st2825 and Inflammation

The inflammatory process implicates homeostasis disruption and increased production of inflammatory mediators. Myeloid differentiation primary response 88 (MyD88) is an essential protein recruited after lipopolysaccharide (LPS) and interleukin (IL)-1β stimulation, a process that converges in nuclear factor kappa B (NF-κB) activation, as well as a transcription of several genes of both pro- and anti-inflammatory cytokines. The inhibition of MyD88 has shown efficacy by decrease inflammatory response, and has demonstrated potential application as a therapeutic target in chronic diseases. In this study, we investigate the effect of MyD88 dimerisation inhibitor ST2825 on cytokine production from rhIL-1β and LPS-stimulated peripheral blood mononuclear cells (PBMC) from healthy blood donors (HBD). ST2825 significantly downregulates the production of IFN-γ, IL-6, IL-12, IL-2, IL-15, IL-7, VEGF, IL-1Ra, IL-4, IL-5, IL-13 and IL-9 (

Topics: Anti-Inflammatory Agents; Dose-Response Relationship, Drug; Down-Regulation; Heterocyclic Compounds, 2-Ring; Humans; Inflammation; Interleukin-1beta; Leukocytes, Mononuclear; Lipopolysaccharides; Myeloid Differentiation Factor 88; Protein Multimerization; Protein Structure, Quaternary; Spiro Compounds

The present study was designed to investigate the role of microRNA‑451 (miRNA‑451) on cerebral ischemia‑reperfusion and to explore its possible mechanism. The expression of miRNA‑451 was downregulated in rats with cerebral ischemia‑reperfusion. In an in vitro model of cerebral ischemia‑reperfusion, the downregulation of miRNA‑451 increased inflammation, demonstrated by increased levels of tumor necrosis factor α, interleukin (IL)‑1b, IL‑6 and IL‑18. However, the upregulation of miRNA‑451 expression decreased inflammation in the same in vitro model of cerebral ischemia‑reperfusion. In addition, it was found that the downregulation of miRNA‑451 induced the expression of Toll‑like receptor 4 (TLR4), myeloid differentiation primary response protein MyD88 (MyD88) and nuclear factor‑κB (NF‑κB)/p65. Moreover, the administration of a MyD88 inhibitor, ST 2825, reduced the expression of MyD88 and NF‑κB/p65 in the in vitro model of cerebral ischemia‑reperfusion, inhibiting the effects of miRNA‑451 upregulation on inflammation. A TLR4 inhibitor, TAK‑242, was used to reduce the expression of TLR4 in the in vitro model of cerebral ischemia‑reperfusion. TAK‑242 suppressed the effects of miRNA‑451 downregulation on inflammation. The present study suggested that miRNA‑451 regulated cerebral ischemia‑reperfusion‑induced inflammation, which is mediated through the TLR4/MyD88/NF‑κB signaling pathway.

Topics: Animals; Brain Injuries; Cytokines; Heterocyclic Compounds, 2-Ring; Inflammation; Male; Mice; MicroRNAs; Myeloid Differentiation Factor 88; Reperfusion Injury; Signal Transduction; Spiro Compounds; Sulfonamides; Toll-Like Receptor 4; Transcription Factor RelA

Accumulating of evidence suggests that activation of nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) exacerbates early brain injury (EBI) following subarachnoid hemorrhage (SAH) by provoking pro-inflammatory and pro-apoptotic signaling. Myeloid differentiation primary response protein 88 (MyD88) is an endogenous adaptor protein in the toll-like receptors (TLRs) and interleukin (IL) -1β family signaling pathways and acts as a bottle neck in the NF-κB and MAPK pathways. Here, we used ST2825, a selective inhibitor of MyD88, to clarify whether inhibiting MyD88 could provide neuroprotection in EBI following SAH. Our results showed that the expression of MyD88 was markedly increased at 24 h post SAH. Intracerebroventricular injection of ST2825 significantly reduced the expression of MyD88 at 24 h post SAH. Involvement of MAPKs and NF-κB signaling pathways was revealed that ST2825 inhibited SAH-induced phosphorylation of TAK1, p38 and JNK, the nuclear translocation of NF-κB p65, and degradation of IκBα. Further, ST2825 administration diminished the SAH-induced inflammatory response and apoptosis. As a result, SAH-induced EBI was alleviated and neurological deficits caused by SAH were reversed. Our findings suggest that MyD88 inhibition confers marked neuroprotection against EBI following SAH. Therefore, MyD88 might be a promising new molecular target for the treatment of SAH.

Topics: Animals; Apoptosis; Brain Injuries; Cell Nucleus; Down-Regulation; Heterocyclic Compounds, 2-Ring; Inflammation; Male; MAP Kinase Signaling System; Myeloid Differentiation Factor 88; Neurons; Neuroprotection; NF-KappaB Inhibitor alpha; Protein Transport; Proteolysis; Rats, Sprague-Dawley; Spiro Compounds; Subarachnoid Hemorrhage; Transcription Factor RelA

Recognition of evolutionarily conserved ligands by Toll-like receptors (TLRs) triggers signaling cascades in innate immune cells to amplify adaptive immune responses. Nearly all TLRs require MyD88 to transduce downstream signaling. MyD88 deficiency has been shown to promote the allograft acceptance in mice. However, direct evidence for therapeutic potential of MyD88 inhibitors remains lacking. Herein, we used a MyD88 inhibitor, namely ST2825, to explore its therapeutic potential and mechanisms in fully allogeneic skin and heart transplant models. Phenotypic maturation of dendritic cells stimulated by TLR ligands was alleviated by ST2825 in parallel with reduced T-cell proliferation in vitro. A short-course treatment with ST2825 significantly prolonged cardiac graft survival (mean survival time = 18.5 ± 0.92 days vs. 7.25 ± 0.46 days). ST2825-treated group had significantly reduced proinflammatory cytokines in allografts compared with control group. ST2825 combined with anti-CD154 induced long-term skin allograft acceptance in about one-third of recipients (>100 days). 'Skin-tolerant' recipients showed attenuated donor-specific IFN-γ responses, intact IL-4 responses, and compromised alloantibody responses. We conclude that MyD88 inhibitor ST2825 attenuates acute cardiac rejection and promotes donor-specific hyporesponsiveness in stringent skin transplant models. The direct evidence suggests that pharmacological inhibition of MyD88 hold promising potential for transplant rejection.

Topics: Animals; CD40 Ligand; CpG Islands; Dendritic Cells; Female; Graft Rejection; Graft Survival; Heart Transplantation; Heterocyclic Compounds, 2-Ring; Inflammation; Isoantibodies; Lymphocytes; Male; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Myeloid Differentiation Factor 88; Skin; Skin Transplantation; Spiro Compounds; Tissue Donors; Transplantation Tolerance; Transplantation, Homologous

MyD88 is an adaptor protein, which plays an essential role in the intracellular signaling elicited by IL-1R and several TLRs. Central to its function is the ability of its Toll/IL-1R translation initiation region (TIR) domain to heterodimerize with the receptor and to homodimerize with another MyD88 molecule to favor the recruitment of downstream signaling molecules such as the serine/threonine kinases IL-1R-associated kinase 1 (IRAK1) and IRAK4. Herein, we have synthesized and tested the activity of a synthetic peptido-mimetic compound (ST2825) modeled after the structure of a heptapeptide in the BB-loop of the MyD88-TIR domain, which interferes with MyD88 signaling. ST2825 inhibited MyD88 dimerization in coimmunoprecipitation experiments. This effect was specific for homodimerization of the TIR domains and did not affect homodimerization of the death domains. Moreover, ST2825 interfered with recruitment of IRAK1 and IRAK4 by MyD88, causing inhibition of IL-1beta-mediated activation of NF-kappaB transcriptional activity. After oral administration, ST2825 dose-dependently inhibited IL-1beta-induced production of IL-6 in treated mice. Finally, we observed that ST2825 suppressed B cell proliferation and differentiation into plasma cells in response to CpG-induced activation of TLR9, a receptor that requires MyD88 for intracellular signaling. Our results indicate that ST2825 blocks IL-1R/TLR signaling by interfering with MyD88 homodimerization and suggest that it may have therapeutic potential in treatment of chronic inflammatory diseases.

Topics: Adjuvants, Immunologic; Administration, Oral; Animals; Biomimetic Materials; Cell Differentiation; Cell Proliferation; Chronic Disease; Dimerization; Female; HeLa Cells; Heterocyclic Compounds, 2-Ring; Humans; Inflammation; Interleukin-1 Receptor-Associated Kinases; Interleukin-1beta; Interleukin-6; Mice; Myeloid Differentiation Factor 88; NF-kappa B; Oligodeoxyribonucleotides; Oligopeptides; Plasma Cells; Protein Structure, Tertiary; Receptors, Interleukin-1; Spiro Compounds; Toll-Like Receptor 9; Transcription, Genetic