TLR2/NFκB signalling regulates endogenous IL-6 release from marrow-derived mesenchymal stromal cells to suppress the apoptosis of PC12 cells injured by oxygen and glucose deprivation

Abstract

Two previous studies published by our group identified that mesenchymal stromal cells (MSCs) conferred neuroprotection in a rat model of hypoxic-ischaemic brain damage (HIBD), and that MSCs secreted abundant interleukin-6 (IL‑6) when co‑cultured with oxygen and glucose deprivation (OGD)‑injured PC12 cells. The present study has further investigated the role of IL‑6, and explored potential signalling pathways in vitro. In vitro models were established by co‑culturing OGD‑injured PC12 cells with MSCs. Subsequently, the expression levels of the signalling molecules, Toll‑like receptor 2 (TLR2)/nuclear factor κB (NFκB), and IL‑6 were altered separately in this in vitro model by treatment with an agonist, antagonist, siRNA or overexpression adenovirus. The expression levels of B cell lymphoma‑associated X (Bax), TLR2, NFκB and IL‑6 were detected by western blot analysis, real‑time polymerase chain reaction or ELISA. The resting membrane potential (RMP) of the PC12 cells was analysed by whole‑cell patch‑clamp recordings. Compared with controls or the PC12 co‑culture group, the MSC co‑cultured group induced less expression of Bax, but more IL‑6 secretion. Up- or down-regulation of the TLR2/NFκB signalling pathway resulted in a corresponding increase or decrease in the IL‑6 expression level in the MSCs. Co‑culture with siIL‑6‑MSCs increased the expression levels of Bax and increased the RMP in the OGD PC12 cells. In conclusion, the release of IL‑6 from MSCs was regulated via the TLR2/NFκB signalling pathway. Endogenous IL‑6 reduced apoptosis and protected OGD‑injured PC12 cells when they were co‑cultured with MSCs. The present study has reported a novel immunomodulatory effect of the microenvironment of neural damage during MSC cytotherapy.

Isolation and characterization of canine placenta‐derived mesenchymal stromal cells for the treatment of neurological disorders in dogs

“…The observed secretory profile of cPMSCs in combination with existing MSC literature suggests the potential for use as a therapeutic; cPMSCs secreted IL‐6, IL‐8, MCP‐1, and VEGF, all paracrine factors secreted by human PMSC lines in our previous studies . IL‐6 is an immunomodulatory cytokine with demonstrated in vitro and in vivo neuroprotective capabilities . IL‐8 is another cytokine with immunomodulatory properties that also promotes angiogenesis .…”

Efficacy of administered mesenchymal stem cells in the initiation and co‐ordination of repair processes by resident disc cells in an ovine (Ovis aries) large destabilizing lesion model of experimental disc degeneration

“…A recent positron emission tomography (PET) imaging study showed that MSCs remained viable for 3 weeks when injected into canine IVDs in an annular lesion model of disc degeneration yet beneficial effects with regards to matrix repair and alleviation of LBP were measurable for up to 6 months post operatively (PO). Further modes of action for MSCs in the healing process have therefore been proposed based on the ability of MSCs to enhance resident cell viability and/or proliferation, reduce cell apoptosis, and, in some cases, modulate immune responses . These are due to paracrine effects due to secreted growth factors, cytokines, and hormones from the MSCs and cell‐cell interactions mediated through communicating nanotubes, which convey extracellular vesicles containing reparative peptides/proteins, mRNA, and microRNAs .…”

Current Status on Canine Foetal Fluid and Adnexa Derived Mesenchymal Stem Cells

“…As previously reported for human placenta derived MSCs [ 95 ], Long et al [ 53 ] and Amorim et al [ 54 ], using a cytokine array demonstrated that unstimulated and stimulated DPCs secrete a number of paracrine factors. VEGF and MCP-1 are implicated in both neuroprotection and angiogenesis [ 56 , 57 ], IL-6 is an immunomodulatory cytokine with in vitro and in vivo demonstrated neuroprotective capabilities [ 58 ], and IL-8 is an immunomodulatory cytokine that promotes angiogenesis [ 59 ].…”