CXC chemokine receptor 1 enhances the ability of human umbilical cord blood-derived mesenchymal stem cells to migrate toward gliomas

LPS induces IL-8 expression through TLR4, MyD88, NF-kappaB and MAPK pathways in human dental pulp stem cells

AIM

To evaluate the effects of lipopolysaccharide (LPS) on interleukin-8 (IL-8) and related intracellular signalling pathways in human dental pulp stem cells (hDPSCs).

METHODOLOGY

Human pulp tissues were isolated from human impacted third molars, and the hDPSCs were cultured and characterized. The effects of LPS on IL-8 and Toll-like receptor 4 (TLR4) gene expression in hDPSCs were investigated using real-time quantitative RT-PCR and ELISA. Whether TLR4/MyD88/NF-кB was involved in the LPS-induced up-regulation of IL-8 in hDPSCs was determined using transient transfection, luciferase assay and ELISA. The involvement of MAPKs in the LPS-induced up-regulation of IL-8 in hDPSCs was investigated via transient transfection, luciferase assay, ELISA and western blot. The data were statistically analysed using Student's t-test or one-way anova followed by the Student-Neumann-Keuls test.

RESULTS

Cells exposed to LPS not only displayed an enhanced expression of TLR4 but also showed an elevated IL-8 gene expression; exposure to LPS also resulted in the induction of IL-8 gene transcription via promoter activation. The LPS-induced IL-8 promoter activation was inhibited through dominant-negative mutations in TLR4 and MyD88, but not in TLR2. The LPS-induced IL-8 protein release was attenuated through the administration of TLR4-neutralizing antibody or MyD88 inhibitory peptide and a dominant-negative mutation in IκBα. In contrast, IL-8 protein release was enhanced through the expression of NF-κB p65. Treatment with PDTC, TPCK or Bay117082 effectively antagonized LPS-induced IL-8 protein release. Moreover, both the promoter activity and the LPS-induced release of IL-8 were diminished upon the administration of U0126 and SB203580, but not SP600125. Moreover, the exposure to LPS activated ERK1/2 and p38 MAPK phosphorylation in cells.

CONCLUSIONS

This study reports the LPS-mediated transcriptional and post-translational up-regulation of IL-8, which is a process that also involves TLR4, MyD88, NF-κB and MAPK.

Mesenchymal stem cells: a potential targeted-delivery vehicle for anti-cancer drug, loaded nanoparticles

The targeted delivery of anticancer agents is a promising field in anticancer therapy. Mesenchymal stem cells (MSCs) have inherent tumor-tropic and migratory properties, which allow them to serve as vehicles for targeted drug delivery systems for isolated tumors and metastatic diseases. MSCs have been successfully studied and discussed as a vehicle for cancer gene therapy. However, MSCs have not yet been discussed adequately as a potential vehicle for traditional anticancer drugs. In this review, we will examine the potential of MSCs as a targeted-delivery vehicle for anticancer drug-loaded nanoparticles (NPs), summarize various challenges, and discuss possible solutions for these challenges.

FROM THE CLINICAL EDITOR

In this review, the feasibility of mesenchymal stem cell-based targeted delivery of anticancer agents is discussed.

Why dapsone stops seizures and may stop neutrophils' delivery of VEGF to glioblastoma

Lopez-Gomez et al. recently published remarkable but mechanistically unexplained empirical evidence that the old antibiotic dapsone has antiepileptic activity. We addressed the question "Why should a sulfone antibiotic reduce seizures?". We report here our conclusions based on data from past studies that seizures are associated with elevated interleukin-8 (IL-8) and that dapsone inhibits IL-8 release and function in several different clinical and experimental contexts. Diverse CNS insults cause an increase in CNS IL-8. Thus, the pro-inflammatory environment generated by increase IL-8 leads to a lower seizure threshold. Together this evidence indicates dapsone exerts anti-seizure activity by diminishing IL-8 signalling. Since IL-8 is clearly upregulated in glioblastoma and contributes to the florid angiogenesis of that disease, and since interference with IL-8 function has been shown to inhibit glioblastoma invasion and growth in several experimental models, and dapsone has been repeatedly been shown to clinically inhibit IL-8 function when used to treat human neutrophilic dermatoses, we believe that dapsone thereby reduces seizures by countering IL-8 function and may similarly retard glioblastoma growth by such anti-IL-8 function.

Soluble intracellular adhesion molecule-1 secreted by human umbilical cord blood-derived mesenchymal stem cell reduces amyloid-β plaques

Presently, co-culture of human umbilical cord blood mesenchymal stem cells (hUCB-MSCs) with BV2 microglia under amyloid-β42 (Aβ42) exposure induced a reduction of Aβ42 in the medium as well as an overexpression of the Aβ-degrading enzyme neprilysin (NEP) in microglia. Cytokine array examinations of co-cultured media revealed elevated release of soluble intracellular adhesion molecule-1 (sICAM-1) from hUCB-MSCs. Administration of human recombinant ICAM-1 in BV2 cells and wild-type mice brains induced NEP expression in time- and dose-dependent manners. In co-culturing with BV2 cells under Aβ42 exposure, knockdown of ICAM-1 expression on hUCB-MSCs by small interfering RNA (siRNA) abolished the induction of NEP in BV2 cells as well as reduction of added Aβ42 in the co-cultured media. By contrast, siRNA-mediated inhibition of the sICAM-1 receptor, lymphocyte function-associated antigen-1 (LFA-1), on BV2 cells reduced NEP expression by ICAM-1 exposure. When hUCB-MSCs were transplanted into the hippocampus of a 10-month-old transgenic mouse model of Alzheimer's disease for 10, 20, or 40 days, NEP expression was increased in the mice brains. Moreover, Aβ42 plaques in the hippocampus and other regions were decreased by active migration of hUCB-MSCs toward Aβ deposits. These data suggest that hUCB-MSC-derived sICAM-1 decreases Aβ plaques by inducing NEP expression in microglia through the sICAM-1/LFA-1 signaling pathway.