SnoN residue (1-366) attenuates hypertrophic scars through resistance to transforming growth factor-β1-induced degradation

BMS-202, a PD-1/PD-L1 inhibitor, decelerates the pro-fibrotic effects of fibroblasts derived from scar tissues via ERK and TGFβ1/Smad signaling pathways

INTRODUCTION

Hypertrophic scar (HS), a fibroproliferative disorder of the skin with some tumor-like properties, is closely related to dysregulated inflammation. PD-1/PD-L1 inhibitor is a promising medication for cancer therapy as its potent functions on adaptive immune response; whether it could be a candidate for HS therapy has aroused our interest. This study aimed to explore the effect and the mechanism of BMS-202, a PD-1/PD-L1 inhibitor, in HS.

METHODS

Ten HS and adjacent normal skin tissues collected from HS patients were used to detect α-SMA, collagen I, and PD-L1 expression by Quantitative reverse transcription-polymerase chain reaction and western blot (WB) analysis. Fibroblasts derived from HS tissues (HFBs) were exposed to diverse concentrations of BMS-202, of which proliferation, migration, apoptosis, and collagen synthesis were evaluated by Cell Counting Kit-8, wound healing, terminal deoxynucleotidyl transferase (TdT) dUTP Nick-End labeling, and [3 H]-proline incorporation assays, respectively. The effect of BMS-202 on α-SMA and collagen I expression, and transforming growth factor beta 1 (TGFβ1)/Smad signaling in HFBs was also determined by WB and enzyme-linked immunosorbent assay.

RESULTS

The expression level of PD-L1 was significantly elevated in both HS tissues and HFBs, which was positively correlated with α-SMA and collagen I expressions. BMS-202 exerted a significant suppression effect on the cell proliferation, migration, collagen synthesis, and α-SMA and collagen I expression of HFBs in a concentration-dependent way; but did not affect apoptosis. Finally, BMS-202 could reduce the phosphorylation of ERK1/2, Smad2, and Smad3, and the TGFβ1 expression once its concentration reached 2.5 nM.

CONCLUSION

BMS-202 effectively suppressed proliferation, migration, and extracellular matrix deposition of HFBs, potentially through the regulation of the ERK and TGFβ1/Smad signaling pathways.

Thrombin improves diabetic wound healing by ERK dependent and independent Smad2/3 linker region phosphorylation

BACKGROUND

Impaired wound healing is one of the most noteworthy features and troublesome complications of diabetes mellitus, which arouse a rising global health concern but without potent remedies. Thrombin is the major hemostatic agent applied at wound healing initiation and recently gained therapeutic credits in later phases. However, a rare investigation achieved prolonged use of thrombin and probed the detailed mechanism.

OBJECTIVE

To investigate the effects and mechanism of thrombin on diabetic skin wound healing.

METHODS

The effect of thrombin on fibroblast proliferation, α-SMA, and Collagen I expression was firstly studied in vitro by Cell Counting Kit 8 (CCK8) and western blotting. Then, the specific phosphorylation site of SMAD2/3 and their ERK1/2 dependence during thrombin treatment were assessed by western blotting for mechanism exploration. After that, full-thickness wound defects were established in diabetic male SD rats and treated with thrombin in the presence or absence of PD98059 to observe the in vivo effects of thrombin and to confirm its ERK dependence.

RESULTS

We found that thrombin promoted fibroblast proliferation and their α-SMA and Collagen I production. Mechanistically, thrombin induced phosphorylation of Smad2 linker region (Ser245/250/255) through ERK1/2 phosphorylation but promoted phosphorylation of Smad3 linker region (Ser204) independent of ERK1/2. Histological results showed that thrombin facilitated wound healing by promoting α-SMA and Collagen I expression, which was not abolished by inhibiting ERK phosphorylation.

CONCLUSION

Collectively, this study validated the therapeutic efficacy of thrombin on diabetic wound healing and identified both ERK-dependent and -independent Smad2/3 linker region phosphorylation as the essential signaling events in this process.

USP15 Enhances the Proliferation, Migration, and Collagen Deposition of Hypertrophic Scar-Derived Fibroblasts by Deubiquitinating TGF-βR1 In Vitro

BACKGROUND

Hypertrophic scar is a fibroproliferative disorder caused by skin injury. The incidence of hypertrophic scar following trauma or burns is 40 to 70 percent or 70 percent, respectively. It has been shown that transforming growth factor (TGF) β1/Smad signaling plays a crucial role in hypertrophic scar, and that USP15 can regulate the activity of TGFβ1/Smad signaling to affect the progression of the disease. However, the underlying mechanism of USP15 in hypertrophic scar remains unclear. The authors hypothesized that USP15 was up-regulated and enhanced the proliferation, migration, invasion, and collagen deposition of hypertrophic scar-derived fibroblasts by deubiquitinating TGF-β receptor I (TβRI) in vitro.

METHODS

Fibroblasts were isolated from human hypertrophic scars in vitro. The knockdown and overexpression of USP15 in hypertrophic scar-derived fibroblasts were performed using lentivirus infection. The effect of USP15 on hypertrophic scar-derived fibroblast proliferation, migration, and invasion, and the expression of TβRI, Smad2, Smad3, α-SMA, COL1, and COL3, were detected by Cell Counting Kit-8, scratch, invasion, quantitative real-time polymerase chain reaction, and Western blot assays. The interaction between USP15 and TβRI was detected by co-immunoprecipitation and ubiquitination assays.

RESULTS

The authors demonstrated that USP15 knockdown significantly inhibited the proliferation, migration, and invasion of hypertrophic scar-derived fibroblasts in vitro and down-regulated the expression of TβRI, Smad2, Smad3, α-SMA, COL1, and COL3; in addition, USP15 overexpression showed the opposite trends (p < 0.05). Co-immunoprecipitation and ubiquitination assays revealed that USP15 interacted with TβRI and deubiquitinated TβRI.

CONCLUSION

USP15 enhances the proliferation, migration, invasion, and collagen deposition of hypertrophic scar-derived fibroblasts by deubiquitinating TβRI in vitro.

Inhibition of Notch Intracellular Domain Suppresses Cell Activation and Fibrotic Factors Production in Hypertrophic Scar Fibroblasts Versus Normal Skin Fibroblasts

BACKGROUND

Hypertrophic scar (HS) is the most common complication after skin injury with unknown etiopathogenesis. There is increasing evidence to suggest that aberrant Notch signaling contributes directly to skin pathogenesis and altered expression of the Notch intracellular domain (NICD) identified in HS. Therefore, the aim of this study was to investigate the effects of Notch signaling pathway in HS pathogenesis.

METHODS

Hypertrophic scar and normal skin samples were collected. Notch intracellular domain expression was detected by immunohistochemistry staining and fibroblasts were separated from the samples. We compared fibrotic factors production, cell viability, migration and apoptosis of HS fibroblasts (HFB) versus normal skin fibroblasts (NFB) by real time quantitative polymerase chain reaction, MTS, cell scratch assay and flow cytometry respectively under the impact of inhibition of Notch signaling by NICD-small-interfering RNA (SiRNA).

RESULTS

The results showed that NICD was overexpressed in the dermis of HS tissues. Inhibition of Notch signaling by NICD-SiRNA suppressed the production of the fibrotic factors including collagen 1, collagen 3, α-SMA, and TGF-β1 by HFB and NFB. Cell viability and migration were reduced in NICD-SiRNA-treated NFB and HFB, whereas cell apoptosis was enhanced by NICD-SiRNA.

CONCLUSIONS

Conclusively, the study demonstrates a potential role for Notch signaling in HS progression, and targeting this pathway may provide a novel strategy for treatment of HS.

The Ubiquitin Proteasome System and Skin Fibrosis

The ubiquitin proteasome system (UPS) is a highly conserved way to regulate protein turnover in cells. The UPS hydrolyzes and destroys variant or misfolded proteins and finely regulates proteins involved in differentiation, apoptosis, and other biological processes. This system is a key regulatory factor in the proliferation, differentiation, and collagen secretion of skin fibroblasts. E3 ubiquitin protein ligases Parkin and NEDD4 regulate multiple signaling pathways in keloid. Tumor necrosis factor (TNF) receptor-associated factor 4 (TRAF4) binding with deubiquitinase USP10 can induce p53 destabilization and promote keloid-derived fibroblast proliferation. The UPS participates in the occurrence and development of hypertrophic scars by regulating the transforming growth factor (TGF)-β/Smad signaling pathway. An initial study suggests that TNFα-induced protein 3 (TNFAIP3) polymorphisms may be significantly associated with scleroderma susceptibility in individuals of Caucasian descent. Sumoylation and multiple ubiquitin ligases, including Smurfs, UFD2, and KLHL42, play vital roles in scleroderma by targeting the TGF-β/Smad signaling pathway. In the future, drugs targeting E3 ligases and deubiquitinating enzymes have great potential for the treatment of skin fibrosis.

Panax Notoginseng Saponins suppresses TRPM7 via the PI3K/AKT pathway to inhibit hypertrophic scar formation in vitro

BACKGROUND

Hypertrophic scar (HS) formation, a type of dermal fibroproliferative condition, is a frequent complication in wound healing resulting from burns, severe trauma, and surgical procedures. The effects of Panax Notoginseng Saponins (PNS) on the HS formation remain relatively under-explored. Hence, this study was intended to interrogate anti-apoptosis and anti-fibrosis effects of PNS on the hypertrophic scar fibroblasts (HSFs) during HS formation and assess the involvement of TRPM7 and PI3K/AKT signaling pathway.

METHODS

Using MTT and CCK-8 assays, we evaluated cell cytotoxicity and cell viability. Collagen I/III (col 1/3) and α-SMA expression levels were assessed through immunofluorescence and western blot, and cell migration, cell apoptosis and cell cycle were examined with applications of wound healing, TUNEL staining and flow cytometry. TRPM7, PI3K/AKT, TGF-β1 and related-proteins were quantified using RT-qPCR and western blot.

RESULTS

PNS administration could suppress TRPM7 expression and the viability of HSFs in a dose-dependent manner. Moreover, PNS could restrain the HS formation and ECM deposition by decreasing col 1/3 and α-SMA synthesis, suppressing cell migration, and boosting apoptosis and G1 arrest. Notably, this study revealed that PNS inhibited PI3K/AKT activation in HSFs. Besides, knockdown of TRPM7 enhanced therapeutic effects of PNS on HSFs, but overexpression markedly reversed above mentioned effects of PNS on HSFs.

CONCLUSION

This study suggested that PNS hampered scar formation might via inhibiting ECM and stimulating cell apoptosis by modulating the PI3K/AKT signaling. Overall, these findings in the present study could support the use of PNS for preventing HS formation, and TRPM7 may be a novel molecular target for treating HS.