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Derangement of the epidermal barrier lipids and dysregulated immune responses are key pathogenic features of atopic dermatitis (AD). The Th2-type cytokines interleukin IL-4 and IL-13 play a prominent role in AD by activating the Janus Kinase/Signal Transduction and Activator of Transcription (JAK/STAT) intracellular signaling axis. This study aimed to investigate the role of JAK/STAT in the lipid perturbations induced by Th2 signaling in 3D epidermal equivalents. Tofacitinib, a low-molecular-mass JAK inhibitor, was used to screen for JAK/STAT-mediated deregulation of lipid metabolism. Th2 cytokines decreased the expression of elongases 1, 3, and 4 and serine-palmitoyl-transferase and increased that of sphingolipid delta(4)-desaturase and carbonic anhydrase 2. Th2 cytokines inhibited the synthesis of palmitoleic acid and caused depletion of triglycerides, in association with altered phosphatidylcholine profiles and fatty acid (FA) metabolism. Overall, the ceramide profiles were minimally affected. Except for most sphingolipids and very-long-chain FAs, the effects of Th2 on lipid pathways were reversed by co-treatment with tofacitinib. An increase in the mRNA levels of CPT1A and ACAT1, reduced by tofacitinib, suggests that Th2 cytokines promote FA beta-oxidation. In conclusion, pharmacological inhibition of JAK/STAT activation prevents the lipid disruption caused by the halted homeostasis of FA metabolism. [ABSTRACT FROM AUTHOR]

α-Synuclein (α-syn) can form oligomers, protofibrils, and fibrils, which are associated with the pathogenesis of Parkinson's disease and other synucleinopathies. Both the lipid peroxidation product 4-oxo-2-nonenal (ONE) and agitation can induce aggregation of α-syn and phosphorylated α-syn. Thus, clarification of the characteristics of different α-syn species could help to select suitable aggregates for diagnosis and elucidate the pathogenesis of diseases. Here, we characterized ONE-induced wild-type (WT) α-syn aggregates (OW), ONE-induced phosphorylated α-syn (p-α-syn) aggregates (OP), agitation-induced α-syn preformed fibrils (PFF), and agitation-induced p-α-syn preformed fibrils (pPFF). Thioflavin T (ThT) dying demonstrated that OW and OP had fewer fibrils than the PFF and pPFF. Transmission electron microscopy revealed that the lengths of PFF and pPFF were similar, but the diameters differed. OW and OP had more compact structures than PFF and pPFF. Aggregation of p-α-syn was significantly faster than WT α-syn. Furthermore, OW and OP were more sodium dodecyl sulfate-stable and proteinase K-resistant, suggesting greater stability and compactness, while aggregates of PFF and pPFF were more sensitive to proteinase K treatment. Both ONE- and agitation-induced aggregates were cytotoxic when added exogenously to SH-SY5Y cells with increasing incubation times, but the agitation-induced aggregates caused cell toxicity in a shorter time and more p-α-syn inclusions. Similarly, p-proteins were more cytotoxic than non-p-proteins. Finally, all four aggregates were used as standard antigens to establish sandwich enzyme-linked immunosorbent assay (ELISA). The results showed that the recognition efficiency of OW and OP was more sensitive than that of PFF and pPFF. The OW- and OP-specific ELISA for detection of p-α-syn and α-syn in plasma samples of Thy1-α-syn transgenic mice showed that the content of aggregates could reflect the extent of disease. ONE and agitation induced the formation of α-syn aggregates with distinct biophysical properties and biomedical applications. [ABSTRACT FROM AUTHOR]

In the last three decades, the presence of phospholipids in the nucleus has been shown and thoroughly investigated. A considerable amount of interest has been raised about nuclear inositol lipids, mainly because of their role in signaling acting. Here, we review the main issues of nuclear phospholipid localization and the role of nuclear inositol lipids and their related enzymes in cellular signaling, both in physiological and pathological conditions. [ABSTRACT FROM AUTHOR]

Vascular smooth muscle cells (VSMCs), in their contractile and differentiated state, are fundamental for maintaining vascular function. Upon exposure to cholesterol (CHO), VSMCs undergo dedifferentiation, adopting characteristics of foam cells—lipid-laden, macrophage-like cells pivotal in atherosclerotic plaque formation. CHO uptake by VSMCs leads to two primary pathways: ABCA1-mediated efflux or storage in lipid droplets as cholesterol esters (CEs). CE formation, involving the condensation of free CHO and fatty acids, is catalyzed by sterol O-acyltransferase 1 (SOAT1). The necessary fatty acids are synthesized by the lipogenic enzyme fatty acid synthase (FASN), which we found to be upregulated in atherosclerotic human coronary arteries. This observation led us to hypothesize that FASN-mediated fatty acid biosynthesis is crucial in the transformation of VSMCs into foam cells. Our study reveals that CHO treatment upregulates FASN in human aortic SMCs, concurrent with increased expression of CD68 and upregulation of KLF4, markers associated with the foam cell transition. Crucially, downregulation of FASN inhibits the CHO-induced upregulation of CD68 and KLF4 in VSMCs. Additionally, FASN-deficient VSMCs exhibit hindered lipid accumulation and an impaired transition to the foam cell phenotype following CHO exposure, while the addition of the fatty acid palmitate, the main FASN product, exacerbates this transition. FASN-deficient cells also show decreased SOAT1 expression and elevated ABCA1. Notably, similar effects are observed in KLF4-deficient cells. Our findings demonstrate that FASN plays an essential role in the CHO-induced upregulation of KLF4 and the VSMC to foam cell transition and suggest that targeting FASN could be a novel therapeutic strategy to regulate VSMC phenotypic modulation. [ABSTRACT FROM AUTHOR]

Different cellular mechanisms influence steatotic liver disease (SLD) progression. The influence of different levels of steatogenic inputs has not been studied in hepatocytes and hepatic stellate cells (HSCs). Methods: HepG2 hepatocytes and LX-2 HSCs were cultured in mild (MS) and severe (SS) steatogenic conditions. TGF-β stimulation was also tested for HSCs in control (T) and steatogenic conditions (MS-T and SS-T). Steatosis was stained with Oil Red, and the proliferation was assayed via WST-8 reduction, apoptosis via flow cytometry, and senescence via SA-β-galactosidase activity. Results: Regarding hepatocytes, steatosis progressively increased; proliferation was lower in MS and SS; and the viability of both conditions significantly decreased at 72 h. Apoptosis increased in MS at 72 h, while it decreased in SS. Senescence increased in MS and diminished in SS. Regarding HSCs, the SS and SS-T groups showed no proliferation, and the viability was reduced in MS at 72 h and in SS and SS-T. The LX-2 cells showed increased apoptosis in SS and SS-T at 24 h, and in MS and MS-T at 72 h. Senescence decreased in MS, SS, and SS-T. Conclusions: Lipid overload induces differential effects depending on the cell type, the steatogenic input level, and the exposure time. Hepatocytes are resilient to mild steatosis but susceptible to high lipotoxicity. HSCs are sensitive to lipid overload, undergoing apoptosis and lowering senescence and proliferation. Collectively, these data may help explain the development of steatosis and fibrosis in SLD. [ABSTRACT FROM AUTHOR]