Search Results (704)

Huntington’s Disease (HD) is characterized by prominent degeneration of the principal neurons of the striatum and by progressive motor and cognitive deterioration. Striatal neurons degenerate in HD due to multiple cell-autonomous and non-autonomous factors. Impaired neurotrophin signaling by brain-derived neurotrophic factor (BDNF) and its cognate receptor Tropomyosin receptor kinase B (TrkB) is an important mechanism underlying neuronal loss in HD. Fingolimod, a clinically approved oral drug for Multiple Sclerosis, was originally developed based on its anti-inflammatory properties. Recent work suggests that fingolimod can also promote BDNF expression and enhance neurotrophic support in the brain. We hypothesized that fingolimod treatment initiated during the presymptomatic phase would increase striatal BDNF levels and protect against motor dysfunction in HD. In wild-type mice, fingolimod treatment increases striatal BDNF levels and enhances BDNF-TrkB signaling. However, chronic fingolimod therapy (0.1 mg/kg, i.p., twice per week, over 7 weeks) initiated at age 4 weeks in the R6/2 mouse model of HD failed to improve behavioral locomotor deficits and exacerbated limb clasping. Furthermore, fingolimod treatment in these presymptomatic R6/2 mice acutely decreased BDNF-TrkB signaling in the striatum in a dose-dependent manner. In contrast, acute administration of fingolimod in symptomatic 7-week-old R6/2 mice increased striatal BDNF-TrkB signaling in a dose-dependent manner, consistent with previous work suggesting that chronic fingolimod can improve motor behavior when given during the symptomatic phase. Thus, the effects of fingolimod striatal BDNF-TrkB signaling and motor behavior in HD are complex and vary with disease stage. Addressing this variability is critical for the design of neuroprotective drug trials in HD, including those utilizing sphingosine-1-phosphate receptor (S1P) modulators. Full article

Sphingosine-1-phosphate receptors (S1PRs) are a family of G protein-coupled transmembrane proteins that play essential roles across nearly all organ systems, including the regulation of pulmonary physiology and immune responses. Expressed across diverse lung cell types, S1PRs mediate critical biological processes such as vascular barrier integrity, immune cell trafficking, and inflammation. While the signaling pathways and physiological functions of S1PR1 and S1PR3 have been extensively characterized, the role of S1PR2 remains less clearly defined and context-dependent. In this review, we summarize current knowledge on S1PR2 signaling within major pulmonary cell populations and explore its contribution to lung homeostasis and disease. By synthesizing evidence from molecular, cellular and in vivo studies, this review aims to summarize the current understanding of S1PR2 signaling across major pulmonary cell populations and its roles in lung homeostasis and disease. The findings of this study could help develop new strategies for treating pulmonary disorders and other diseases by targeting S1PR2. Full article

Calcium (Ca²⁺) is a signal messenger for ion flow in and out of microbial, parasitic, and host defense cells. Manipulation of calcium ion signaling with ion blockers and calcineurin inhibitors may improve host defense while decreasing microbial/parasitic resistance to therapy. Ca²⁺ release from intracellular storage sites controls many host defense functions (cell integrity, movement, and growth). The transformation of phospholipids in the erythrocyte membrane is associated with changes in deformability. This type of lipid bilayer defense mechanism helps to prevent attack by Plasmodium. Patients with sickle cell disease (SS hemoglobin) do not have this protection and are extremely vulnerable to massive hemolysis from parasitic infestation. Patients with thalassemia major also lack parasite protection. Alteration of Ca²⁺ ion channels responsive to environmental stimuli (transient receptor potential) results in erythrocyte protection from Plasmodium. Similarly, calcineurin inhibitors (cyclosporine) reduce heart and brain inflammation injury with Trypanosoma and Taenia. Ca²⁺ channel blockers interfere with malarial life cycles. Several species of parasites are known to invade hepatocytes: Plasmodium, Echinococcus, Schistosoma, Taenia, and Toxoplasma. Ligand-specific membrane channel constituents (inositol triphosphate and sphingosine phospholipid) constitute membrane surface signal messengers. Plasmodium requires Ca²⁺ for energy to grow and to occupy red blood cells. A cascade of signals proceeds from Ca²⁺ to two proteins: calmodulin and calcineurin. Inhibitors of calmodulin were found to blunt the population growth of Plasmodium. An inhibitor of calcineurin (cyclosporine) was found to retard population growth of both Plasmodium and Schistosoma. Calcineurin also controls sensitivity and resistance to antibiotics. After exposure to cyclosporine, the liver directs Ca²⁺ ions into storage sites in the endoplasmic reticulum and mitochondria. Storage of large amounts of Ca²⁺ would be useful if pathogens began to occupy both red blood cells and liver cells. We present scientific evidence supporting the benefits of calcium channel blockers and calcineurin inhibitors to potentiate current antiparasitic therapies. Full article

Sphingolipids are essential for cellular structure and signaling, and recent evidence implicates them in chronic inflammation. We hypothesized that altered sphingolipid metabolism contributes to the disease activity of systemic lupus erythematosus (SLE). Serum sphingolipids were quantified by liquid chromatography–tandem mass spectrometry in 38 female SLE patients (11 with lupus nephritis [LN], 27 without LN) and 30 age-matched healthy controls (HCs). Serum ceramide (Cer)16/sphingosine-1-phosphate (S1P) ratios were elevated in SLE compared to HCs (0.33 [0.26–0.38] vs. 0.25 [0.21–0.3], p = 0.019). Notably, Cer16/S1P levels were significantly higher in the LN group (0.33 [0.26–0.38]) than in non-LN SLE (0.27 [0.2–0.34], p = 0.027). ROC analysis showed good diagnostic potential for LN (AUC = 0.739). Cer16/S1P correlated positively with disease activity markers, including erythrocyte sedimentation rate (r = 0.519, p = 0.001), SLE Disease Activity Index 2000 (SLEDAI-2k) score (r = 0.547, p < 0.001), anti-double stranded DNA antibody levels (r = 0.359, p = 0.027), and the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (r = 0.327, p = 0.045). The serum Cer16/S1P ratio may serve as a surrogate marker of disease activity in patients with LN. Full article

Background: Multiple sclerosis (MS), a debilitating chronic disease of the central nervous system, is characterized by both inflammatory and neurodegenerative processes that lead to demyelination and neuronal damage. While MS remains incurable, therapies like fingolimod can slow disease progression by modulating immune function. Fingolimod acts as a sphingosine-1-phosphate receptor modulator, limiting lymphocyte migration into the central nervous system and thereby reducing inflammation. Methods: In this study, we developed a computational model to describe fingolimod’s impact on immune dynamics in MS, focusing on CD8⁺ T-cell migration blockade. Model calibration utilized cohort data, enabling the comparison of simulated outcomes with observed clinical metrics. Results: The results indicate that our model effectively captures the timing and extent of CD8⁺ T-cell sequestration, consistent with key features in the patient data. Conclusions: These findings suggest that computational modeling can provide quantitative insight into the fingolimod’s mechanism of action and assist in predicting treatment response, offering a promising framework for exploring personalized fingolimod dosing strategies and enhancing therapeutic planning in MS. Full article

Type 2 diabetes (T2D) is associated with normal or higher bone mineral density (BMD), but there is a higher fracture rate. Hypoglycaemia does not affect BMD but may cause fractures directly through falls and may affect bone cellular metabolism. We examined circulating bone marker proteins (BMPs) in response to induced hypoglycaemia in T2D versus controls. A prospective exploratory parallel study design was conducted in T2D patients (n = 23) and healthy controls (n = 23) who underwent blood SOMAscan proteomic analysis of bone biomarkers at baseline, hypoglycaemia, and post-hypoglycaemia time points. Unadjusted repeated measures linear mixed modeling was used for analysis. Linear mixed modeling of the proteins showed that the way most BMPs changed over time did not differ between groups. At baseline, Dickkopf-related protein 1 (DKK1), cathepsin A, cathepsin S, and cathepsin Z were increased in T2D versus controls (p < 0.05), whilst fibroblast growth factor 23 (FGF23) was lower in T2D versus controls (p ≤ 0.05). Following hypoglycemia, transient changes from baseline occurred in DKK1, cathepsin A, cathepsin G, cathepsin H, cathepsin S, cathepsin Z, parathyroid hormone (PTH), Sphingosine kinase 1 and 2 (SPK1/2), and interleukin-1 beta (IL1 beta) over the post-hypoglycaemia time course. There was decreased cathepsin S in T2D from baseline to 24 h compared to the control group, and increased cathepsin Z at 24 h for both groups overall compared to baseline (p < 0.05). Baseline-raised cathepsins (A, S, Z) in T2D may enhance osteoclastic resorption, whilst raised DKK1 could inhibit osteoblast differentiation and suppress bone formation. Hypothetically, this may lead to a decline in bone quality through a resorption-enhanced, low bone formation imbalance. The effects of hypoglycaemia on bone physiology appear to extend significantly beyond the initial insult, as seen for cathepsin S and Z, which differed at 24 h compared to baseline. Full article

Stroke is the leading cause of death and long-term disability worldwide, with ischemic stroke accounting for nearly 87% of all cases. Vascular occlusion, a key pathological event in ischemic stroke, has been reliably reproduced in preclinical studies using permanent ischemic stroke models. This study demonstrated the neuroprotective effect of NXC736, a functional antagonist of sphingosine-1-phosphate receptor 4 (S1P₄, currently in phase II clinical trials for alopecia areata), against acute injury in mice with permanent middle cerebral artery occlusion (pMCAO). pMCAO-challenged mice received oral NXC736 1 h after occlusion. NXC736 demonstrated substantial therapeutic activity against permanent ischemic stroke by attenuating pMCAO-induced acute brain infarction, neurological deficits, and apoptosis. Additionally, NXC736 reduced blood–brain barrier disruption and edema in the injured brain. Moreover, NXC736 reduced microglial activation and proliferation, oxidative stress, and suppressed pro-inflammatory cytokine expression, suggesting that the efficacy of NXC736 in permanent ischemic stroke is associated with the suppression of neuroinflammatory responses. Mechanistically, we found that NXC736-mediated neuroprotective effects were dependent on the inactivation of NF-κB and MAPKs, including ERK1/2, JNK, and p38. Collectively, our findings indicate that NXC736 is an effective neuroprotective drug for permanent ischemic brain stroke, highlighting S1P₄ as a promising therapeutic target for ischemic stroke. Full article

Sphingolipids are a large group of molecules, crucial components of all mammalian cells, that are particularly abundant in the central and peripheral nervous system and associated with important human brain functions. Sphingolipids are necessary for membrane organization and driving functions. Ceramide, sphingosine-1-phosphate and GM1, show bioactive properties. Ceramide and sphingosine-1-phosphate play a crucial role in the regulation of physio-pathological conditions. Small changes in their levels, in the ratio sphingosine-1-phosphate/ceramide as well as in chain length profiles of sphingolipids contribute to alter signaling pathways in neurons and glia, contributing to various neurological disorders. GM1 is considered a neurotrophic and neuroprotective compound and seems to be necessary for the correct functioning of neuronal membrane receptors, suggesting that a reduction in its level in the brain can be involved in neurodegenerative diseases. In this review, we give an overview of sphingolipid metabolism, summarizing the role of ceramide, sphingosine-1-phosphate, and GM1 in maintaining human health. Full article

Background: Pseudomonas aeruginosa infection is a major driver of morbidity and mortality in cystic fibrosis (CF), yet disease severity varies widely among people with CF (pwCF). This clinical heterogeneity suggests the involvement of host genetic modifiers beyond CFTR. We previously identified sphingosine 1-phosphate receptor 1 (S1PR1) as a candidate gene associated with susceptibility to P. aeruginosa. Here, we investigated its role in modulating airway epithelial responses to infection. Methods: Using CRISPR/Cas9, we generated S1PR1-knockout bronchial epithelial cells with (IB3-1) and without (C38) CFTR mutations. We assessed cell viability, cytotoxicity, and interleukin-8 secretion following exposure to P. aeruginosa exoproducts. S1PR1 protein expression was evaluated in lung tissue from pwCF and non-CF individuals using immunohistochemistry. Results: S1PR1-mutant cells produced truncated, non-functional peptides. In CFTR-mutant cells, S1PR1 loss reduced viability, increased cytotoxicity, and significantly enhanced interleukin-8 production in response to P. aeruginosa exoproducts. These effects were not observed in CFTR-competent cells. Notably, S1PR1 protein levels were markedly lower in lung tissue from pwCF compared to non-CF individuals. Conclusions: S1PR1 deficiency exacerbates epithelial damage and inflammatory responses to P. aeruginosa in CF models. These findings highlight S1PR1 as a potential contributor to infection severity and a promising target for therapeutic strategies in pwCF. Full article

Hashimoto’s thyroiditis (HT) is the most common autoimmune thyroid disorder, characterized by progressive lymphocytic infiltration, follicular destruction, tissue fibrosis, and an elevated risk of thyroid carcinoma. While the precise mechanisms underlying HT remain incompletely defined, emerging evidence implicates dysregulated sphingolipid (SPL) metabolism, particularly the sphingosine-1-phosphate (S1P) signaling axis, as a central contributor to disease pathogenesis. S1P, a bioactive lipid mediator, integrates metabolic and immunological cues to regulate immune cell trafficking, cytokine production, apoptosis, and fibroblast activation. Aberrant activation of the sphingosine kinase (SPHK)/sphingosine-1-phosphate (S1P)/S1P receptor (S1PR) pathway has been linked to persistent T helper 1 (Th1) cell recruitment, signal transducer and activator of transcription 3 (STAT3)-mediated immune polarization, epithelial–mesenchymal transition, extracellular matrix remodeling, and the establishment of a chronic inflammatory and fibrotic microenvironment. Moreover, S1P signaling may foster a pro-tumorigenic niche, providing a mechanistic explanation for the strong epidemiological association between HT and papillary thyroid carcinoma. This review summarizes current insights into the role of SPL metabolism in HT, highlighting its potential as a mechanistic link between autoimmunity, fibrosis, and carcinogenesis. Full article

The pathogenesis of Inflammatory Bowel Disease is complex and not completely understood, resulting from multifactorial interactions between genetic predisposition, environmental triggers, and dysregulation of both innate and adaptive immune responses. Cytokines, produced by dysregulated immune cells, trigger chronic intestinal inflammation leading to tissue damage, carcinogenesis, and disease perpetuation. Current advanced therapies—including tumor necrosis factor (TNF)-α antagonists, adhesion and trafficking inhibitors (such as anti-integrin agents and sphingosine-1-phosphate receptor modulators), interleukin inhibitors, and Janus kinase inhibitors—have improved patient outcomes, but targeting a single inflammatory pathway is often insufficient for long-term disease control. To further improve therapeutic efficacy, novel approaches are under investigation, including advanced combination therapies that simultaneously inhibit multiple pro-inflammatory pathways and microbiome-based treatments to restore intestinal homeostasis. In this evolving therapeutic scenario, precision medicine and advanced combination therapies appear promising for breaking through the current therapeutic ceiling. This review highlights current knowledge on the role of cytokines in IBD pathogenesis and explores how their modulation can modify and control disease course. Full article

Inflammatory bowel disease commonly requires advanced therapies to induce and maintain durable remission. Sphingosine-1-phosphate receptor modulators are the latest class of orally administered small molecules that have been added to the therapeutic armamentarium for inflammatory bowel disease. These molecules reduce inflammation by sequestering lymphocytes in lymph nodes, thereby reducing immune cell trafficking to the gut. Etrasimod and ozanimod are both licensed for moderate-to-severe ulcerative colitis and have both shown superiority over placebo, with emerging data for their use in Crohn’s disease. By modulating immune cell distribution, without reducing overall immune function, they offer a highly favourable safety profile. This narrative review explores the pharmacology, safety and efficacy of sphingosine-1-phosphate receptor modulators based on clinical trials and real-world evidence and offers practical guidance on their initiation and monitoring. Full article

Ascoviruses (AVs) are obligate intracellular pathogens that target the larval and pupal stages of lepidopteran insects, specifically moth caterpillars. AVs are unique among viruses in their (i) transmission mode, (ii) gross pathology, (iii) virion ultrastructure, (iv) genomic architecture featuring a remarkable combination of genes, and (v) ability to reprogram host cell death and lipid biosynthetic pathways to generate virion-containing vesicles (VCVs). The metabolically active acellular VCVs are repurposed to complete virogenesis and to facilitate dissemination by endoparasitoid wasps. Since their discovery in the late 20th century, research has focused on these distinctive traits and, to a lesser extent, their potential for biological control. Among AV proteins are the large DNA-binding P64 family, inhibitor of apoptosis-like proteins (IAPs), executioner caspase and caspase-like proteins, and lipid-modifying enzymes, which together drive their novel cytopathology. This review synthesizes current knowledge of AV biology and proposes a framework for understanding VCV formation by integrating predicted viral protein functions with host cellular pathways, including the ceramide–sphingosine-1-phosphate rheostat and apoptosis. Full article

Hormonal alterations associated with polycystic ovary syndrome (PCOS) also impact bone metabolism, though it is unclear if this is bone-protective or not. Bone marker dysfunction has been reported in PCOS and appears to be associated with obesity. This study sought to determine whether a panel of bone marker proteins (BMPs) would be dysregulated in PCOS stratified by BMI as a potential biomarker for bone in PCOS. In this exploratory cross-sectional study, plasma was collected from 234 women (137 with PCOS and 97 controls) from a biobank cohort and compared to a nonobese, non-insulin resistant population (24 with PCOS and 24 controls). Slow Off-rate Modified Aptamer (SOMA)-scan plasma protein measurement was undertaken for the following BMPs: sclerostin; Dickkopf-related protein-1; glycogen synthase kinase-3 alpha/beta; periostin; tumor necrosis factor ligand superfamily member 11; fibroblast growth factor 23; sphingosine kinase 1; sphingosine kinase 2; cathepsins A, B, D, E, G, L2, S and Z; parathyroid hormone; osteocalcin; tumor necrosis factor ligand superfamily member 11 (sRANKL) and interleukin-1 beta. Four BMPs differed in the PCOS cohort (whole set without matching for body mass index (BMI) or insulin resistance (IR)): periostin (p = 0.05), cathepsin L (p = 0.05) and osteocalcin (p = 0.02) decreased in PCOS, whilst cathepsin D (p = 0.02) increased; however, linear regression showed that only cathepsins D and L and osteocalcin differed. None of the BMPs differed in the nonobese women with and without PCOS, nor in obese PCOS and controls stratified by BMI greater than 30 kg/m². In subgroup analysis, periostin (p = 0.001), sphingosine kinase 2 (p = 0.01) and cathepsin L (p = 0.001) were higher in obese versus nonobese PCOS (p = 0.01). Cathepsin Z (p = 0.02), sphingosine kinase 2 (p = 0.04) and lysosomal protective protein (p = 0.05) were lower in obese versus nonobese controls. Changes in BMPs indicative of impaired bone physiology were associated with BMI in both controls and PCOS, but did not differ between women with and without PCOS when BMI was matched. Hyperandrogenemia in PCOS did not affect BMP levels. Full article

Background: Type 2 diabetes mellitus (T2DM) is a rapidly expanding worldwide health issue associated with impairments in memory and executive functions. The bioactive sphingolipid sphingosine-1-phosphate (S1P) regulates cell death/survival and the inflammatory response by acting on S1P receptors (S1PRs). Unfortunately, the role of S1PRs signaling in the T2DM brain remains elusive. Methods: The effect of fingolimod (FTY720, S1PRs modulator) on the behavior and expression profile of genes encoding S1PRs, sphingosine kinases (SPHK1 and 2), glucose transporters, proteins engaged in insulin signaling, sirtuin 1 (SIRT1), and proinflammatory cytokines in the brain cortex and hippocampus of diabetic mice was examined. Results: We observed a significant reduction in S1pr1, Sirt1, and insulin-like growth factor-1 (Igf1) gene expression that was accompanied by elevation of Sphk2, S1pr3, Il6, and Tnf in T2DM mice. Moreover, animals showed anxiety-like behavior and memory deficits. Fingolimod administration recovered downregulated S1pr1, Sirt1, and Igf1 expression and upregulated Slc2a4 (GLUT-4) and Ide (insulin-degrading enzyme). Furthermore, FTY720 reduced the elevated expression of Il6 and Tnf. Fingolimod also exerted an anxiolytic effect in T2DM. Conclusions: Results indicate an important role of S1PR modulation in T2DM. Moreover, fingolimod affected mRNA levels of proteins engaged in glucose metabolism/insulin signaling and improved the behavior of diabetic mice. Full article