Cilostazol pretreatment prevents PTSD-related anxiety behavior through reduction of hippocampal neuroinflammation

Current pharmacological treatments against post-traumatic stress disorder (PTSD) lack adequate efficacy. As a result, intense research has focused on identifying other molecular pathways mediating the pathogenesis of this condition. One such pathway is neuroinflammation, which has demonstrated a role in PTSD pathogenesis by causing synaptic dysfunction, neuronal death, and functional impairment in the hippocampus. Phosphodiesterase (PDE) inhibitors (PDEIs) have emerged as promising therapeutic agents against neuroinflammation in other neurological conditions. Furthermore, PDEIs have shown some promise in animal models of PTSD. However, the current model of PTSD pathogenesis, which is based on dysregulated fear learning, implies that PDE inhibition in neurons should enhance the acquisition of fear memory from the traumatic event. As a result, we hypothesized that PDEIs may improve PTSD symptoms through inhibiting neuroinflammation rather than long-term potentiation-related mechanisms. To this end, we tested the therapeutic efficacy of cilostazol, a selective inhibitor of PDE3, on PTSD-related anxiety symptoms in the underwater trauma model of PTSD. PDE3 is expressed much more richly in microglia and astrocytes compared to neurons in the murine brain. Furthermore, we used hippocampal indolamine 2,3-dioxygenase 1 (IDO) expression and interleukin 1 beta (IL-1β) concentration as indicators of neuroinflammation. We observed that cilostazol pretreatment prevented the development of anxiety symptoms and the increase in hippocampal IDO and IL-1β following PTSD induction. As a result, PDE3 inhibition ameliorated the neuroinflammatory processes involved in the development of PTSD symptoms. Therefore, cilostazol and other PDEIs may be promising candidates for further investigation as pharmacological therapies against PTSD.

Recombinant Human Bone Morphogenetic Protein-2 Priming of Mesenchymal Stem Cells Ameliorate Acute Lung Injury by Inducing Regulatory T Cells

Mesenchymal stromal/stem cells (MSCs) possess immunoregulatory properties and their regulatory functions represent a potential therapy for acute lung injury (ALI). However, uncertainties remain with respect to defining MSCs-derived immunomodulatory pathways. Therefore, this study aimed to investigate the mechanism underlying the enhanced effect of human recombinant bone morphogenic protein-2 (rhBMP-2) primed ES-MSCs (MSCBMP2) in promoting Tregs in ALI mice. MSC were preconditioned with 100 ng/ml rhBMP-2 for 24 h, and then administrated to mice by intravenous injection after intratracheal injection of 1 mg/kg LPS. Treating MSCs with rhBMP-2 significantly increased cellular proliferation and migration, and cytokines array reveled that cytokines release by MSCBMP2 were associated with migration and growth. MSCBMP2 ameliorated LPS induced lung injury and reduced myeloperoxidase activity and permeability in mice exposed to LPS. Levels of inducible nitric oxide synthase were decreased while levels of total glutathione and superoxide dismutase activity were further increased via inhibition of phosphorylated STAT1 in ALI mice treated with MSCBMP2. MSCBMP2 treatment increased the protein level of IDO1, indicating an increase in Treg cells, and Foxp3+CD25+ Treg of CD4+ cells were further increased in ALI mice treated with MSCBMP2. In co-culture assays with MSCs and RAW264.7 cells, the protein level of IDO1 was further induced in MSCBMP2. Additionally, cytokine release of IL-10 was enhanced while both IL-6 and TNF-α were further inhibited. In conclusion, these findings suggest that MSCBMP2 has therapeutic potential to reduce massive inflammation of respiratory diseases by promoting Treg cells.