UHPLC–MS/MS analysis of sphingosine 1‐phosphate in joint cavity dialysate and hemodialysis solution of adjuvant arthritis rats: Application to geniposide pharmacodynamic study

Determination of endogenous sphingolipid content in stroke rats and HT22 cells subjected to oxygen-glucose deprivation by LC‒MS/MS

BACKGROUND

Stroke is the leading cause of death in humans worldwide, and its incidence increases every year. It is well documented that lipids are closely related to stroke. Analyzing the changes in lipid content in the stroke model after absolute quantification and investigating whether changes in lipid content can predict stroke severity provides a basis for the combination of clinical stroke and quantitative lipid indicators.

METHODS

This paper establishes a rapid, sensitive, and reliable LC‒MS/MS analytical method for the detection of endogenous sphingolipids in rat serum and brain tissue and HT22 cells and quantifies the changes in sphingolipid content in the serum and brain tissue of rats from the normal and pMCAO groups and in cells from the normal and OGD/R groups. Using sphingosine (d17:1) as the internal standard, a chloroform: methanol (9:1) mixed system was used for protein precipitation and lipid extraction, followed by analysis by reversed-phase liquid chromatography coupled to triple quadrupole mass spectrometry.

RESULTS

Based on absolute quantitative analysis of lipids in multiple biological samples, our results show that compared with those in the normal group, the contents of sphinganine (d16:0), sphinganine (d18:0), and phytosphingosine were significantly increased in the model group, except sphingosine-1-phosphate, which was decreased in various biological samples. The levels of each sphingolipid component in serum fluctuate with time.

CONCLUSION

This isotope-free and derivatization-free LC‒MS/MS method can achieve absolute quantification of sphingolipids in biological samples, which may also help identify lipid biomarkers of cerebral ischemia.

Inhibition of sphingosine 1-phosphate (S1P) receptor 1/2/3 ameliorates biological dysfunction in rheumatoid arthritis fibroblast-like synoviocyte MH7A cells through Gαi/Gαs rebalancing

Sphingosine 1-phosphate (S1P) exerts its various physiological and pathological effects by interacting with G protein-coupled receptors. In addition, S1P can induce biological dysfunction in fibroblast-like synoviocytes (FLSs) in the development of rheumatoid arthritis (RA). However, the mechanism underlying this S1P-induced dysfunction remains unclear. An imbalance between Gαi and Gαs can affect the level of cAMP, an important regulator of numerous cell functions. Therefore, we studied the effects of S1P receptor (S1PR) 1-, 2-, and 3-associated Gαi/Gαs imbalance on the biological function of rheumatoid arthritis fibroblast-like synoviocyte (MH7A cells). The results showed that blocking S1PR1/3 and Gαi, and activating Gαs, inhibited the proliferation, migration, invasion, and proinflammatory cytokine release of MH7A cells in a S1P-induced inflammation model, whereas suppressing S1PR2 only affected the invasion and the release of proinflammatory cytokines of these cells. Analysis of the expression of S1PR1/2/3 and Gαi/Gαs further showed that S1PR1/2/3 could regulate the Gαi/Gαs balance. Furthermore, our data suggested that the level of cAMP was also affected. Combined, our results showed that impaired S1PR1/2/3 signalling can affect MH7A cells biological function via Gαi/Gαs-cAMP signalling, which can provide a new idea for the treatment of RA.

The interplay between fibroblast-like synovial and vascular endothelial cells leads to angiogenesis via the sphingosine-1-phosphate-induced RhoA-F-Actin and Ras-Erk1/2 pathways and the intervention of geniposide

The changes of fibroblast-like synoviocytes (FLSs) and vascular endothelial cells (VECs) biological functions are closely related to angiogenesis in rheumatoid arthritis (RA). Nevertheless, how the crosstalk between FLSs and VECs interferes with RA is far from being clarified. Herein, we studied the effect of the reciprocal interactions between FLSs and VECs on angiogenesis and mechanism of geniposide (GE). After administration of GE, improvement of synovial hyperplasia in adjuvant arthritis rats was accompanied by downregulation of SphK1 and p-Erk1/2. The dynamic interaction between FLSs and VECs triggers the release of S1P by activating p-Erk1/2 and SphK1, then activating RhoA-F-actin and Ras-Erk1/2 pathways. When exposed to the inflammatory microenvironment mediated by FLSs-VECs crosstalk, proliferation, migration, and permeability of VECs were enhanced, the angiogenic factors were imbalanced. Meanwhile, the proliferation and secretory ability of FLSs increased. Interestingly, depletion of S1P or blocking of the activation of SphK1 by GE and PF-543 prevented the changes. In conclusion, S1P released during FLSs-VECs crosstalk changed their biological functions by activating RhoA-F-actin and Ras-Erk1/2 pathways. GE acted on p-Erk1/2 and SphK1, inhibited the secretion of S1P, and blocked the interplay between FLSs and VECs. These results provide new insights into the mechanism of angiogenesis in RA.

Properties and molecular mechanisms underlying geniposide-mediated therapeutic effects in chronic inflammatory diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Geniposide (GE) is ubiquitous in nearly 40 species of plants, among which Gardenia jasminoides J. Ellis has the highest content, and has been used ethnopharmacologically to treat chronic inflammatory diseases. As a traditional Chinese medicine, Gardenia jasminoides J. Ellis has a long history of usage in detumescence and sedation, liver protection and cholestasis, hypotension and hemostasis. It is commonly used in the treatment of diabetes, hypertension, jaundice hepatitis, sprain and contusion. As a type of iridoid glycosides extracted from Gardenia jasminoides J. Ellis, GE has many pharmacological effects, such as anti-inflammatory, anti-angiogenesic, anti-oxidative, etc. AIM OF THE REVIEW: In this article, we reviewed the sources, traditional usage, pharmacokinetics, toxicity and therapeutic effect of GE on chronic inflammatory diseases, and discussed its potential regulatory mechanisms and clinical application.

RESULTS

GE is a common iridoid glycoside in medicinal plants, which has strong activity in the treatment of chronic inflammatory diseases. A large number of in vivo and in vitro experiments confirmed that GE has certain therapeutic value for a variety of chronic inflammation disease. Its mechanism of function is mainly based on its anti-inflammatory, anti-oxidant, neuroprotective properties, as well as regulation of apoptotsis. GE plays a role in the treatment of chronic inflammatory diseases by regulating cell proliferation and apoptosis, realizing the dynamic balance of pro/anti-inflammatory factors, improving the state of oxidative stress, and restoring abnormally expressed inflammation-related pathways.

CONCLUSION

According to its extensive pharmacological effects, GE is a promising drug for the treatment of chronic inflammatory diseases.

Anti-Inflammatory Effect of Geniposide on Regulating the Functions of Rheumatoid Arthritis Synovial Fibroblasts via Inhibiting Sphingosine-1-Phosphate Receptors1/3 Coupling Gαi/Gαs Conversion

The activated Gα protein subunit (Gαs) and the inhibitory Gα protein subunit (Gαi) are involved in the signal transduction of G protein coupled receptors (GPCRs). Moreover, the conversion of Gαi/Gαs can couple with sphingosine-1-phosphate receptors (S1PRs) and have a critical role in rheumatoid arthritis (RA). Through binding to S1PRs, sphingosine-1-phosphate (S1P) leads to activation of the pro-inflammatory signaling in rheumatoid arthritis synovial fibroblasts (RASFs). Geniposide (GE) can alleviate RASFs dysfunctions to against RA. However, its underlying mechanism of action in RA has not been elucidated so far. This study aimed to investigate whether GE could regulate the biological functions of MH7A cells by inhibiting S1PR1/3 coupling Gαi/Gαs conversion. We use RASFs cell line, namely MH7A cells, which were obtained from the patient with RA and considered to be the main effector cells in RA. The cells were stimulated with S1P (5 μmol/L) and then were treated with or without different inhibitors: Gαi inhibitor pertussis toxin (0.1 μg/mL), S1PR1/3 inhibitor VPC 23019 (5 μmol/L), Gαs activator cholera toxin (1 μg/mL) and GE (25, 50, and 100 μmol/L) for 24 h. The results showed that GE may inhibit the abnormal proliferation, migration and invasion by inhibiting the S1P-S1PR1/3 signaling pathway and activating Gαs or inhibiting Gαi protein in MH7A cells. Additionally, GE could inhibit the release of inflammatory factors and suppress the expression of cAMP, which is the key factor of the conversion of Gαi and Gαs. GE could also restore the dynamic balance of Gαi and Gαs by suppressing S1PR1/3 and inhibiting Gαi/Gαs conversion, in a manner, we demonstrated that GE inhibited the activation of Gα downstream ERK protein as well. Taken together, our results indicated that down-regulation of S1PR1/3-Gαi/Gαs conversion may play a critical role in the effects of GE on RA and GE could be an effective therapeutic agent for RA.

Development and validation of a QTrap method for sensitive quantification of sphingosine 1-phosphate

Sphingosine 1-phosphate (S1P) is a bioactive phospholipid and ligand for five G protein-coupled cell-surface receptors designated S1PR1-5. The determination of low levels of S1P remains a challenge and usually requires sophisticated analytical instrumentation and methodology. This report describes a technique using the linear ion trap mode of a basic QTrap triple-quadrupole mass spectrometer. S1P was extracted from acidified biological samples using a modified Folch extraction procedure. After the addition of C17-sphingosine as an internal standard, a step gradient LC method was used to separate the analytes on a reversed-phase C18 MultoHigh analytical column. After the internal standard C17-sphingosine was detected by multiple reaction monitoring (MRM), the detection mode was switched to enhanced product ion (EPI) mode for the detection of S1P. The mode was switched back to MRM again for the detection of other analytes. Using this QTrap method, we reached a limit of detection of 1 nM and a limit of quantification of 3 nM for S1P, which was up to 30 times more sensitive than the MRM mode with the same instrument. Intra-day precision ranged between -3.8 and 6.3%, and inter-day precision was between -13.8 and 3.3%, depending on the spiked S1P concentration.