SMAD3 expression and regulation of fibroplasia in vocal fold injury

Electrospun composite-coated endotracheal tubes with controlled siRNA and drug delivery to lubricate and minimize upper airway injury

Endotracheal Tubes (ETTs) maintain and secure a patent airway; however, prolonged intubation often results in unintended injury to the mucosal epithelium and inflammatory sequelae which complicate recovery. ETT design and materials used have yet to adapt to address intubation associated complications. In this study, a composite coating of electrospun polycaprolactone (PCL) fibers embedded in a four-arm polyethylene glycol acrylate matrix (4APEGA) is developed to transform the ETT from a mechanical device to a dual-purpose device capable of delivering multiple therapeutics while preserving coating integrity. Further, the composite coating system (PCL-4APEGA) is capable of sustained delivery of dexamethasone from the PCL phase and small interfering RNA (siRNA) containing polyplexes from the 4APEGA phase. The siRNA is released rapidly and targets smad3 for immediate reduction in pro-fibrotic transforming growth factor-beta 1 (TGFϐ1) signaling in the upper airway mucosa as well as suppressing long-term sequelae in inflammation from prolonged intubation. A bioreactor was used to study mucosal adhesion to the composite PCL-4APEGA coated ETTs and investigate continued mucus secretory function in ex vivo epithelial samples. The addition of the 4APEGA coating and siRNA delivery to the dexamethasone delivery was then evaluated in a swine model of intubation injury and observed to restore mechanical function of the vocal folds and maintain epithelial thickness when observed over 14 days of intubation. This study demonstrated that increase in surface lubrication paired with surface stiffness reduction significantly decreased fibrotic behavior while reducing epithelial adhesion and abrasion.

SOCS3 Silencing Promotes Activation of Vocal Fold Fibroblasts via JAK2/STAT3 Signaling Pathway

Suppressor of cytokine signaling 3 (SOCS3) is a negative regulatory protein that has been identified as a key inhibitory regulator of JAK/STAT signaling pathway. However, the mutual regulatory relationship between SOCS3 and JAK2/STAT3 signaling pathway after vocal fold injury remains unclear. In this study, we used small interfering RNA (siRNA) to investigate the mechanism of SOCS3 regulating of fibroblasts through JAK2/STAT3 signaling pathway after vocal fold injury. Our data shows that SOCS3 silencing promotes the transformation of normal vocal fold fibroblasts (VFFs) into an fibrotic phenotype and activates the JAK2/STAT3 signaling pathway. JAK2 silencing significantly inhibits the increase in type I collagen and α-smooth muscle actin (α-SMA) secretion in VFFs induced by TGF-β but has no significant effect on normal VFFs. The silencing of SOCS3 and JAK2 reverses the fibrotic phenotype of VFFs induced by SOCS3 silencing. Therefore, we suggest that SOCS3 can affect the activation of vocal fold fibroblasts by regulating the JAK2/STAT3 signaling pathway after vocal fold injury. It provides a new insight for promoting the repair of vocal fold injury and preventing the formation of fibrosis.

A xenograft study of human adipose stromal cell-based vocal fold mucosal replacement in rabbits

Objectives

Vocal fold (VF) scarring, manifested by increased collagen, decreased glycosaminoglycans (GAGs), and disrupted elastic fibers, remains a negative consequence of VF injury or resection. The objective of this study is to compare four reconstructive options after Vf mucosal resection in rabbits. A Cell-Based Outer Vocal fold Replacement (COVR) using human adipose-derived mesenchymal stromal cells (hASCs) in fibrin scaffold is directly compared with a decellularized scaffold implant, hASC injection, and resection alone without reconstruction. The primary hypothesis is that the cells-in-scaffold construct better reconstitutes the VF structure than either cells or scaffold alone, or than healing by secondary intention.

Methods

A total of49 rabbits received bilateral VF cordectomy, followed by either COVR implant, decellularized scaffold implant, hASC injection, or no reconstruction (injured control group). Larynges were harvested after 6 weeks.

Results

Histology demonstrated greater lamina propria thickness, less collagen deposition, and more GAGs in COVR animals versus all other treatment groups. Evidence of persistent human cells was found in about half of the cell-treated animals. RNA levels of fibrosis pathway and macrophage phenotype markers were statistically unchanged among treatment groups at 6 weeks.

Conclusion

These data support the efficacy of COVR implantation in restoring VF microstructure in rabbits. The intact COVR was required; isolated components of decellularized scaffold or injected hASC still produced histologic scarring. We propose that the unique bilayered cell structure within fibrin enables controlled matrix remodeling to minimize wound contraction and fibrosis, and to promote GAG deposition.

Level of Evidence

Basic science study.

Asiatic Acid Improves Extracellular Matrix Remodeling in Vocal Fold Scarring Via SMAD7 Activation

OBJECTIVES/HYPOTHESIS

Vocal fold (VF) fibroblasts are the central target for developing new strategies for the treatment of VF scarring and fibrosis. Asiatic acid (AA) is a triterpenoid derivate with antifibrotic properties. However, the effect of AA in VF scarring is poorly understood. The objective of this study was to investigate the potential application of AA as a therapeutic treatment in VF scarring.

STUDY DESIGN

Xxxxx.

METHODS

The functional expression of SMAD7 was knocked down with recombinant adenoviruses and adeno-associated viruses carrying shRNAs in the in vitro and in vivo models, which were constructed to investigate AA's antifibrotic function. The expression of collagens and SMADs in cultured human and rabbit cell lines and animal models was evaluated with quantitative reverse transcription polymerase chain reaction and immunohistochemistry labeling, respectively. Cell migration capacity and contraction in VF fibroblast cell lines were also evaluated.

RESULTS

AA downregulated the downstream fibrotic activation in a dose-dependent manner. Meanwhile, AA attenuated VF scarring/fibrosis by reducing collagen deposition. Furthermore, the antifibrotic effects of AA were associated with the upregulation of SMAD7. In contrast, knockdown of SMAD7 inhibited the effect of AA on transforming growth factor-beta-1 (TGF-β1) stimulation, which suggests a central role for SMAD7 in AA-induced antifibrotic activities during VF fibrosis.

CONCLUSION

We concluded that AA, which is a novel therapeutic candidate for preventing VF scarring/fibrosis, might exert its antifibrotic effect via the TGF-β1/SMAD signaling pathway.

LEVEL OF EVIDENCE

N/A Laryngoscope, 2021.

Concurrent YAP/TAZ and SMAD signaling mediate vocal fold fibrosis

Vocal fold (VF) fibrosis is a major cause of intractable voice-related disability and reduced quality of life. Excision of fibrotic regions is suboptimal and associated with scar recurrence and/or further iatrogenic damage. Non-surgical interventions are limited, putatively related to limited insight regarding biochemical events underlying fibrosis, and downstream, the lack of therapeutic targets. YAP/TAZ integrates diverse cell signaling events and interacts with signaling pathways related to fibrosis, including the TGF-β/SMAD pathway. We investigated the expression of YAP/TAZ following vocal fold injury in vivo as well as the effects of TGF-β1 on YAP/TAZ activity in human vocal fold fibroblasts, fibroblast-myofibroblast transition, and TGF-β/SMAD signaling. Iatrogenic injury increased nuclear localization of YAP and TAZ in fibrotic rat vocal folds. In vitro, TGF-β1 activated YAP and TAZ in human VF fibroblasts, and inhibition of YAP/TAZ reversed TGF-β1-stimulated fibroplastic gene upregulation. Additionally, TGF-β1 induced localization of YAP and TAZ in close proximity to SMAD2/3, and nuclear accumulation of SMAD2/3 was inhibited by a YAP/TAZ inhibitor. Collectively, YAP and TAZ were synergistically activated with the TGF-β/SMAD pathway, and likely essential for the fibroplastic phenotypic shift in VF fibroblasts. Based on these data, YAP/TAZ may evolve as an attractive therapeutic target for VF fibrosis.

Inhibitory effects of alkaline extract from the pericarp of Citrus reticulata Blanco on collagen behavior in bleomycin-induced pulmonary fibrosis

ETHNOPHARMACOLOGICAL RELEVANCE

Peel of Citrus reticulata, a Chinese herbal drug with functions of regulating Qi and expelling phlegm, has been used for the treatment of lung related diseases in Chinese medicine for a long time. Its detailed effects on collagen in anti-idiopathic pulmonary fibrosis (IPF) is still unclear.

AIM OF THE STUDY

To explore the effects of citrus alkaline extract (CAE) on collagen synthesis, crosslinking and deposition in pulmonary fibrosis and understand the possible signal pathways involved in the activity.

MATERIALS AND METHODS

CAE was prepared from C. reticulata. Bleomycin-induced pulmonary fibrosis mouse model was applied. Pulmonary fibrosis of lung was estimated with histopathology analysis, and collagen deposition was evaluated with immunohistochemistry. Collagen crosslinking related biomarkers and enzymes were analyzed with chemical methods, immunohistochemical and western blot analyses.

RESULTS

CAE oral administration lowered hydroxyproline content, inhibited the collagen deposition including expressions of collagen I and III, and relieved bleomycin-induced pulmonary fibrosis in mice model. The productions of a collagen crosslink pyridinoline and crosslinking related enzymes including lysyl oxidase (LOX), lysyl oxidase-like protein 1 (LOXL1) in lung were suppressed by CAE treatment. Furthermore, the protein expressions of TGF-β1 and Smad3 levels in lungs were also downregulated by CAE.

CONCLUSIONS

This study demonstrated that CAE inhibited collagen synthesis, crosslinking and deposition, and ameliorated bleomycin-induced pulmonary fibrosis. Preliminary mechanism study revealed that CAE exerted its bioactivity at least via downregulation of TGF-β1/Smad3 pathway. Our findings provided a great potential in fighting IPF based on CAE.

Antifibrotic effects of eupatilin on TGF-β1-treated human vocal fold fibroblasts

Vocal fold scarring is a major cause of dysphonia. Vocal fold fibroblasts (VFFs) and the TGF-β signaling pathway play important roles in scar formation. Eupatilin, a chromone derivative of the Artemisia species, is a traditional folk remedy for wound healing. However, until recently, few studies investigated the therapeutic effects of eupatilin. We investigated the antifibrogenic effects of eupatilin on TGF-β1-treated human vocal fold fibroblasts (hVFFs). The optimal concentration of eupatilin was determined by a cell viability assay. Western blotting was used to measure the expression of alpha-smooth muscle actin during myofibroblast differentiation, fibronectin (FN), collagen type I (Col I), and collagen type III (Col III) extracellular matrix proteins, and Smad2, Smad3, and p38 in the fibrotic pathway. Measurements were made before and after eupatilin treatment. Eupatilin at 100 nM was shown to be safe for use in hVFFs. TGF-β1 induced hVFFs to proliferate and differentiate into myofibroblasts and increased Col III and FN synthesis in a time- and dose-dependent manner. Eupatilin suppressed TGF-β1-induced hVFF proliferation and differentiation into myofibroblasts through the Smad and p38 signaling pathways. Furthermore, eupatilin inhibited TGF-β1-induced FN, Col I, and Col III synthesis in hVFFs. Our in vitro findings show that eupatilin effectively suppressed TGF-β1-induced fibrotic changes in hVFFs via the Smad and p38 signaling pathways. Thus, eupatilin may be considered a novel therapeutic agent for the treatment of vocal fold fibrosis.

Quantifying vocal fold wound-healing biomechanical property changes

OBJECTIVES

Development of novel vocal fold (VF) therapeutics is limited by a lack of standardized, meaningful outcomes. We hypothesize that automated microindentation-based VF biomechanical property mapping matched to histology permits quantitative assessment.

STUDY DESIGN

Ex vivo.

METHODS

Twelve anesthetized New Zealand white rabbits underwent endoscopic right VF injury. Larynges were harvested/bisected day 7, 30, or 60 (n = 4/group), with four uninjured controls. Biomechanical measurements (normal force, structural stiffness, and displacement at 1.96 mN) were calculated using automated microindentation mapping (0.3 mm depth, 1.2 mm/s, 2 mm spherical indenter) with a grid overlay (>50 locations weighted toward VF edge, separated into 14 zones). Specimens were marked/fixed/sectioned, and slides matched to measurement points.

RESULTS

In the injury zone, normal force/structural stiffness (mean, standard deviation [SD]/mean, SD) increased from uninjured (2.2 mN, 0.64/7.4 mN/mm, 2.14) and day 7 (2.7 mN, 0.75/9.0 mN/mm, 2.49) to day 30 (4.3 mN, 2.11/14.2 mN/mm, 7.05) and decreased at 60 days (2.7 mN, 0.77/9.1 mN/mm, 2.58). VF displacement decreased from control (0.28 mm, 0.05) and day 7 (0.26 mm, 0.05) to day 30 (0.20 mm, 0.05), increasing at day 60 (0.25 mm, 0.06). A one-way ANOVA was significant; Tukey's post hoc test confirmed day-30 samples differed from other groups (P < 0.05), consistent across adjacent zones. Zones far from injury remained similar across groups (P = 0.143 to 0.551). These measurements matched qualitative histologic variations.

CONCLUSION

Quantifiable VF biomechanical properties can be linked to histology. This technological approach is the first to simultaneously correlate functional biomechanics with histology and is ideal for future preclinical studies.

LEVEL OF EVIDENCE

NA Laryngoscope, 130:454-459, 2020.

Implementing Efficient Peptoid-Mediated Delivery of RNA-Based Therapeutics to the Vocal Folds

Objective

We hypothesize that Smad3 is a master regulator of fibrosis in the vocal folds (VFs) and RNA-based therapeutics targeting Smad3 hold therapeutic promise. Delivery remains challenging. We previously described a novel synthetic peptoid oligomer, lipitoid L0, complexed with siRNA to improve stability and cellular uptake. An advantage of these peptoids, however, is tremendous structural and chemical malleability to optimize transfection efficiency. Modifications of L0 were assayed to optimize siRNA-mediated alteration of gene expression.

Methods

In vitro, Smad3 knockdown by various lipitoid variants was evaluated via quantitative real-time polymerase chain reaction in human VF fibroblasts. Cytotoxicity was quantified via colorimetric assays. In vivo, a rabbit model of VF injury was employed to evaluate the temporal dynamics of Smad3 knockdown following injection of the L0-siRNA complex.

Results

In vitro, similar reductions in Smad3 expression were established by all lipitoid variants, with one exception. Sequence variants also exhibited similar nontoxic characteristics; no statistically significant differences in cell proliferation were observed. In vivo, Smad3 expression was significantly reduced in injured VFs following injection of L0-complexed Smad3 siRNA at 1 day postinjection. Qualitative suppression of Smad3 expression persisted to 3 days following injury, but did not achieve statistical significance.

Conclusions

In spite of the chemical diversity of these peptoid transfection reagents, the sequence variants generally provided consistently efficient reductions in Smad3 expression. L0 yielded effective, yet temporally limited knockdown of Smad3 in vivo. Peptoids may provide a versatile platform for the discovery of siRNA delivery vehicles optimized for clinical application.

Level of Evidence

NA.

The saturated fatty acid palmitate induces insulin resistance through Smad3-mediated down-regulation of FNDC5 in myotubes

Elevated plasma free fatty acid (FFA) levels are associated with insulin resistance and can cause lipotoxicity in skeletal muscles. In response to FFAs, skeletal muscle can secrete a variety of cytokines. Irisin, one such muscle-secreted cytokine, can improve glucose tolerance, glucose uptake, and lipid metabolism. It is produced by the transmembrane protein fibronectin type Ⅲ domain containing 5 (FNDC5) by specific proteases. The purpose of this study was to investigate the regulatory mechanisms of the FNDC5 response to palmitate and their relationships with insulin resistance in C2C12 myotubes. RNA sequencing analysis results from C2C12 myotubes treated with palmitate showed that palmitate could activate the TGF-β signaling pathway. Palmitate directly affected the expression of Smad3, but not its phosphorylation level, in C2C12 myotubes. Furthermore, knockdown and knockout of Smad3 alleviated the inhibitory effect of palmitate on the expression of FNDC5. In contrast, overexpression of Smad3 aggravated the inhibition of FNDC5 expression. There is a Smad3 binding motif in the -660 bp to -649 bp region of the Fndc5 promoter. CRISPR/Cas9 knockout of this region also alleviated the inhibition of FNDC5 expression in response to palmitate. More importantly, inhibition of FNDC5 expression mediated by Smad3 led to a decrease in insulin sensitivity in C2C12 myotubes. Collectively, these findings suggest that palmitate could induce insulin resistance through Smad3-mediated down-regulation of the Fndc5 gene.

The effects of cytosporone-B, a novel antifibrotic agent, on vocal fold fibroblasts

OBJECTIVES/HYPOTHESIS

Our laboratory recently described NR4A1 as an endogenous inhibitor of TGF-β-induced vocal fold (VF) fibrosis. Our prior report described the temporal expression of NR4A1 during VF healing in vivo and the effects of NR4A1 knockdown on fibroplastic cell activities in vitro. Based on these findings, we hypothesized that cytosporone-B (Csn-B), an NR4A1 agonist, may hold significant therapeutic potential.

STUDY DESIGN

In vitro.

METHODS

Human VF fibroblasts were exposed to TGF-β1+/-Csn-B. Expression of genes related to fibrosis were quantified. In addition, contraction was assayed as a surrogate for the fibrotic phenotype in our cell line.

RESULTS

TGF-B1 stimulated COL1A1 and ACTA2, as expected. Csn-B significantly downregulated TGF-β1-mediated upregulation of these genes (P = .009, P = .03, respectively). Csn-B had no effect on genes related to TGF-β/Smad signaling. Csn-B also decreased the TGF-β1-mediated contractile phenotype in our cells (P = .004).

CONCLUSIONS

NR4A1 is an endogenous inhibitor of fibrosis in the vocal folds and Csn-B, as an NR4A1 agonist, may evolve as an ideal, therapeutic candidate for this challenging condition.

LEVEL OF EVIDENCE

NA Laryngoscope, 128:E425-E428, 2018.

The Ability of Human Nasal Inferior Turbinate-Derived Mesenchymal Stem Cells to Repair Vocal Fold Injuries

Objective This study investigated the ability of implanted human nasal inferior turbinate-derived mesenchymal stem cells (hTMSCs) to repair injured vocal folds. To this end, we used quantitative real-time polymerase chain reaction (PCR) to analyze the early phase of wound healing and histopathological analysis to explore the late phase of wound healing in xenograft animal models. Study Design Prospective animal study. Setting Research laboratory. Subjects and Methods The right-side lamina propria of the vocal fold was injured in 20 rabbits and 30 rats. Next, hTMSCs were implanted into half of the injured vocal folds (hTMSC groups). As a control, phosphate-buffered saline (PBS) was injected into the other half of the injured vocal folds (PBS groups). Rat vocal folds were harvested for polymerase chain reaction (PCR) at 1 week after injury. Rabbit vocal folds were evaluated endoscopically and the larynges harvested for histological and immunohistochemical examination at 2 and 8 weeks after injury. Results In the hTMSC group, PCR showed that hyaluronan synthase ( HAS) 1, HAS 2, and transforming growth factor ( TGF)-β1 were significantly upregulated compared with the PBS group. Procollagen type III ( COL III) messenger RNA expression was significantly upregulated in the PBS group compared with the normal group. Histological analyses showed that hTMSC administration afforded more favorable collagen and hyaluronic acid deposition than was evident in the controls. Implanted hTMSCs were observed in injured vocal folds 2 weeks after implantation. Conclusions Our results show that hTMSCs implantation into injured vocal folds facilitated vocal fold regeneration, with presenting antifibrotic effects.

Nanoparticle delivery of RNA-based therapeutics to alter the vocal fold tissue response to injury

OBJECTIVES/HYPOTHESIS

Our laboratory and others hypothesized that Smad3 is a principle mediator of the fibrotic phenotype in the vocal folds (VFs), and we further posited that alteration of Smad3 expression through short interfering (si)RNA holds therapeutic promise, yet delivery remains challenging. To address this issue, we employed a novel synthetic oligomer, lipitoid, complexed with siRNA to improve stability and cellular uptake with the goal of increased efficiency of RNA-based therapeutics.

STUDY DESIGN

In vitro study and in vivo animal model.

METHODS

In vitro, lipitoid cytotoxicity was quantified via colorimetric and LIVE/DEAD assays in immortalized human VF fibroblasts and primary rabbit VF fibroblasts. In addition, optimal incubation interval and solution for binding siRNA to lipitoid for intracellular delivery were determined. In vivo, a rabbit model of VF injury was employed to evaluate Smad3 knockdown following locally injected lipitoid-complexed siRNA.

RESULTS

In vitro, lipitoid did not confer additional toxicity compared to commercially available reagents. In addition, 20-minute incubation in 1× phosphate-buffered saline resulted in maximal Smad3 knockdown. In vivo, Smad3 expression increased following VF injury. This response was significantly reduced in injured VFs at 4 and 24 hours following injection (P = .035 and .034, respectively).

CONCLUSIONS

The current study is the first to demonstrate targeted gene manipulation in the VFs as well as the potential utility of lipitoid for localized delivery of genetic material in vivo. Ideally, these data will serve as a platform for future investigation regarding the functional implications of therapeutic gene manipulation in the VFs.

LEVEL OF EVIDENCE

NA. Laryngoscope, 128:E178-E183, 2018.