Probes for TGF-β

Abstract

BACKGROUND:

Low back pain is one of the most common ailments in western countries afflicting more than 80% of the population and the main cause is considered to be degeneration of intervertebral discs (IVDs). IL-1β is a vital inflammatory cytokine found in abundance in degenerated disc environment whereas BMP-3 is believed to promote chondrogenesis through TGF-β pathway.

AIM:

The aim was to study the effects of BMP-3, IL-1β and combination (pre-treatment with IL-1β) on hMSCs encapsulated in PuraMatrix™ hydrogel (Phg) especially in the absence of TGF-β in order to investigate the proliferation, and differentiation ability of hMSCs over 28 days period.

METHOD:

100µL of hMSCs cell suspension was encapsulated between two layers of 100 µL hydrogels forming a sandwich-like structure. The encapsulated hMSCs were cultured in two sets of media, chondrogenic (C) and non-chondrogenic (nC) media along with addition of BMP-3 (10ng/mL) and IL-1β (10ng/mL). To study the combined effects of BMP-3 and IL-1β, the encapsulated hMSCs were first pre-treated with relevant media containing IL-1β for 24 hours, and then the media was replaced by media containing BMP-3 for the remaining experimental time period. IL-1β pre-treatment was carried out in both C and nC media. The samples were collected at day 7, 14, and 28.

RESULTS:

Proliferation and differentiation of hMSCs into chondrocyte-like cells was observed in all samples. Proteoglycans accumulation was observed in pre-treatment samples in C media. The protein and gene expression of Sox-9 and COL2A1 respectively, showed the occurrence of chondrogenesis in all samples.

CONCLUSION:

High cell viability, proliferation and differentiation was achieved in this in vitro model confirming that BMP-3 alone in the absence of TGF-β could drive hMSCs into chondrogenic lineage. Pre-treatment with IL-1β followed by BMP-3 stimulation resulted in high proteoglycans accumulation compared to stimulation with growth factors or cytokine alone. This suggests that pre-treatment with a pro-inflammatory cytokine before driving them into a chondrogeneic lineage might be of importance also in vivo.

Abstract

RATIONALE:

Given the paucity of effective treatments for Idiopathic Pulmonary Fibrosis (IPF), new insights into the deleterious mechanisms controlling lung fibroblast activation, the key cell type driving the fibrogenic process, are essential to develop new therapeutic strategies. Transforming growth factor β (TGF-β) is the main pro-fibrotic factor, but its inhibition is associated with severe side effects due to its pleiotropic role.

OBJECTIVES:

We hypothesized that downstream non-coding effectors of TGF-β in fibroblasts may represent new effective therapeutic targets whose modulation may be well-tolerated.

METHODS:

We investigated the whole non-coding fraction of TGF-β-stimulated lung fibroblast transcriptome to identify new genomic determinants of lung fibroblast differentiation into myofibroblast. Differential expression of the long non-coding RNA DNM3OS and its associated miRNAs was validated in a murine model of pulmonary fibrosis and in IPF tissue samples. Distinct and complementary antisense oligonucleotide-based strategies aiming at interfering with DNM3OS were used to elucidate the role of DNM3OS and its associated miRNAs in IPF pathogenesis.

MEASUREMENTS AND MAIN RESULTS:

We identified DNM3OS as a fibroblast-specific critical downstream effector of TGF-β-induced lung myofibroblast activation. Mechanistically, DNM3OS regulates this process in trans by giving rise to three distinct profibrotic mature miRNAs (i.e. miR-199a-5p/3p and miR-214-3p), which influence both SMAD and non-SMAD components of TGF-β signaling in a multifaceted way. In vivo, we showed that interfering with DNM3OS function not only prevents lung fibrosis but also improves established pulmonary fibrosis.

CONCLUSION:

Pharmacological approaches aiming at interfering with DNM3OS may represent new effective therapeutic strategies in IPF.