Sphk1/S1P/S1PR1 Signaling is Involved in the Development of Autoimmune Thyroiditis in Patients and NOD.H-2h4 Mice

Research progress in the construction of animal models of autoimmune thyroiditis

Autoimmune thyroiditis (AIT), also known as Hashimoto's thyroiditis (HT), is an autoimmune disease that is characterised by elevated thyroid-specific antibody titres. The incidence of AIT is increasing year over year, making it urgent to establish a suitable animal model for this condition, in order to better explore its pathogenesis and potential pharmaceutical mechanisms for treatment. Owing to a lack of basic research on this disease, problems such as disparate modelling methods with unclear and varying success rates make it difficult for researchers to obtain effective information on AIT in the short term. This report summarises and analyzes the current literature on AIT and combines actual operability to explain the selection and specific implementation processes behind the uses of different modelling approaches, to provide a better overall understanding of autoimmune thyroid diseases.

Targeting the SPHK1/S1P/S1PR2 axis ameliorates GH-secreted pituitary adenoma progression

BACKGROUND

Growth hormone-secreted pituitary adenoma (GHPA) is a prominent subtype of pituitary adenoma (PA) associated with progressive somatic disfigurement, various complications, and elevated mortality rates. Existing treatment options have limited efficacy, highlighting the urgent need for novel pharmacological interventions. Previous studies have revealed that sphingosine kinase 1 (SphK1)/sphingosine-1-phosphate (S1P)/S1P receptors (S1PRs) signalling have critical roles in the tumour microenvironment, but their role in GHPA remains unclear.

METHODS

We performed integrative analyses including bioinformatics analyses, functional studies, and clinical validation to investigate the pathological roles of SPHK1/S1P and evaluated the effectiveness of the S1P receptor 2 (S1PR2) inhibitor JTE-013 in GHPA treatment.

RESULTS

SPHK1/S1P signalling is abnormally expressed in patients with GHPA. Knockdown of SPHK1 suppresses S1P-mediated cell proliferation in GH3 Cells. Mechanistically, S1P inhibits apoptosis and autophagy while promoting the secretion of Growth Hormone (GH) by binding to the S1P receptor subtype 2 (S1PR2) in GH3 cells. Moreover, the function of S1PR2 in GH3 cells is mediated by the downstream Akt-Creb pathway. We then identify the S1PR2 as a novel target for therapeutic intervention in GHPA. Systemic administration of the potent and selective S1PR2 antagonist, JTE-013, significantly reduces both tumour size and GH secretion. Importantly, we identify preoperative serum S1P levels as a biomarker predicting poor prognosis in GHPA patients at follow-up.

CONCLUSION

Our study shows that blocking SPHK1/S1P/S1PR2 axis can ameliorate the progression of GHPA, providing evidence of a promising therapeutic target for GHPA.

The Influence of Autoimmune Thyroid Diseases on Viral Pneumonia Development, Including COVID-19: A Two-Sample Mendelian Randomization Study

The association between thyroid function and viral pneumonia has undergone extensive examination, yet the presence of a causal link remains uncertain. The objective of this paper was to employ Two-Sample Mendelian Randomization (MR) analysis to investigate the connections between three thyroid diseases and thyroid hormone indicators with viral pneumonia and COVID-19. We obtained summary statistics datasets from seven genome-wide association studies (GWASs). The primary method used for estimating relationships was inverse-variance weighting (IVW). In addition, we employed weighted median, weighted mode, MR-Egger, and MR-PRESSO as supplementary analytical tools. Sensitivity analyses encompassed Cochran's Q test, MR-Egger intercept test, and MR-PRESSO. Our study revealed significant causal relationships between having a genetic predisposition to autoimmune thyroid disease (AITD) and an increased susceptibility to viral pneumonia (odds ratio [OR]: 1.096; 95% confidence interval [CI]: 1.022-1.176). Moreover, it demonstrated a heightened susceptibility and severity of COVID-19 (OR for COVID-19 susceptibility, COVID-19 hospitalization, and COVID-19 critical illness, with 95% CIs of 1.016, 1.001-1.032; 1.058, 1.003-1.116; 1.045, 1.010-1.081). However, no statistically significant associations were found between TSH, FT4, subclinical hypo- or hyperthyroidism, and the risk of viral pneumonia incidence, or the susceptibility and severity of COVID-19 (all p > 0.05). This study establishes a cause-and-effect relationship between AITD and the development of viral pneumonia, as well as the susceptibility and severity of COVID-19.

CircPTPN22 modulates T-cell activation by sponging miR-4689 to regulate S1PR1 expression in patients with systemic lupus erythematosus

BACKGROUND

Circular RNAs are involved in autoimmune disease pathogenesis. Our previous study indicated that circPTPN22 is involved in autoimmune diseases, such as systemic lupus erythematosus (SLE) and rheumatoid arthritis, but the underlying mechanisms remain unclear.

METHODS

First, the expression of circPTPN22 was detected by real-time PCR and western blotting. After overexpression or knockdown of circPTPN22, the proliferation of Jurkat cells was detected by the CCK-8 assay, and the apoptosis of Jurkat cells was detected by flow cytometry. In addition, the relationship between circPTPN22-miR-4689-S1PR1 was confirmed by bioinformatic analyses, fluorescence in situ hybridization assays, RNA-binding protein immunoprecipitation, and dual luciferase reporter assays.

RESULTS

We found that circPTPN22 expression was downregulated in the PBMCs of SLE patients compared to those of healthy controls. Overexpression of circPTPN22 increased proliferation and inhibited apoptosis of Jurkat T cells, whereas knockdown of circPTPN22 exerted the opposite effects. CircPTPN22 acts as a miR-4689 sponge, and S1PR1 is a direct target of miR-4689. Importantly, the circPTPN22/miR-4689/S1PR1 axis inhibited the secretion of TNF-α and IL-6 in Jurkat T cells.

CONCLUSIONS

CircPTPN22 acts as a miR-4689 sponge to regulate T-cell activation by targeting S1PR1, providing a novel mechanism for the pathogenesis of SLE.

COVID-19-induced autoimmune thyroiditis: Exploring molecular mechanisms

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) damages multiple organs, including the thyroid, by direct invasion and cell entry via angiotensin-converting enzyme 2 or indirectly by promoting excessive inflammation in the body. The immune system is a critical factor in antiviral immunity and disease progression. In the context of SARS-CoV-2 infection, the immune system may become overly activated, resulting in a shift from regulatory to effector responses, which may subsequently promote the development and progression of autoimmune diseases. The incidence of autoimmune thyroid diseases, such as subacute thyroiditis, Graves' disease, and Hashimoto's thyroiditis, increases in individuals with COVID-19 infection. This phenomenon may be attributed to aberrant responses of T-cell subtypes, the presence of autoantibodies, impaired regulatory cell function, and excessive production of inflammatory cytokines, namely interleukin (IL)-6, IL-1β, interferon-γ, and tumor necrosis factor-α. Therefore, insights into the immune responses involved in the development of autoimmune thyroid disease according to COVID-19 can help identify potential therapeutic approaches and guide the development of effective interventions to alleviate patients' symptoms.

Dialogue between VE-Cadherin and Sphingosine 1 Phosphate Receptor1 (S1PR1) for Protecting Endothelial Functions

The endothelial cells (EC) of established blood vessels in adults remain extraordinarily quiescent in the sense that they are not actively proliferating, but they fulfill the necessary role to control the permeability of their monolayer that lines the interior of blood vessels. The cell-cell junctions between ECs in the endothelium comprise tight junctions and adherens homotypic junctions, which are ubiquitous along the vascular tree. Adherens junctions are adhesive intercellular contacts that are crucial for the organization of the EC monolayer and its maintenance and regulation of normal microvascular function. The molecular components and underlying signaling pathways that control the association of adherens junctions have been described in the last few years. In contrast, the role that dysfunction of these adherens junctions has in contributing to human vascular disease remains an important open issue. Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid mediator found at high concentrations in blood which has important roles in the control of the vascular permeability, cell recruitment, and clotting that follow inflammatory processes. This role of S1P is achieved through a signaling pathway mediated through a family of G protein-coupled receptors designated as S1PR1. This review highlights novel evidence for a direct linkage between S1PR1 signaling and the mediation of EC cohesive properties that are controlled by VE-cadherin.

Cellular and molecular basis of thyroid autoimmunity

Autoimmune thyroid disease (AITD) is the most common human autoimmune disease. The two major clinical manifestations of AITD are Graves' disease and Hashimoto's thyroiditis (HT). AITD is characterized by lymphocytic infiltration of the thyroid gland, leading either to follicular cell damage, thyroid gland destruction, and development of hypothyroidism (in HT) or thyroid hyperplasia, induced by thyroid antibodies which activate thyrotropin receptor (TSHR) on thyrocytes, leading to hyperthyroidism. The aim of this review is to present up-to-date picture of the molecular and cellular mechanisms that underlie the pathology of AITD. Based on studies involving patients, animal AITD models, and thyroid cell lines, we discuss the key events leading to the loss of immune tolerance to thyroid autoantigens as well as the signaling cascades leading to the destruction of thyroid gland. Special focus is given on the interplay between the environmental and genetic factors, as well as ncRNAs and microbiome contributing to AITD development. In particular, we describe mechanistic models by which SNPs in genes involved in immune regulation and thyroid function, such as CD40, TSHR, FLT3, and PTPN22, underlie AITD predisposition. The clinical significance of novel diagnostic and prognostic biomarkers based on ncRNAs and microbiome composition is also underscored. Finally, we discuss the possible significance of probiotic supplementation on thyroid function in AITD.

Geniposide downregulates the VEGF/SphK1/S1P pathway and alleviates angiogenesis in rheumatoid arthritis in vivo and in vitro

The VEGF/SphK1/S1P pathway is closely related to angiogenesis in rheumatoid arthritis (RA), but the precise underlying mechanisms are unclear at present. Here, we explored the involvement of the VEGF/SphK1/S1P cascade in RA models and determined the effects of GE intervention. Our results showed abnormal expression of proteins related to this pathway in RA synovial tissue. Treatment with GE effectively regulated the signal axis, inhibited angiogenesis, and alleviated RA symptoms. In vitro, TNF-ɑ enhanced the VEGF/SphK1/S1P pathway in a co-culture model of fibroblast-like synoviocytes (FLS) and vascular endothelial cells (VEC). GE induced downregulation of VEGF in FLS, restored the dynamic balance of pro-/antiangiogenic factors, and suppressed SphK1/S1P signaling in VEC, resulting in lower proliferation activity, migration ability, tube formation ability, and S1P secretion ability of VEC cells. Additionally, SphK1-specific small interfering RNA (siRNA) blocked the VEGF/SphK1/S1P cascade, which can effectively alleviate the stimulatory effect of FLS on VEC and further enhanced the therapeutic effect of GE. Taken together, our results demonstrate that GE suppresses the VEGF/SphK1/S1P pathway and alleviates the stimulation of VEC by FLS, thereby preventing angiogenesis and promoting therapeutic effects against RA.

Comprehensive Metabolomics Study in Children With Graves' Disease

OBJECTIVE

Graves' disease (GD) related hyperthyroidism (HT) has profound effects on metabolic activity and metabolism of macromolecules affecting energy homeostasis. In this study, we aimed to get a comprehensive understanding of the metabolic changes and their clinical relevance in GD children.

METHODS

We investigated serum substances from 30 newly diagnosed GD children and 30 age- and gender-matched healthy controls. We explored the metabolomics using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF/MS) analysis, and then analyzed the metabolomic data via multivariate statistical analysis.

RESULTS

By untargeted metabolomic analysis, a total of 730 metabolites were identified in all participants, among which 48 differential metabolites between GD and control groups were filtered out, including amino acids, dipeptides, lipids, purines, etc. Among these metabolites, 33 were detected with higher levels, while 15 with lower levels in GD group compared to controls. Pathway analysis showed that HT had a significant impact on aminoacyl-transfer ribonucleic acid (tRNA) biosynthesis, several amino acids metabolism, purine metabolism, and pyrimidine metabolism.

CONCLUSION

In this study, via untargeted metabolomics analysis, significant variations of serum metabolomic patterns were detected in GD children.

Sphingosine-1-phosphate signal transducer and activator of transcription 3 signaling pathway contributes to baicalein-mediated inhibition of dextran sulfate sodium-induced experimental colitis in mice

Background:

Baicalein has been shown to have anti-inflammatory and anti-tumor activities. However, the mechanisms underlying its anti-inflammatory effect on colitis remain unclear.

Methods:

A dextran sodium sulfate (DSS)-induced model of acute colitis was established in BALB/c mice (6–8 weeks old, weighing 18–22 g). Six groups of mice received: (1) water for 10 days (control), n = 6; (2) DSS 4% solution in the drinking water for 7 days, followed by normal water for 3 days, n = 7; (3), (4), and (5) as for group 2 plus baicalein (10, 20, 40 mg/kg) administered once daily starting on day 1, n = 6; and (6) as for (2) plus 5-aminosalicylic acid (50 mg/kg) administered once daily starting on day 1, n = 6. Body weights, stool consistency, and hematochezia were recorded, and the severity of colitis was evaluated using a disease activity index. On day 11, the mice were euthanized, and organs and blood were collected for analysis. Serum inflammatory factors were detected by enzyme-linked immunosorbent assay; CD11b-positive cells were analyzed by immunofluorescence microscopy; expression of retinoic-acid-receptor-related orphan nuclear receptor gamma, sphingosine kinase 1 (SPHK1), and phosphorylated signal transducer and activator of transcription 3 (p-STAT3) was detected by immunohistochemistry; and expression of nucleotide-binding oligomerization domain 2 (NOD2), SPHK1, sphingosine 1-phosphate receptor 1 (S1PR1), total STAT3, and p-STAT3 were detected by western blotting analysis. Inter-group differences were compared using Student's t test.

Results:

Baicalein treatment dose-dependently reduced DSS-induced weight loss (P < 0.01 or P < 0.05), splenomegaly (P < 0.01), and colonic damage, as reflected by amelioration of diarrhea, rectal bleeding, and colonic ulceration, congestion, edema (shown as colon length, P < 0.05 or P < 0.01), and inflammatory cell infiltration. Baicalein also significantly decreased the levels of inflammatory mediators in the serum (P < 0.01) and colon, and significantly inhibited expression of NOD2 SPHK1, S1PR1, and p-STAT3 in the colon (P < 0.05).

Conclusions:

Baicalein treatment ameliorated colitis in mice by inhibiting S1P-STAT3 signaling, suggesting that this flavonoid might be beneficial in the treatment of colitis.

The S1P-S1PR Axis in Neurological Disorders-Insights into Current and Future Therapeutic Perspectives

Sphingosine 1-phosphate (S1P), derived from membrane sphingolipids, is a pleiotropic bioactive lipid mediator capable of evoking complex immune phenomena. Studies have highlighted its importance regarding intracellular signaling cascades as well as membrane-bound S1P receptor (S1PR) engagement in various clinical conditions. In neurological disorders, the S1P–S1PR axis is acknowledged in neurodegenerative, neuroinflammatory, and cerebrovascular disorders. Modulators of S1P signaling have enabled an immense insight into fundamental pathological pathways, which were pivotal in identifying and improving the treatment of human diseases. However, its intricate molecular signaling pathways initiated upon receptor ligation are still poorly elucidated. In this review, the authors highlight the current evidence for S1P signaling in neurodegenerative and neuroinflammatory disorders as well as stroke and present an array of drugs targeting the S1P signaling pathway, which are being tested in clinical trials. Further insights on how the S1P–S1PR axis orchestrates disease initiation, progression, and recovery may hold a remarkable potential regarding therapeutic options in these neurological disorders.

Potential sphingosine-1-phosphate-related therapeutic targets in the treatment of cerebral ischemia reperfusion injury

Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid that regulates lymphocyte trafficking, glial cell activation, vasoconstriction, endothelial barrier function, and neuronal death pathways in the brain. Research has increasingly implicated S1P in the pathology of cerebral ischemia reperfusion (IR) injury. As a high-affinity agonist of S1P receptor, fingolimod exhibits excellent neuroprotective effects against ischemic challenge both in vivo and in vitro. By summarizing recent progress on how S1P participates in the development of brain IR injury, this review identifies potential therapeutic targets for the treatment of brain IR injury.

Hashimoto Thyroiditis and Dyslipidemia in Childhood: A Review

Hashimoto autoimmune thyroiditis (AIT) is the most common cause of acquired hypothyroidism in the pediatric population. Development of AIT is mediated mainly by cellular immune response directed toward thyroid autoantigens, leading to inflammation and impaired function of thyroid gland. Both thyroid dysfunction and inflammation affect the metabolism of plasma lipoproteins. The alterations in lipid profile worsen with the advancement of hypothyroidism, ranging from discrete changes in euthyroid AIT patients, to atherogenic dyslipidemia in the overt hypothyroidism. In this review, characteristics of dyslipidemia in pediatric AIT patients, and the consequences in respect to the risk for cardiovascular disease (CVD) development are discussed. Additionally, benefit of L-thyroxine treatment on serum lipid profile in pediatric AIT patients is addressed. Finally, potential usefulness of novel lipid biomarkers, such as proprotein convertase subtilisin/kexin type 9 (PCSK9), non-cholesterol sterols, low-density lipoprotein particle size and number, and high-density lipoprotein structure and functionality in AIT patients is also covered. Further longitudinal studies are needed in order to elucidate the long-term cardiovascular outcomes of dyslipidemia in pediatric patients with Hashimoto AIT.