Adrenic Acid-Derived Epoxy Fatty Acids Are Naturally Occurring Lipids and Their Methyl Ester Prodrug Reduces Endoplasmic Reticulum Stress and Inflammatory Pain

Metabolic Analysis and Renal Protective Effects of Linagliptin and Empagliflozin in Alport Syndrome

Key Points

Linagliptin reduces kidney function decline and extends lifespan in Alport syndrome mice. Inhibiting the generation of glucose metabolites could serve as a potential therapeutic strategy for the treatment of Alport syndrome.

Background

We previously demonstrated that empagliflozin (Empa), a sodium-glucose cotransporter-2 inhibitor, reduces intrarenal lipid accumulation and slows kidney function decline in experimental Alport syndrome (AS). In this study, we aimed to evaluate the renal protective benefits of linagliptin (Lina), a dipeptidyl peptidase-4 inhibitor in AS, and compare it with Empa.

Methods

Metabolite distribution in kidney cortices was assessed using mass spectrometry imaging. We examined albuminuria and histological changes in kidneys from AS mice treated with Lina and/or Empa or vehicle.

Results

Several metabolites, including adrenic acid and glucose, were increased in renal cortices of AS mice compared with wild-type (WT) mice, whereas eicosapentaenoic acid levels were decreased. In addition, a redistribution of adrenic acid from the glomerular compartment in WT mice to the tubulointerstitial compartment in AS mice was observed. Both Lina and Empa treatments were found to reduce albuminuria to extend the survival of AS mice for about 10 days and to decrease glomerulosclerosis and tubulointerstitial fibrosis compared with WT mice. There were no significant differences with regard to the renal phenotype observed between Empa- and Lina-treated AS mice, and the combination of Lina and Empa was not superior to individual treatments. In vitro experiments revealed that dipeptidyl peptidase-4 is expressed in podocytes and tubular cells derived from both AS and WT mice. Differently from what we have reported for Empa, Lina treatment was found to reduce glucose-driven respiration in AS tubular cells but not in AS podocytes.

Conclusions

Renal expression patterns and spatial distribution of several metabolites differ in AS compared with WT mice. Although Lina and Empa treatments similarly partially slow the progression of kidney disease in AS, the metabolic mechanisms conferring the protective effect may be different.

Active Molecular Network Discovery Links Lifestyle Variables to Breast Cancer in the Long Island Breast Cancer Study Project

A healthy lifestyle has been associated with decreased risk of developing breast cancer. Using untargeted metabolomics profiling, which provides unbiased information regarding lifestyle choices such as diet and exercise, we aim to identify the molecular mechanisms connecting lifestyle and breast cancer through network analysis. A total of 100 postmenopausal women, 50 with breast cancer and 50 cancer-free controls, were selected from the Long Island Breast Cancer Study Project (LIBCSP). We measured untargeted plasma metabolomics using liquid chromatography-high-resolution mass spectrometry (LC-HRMS). Using the "enet" package, we retained highly correlated metabolites representing active molecular network (AMN) clusters for analysis. LASSO was used to examine associations between cancer status and AMN metabolites and covariates such as BMI, age, and reproductive factors. LASSO was then repeated to examine associations between AMN metabolites and 10 lifestyle-related variables including smoking, physical activity, alcohol consumption, meat consumption, fruit and vegetable consumption, and supplemental vitamin use. Results were displayed as a network to uncover biological pathways linking lifestyle factors to breast cancer status. After filtering, 851 "active" metabolites out of 1797 metabolomics were retained in 197 correlation AMN clusters. Using LASSO, breast cancer status was associated with 71 "active" metabolites. Several of these metabolites were associated with lifestyle variables including meat consumption, alcohol consumption, and supplemental β-carotene, B12, and folate use. Those metabolites could potentially serve as molecular-level biological intermediaries connecting healthy lifestyle factors to breast cancer, even though direct associations between breast cancer and the investigated lifestyles at the phenotype level are not evident. In particular, DiHODE, a metabolite linked with inflammation, was associated with breast cancer status and connected to β-carotene supplement usage through an AMN. We found several plasma metabolites associated with lifestyle factors and breast cancer status. Future studies investigating the mechanistic role of inflammation in linking supplement usage to breast cancer status are warranted.

Implications of metabolism on multi-systems healthy aging across the lifespan

Aging is increasingly thought to involve dysregulation of metabolism in multiple organ systems that culminate in decreased functional capacity and morbidity. Here, we seek to understand complex interactions among metabolism, aging, and systems-wide phenotypes across the lifespan. Among 2469 adults (mean age 74.7 years; 38% Black) in the Health, Aging and Body Composition study we identified metabolic cross-sectionally correlates across 20 multi-dimensional aging-related phenotypes spanning seven domains. We used LASSO-PCA and bioinformatic techniques to summarize metabolome-phenome relationships and derive metabolic scores, which were subsequently linked to healthy aging, mortality, and incident outcomes (cardiovascular disease, disability, dementia, and cancer) over 9 years. To clarify the relationship of metabolism in early adulthood to aging, we tested association of these metabolic scores with aging phenotypes/outcomes in 2320 participants (mean age 32.1, 44% Black) of the Coronary Artery Risk Development in Young Adults (CARDIA) study. We observed significant overlap in metabolic correlates across the seven aging domains, specifying pathways of mitochondrial/cellular energetics, host-commensal metabolism, inflammation, and oxidative stress. Across four metabolic scores (body composition, mental-physical performance, muscle strength, and physical activity), we found strong associations with healthy aging and incident outcomes, robust to adjustment for risk factors. Metabolic scores for participants four decades younger in CARDIA were related to incident cardiovascular, metabolic, and neurocognitive performance, as well as long-term cardiovascular disease and mortality over three decades. Conserved metabolic states are strongly related to domain-specific aging and outcomes over the life-course relevant to energetics, host-commensal interactions, and mechanisms of innate immunity.

Specialized Pro-resolving Mediator Improves Vascular Relaxation via Formyl Peptide Receptor-2

BACKGROUND

The resolution of inflammation is an active phenomenon important for switching off inflammatory processes once the harmful stimuli are removed and facilitate the return to homeostasis. Specialized pro-resolving mediators (SPMs), such as lipoxin A4, resolvin D1, and resolvin E1, derived from ω-3 or ω-6 polyunsaturated fatty acids, are crucial for the resolution of inflammation. We hypothesized that SPMs are decreased in hypertension which contributes to the acetylcholine-induced contraction in resistance arteries, which are well known to be mediated by leukotrienes and prostaglandins. Moreover, treatment with SPMs will decrease this contraction via formyl peptide receptor-2 (FPR-2) in resistance arteries from spontaneously hypertensive rats (SHR).

METHODS AND RESULTS

We performed a comprehensive eicosanoid lipid panel analysis, and our data showed for the first time that precursors of SPMs are decreased in SHR, limiting the production of SPMs and resolution of inflammation in vivo. This phenomenon was associated with an increase in lipid peroxidation in resistance arteries. Although SPMs did not abolish acetylcholine-induced contraction, these lipid mediators improved endothelial function in arteries from SHR via FPR-2 activation at nanomolar concentrations. SPMs also buffered TNF-α-induced reactive oxygen species generation in endothelial cells from C57Bl/6 mice.

CONCLUSIONS

We suggest that FPR-2 and SPMs could be revealed as a new target or therapeutic agent to improve vascular function in arteries from hypertensive rats.

Metabolic Changes Associated with Different Levels of Energy Deficits in Mediterranean Buffaloes during the Early Lactation Stage: Type and Role of the Main Lipid Fractions Involved

Cell function and energy redistribution are influenced by lipid classes (phospholipids (PLs), free fatty acids (FFAs), triglycerides (TGs), and cholesterol esters (CEs)). The aim of this study was to investigate metabolic alterations that are related to changes in lipid classes according to different levels of energy deficits in early lactating Mediterranean buffaloes (MBs). Sixty-three MBs were enrolled at the beginning of lactation using an observational study with a cross-sectional experimental design. Serum β-hydroxybutyrate (BHB) levels were used to group the animals into a healthy group (Group H; n = 38; BHB < 0.70 mmol/L) and hyperketonemia risk group (Group K; n = 25; BHB ≥ 0.70 mmol/L). Statistical analysis was performed using a linear model that included the effect of the group and body condition score to assess differences in fatty acid (FA) concentrations. A total of 40 plasma FAs were assessed in each lipid class. Among the FAs, eight PLs, seven FFAs, four TGs, and four CEs increased according to BHB levels, while three FFAs, three TGs, and one CE decreased. The changes among lipid class profiles suggested the influence of inflammatory response, liver metabolism, and the state of body lipid reserves. In addition, the possible similarities of buffaloes at risk of hyperketonemia with ketotic cows suggest the necessity of further investigations in these ruminants.

Melatonin Activates Anti-Inflammatory Features in Microglia in a Multicellular Context: Evidence from Organotypic Brain Slices and HMC3 Cells

Melatonin (MEL) is a neurohormone endowed with neuroprotective activity, exerted both directly on neuronal cells and indirectly through modulation of responsive glial cells. In particular, MEL's effects on microglia are receptor-mediated and in part dependent on SIRT1 activation. In the present study, we exploited the highly preserved cytoarchitecture of organotypic brain cultures (OC) to explore the effects of MEL on hippocampal microglia in a 3D context as compared to a single cell type context represented by the human HMC3 cell line. We first evaluated the expression of MEL receptor MT1 and SIRT1 and then investigated MEL action against an inflammatory stimulation with LPS: OCs were cultured for a total of 2 weeks and during this time exposed to 0.1 μg/mL of LPS for 24 h either on day 1 (LPS 1°) or on day 11 (LPS 11°). MEL was added immediately after plating and kept for the entire experiment. Under these conditions, both MEL and LPS induced amoeboid microglia. However, the same round phenotype matched different polarization features. LPS increased the number of nuclear-NF-kB+ round cells and MEL alone or in combination with LPS increased BDNF+ round microglia. In addition, MEL contrasted LPS effects on NF-kB expression. Data from HMC3 microglia confirmed MEL's anti-inflammatory effects against LPS in terms of CASP1 induction and BDNF release, identifying SIRT1 as a mediator. However, no effects were evident for MEL alone on HMC3 microglia. Overall, our results point to the importance of the multicellular context for full MEL activity, especially in a preventive view, and support the use of OCs as a favorable model to explore inflammatory responses.

Soluble epoxide hydrolase inhibition alleviates chemotherapy induced neuropathic pain

Chemotherapy induced peripheral neuropathy (CIPN) is a particularly pernicious form of neuropathy and the associated pain is the primary dose-limiting factor of life-prolonging chemotherapy treatment. The prevalence of CIPN is high and can last long after treatment has been stopped. Currently, late in the COVID-19 pandemic, there are still increased psychological pressures on cancer patients as well as additional challenges in providing analgesia for them. These include the risks of nonsteroidal anti-inflammatory drug (NSAID) analgesics potentially masking early infection symptoms and the immunosuppression of steroidal and opiate based approaches. Even without these concerns, CIPN is often inadequately treated with few therapies that offer significant pain relief. The experiments we report use soluble epoxide hydrolase inhibitors (sEHI) which relieved this intractable pain in preclinical models. Doses of EC5026, an IND candidate intended to treat neuropathic pain, elicited dose dependent analgesic responses in multiple models including platinum-based, taxane, and vinca alkaloid-based CIPN pain in Sprague Dawley rats. At the same time as a class, the sEHI are known to result in fewer debilitating side effects of other analgesics, likely due to their novel mechanism of action. Overall, the observed dose-dependent analgesia in both male and female rats across multiple models of chemotherapy induced neuropathic pain holds promise as a useful tool when translated to the clinic.

Causal effects of fatty acids on depression: Mendelian randomization study

Objectives

Fatty acids (FA) are widely believed to play a role in the pathophysiology of depression. However, the causal relationships between FA and depression remain elusive and warrant further research. We aimed to investigate the potential causal relationship between FA [saturated fatty acids (SFA), mono-unsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA)] and the risk of depression using Mendelian randomization (MR) analysis.

Methods

We conducted a two-sample MR analysis using large-scale European-based genome-wide association studies (GWASs) summary data related to depression (n = 500,199 individuals) and FA [saturated fatty acids (SFA), mono-unsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA)] levels. MR analysis was performed using the Wald ratio and inverse variance-weighted (IVW) methods, and sensitivity analysis was conducted by the simple mode, weighted mode, weighted median method, and MR-Egger method.

Results

We found the causal effects for the levels of oleic acid (OA; OR = 1.07, p = 5.72 × 10^-4), adrenic acid (OR = 0.74, p = 1.01 × 10^-3), α-linolenic acid (ALA; OR = 2.52, p = 1.01 × 10^-3), eicosapentaenoic acid (EPA; OR = 0.84, p = 3.11 × 10^-3) on depression risk, after Bonferroni correction. The sensitivity analyses indicated similar trends. No causal effect between the levels of SFA and depression risk was observed.

Conclusion

Our study suggests that adrenic acid and EPA are protective against the risk of depression, while OA and ALA are potential risk factors for depression. Nonetheless, the underlying mechanisms that mediate the association between these FAs and depression risk should be investigated in further experiments.

Changes in plasma fatty acids profile in hyperketonemic ewes during early lactation: a preliminary study

The transition from late pregnancy to early lactation is characterized by marked changes in energy balance of dairy ruminants. The mobilization of adipose tissue led to an increase in plasma non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHB). The aim of this study was to analyze the total plasma fatty acids of healthy and hyperketonemic dairy ewes in early lactation through gas chromatography (GC) to evaluate metabolic alterations. An observational study was used with a cross-sectional experimental design. Forty-six Sarda dairy ewes were enrolled in the immediate post-partum (7 ± 3 days in milk) and divided into two groups according to serum BHB concentration: non-hyperketonemic group (n = 28; BHB < 0.86 mmol/L) and hyperketonemic group (n = 18; BHB ≥ 0.86 mmol/L). A two-way ANOVA included the effect of group and parity was used to evaluate differences in fatty acids (FA) concentrations. A total of 34 plasma FA was assessed using GC. 12 out of 34 FA showed a significant different between groups and 3 out of 34 were tended to significance. Only NEFA concentration and stearic acid were influenced by parity. The results may suggest possible links with lipid metabolism, inflammatory and immune responses in hyperketonemic group. In conclusion, GC represents a useful tool in the study of hyperketonemia and primiparous dairy ewes might show a greater risk to develop this condition.

[Fatty acid epoxides in the regulation of the inflammation]

Cyclooxygenase and lipoxygenase derived lipid metabolites of polyunsaturated fatty acids (PUFAs), as well as their role in the inflammation, have been studied quite thoroughly. However, cytochrome P450 derived lipid mediators, as well as their participation in the regulation of the inflammation, need deeper understanding. In recent years, it has become known that PUFAs are oxidized by cytochrome P450 epoxygenases to epoxy fatty acids, which act as the extremely powerful lipid mediators involved in resolving inflammation. Recent studies have shown that the anti-inflammatory mechanisms of ω-3 PUFAs are also mediated by their conversion to the endocannabinoid epoxides. Thus, it is clear that a number of therapeutically relevant functions of PUFAs are due to their conversion to PUFA epoxides. However, with the participation of cytochrome P450 epoxygenases, not only PUFA epoxides, but also other metabolites are formed. They are further are converted by epoxide hydrolases into pro-inflammatory dihydroxy fatty acids and anti-inflammatory dihydroxyeicosatrienoic acids. The study of the role of PUFA epoxides in the regulation of the inflammation and pharmacological modeling of the activity of epoxide hydrolases are the promising strategies for the treatment of the inflammatory diseases. This review systematizes the current literature data of the fatty acid epoxides, in particular, the endocannabinoid epoxides. Their role in the regulation of inflammation is discussed.

New Alkoxy- Analogues of Epoxyeicosatrienoic Acids Attenuate Cisplatin Nephrotoxicity In Vitro via Reduction of Mitochondrial Dysfunction, Oxidative Stress, Mitogen-Activated Protein Kinase Signaling, and Caspase Activation

The usage of cisplatin, a highly potent chemotherapeutic, is limited by its severe nephrotoxicity. Arachidonic acid (ARA)-derived epoxyeicosatrienoic acids (EETs) and soluble epoxide hydrolase (sEH) inhibitors were shown to ameliorate this dose-limiting side effect, but both approaches have some pharmacological limitations. Analogues of EETs are an alternative avenue with unique benefits, but the current series of analogues face concerns regarding their structure and mimetic functionality. Hence, in this study, regioisomeric mixtures of four new ARA alkyl ethers were synthesized, characterized, and assessed as EET analogues against the concentration- and time-dependent toxicities of cisplatin in porcine proximal tubular epithelial cells. All four ether groups displayed bioisostere activity, ranging from marginal for methoxy- (1), good for n-propoxy- (4), and excellent for ethoxy- (2) and i-propoxy- (3). Compounds 2 and 3 displayed cytoprotective effects comparable to that of an EET regioisomeric mixture (5) against high, acute cisplatin exposures but were more potent against low to moderate, chronic exposures. Compounds 2 and 3 (and 5) acted through stabilization of the mitochondrial transmembrane potential and attenuation of reactive oxygen species, leading to reduced phosphorylation of mitogen-activated protein kinases p38 and JNK and decreased activation of caspase-9 and caspase-3. This study demonstrates that alkoxy- groups are potent and more metabolically stable bioisostere alternatives to the epoxide within EETs that enable sEH-independent activity. It also illustrates the potential of ether-based mimics of EETs and other epoxy fatty acids as promising nephroprotective agents to tackle the clinically relevant side effect of cisplatin without compromising its antineoplastic function.