Proinflammatory intervertebral disc cell and organ culture models induced by tumor necrosis factor alpha

Abstract

Inflammation plays an important role in the pathogenesis of intervertebral disc (IVD) degeneration. The proinflammatory cytokine tumor necrosis factor alpha (TNF-α) has shown markedly higher expression in degenerated human disc tissue compared with healthy controls. Anti-inflammatory treatment targeting TNF-α has shown to alleviate discogenic pain in patients with low back pain. Therefore, in vitro and ex vivo inflammatory models utilizing TNF-α provide relevant experimental conditions for drug development in disc degeneration research. The current method article addressed several specific questions related to the model establishment. (a) The effects of bovine and human recombinant TNF-α on bovine nucleus pulposus (NP) cells were compared. (b) The required dose for an inflammatory IVD organ culture model with intradiscal TNF-α injection was studied. (c) The effect of TNF-α blocking at different stages of inflammation was evaluated. Outcomes revealed that bovine and human recombinant TNF-α induced equivalent inflammatory effects in bovine NP cells. A bovine whole IVD inflammatory model was established by intradiscal injection of 100 ng TNF-α/ cm 3 disc volume, as indicated by increased nitric oxide, glycosaminoglycan, interleukin 6 (IL-6), and interleukin 8 (IL-8) release in culture media, and upregulation of MMP3, ADAMTS4, IL-8, IL-6, and cyclooxygenase (COX)-2 expression in NP tissue. However, results in human NP cells showed that the time point of anti-inflammatory treatment was crucial to achieve significant effects. Furthermore, anticatabolic therapy in conjunction with TNF-α inhibition would be required to slow down the pathologic cascade of disc degeneration.

Investigating the physiological relevance of ex vivo disc organ culture nutrient microenvironments using in silico modeling and experimental validation

“…Additionally, it could be developed further to model the impact of delivering cells into a degenerated disc model, as well as identifying an optimal cell number to sustain viability without adversely affecting the local nutrient microenvironment. Despite promising characterization of the metabolite microenvironment of a relatively straightforward ex vivo disc organ culture system, more work is needed to experimentally characterize the effect of introducing pro‐inflammatory cytokines on the nutrient microenvironment and cellular metabolism 23,45 . A recent agent‐based model has shown promising advancement in in silico modeling by developing an inflammation and mRNA expression sub‐model to capture cellular behavior in a more multifactorial, biochemical environment 99 .…”

“…Gantenbein et al (2015) has compiled a comprehensive overview of disc organ culture bioreactor‐platforms highlighting the different methods being used to establish degeneration or injury models 21 . More recent advances have been made to recapitulate the pro‐inflammatory and catabolic niche associated with human degeneration through intradiscal injection or culture media supplementation of pro‐inflammatory cytokines 23,45 . However, despite the promising development and increased complexity of disc organ culture, standardization of in vitro and in vivo protocols is a hot topic across the research field.…”

Angiotensin II Type 1 Receptor Antagonist Losartan Inhibits TNF-α Induced Inflammation and Degeneration Processes in Human Nucleus Pulposus Cells

“…These strategies try to reduce the inflammatory microenvironment of the IVD in order to slow down the progressive degenerative cascade [12][13][14][15].…”

Activation of nuclear factor-kappa B by TNF promotes nucleus pulposus mineralization through inhibition of ANKH and ENPP1

“…There is a tremendous amount of development left to complete, but if the current method of delivering NP cells overexpressing TNAP/TNF were to be applied clinically now, there would appear to be a clear risk for inducing rapid IDD and discogenic pain, not to mention local escape of induced bone from the IVD receiving treatment, that could lead to spinal stenosis or other entrapment pathologies. TNF induces several genes contributing to IDD as already mentioned, and it has also been shown to increase expression of nerve growth factor (NGF) 74 , 75 and IL-6 76 . NGF is a neurotrophin that supports nerve growth and substance p expression in vitro 77 , 78 , and may contribute to painful sensory nerves penetrating and growing into the disc.…”