Glucocorticoids regulate lipid mediator networks by reciprocal modulation of 15-lipoxygenase isoforms affecting inflammation resolution.

Glucocorticoids (GC) are potent anti-inflammatory agents, broadly used to treat acute and chronic inflammatory diseases, e.g., critically ill COVID-19 patients or patients with chronic inflammatory bowel diseases. GC not only limit inflammation but also promote its resolution although the underlying mechanisms are obscure. Here, we reveal reciprocal regulation of 15-lipoxygenase (LOX) isoform expression in human monocyte/macrophage lineages by GC with respective consequences for the biosynthesis of specialized proresolving mediators (SPM) and their 15-LOX-derived monohydroxylated precursors (mono-15-OH). Dexamethasone robustly up-regulated pre-mRNA, mRNA, and protein levels of ALOX15B/15-LOX-2 in blood monocyte-derived macrophage (MDM) phenotypes, causing elevated SPM and mono-15-OH production in inflammatory cell types. In sharp contrast, dexamethasone blocked ALOX15/15-LOX-1 expression and impaired SPM formation in proresolving M2-MDM. These dexamethasone actions were mimicked by prednisolone and hydrocortisone but not by progesterone, and they were counteracted by the GC receptor (GR) antagonist RU486. Chromatin immunoprecipitation (ChIP) assays revealed robust GR recruitment to a putative enhancer region within intron 3 of the ALOX15B gene but not to the transcription start site. Knockdown of 15-LOX-2 in M1-MDM abolished GC-induced SPM formation and mono-15-OH production. Finally, ALOX15B/15-LOX-2 upregulation was evident in human monocytes from patients with GC-treated COVID-19 or patients with IBD. Our findings may explain the proresolving GC actions and offer opportunities for optimizing GC pharmacotherapy and proresolving mediator production.

Cannabidiol acts as molecular switch in innate immune cells to promote the biosynthesis of inflammation-resolving lipid mediators.

Cannabinoids are phytochemicals from cannabis with anti-inflammatory actions in immune cells. Lipid mediators (LM), produced from polyunsaturated fatty acids (PUFA), are potent regulators of the immune response and impact all stages of inflammation. How cannabinoids influence LM biosynthetic networks is unknown. Here, we reveal cannabidiol (CBD) as a potent LM class-switching agent that stimulates the production of specialized pro-resolving mediators (SPMs) but suppresses pro-inflammatory eicosanoid biosynthesis. Detailed metabololipidomics analysis in human monocyte-derived macrophages showed that CBD (i) upregulates exotoxin-stimulated generation of SPMs, (ii) suppresses 5-lipoxygenase (LOX)-mediated leukotriene production, and (iii) strongly induces SPM and 12/15-LOX product formation in resting cells by stimulation of phospholipase A2-dependent PUFA release and through Ca2+-independent, allosteric 15-LOX-1 activation. Finally, in zymosan-induced murine peritonitis, CBD increased SPM and 12/15-LOX products and suppressed pro-inflammatory eicosanoid levels in vivo. Switching eicosanoid to SPM production is a plausible mode of action of CBD and a promising inflammation-resolving strategy.

Local dielectric function of hBN-encapsulated WS2flakes grown by chemical vapor deposition.

Hexagonal boron nitride (hBN), sometimes referred to as white graphene, receives growing interest in the scientific community, especially when combined into van der Waals (vdW) homo- and heterostacks, in which novel and interesting phenomena may arise. hBN is also commonly used in combination with two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDCs). The realization of hBN-encapsulated TMDC homo- and heterostacks can indeed offer opportunities to investigate and compare TMDC excitonic properties in various stacking configurations. In this work, we investigate the optical response at the micrometric scale of mono- and homo-bilayer WS2grown by chemical vapor deposition and encapsulated between two single layers of hBN. Imaging spectroscopic ellipsometry is exploited to extract the local dielectric functions across one single WS2flake and detect the evolution of excitonic spectral features from monolayer to bilayer regions. Exciton energies undergo a redshift by passing from hBN-encapsulated single layer to homo-bilayer WS2, as also confirmed by photoluminescence spectra. Our results can provide a reference for the study of the dielectric properties of more complex systems where hBN is combined with other 2D vdW materials into heterostructures and are stimulating towards the investigation of the optical response of other technologically-relevant heterostacks.

Identification of 2-Aminoacyl-1,3,4-thiadiazoles as Prostaglandin E2 and Leukotriene Biosynthesis Inhibitors.

The application of a multi-step scientific workflow revealed an unprecedented class of PGE2/leukotriene biosynthesis inhibitors with in vivo activity. Specifically, starting from a combinatorial virtual library of ∼4.2 × 105 molecules, a small set of compounds was identified for the synthesis. Among these, four novel 2-aminoacyl-1,3,4-thiadiazole derivatives (3, 6, 7, and 9) displayed marked anti-inflammatory properties in vitro by strongly inhibiting PGE2 biosynthesis, with IC50 values in the nanomolar range. The hit compounds also efficiently interfered with leukotriene biosynthesis in cell-based systems and modulated IL-6 and PGE2 biosynthesis in a lipopolysaccharide-stimulated J774A.1 macrophage cell line. The most promising compound 3 showed prominent in vivo anti-inflammatory activity in a mouse model, with efficacy comparable to that of dexamethasone, attenuating zymosan-induced leukocyte migration in mouse peritoneum with considerable modulation of the levels of typical pro-/anti-inflammatory cytokines.

Highly potent and selective 5-lipoxygenase inhibition by new, simple heteroaryl-substituted catechols for treatment of inflammation.

5-Lipoxygenase (LO) catalyzes the first steps in the formation of pro-inflammatory leukotrienes (LT) that are pivotal lipid mediators contributing to allergic reactions and inflammatory disorders. Based on its key role in LT biosynthesis, 5-LO is an attractive drug target, demanding for effective and selective inhibitors with efficacy in vivo, which however, are still rare. Encouraged by the recent identification of the catechol 4-(3,4-dihydroxyphenyl)dibenzofuran 1 as 5-LO inhibitor, simple structural modifications were made to yield even more effective and selective catechol derivatives. Within this new series, the two most potent compounds 3,4-dihydroxy-3'-phenoxybiphenyl (6b) and 2-(3,4-dihydroxyphenyl)benzo[b]thiophene (6d) potently inhibited human 5-LO in cell-free (IC506b and 6d = 20 nM) and cell-based assays (IC506b = 70 nM, 6d = 60 nM). Inhibition of 5-LO was reversible, unaffected by exogenously added substrate arachidonic acid, and not primarily mediated via radical scavenging and antioxidant activities. Functional 5-LO mutants expressed in HEK293 cells were still prone to inhibition by 6b and 6d, and docking simulations revealed distinct binding of the catechol moiety to 5-LO at an allosteric site. Analysis of 5-LO nuclear membrane translocation and intracellular Ca2+ mobilization revealed that these 5-LO-activating events are hardly affected by the catechols. Importantly, the high inhibitory potency of 6b and 6d was confirmed in human blood and in a murine zymosan-induced peritonitis model in vivo. Our results enclose these novel catechol derivatives as highly potent, novel type inhibitors of 5-LO with high selectivity and with marked effectiveness under pathophysiological conditions.

Allosteric Activation of 15-Lipoxygenase-1 by Boswellic Acid Induces the Lipid Mediator Class Switch to Promote Resolution of Inflammation.

Specialized pro-resolving mediators (SPM), primarily produced in innate immune cells, exert crucial bioactions for resolving inflammation. Among various lipoxygenases (LOX), 15-LOX-1 is key for SPM biosynthesis, but cellular activation principles of 15-LOX-1 are unexplored. It was shown that 3-O-acetyl-11-keto-ß-boswellic acid (AKBA) shifts 5-LOX regiospecificity from 5- to 12-lipoxygenation products. Here, it is demonstrated that AKBA additionally activates cellular 15-LOX-1 via an allosteric site accomplishing robust SPM formation in innate immune cells, particularly in M2 macrophages. Compared to ionophore, AKBA-induced LOX activation is Ca2+ - and phosphorylation-independent, with modest induction of 5-LOX products. AKBA docks into a groove between the catalytic and regulatory domains of 15-LOX-1 interacting with R98; replacement of R98 by alanine abolishes AKBA-induced 15-LOX product formation in HEK293 cells. In zymosan-induced murine peritonitis, AKBA strikingly elevates SPM levels and promotes inflammation resolution. Together, targeted allosteric modulation of LOX activities governs SPM formation and offers new concepts for inflammation resolution pharmacotherapy.

Discovery and Optimization of Indoline-Based Compounds as Dual 5-LOX/sEH Inhibitors: In Vitro and In Vivo Anti-Inflammatory Characterization.

The design of multitarget drugs represents a promising strategy in medicinal chemistry and seems particularly suitable for the discovery of anti-inflammatory drugs. Here, we describe the identification of an indoline-based compound inhibiting both 5-lipoxygenase (5-LOX) and soluble epoxide hydrolase (sEH). In silico analysis of an in-house library identified nine compounds as potential 5-LOX inhibitors. Enzymatic and cellular assays revealed the indoline derivative 43 as a notable 5-LOX inhibitor, guiding the design of new analogues. These compounds underwent extensive in vitro investigation revealing dual 5-LOX/sEH inhibitors, with 73 showing the most promising activity (IC50s of 0.41 ± 0.01 and 0.43 ± 0.10 µM for 5-LOX and sEH, respectively). When challenged in vivo in zymosan-induced peritonitis and experimental asthma in mice, compound 73 showed remarkable anti-inflammatory efficacy. These results pave the way for the rational design of 5-LOX/sEH dual inhibitors and for further investigation of their potential use as anti-inflammatory agents.

Mycobacterium tuberculosis-Induced Upregulation of the COX-2/mPGES-1 Pathway in Human Macrophages Is Abrogated by Sulfasalazine.

Macrophages are the primary human host cells of intracellular Mycobacterium tuberculosis (M.tb) infection, where the magnitude of inflammatory reactions is crucial for determining the outcome of infection. Previously, we showed that the anti-inflammatory drug sulfasalazine (SASP) significantly reduced the M.tb bactericidal burden and histopathological inflammation in mice. Here, we asked which genes in human inflammatory macrophages are affected upon infection with M.tb and how would potential changes impact the functional state of macrophages. We used a flow cytometry sorting system which can distinguish the dead and alive states of M.tb harbored in human monocyte-derived macrophages (MDM). We found that the expression of cyclooxygenase-2 and microsomal prostaglandin E2 synthase (mPGES)-1 increased significantly in tagRFP+ MDM which were infected with alive M.tb. After exposure of polarized M1-MDM to M.tb (H37Rv strain)-conditioned medium (MTB-CM) or to the M.tb-derived 19-kD antigen, the production of PGE2 and pro-inflammatory cytokines increased 3- to 4-fold. Upon treatment of M1-MDM with SASP, the MTB-CM-induced expression of COX-2 and the release of COX products and cytokines decreased. Elevation of PGE2 in M1-MDM upon MTB-CM stimulation and modulation by SASP correlated with the activation of the NF-κB pathway. Together, infection of human macrophages by M.tb strongly induces COX-2 and mPGES-1 expression along with massive PGE2 formation which is abrogated by the anti-inflammatory drug SASP.

Modulation of Inflammation-Related Lipid Mediator Pathways by Celastrol During Human Macrophage Polarization.

Background and Purpose: Celastrol (CS) is a major active ingredient of the Chinese/Asian herb Tripterygium wilfordii that is frequently used as phytomedicine to treat inflammation and autoimmune diseases. We showed before that short-term exposure to CS (1 µM) favorably impacts the biosynthesis of inflammation-related lipid mediators (LM) in human polarized macrophages by modulating the activities of different lipoxygenases (LOXs). However, whether CS regulates the expression of LOXs and other related LM-biosynthetic enzymes during macrophage polarization is unknown. Here, we investigated how CS affects LM-biosynthetic enzyme expression on the protein level and studied concomitant LM signature profiles during polarization of human monocyte-derived macrophages (MDM) towards M1- and M2-like phenotypes. Methods and Results: We used LM metabololipidomics to study the long-term effects of CS on LM profile signatures after manipulation of human monocyte-derived macrophages (MDM) during polarization. Exposure of MDM to low concentrations of CS (ie, 0.2 µM) during polarization to an inflammatory M1 phenotype potently suppressed the formation of pro-inflammatory cyclooxygenase (COX)- and 5-LOX-derived LM, especially prostaglandin (PG)E2. Notably, gene and enzyme expression of COX-2 and microsomal PGE2 synthase (mPGES)-1 as well as M1 markers were strongly decreased by CS during M1-MDM polarization, along with impaired activation of nuclear factor-κB and p38 mitogen-activated protein kinase. During IL-4-induced M2 polarization, CS decreased the capacity of the resulting M2-MDM to generate pro-inflammatory COX and 5-LOX products as well but it also reduced the formation of 12/15-LOX products and specialized pro-resolving mediators, without affecting the levels of liberated fatty acid substrates. Conclusion: Depending on the timing and concentration, CS not only favorably affects LOX activities in macrophages but also the expression of LM-biosynthetic enzymes during macrophage polarization connected to changes of inflammation-related LM which might be of relevance for potential application of CS to treat inflammatory disorders.

Staphylococcus aureus controls eicosanoid and specialized pro-resolving mediator production via lipoteichoic acid.

Staphylococcus aureus causes severe infections associated with inflammation, such as sepsis or osteomyelitis. Inflammatory processes are regulated by distinct lipid mediators (LMs) but how their biosynthetic pathways are orchestrated in S. aureus infections is elusive. We show that S. aureus strikingly not only modulates pro-inflammatory, but also inflammation-resolving LM pathways in murine osteomyelitis and osteoclasts as well as in human monocyte-derived macrophages (MDMs) with different phenotype. Targeted LM metabololipidomics using ultra-performance liquid chromatography-tandem mass spectrometry revealed massive generation of LM with distinct LM signature profiles in acute and chronic phases of S. aureus-induced murine osteomyelitis in vivo. In human MDM, S. aureus elevated cyclooxygenase-2 (COX-2) and microsomal prostaglandin E2  synthase-1 (mPGES-1), but impaired the levels of 15-lipoxygenase-1 (15-LOX-1), with respective changes in LM signature profiles initiated by these enzymes, that is, elevated PGE2 and impaired specialized pro-resolving mediators, along with reduced M2-like phenotypic macrophage markers. The cell wall component, lipoteichoic acid (LTA), mimicked the impact of S. aureus elevating COX-2/mPGES-1 expression via NF-κB and p38 MAPK signalling in MDM, while the impairment of 15-LOX-1 correlates with reduced expression of Lamtor1. In conclusion, S. aureus dictates LM pathways via LTA resulting in a shift from anti-inflammatory M2-like towards pro-inflammatory M1-like LM signature profiles.

Unexpected Electron Transport Suppression in a Heterostructured Graphene-MoS2 Multiple Field-Effect Transistor Architecture.

We demonstrate a graphene-MoS2 architecture integrating multiple field-effect transistors (FETs), and we independently probe and correlate the conducting properties of van der Waals coupled graphene-MoS2 contacts with those of the MoS2 channels. Devices are fabricated starting from high-quality single-crystal monolayers grown by chemical vapor deposition. The heterojunction was investigated by scanning Raman and photoluminescence spectroscopies. Moreover, transconductance curves of MoS2 are compared with the current-voltage characteristics of graphene contact stripes, revealing a significant suppression of transport on the n-side of the transconductance curve. On the basis of ab initio modeling, the effect is understood in terms of trapping by sulfur vacancies, which counterintuitively depends on the field effect, even though the graphene contact layer is positioned between the backgate and the MoS2 channel.

The α-tocopherol-derived long-chain metabolite α-13'-COOH mediates endotoxin tolerance and modulates the inflammatory response via MAPK and NFκB pathways.

SCOPE: The long-chain metabolites of (LCM) vitamin E are proposed as the active regulatory metabolites of vitamin E providing, with their anti-inflammatory properties, an explanatory approach for the inconsistent effects of vitamin E on inflammatory-driven diseases. We examined the modulation of cytokine expression and release from macrophages, a fundamental process in many diseases, to gain insights into the anti-inflammatory mechanisms of the α-tocopherol-derived LCM α-13'-COOH. METHODS AND RESULTS: Suppressed gene expression of C-C motif chemokine ligand 2 (Ccl2), tumor necrosis factor (Tnf), and interleukin (Il) 6 in response to lipopolysaccharides by 24 h pre-treatment with α-13'-COOH in RAW264.7 macrophages was revealed using quantitative reverse transcription PCR. Further, reduced secretion of IL1ß and CCL2 was found in this setup using flow cytometry. In contrast, 1 h pre-treatment suppressed only CCL2. Consequent gene expression analysis within 24 h of α-13'-COOH treatment revealed the induction of mitogen-activated protein kinases (MAPK) and nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) negative feedback regulators including the 'master regulators' dual-specificity phosphatase 1 (Dusp1/Mkp1) and tumor necrosis factor induced protein 3 (Tnfaip3/A20). Approaches with immunoblots and chemical antagonists suggest a feedback induction via activation of extracellular-signal regulated kinase (ERK), p38 MAPK and NFκB pathways. CONCLUSIONS: CCL2 is suppressed in murine macrophages by α-13'-COOH and the indirect suppression of MAPK and NFκB pathways is likely a relevant process contributing to anti-inflammatory actions of α-13'-COOH. These results improve the understanding of the effects of α-13'-COOH and provide a basis for new research strategies in the context of inflammatory diseases.

Local Optical Properties in CVD-Grown Monolayer WS2 Flakes.

Excitons dominate the light absorption and re-emission spectra of monolayer transition-metal dichalcogenides (TMD). Microscopic investigations of the excitonic response in TMD almost invariably extract information from the radiative recombination step, which only constitutes one part of the picture. Here, by exploiting imaging spectroscopic ellipsometry (ISE), we investigate the spatial dependence of the dielectric function of chemical vapor deposition (CVD)-grown WS2 flakes with a microscopic lateral resolution, thus providing information about the spatially varying, exciton-induced light absorption in the monolayer WS2. Comparing the ISE results with imaging photoluminescence spectroscopy data, the presence of several correlated features was observed, along with the unexpected existence of a few uncorrelated characteristics. The latter demonstrates that the exciton-induced absorption and emission features are not always proportional at the microscopic scale. Microstructural modulations across the flakes, having a different influence on the absorption and re-emission of light, are deemed responsible for the effect.

From Vietnamese plants to a biflavonoid that relieves inflammation by triggering the lipid mediator class switch to resolution.

Chronic inflammation results from excessive pro-inflammatory signaling and the failure to resolve the inflammatory reaction. Lipid mediators orchestrate both the initiation and resolution of inflammation. Switching from pro-inflammatory to pro-resolving lipid mediator biosynthesis is considered as efficient strategy to relieve chronic inflammation, though drug candidates exhibiting such features are unknown. Starting from a library of Vietnamese medical plant extracts, we identified isomers of the biflavanoid 8-methylsocotrin-4'-ol from Dracaena cambodiana, which limit inflammation by targeting 5-lipoxygenase and switching the lipid mediator profile from leukotrienes to specialized pro-resolving mediators (SPM). Elucidation of the absolute configurations of 8-methylsocotrin-4'-ol revealed the 2S,γS-isomer being most active, and molecular docking studies suggest that the compound binds to an allosteric site between the 5-lipoxygenase subdomains. We identified additional subordinate targets within lipid mediator biosynthesis, including microsomal prostaglandin E2 synthase-1. Leukotriene production is efficiently suppressed in activated human neutrophils, macrophages, and blood, while the induction of SPM biosynthesis is restricted to M2 macrophages. The shift from leukotrienes to SPM was also evident in mouse peritonitis in vivo and accompanied by a substantial decrease in immune cell infiltration. In summary, we disclose a promising drug candidate that combines potent 5-lipoxygenase inhibition with the favorable reprogramming of lipid mediator profiles.

Exploration of Long-Chain Vitamin E Metabolites for the Discovery of a Highly Potent, Orally Effective, and Metabolically Stable 5-LOX Inhibitor that Limits Inflammation.

Endogenous long-chain metabolites of vitamin E (LCMs) mediate immune functions by targeting 5-lipoxygenase (5-LOX) and increasing the systemic concentrations of resolvin E3, a specialized proresolving lipid mediator. SAR studies on semisynthesized analogues highlight α-amplexichromanol (27a), which allosterically inhibits 5-LOX, being considerably more potent than endogenous LCMs in human primary immune cells and blood. Other enzymes within lipid mediator biosynthesis were not substantially inhibited, except for microsomal prostaglandin E2 synthase-1. Compound 27a is metabolized by sulfation and ß-oxidation in human liver-on-chips and exhibits superior metabolic stability in mice over LCMs. Pharmacokinetic studies show distribution of 27a from plasma to the inflamed peritoneal cavity and lung. In parallel, 5-LOX-derived leukotriene levels decrease, and the inflammatory reaction is suppressed in reconstructed human epidermis, murine peritonitis, and experimental asthma in mice. Our study highlights 27a as an orally active, LCM-inspired drug candidate that limits inflammation with superior potency and metabolic stability to the endogenous lead.

Beneficial Modulation of Lipid Mediator Biosynthesis in Innate Immune Cells by Antirheumatic Tripterygium wilfordii Glycosides.

Tripterygium wilfordii glycosides (TWG) is a traditional Chinese medicine with effectiveness against rheumatoid arthritis (RA), supported by numerous clinical trials. Lipid mediators (LM) are biomolecules produced from polyunsaturated fatty acids mainly by cyclooxygenases (COX) and lipoxygenases (LOX) in complex networks which regulate inflammation and immune responses and are strongly linked to RA. The mechanism by which TWG affects LM networks in RA treatment remains elusive. Employing LM metabololipidomics using ultra-performance liquid chromatography-tandem mass spectrometry revealed striking modulation of LM pathways by TWG in human monocyte-derived macrophage (MDM) phenotypes. In inflammatory M1-MDM, TWG (30 µg/mL) potently suppressed agonist-induced formation of 5-LOX products which was confirmed in human PMNL and traced back to direct inhibition of 5-LOX (IC50 = 2.9 µg/mL). TWG also efficiently blocked thromboxane formation in M1-MDM without inhibiting other prostanoids and COX enzymes. Importantly, in anti-inflammatory M2-MDM, TWG (30 µg/mL) induced pronounced formation of specialized pro-resolving mediators (SPM) and related 12/15-LOX-derived SPM precursors, without COX and 5-LOX activation. During MDM polarization, TWG (1 µg/mL) decreased the capacity to generate pro-inflammatory 5-LOX and COX products, cytokines and markers for M1 phenotypes. Together, suppression of pro-inflammatory LM but SPM induction may contribute to the antirheumatic properties of TWG.

Anti-inflammatory celastrol promotes a switch from leukotriene biosynthesis to formation of specialized pro-resolving lipid mediators.

The pentacyclic triterpenoid quinone methide celastrol (CS) from Tripterygium wilfordii Hook. F. effectively ameliorates inflammation with potential as therapeutics for inflammatory diseases. However, the molecular mechanisms underlying the anti-inflammatory and inflammation-resolving features of CS are incompletely understood. Here we demonstrate that CS potently inhibits the activity of human 5-lipoxygenase (5-LOX), the key enzyme in pro-inflammatory leukotriene (LT) formation, in cell-free assays with IC50 = 0.19-0.49 µM. Employing metabololipidomics using ultra-performance liquid chromatography coupled to tandem mass spectrometry in activated human polymorphonuclear leukocytes or M1 macrophages we found that CS (1 µM) potently suppresses 5-LOX-derived products without impairing the formation of lipid mediators (LM) formed by 12-/15-LOXs as well as fatty acid substrate release. Intriguingly, CS induced the generation of 12-/15-LOX-derived LM including the specialized pro-resolving mediator (SPM) resolvin D5 in human M2 macrophages. Finally, intraperitoneal pre-treatment of mice with 10 mg/kg CS strongly impaired zymosan-induced LT formation and simultaneously elevated the levels of SPM and related 12-/15-LOX-derived LM in peritoneal exudates, spleen and plasma in vivo. Conclusively, CS promotes a switch from LT biosynthesis to formation of SPM which may underlie the anti-inflammatory and inflammation-resolving effects of CS, representing an interesting pharmacological strategy for intervention with inflammatory disorders.

Aging drives organ-specific alterations of the inflammatory microenvironment guided by immunomodulatory mediators in mice.

Aging is accompanied by chronic, low-grade systemic inflammation, termed inflammaging, a main driver of age-associated diseases. Such sterile inflammation is typically characterized by elevated levels of pro-inflammatory mediators, such as cytokines, chemokines and reactive oxygen species causing organ damage. Lipid mediators play important roles in the fine-tuning of both the promotion and the resolution of inflammation. Yet, it remains unclear how lipid mediators fit within the concept of inflammaging and how their biosynthesis and function is affected by aging. Here, we provide comprehensive signature profiles of inflammatory markers in organs afflicted with inflammation of young and old C57BL/6 mice. We reveal an organ-specific footprint of inflammation-related cytokines, chemokines and lipid mediators, which are distinctively affected by aging. While some organs are characterized by a pronounced pro-inflammatory microenvironment and impaired resolution during aging, others display elevated levels of pro-resolving mediators or an overall decrease in inflammatory signaling. Our results demonstrate that it proves difficult to establish a unifying concept for alterations of immunomodulatory mediators as consequence of aging and that organ specificity needs to be considered. Moreover, our data imply that inclusion of lipid mediators into the concept of inflammaging provides a comprehensive tool to characterize the inflammatory microenvironment during aging on a broader and yet, more detailed scope.

Synthesis of Large-Scale Monolayer 1T'-MoTe2 and Its Stabilization via Scalable hBN Encapsulation.

Out of the different structural phases of molybdenum ditelluride (MoTe2), the distorted octahedral 1T' possesses great interest for fundamental physics and is a promising candidate for the implementation of innovative devices such as topological transistors. Indeed, 1T'-MoTe2 is a semimetal with superconductivity, which has been predicted to be a Weyl semimetal and a quantum spin Hall insulator in bulk and monolayer form, respectively. Large instability of monolayer 1T'-MoTe2 in environmental conditions, however, has made its investigation extremely challenging so far. In this work, we demonstrate homogeneous growth of large single-crystal (up to 500 µm) monolayer 1T'-MoTe2 via chemical vapor deposition (CVD) and its stabilization in air with a scalable encapsulation approach. The encapsulant is obtained by electrochemically delaminating CVD hexagonal boron nitride (hBN) from copper foil, and it is applied on the freshly grown 1T'-MoTe2 via a top-down dry lamination step. The structural and electrical properties of encapsulated 1T'-MoTe2 have been monitored over several months to assess the degree of degradation of the material. We find that when encapsulated with hBN, the lifetime of monolayer 1T'-MoTe2 successfully increases from a few minutes to more than a month. Furthermore, the encapsulated monolayer can be subjected to transfer, device processing, and heating and cooling cycles without degradation of its properties. The potential of this scalable heterostack is confirmed by the observation of signatures of low-temperature phase transition in monolayer 1T'-MoTe2 by both Raman spectroscopy and electrical measurements. The growth and encapsulation methods reported in this work can be employed for further fundamental studies of this enticing material as well as facilitate the technological development of monolayer 1T'-MoTe2.

Sex Hormone-Dependent Lipid Mediator Formation in Male and Female Mice During Peritonitis.

Introduction: Sex differences in inflammation are obvious and contribute to divergences in the incidence and severity of inflammation-related diseases that frequently preponderate in women. Lipid mediators (LMs), mainly produced by lipoxygenase (LOX) and cyclooxygenase (COX) pathways from polyunsaturated fatty acids (PUFAs), regulate all stages of inflammation. Experimental and clinical studies revealed sex divergences for selected LM pathways without covering the entire LM spectrum, and only few studies have addressed the respective role of sex hormones. Here, we performed the comprehensive LM profile analysis with inflammatory peritoneal exudates and plasma from male and female mice in zymosan-induced peritonitis to identify the potential sex differences in LM biosynthesis during the inflammatory response. We also addressed the impact of sex hormones by employing gonadectomy. Methods: Adult male and female CD1 mice received intraperitoneal injection of zymosan to induce peritonitis, a well-established experimental model of acute, self-resolving inflammation. Mice were gonadectomized 5 weeks prior to peritonitis induction. Peritoneal exudates and plasma were taken at 4 (peak of inflammation) and 24 h (onset of resolution) post zymosan and subjected to UPLC-MS-MS-based LM signature profiling; exudates were analyzed for LM biosynthetic proteins by Western blot; and plasma was analyzed for cytokines by ELISA. Results: Pro-inflammatory COX and 5-LOX products predominated in the peritoneum of males at 4 and 24 h post-zymosan, respectively, with slightly higher 12/15-LOX products in males after 24 h. Amounts of COX-2, 5-LOX/FLAP, and 15-LOX-1 were similar in exudates of males and females. In plasma of males, only moderate elevation of these LMs was apparent. At 4 h post-zymosan, gonadectomy strongly elevated 12/15-LOX products in the exudates of males, while in females, free PUFA and LOX products were rather impaired. In plasma, gonadectomy impaired most LMs in both sexes at 4 h with rather up-regulatory effects at 24 h. Finally, elevated 15-LOX-1 protein was evident in exudates of males at 24 h which was impaired by orchiectomy without the striking impact of gonadectomy on other enzymes in both sexes. Conclusions: Our results reveal obvious sex differences and roles of sex hormones in LM biosynthetic networks in acute self-resolving inflammation in mice, with several preponderances in males that appear under the control of androgens.