Apremilast interferes with the TGFβ1-induced transition of human skin fibroblasts into profibrotic myofibroblasts: in vitro study

Antifibrotic effect of apremilast in systemic sclerosis dermal fibroblasts and bleomycin-induced mouse model

Phosphodiesterase (PDE) 4 inhibitors have been reported to suppress the progression of dermal fibrosis in patients with systemic sclerosis (SSc); however, the precise mechanisms remain to be elucidated. Therefore, we conducted experiments focusing on the antifibrotic and anti-inflammatory effects of apremilast using dermal fibroblasts derived from patients with SSc and an SSc mouse model. Dermal fibroblasts derived from healthy controls and patients with SSc were incubated with apremilast in the presence or absence of 10 ng/ml transforming growth factor (TGF)-β1 for the measurement of intracellular cAMP levels and evaluation of mRNA and protein expression. A bleomycin-induced dermal fibrosis mouse model was used to evaluate the inhibitory effects of apremilast on the progression of dermal fibrosis. Intracellular cAMP levels were significantly reduced in dermal fibroblasts derived from patients with SSc compared with those derived from healthy controls. Apremilast reduced the mRNA expression of profibrotic markers and the protein expression of type I collagen and Cellular Communication Network Factor 2 (CCN2) in dermal fibroblasts. Additionally, apremilast inhibited the progression of dermal fibrosis in mice, partly by acting on T cells. These results suggest that apremilast may be a potential candidate for treating dermal fibrosis in SSc.

Transdermal delivery of Protocatechuic aldehyde using hyaluronic acid/gelatin-based microneedles for the prevention and treatment of hypertrophic scars

The formation of hypertrophic scar (HS) involves many pathological processes, such as reduced apoptosis in fibroblasts, excessive collagen deposition by fibroblasts, over-abundant angiogenesis, etc. The therapeutic effects of current treatments targeting one single pathological process are limited. Due to their diverse biological activities, natural products offer a potential solution to this issue. In this study reported herein, we investigated the effects of Protocatechuic aldehyde (PA) on both hypertrophic scar-derived fibroblasts (HSF) and vascular endothelial growth factor (VEGF)-stimulated human umbilical vein endothelial cells (HUVECs). Microneedles (MN) containing PA and hyaluronic acid (HA) or containing PA, HA, and gelatin were prepared by mixing PA stock solution with HA or HA/gelatin at a ratio of 1:10. The HS prevention and treatment outcomes of these HA-PA-MN and HA/gelatin-PA-MN were tested using a rabbit ear HS model. Our data indicate that PA induces apoptosis and reduces collagen deposition in HSF. In addition, PA attenuates VEGF-stimulated angiogenesis of HUVECs. Furthermore, HA-PA-MN or HA/gelatin-PA-MN are able to effectively penetrate the epidermis of the HS tissues and then quickly dissolve, enabling the fast release of PA directly into the dermis of the HS tissues. HA-PA-MN or HA/Gelatin-PA-MN have also been found to effectively prevent or alleviate HS in a rabbit ear HS model. In conclusion, this study demonstrates that PA can be used to prevent and treat HS by simultaneously regulating HSF and HUVECs, which offers a potential novel reagent for HS management.

Clinical Implication of Phosphodiesterase-4-Inhibition

The pleiotropic function of 3′,5′-cyclic adenosine monophosphate (cAMP)-dependent pathways in health and disease led to the development of pharmacological phosphodiesterase inhibitors (PDE-I) to attenuate cAMP degradation. While there are many isotypes of PDE, a predominant role of PDE4 is to regulate fundamental functions, including endothelial and epithelial barrier stability, modulation of inflammatory responses and cognitive and/or mood functions. This makes the use of PDE4-I an interesting tool for various therapeutic approaches. However, due to the presence of PDE4 in many tissues, there is a significant danger for serious side effects. Based on this, the aim of this review is to provide a comprehensive overview of the approaches and effects of PDE4-I for different therapeutic applications. In summary, despite many obstacles to use of PDE4-I for different therapeutic approaches, the current data warrant future research to utilize the therapeutic potential of phosphodiesterase 4 inhibition.