation and vascularization in rat calvarial defects.

Excessive inflammatory response to infection in experimental peri-implantitis: Resolution by Resolvin D2

AIM

The aetiology and pathogenesis of peri-implantitis are currently under active research. This study aimed to dissect the pathogenesis of murine experimental peri-implantitis and assess Resolvin D2 (RvD2) as a new treatment modality.

MATERIALS AND METHODS

Four weeks following titanium implant insertion, mice were infected with Porphyromonas gingivalis using single or multiple oral lavages. RvD2 was administrated following infection, and tissues were analysed using flow cytometry, quantitative RT-PCR, taxonomic profiling, and micro-computed tomography.

RESULTS

Repeated infections with Pg resulted in microbial dysbiosis and a higher influx of innate and adaptive leukocytes to the peri-implant mucosa (PIM) than to gingiva surrounding the teeth. This was accompanied by increased expression levels of IFN-α, IL-1β, and RANKL\OPG ratio. Interestingly, whereas repetitive infections resulted in bone loss around implants and teeth, a single infection induced bone loss only around implants, suggesting a higher susceptibility of the implants to infection. Treatment with RvD2 prevented Pg-driven bone loss and reduced leukocyte infiltration to the PIM.

CONCLUSIONS

Murine dental implants are associated with dysregulated local immunity and increase susceptibility to pathogen-induced peri-implantitis. However, the disease can be prevented by RvD2 treatment, highlighting the promising therapeutic potential of this treatment modality.

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

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

Lipid metabolism in type 1 diabetes mellitus: Pathogenetic and therapeutic implications

Type 1 diabetes mellitus (T1DM) is a chronic autoimmune disease with insulin deficiency due to pancreatic β cell destruction. Multiple independent cohort studies revealed specific lipid spectrum alterations prior to islet autoimmunity in T1DM. Except for serving as building blocks for membrane biogenesis, accumulative evidence suggests lipids and their derivatives can also modulate different biological processes in the progression of T1DM, such as inflammation responses, immune attacks, and β cell vulnerability. However, the types of lipids are huge and majority of them have been largely unexplored in T1DM. In this review, based on the lipid classification system, we summarize the clinical evidence on dyslipidemia related to T1DM and elucidate the potential mechanisms by which they participate in regulating inflammation responses, modulating lymphocyte function and influencing β cell susceptibility to apoptosis and dysfunction. This review systematically recapitulates the role and mechanisms of various lipids in T1DM, providing new therapeutic approaches for T1DM from a nutritional perspective.

The function of omega-3 polyunsaturated fatty acids in response to cadmium exposure

Throughout history, pollution has become a part of our daily life with the improvement of life quality and the advancement of industry and heavy industry. In recent years, the adverse effects of heavy metals, such as cadmium (Cd), on human health have been widely discussed, particularly on the immune system. Here, this review summarizes the available evidence on how Cd exposure may affect health. By analyzing the general manifestations of inflammation caused by Cd exposure, we find that the role of omega-3 (n-3) polyunsaturated fatty acids (PUFAs) in vivo can counteract Cd-induced harm. Additionally, we elucidate the effects of n-3 PUFAs on the immune system, and analyze their prophylactic and therapeutic effects on Cd exposure. Overall, this review highlights the role of n-3 PUFAs in the pathological changes induced by Cd exposure. Although n-3 PUFAs remain to be verified whether they can be used as therapeutic agents, as rehabilitation therapy, supplementation with n-3 PUFAs is reliable and effective.

Impact of preweaning vaccination on host gene expression and antibody titers in healthy beef calves

The impact of preweaning vaccination for bovine respiratory viruses on cattle health and subsequent bovine respiratory disease morbidity has been widely studied yet questions remain regarding the impact of these vaccines on host response and gene expression. Six randomly selected calves were vaccinated twice preweaning (T1 and T3) with a modified live vaccine for respiratory pathogens and 6 randomly selected calves were left unvaccinated. Whole blood samples were taken at first vaccination (T1), seven days later (T2), at revaccination and castration (T3), and at weaning (T4), and utilized for RNA isolation and sequencing. Serum from T3 and T4 was analyzed for antibodies to BRSV, BVDV1a, and BHV1. Sequenced RNA for all 48 samples was bioinformatically processed with a HISAT2/StringTie pipeline, utilizing reference guided assembly with the ARS-UCD1.2 bovine genome. Differentially expressed genes were identified through analyzing the impact of time across all calves, influence of vaccination across treatment groups at each timepoint, and the interaction of time and vaccination. Calves, regardless of vaccine administration, demonstrated an increase in gene expression over time related to specialized proresolving mediator production, lipid metabolism, and stimulation of immunoregulatory T-cells. Vaccination was associated with gene expression related to natural killer cell activity and helper T-cell differentiation, enriching for an upregulation in Th17-related gene expression, and downregulated genes involved in complement system activity and coagulation mechanisms. Type-1 interferon production was unaffected by the influence of vaccination nor time. To our knowledge, this is the first study to evaluate mechanisms of vaccination and development in healthy calves through RNA sequencing analysis.

Mechanisms Underlying Anti-Inflammatory and Anti-Cancer Properties of Stretching-A Review

Stretching is one of the popular elements in physiotherapy and rehabilitation. When correctly guided, it can help minimize or slow down the disabling effects of chronic health conditions. Most likely, the benefits are associated with reducing inflammation; recent studies demonstrate that this effect from stretching is not just systemic but also local. In this review, we present the current body of knowledge on the anti-inflammatory properties of stretching at a molecular level. A total of 22 papers, focusing on anti-inflammatory and anti-cancer properties of stretching, have been selected and reviewed. We show the regulation of oxidative stress, the expression of pro- and anti-inflammatory genes and mediators, and remodeling of the extracellular matrix, expressed by changes in collagen and matrix metalloproteinases levels, in tissues subjected to stretching. We point out that a better understanding of the anti-inflammatory properties of stretching may result in increasing its importance in treatment and recovery from diseases such as osteoarthritis, systemic sclerosis, and cancer.

Lipid metabolism and retinal diseases

PURPOSE

The retina has enormous lipids demands and must meet those needs. Retinal lipid homeostasis appears to be based on the symbiosis between neurons, Müller glial cells (MGC), and retinal pigment epithelium (RPE) cells, which can be impacted in several retinal diseases. The current research challenge is to better understand lipid-related mechanisms involved in retinal diseases, such as age-related macular degeneration (AMD) and glaucoma.

RESULTS

In a first axis, in vitro and focus on Müller glial cell, we aimed to characterize whether the 24S-hydroxycholesterol (24S-OHC), an overexpressed end-product of cholesterol elimination pathway in neural tissue and likely produced by suffering retinal ganglion cells in glaucoma, may modulate MGC membrane organization, such as lipid rafts, to trigger cellular signalling pathways related to retinal gliosis. We have found that lipid composition appears to be a key factor of membrane architecture, especially for lipid raft microdomain formation, in MGC. However, 24S-OHC did not appear to trigger retinal gliosis via the modulation of lipid or protein composition within lipid rafts microdomains. This study provided a better understanding of the complex mechanisms involved in the pathophysiology of glaucoma. On a second clinical ax, we focused on the lipid-related mechanisms involved in the dysfunction of aging RPE and the appearance of drusenoid deposits in AMD. Using the Montrachet population-based study, we intend to report the frequency of reticular pseudodrusen (RPD) and its ocular and systemic risk factors, particularly related to lipid metabolisms, such as plasma lipoprotein levels, carotenoids levels, and lipid-lowering drug intake. Our study showed that RPD was less common in subjects taking lipid-lowering drugs. Lipid-lowering drugs, such as statins, may reduce the risk of RPD through their effect on the production and function of lipoproteins. This observation highlights the potential role of retinal lipid trafficking via lipoproteins between photoreceptors and retinal pigment epithelium cells in RPD formation. Those findings have been complemented with preliminary results on the analysis of plasma fatty acid (FA) profile, a surrogate marker of short-term dietary lipid intake, according to the type of predominant drusenoid deposit, soft drusen or RPD, in age-related maculopathy.

CONCLUSION

Further research on lipid metabolism in retinal diseases is warranted to better understand the pathophysiology of retinal diseases and develop new promising diagnostic, prognostic, and therapeutic tools for our patients.