The S1P1 regulator IMMH002 and its therapeutic effect and mechanism on autoimmune hepatitis / 药学学报

This study assessed and explored the pharmacological effects and mechanisms of action of IMMH002 {2-amino-2-(2-(4ʹ-(2-ethyloxazol-4-yl)-[1,1ʹ-biphenyl]-4-yl)ethyl)propane-1,3-dio}, a selective sphingosine-1-phosphate receptor subtype 1 (S1P1) modulator, in a concanavalin A (ConA)-induced autoimmune hepatitis (AIH) mouse model. The experimental protocol strictly adhered to the guidelines of the Ethics Committee for Animal Research of the Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College (Approval No.: 00004046). Male ICR mice were pre-treated with the drug for four days, followed by induction of AIH through tail vein injection of ConA protein. Liver function, hepatic tissue pathology, peripheral blood parameters, as well as immunoglobulin G (IgG), inflammatory cytokines, T cell distribution, and inflammatory pathways were evaluated in mice. Results demonstrated that IMMH002 significantly reduced liver function indicators such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST), alleviated hepatic tissue inflammation and necrotic damage, decreased serum IgG levels, and lowered the expression of inflammatory mediators including interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), and interferon γ (IFN-γ). Additionally, it facilitated T lymphocyte homing, downregulated the phosphorylation of nuclear factor kappa-B (NF-κB), IκB kinase β (IKKβ) and nuclear factor inhibitor protein-α (IκBα) proteins in hepatic tissue and cellular inflammation models. Collectively, IMMH002 effectively ameliorated ConA-induced autoimmune hepatitis in mice, exhibiting extensive anti-inflammatory and anti-necrotic effects, thereby laying a theoretical foundation for AIH clinical treatment.

Sphingosine-1-phosphate receptor subtype 1 activation in the central nervous system contributes to morphine withdrawal in rodents.

Opioid therapies for chronic pain are undermined by many adverse side effects that reduce their efficacy and lead to dependence, abuse, reduced quality of life, and even death. We have recently reported that sphingosine-1-phosphate (S1P) 1 receptor (S1PR1) antagonists block the development of morphine-induced hyperalgesia and analgesic tolerance. However, the impact of S1PR1 antagonists on other undesirable side effects of opioids, such as opioid-induced dependence, remains unknown. Here, we demonstrate that naloxone-precipitated morphine withdrawal in mice altered de novo sphingolipid metabolism in the dorsal horn of the spinal cord and increased S1P that accompanied the manifestation of several withdrawal behaviors. Blocking de novo sphingolipid metabolism with intrathecal administration of myriocin, an inhibitor of serine palmitoyltransferase, blocked naloxone-precipitated withdrawal. Noteworthy, we found that competitive (NIBR-15) and functional (FTY720) S1PR1 antagonists attenuated withdrawal behaviors in mice. Mechanistically, at the level of the spinal cord, naloxone-precipitated withdrawal was associated with increased glial activity and formation of the potent inflammatory/neuroexcitatory cytokine interleukin-1ß (IL-1ß); these events were attenuated by S1PR1 antagonists. These results provide the first molecular insight for the role of the S1P/S1PR1 axis during opioid withdrawal. Our data identify S1PR1 antagonists as potential therapeutics to mitigate opioid-induced dependence and support repurposing the S1PR1 functional antagonist FTY720, which is FDA-approved for multiple sclerosis, as an opioid adjunct.

Activation of Sphingosine-1-Phosphate Receptor 1 in the Spinal Cord Produces Mechanohypersensitivity Through the Activation of Inflammasome and IL-1ß Pathway.

Sphingosine-1-phosphate (S1P) receptor 1 subtype (S1PR1) activation by its ligand S1P in the dorsal horn of the spinal cord causes mechanohypersensitivity. The cellular and molecular pathways remain poorly understood. We report that the activation of S1PR1 with an intrathecal injection of the highly selective S1PR1 agonist SEW2871 led to the development of mechanoallodynia by activating the nod-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome (increased expression of NLRP3, cleaved caspase 1 and mature IL-1ß) in the dorsal horn of the spinal cord. The functional S1PR1 antagonist FTY720 blocked NLRP3 activation and IL-1ß production. Moreover, inhibiting IL-10 signaling with an intrathecal injection of an anti-IL-10 antibody attenuated the beneficial effects exerted by FTY720. This finding suggests that disrupting S1PR1 signaling engages beneficial IL-10-dependent pathways. Notably, we found that mice with astrocyte-specific deletions of S1pr1 did not develop mechanoallodynia after intrathecal injection of SEW2871 and exhibited decreased levels of cleaved caspase 1, identifying astrocytes as a key cellular locus for S1PR1 activity. Our findings provide novel mechanistic insights on how S1PR1 activation in the spinal cord contributes to the development of nociception while identifying the cellular substrate for these activities. PERSPECTIVE: This study is the first to link the activation of NLRP3 and IL-1ß signaling in the spinal cord and S1PR1 signaling in astrocytes to the development of S1PR1-evoked mechanoallodynia. These findings provide critical basic science insights to support the development of therapies targeted toward S1PR1.