Comprehensive chromatographic assessment of forced degraded in vitro transcribed mRNA.

Heightened interest in messenger RNA (mRNA) therapeutics has accelerated the need for analytical methodologies that facilitate the production of supplies for clinical trials. Forced degradation studies are routinely conducted to provide an understanding of potential weak spots in the molecule that are exploited by stresses encountered during bulk purification, production, shipment, and storage. Consequently, temperature fluctuations and excursions are often experienced during these unit operations and may accelerate mRNA degradation. Here, we present a concise panel of chromatography-based stability-indicating assays for evaluating thermally stressed in vitro transcribed (IVT) mRNA as part of a forced degradation study. We found that addition of EDTA to the mRNAs prior to heat exposure reduced the extent of degradation, suggesting that transcripts may be fragmenting via a divalent metal-ion mediated pathway. Trace divalent metal contamination that can accelerate RNA instability is likely carried over from upstream steps. We demonstrate the application of these methods to evaluate the critical quality attributes (CQAs) of mRNAs as well as to detect intrinsic process- and product-related impurities.

Enrichment strategy and initial characterization of heterodimers enriched from a co-formulated cocktail of therapeutic antibodies against SARS-COV-2.

Co-formulation of multiple drug products is an efficient and convenient approach to simultaneously deliver multiple biotherapeutics with the potentially added benefit of a synergistic therapeutic effect. However, co-formulation also increases the risk of heteromeric interactions, giving rise to unique impurities with unknown efficacy and immunogenicity. Therefore, it is critical to develop methods to evaluate the risk of heteromers as an impurity that could affect potency, efficacy, and/or immunogenicity. The most direct strategy to evaluate antibody heteromers is via specific enrichment. However, the fact that antibody heterodimers generated from the co-formulated cocktail share highly similar molar mass and size properties as homodimers natively present in each individual antibody drug product poses a unique purification challenge. Here, we report the path to successful enrichment of heterodimers from co-formulated REGEN-COVⓇ and discuss its potential impacts on drug quality.

Development of Biolayer Interferometry (BLI)-Based Double-Stranded RNA Detection Method with Application in mRNA-Based Therapeutics and Vaccines.

Background: In vitro-transcribed (IVT) mRNA has been established as a promising platform for therapeutics and vaccine development. Double-stranded RNA (dsRNA) is a major impurity of IVT mRNA and can trigger unfavored immune responses, potentially causing adverse events in patients. Existing dsRNA detection and quantitation methods, such as gel electrophoresis, ELISA, or homogeneous time-resolved fluorescence (HTRF), have low sensitivity or are time-consuming. A recently published lateral flow immunoassay (LFSA) was shown to be fast, but it lacks the sensitivity for dsRNA with uridine modifications. Methods: In this study, we provided a possible explanation for the reduced sensitivity of existing quantitation methods for dsRNA with modified uridines by characterizing the binding affinities of commonly used anti-dsRNA antibodies. Then, a rapid and sensitive biolayer interferometry (BLI) dsRNA detection assay utilizing Flock House Virus (FHV) B2 protein was developed to overcome the challenges in dsRNA detection and the reduced sensitivity. Results: This assay allows the detection of dsRNA with different uridine modifications (ψ, m1ψ, 5 moU) with similar sensitivity as dsRNA without modification. Furthermore, we demonstrated this method can be used to quantify both short and long dsRNA, as well as hairpin-structured dsRNA, providing a more comprehensive detection for dsRNA impurities. Moreover, we applied this assay to monitor dsRNA removal through a purification process. Conclusions: Taken together, this BLI method could enable real-time monitoring of impurities in IVT mRNA production to prevent immunogenicity stemming from dsRNA.

Comparison of capillary electrophoresis-based methods for the analytical characterization of purity and stability of in vitro transcribed mRNA.

Messenger RNA (mRNA) is rapidly growing as a therapeutic modality for vaccination and the treatment of a wide range of diseases. As a result, there is an increased demand for mRNA-based analytical methods capable of assessing purity and stability, which are considered critical quality attributes (CQAs). In recent decades capillary electrophoresis (CE) has emerged alongside liquid chromatography (LC) as an important tool for the assessment of purity and stability of mRNA therapeutics. CE offers a variety of advantages over conventional LC or gel-based analytical methods, including reduced injection volume, increased resolution, and increased separation efficiency. In this study we compared CE-based analytical methods: the Agilent RNA 6000 Nano Kit, the Revvity RNA Reagent Kit, the Sciex RNA 9000 Purity and Integrity Kit, and the Agilent HS RNA Kit. These methods were evaluated on their vendor-recommended instruments: the Bioanalyzer, LabChip GXII, PA800 Plus, and Fragment Analyzer, respectively. We assessed the ability of these methods to measure mRNA integrity, purity, and stability. Furthermore, several parameters for each method were also assessed: selectivity, precision, resolution, analysis time, and ease of use. Based on our results, all four methods are suitable for use in the characterization of in vitro transcribed (IVT) mRNA, depending on the intended application. The Sciex RNA 9000 Purity and Integrity kit method achieved the highest selectivity and resolving power compared with the other methods, making it the most suitable for high-resolution, in-depth sample characterization. In comparison, the Agilent RNA 6000 Nano Kit, Revvity RNA Reagent Kit, and Agilent HS RNA Kit achieved lower selectivity and resolution, but their faster analysis times make them more suitable for high-throughput and screening applications.

Berberine inhibits myofibroblast differentiation in nasal polyp-derived fibroblasts via the p38 pathway.

The purposes of this study were to determine whether berberine has any effect on phenotype changes and extracellular matrix (ECM) production in nasal polyp-derived fibroblasts (NPDFs) and to investigate the underlying molecular mechanism. NPDFs were pre-treated with berberine prior to induction by transforming growth factor (TGF)-ß1. The expression of α-smooth muscle actin (SMA) and collagen type I mRNA was determined by a reverse transcription-polymerase chain reaction, and the expression of α-SMA protein and collagen type I was determined by western blotting and/or immunofluorescent staining. The total soluble collagen production was analysed by the SirCol collagen assay. The expression of several signaling molecules of the TGF-ß1 pathway was evaluated by western blot analysis. In TGF-ß1-induced NPDFs, berberine significantly inhibited the expression of α-SMA and collagen type I mRNA and reduced α-SMA and collagen protein levels. Berberine only suppressed the expression of pp38 among the evaluated signaling molecules. SB203580 (a specific inhibitor of p38 kinase) markedly suppressed the increased expression of collagen type I and α-SMA in TGF-ß1-induced NPDFs. Berberine exerts suppressive effects on phenotype changes and ECM production in NPDFs via p38 signaling pathway interference. The findings provide new therapeutic options for ECM production in nasal polyps.

Understanding the structure-property relationship of bispecific monoclonal antibodies with Fc site-specific substitutions.

Development of novel bispecific antibody (bsAb) platforms offers unprecedented opportunities for a wide variety of therapeutic applications. However, the expression and manufacturing of bsAbs with desired structures can be challenging. Owing to the uniqueness of each bsAb platform, more comprehensive and customized structural characterization is particularly important to understand the chemical or biological reactivity of bsAbs, as well as to guide process development, risk assessment, and manufacturing. In this work, we performed higher order structure characterization of the Regeneron bsAb platform with Fc site-specific substitutions through hydrogen deuterium exchange mass spectrometry (HDX-MS). Structural deprotection was identified at the CH2-CH3 interface in the Fc domain, owing to the site-specific substitutions. The structural deprotection was found to correlate with the decreased conformational stability of Fc domain. Under oxidative and thermal stress conditions, the Met residues located near the structurally deprotected region were identified to be susceptible to oxidation. In addition, the introduction of substitutions in the bsAb Fc resulted in a slight reduction of its binding affinity to the neonatal Fc receptor (FcRn). The detailed structural elucidation by HDX-MS improves understanding of the structure-property relationship of the Regeneron bsAb format, thus greatly aiding in process development, risk assessment, and manufacturing.

Comprehensive biophysical characterization of AAV-AAVR interaction uncovers serotype- and pH-dependent interaction.

After more than two decades of research and development, adeno-associated virus (AAV) has become one of the dominant delivery vectors in gene therapy. Despite the focused research, the cell entry pathway for AAV is still not fully understood. Universal AAV receptor (AAVR) has been identified to be involved in cellular entry of different AAV serotypes. With the unveiling of the high-resolution AAV-AAVR complex structure by cryogenic electron microscopy, the atomic level interaction between AAV and AAVR has become the focus of study in recent years. However, the serotype dependence of this binding interaction and the effect of pH have not been studied. Here, orthogonal approaches including bio-layer interferometry (BLI), size-exclusion chromatography coupled to multi-angle laser scattering (SEC-MALS) and sedimentation velocity analytical ultracentrifugation (SV-AUC) were utilized to study the interaction between selected AAV serotypes and AAVR under different pH conditions. A robust BLI method was developed and the equilibrium dissociation binding constants (KD) between different AAV serotypes (AAV1, AAV5 and AAV8) and AAVR was measured. The binding constants measured by BLI together with orthogonal methods (SEC-MALS and SV-AUC) all confirmed that AAV5 has the strongest binding affinity followed by AAV1 while AAV8 binds the weakest. It was also observed that lower pH promotes the binding between AAV and AAVR and neutral or slightly basic conditions lead to very weak binding. These data indicate that for certain serotypes, AAVR may play a prominent role in trafficking AAV to the Golgi rather than acting as a host cell receptor. Information obtained from these combinatorial biophysical methods can be used to engineer future generations of AAVs to have better transduction efficiency.

A single-nucleotide resolution capillary gel electrophoresis workflow for poly(A) tail characterization in the development of mRNA therapeutics and vaccines.

The 3' poly(A) tail is an important component of messenger RNA (mRNA). The length of the poly(A) tail has direct impact on the stability and translation efficiency of the mRNA molecule and is therefore considered to be a critical quality attribute (CQA) of mRNA-based therapeutics and vaccines. Various analytical methods have been developed to monitor this CQA. Methods like ion-pair reversed-phase liquid chromatography (IPRP-LC) can be used to quantify the percentage of mRNA with poly(A) tail but fail to provide further information on the actual length of poly(A). High-resolution methods such as liquid chromatography coupled with mass spectrometry (LC-MS) or next generation sequencing (NGS) can separate poly(A) tail length by one nucleotide (n/n + 1 resolution) but are complicated to implement for release testing of manufactured mRNA. In this study, a workflow utilizing capillary gel electrophoresis (CGE) for characterizing the poly(A) tail length of mRNA was developed. The CGE method demonstrated resolution comparable with the LC-MS method. With UV detection and the addition of poly(A) length markers, this method can provide poly(A) tail length information and can also provide quantitation of each poly(A) length, making it a suitable release method to monitor the CQA of poly(A) tail length.

Nox4 mediates hypoxia-stimulated myofibroblast differentiation in nasal polyp-derived fibroblasts.

BACKGROUND: Chronic hypoxia is associated with remodeling in various organs. Reactive oxygen species (ROS) derived from NADPH oxidases (Nox), and transforming growth factor-ß(1) (TGF-ß(1)) have been implicated in the pathogenesis of hypoxia-induced remodeling. The aims of this study were to determine in hypoxia-stimulated nasal polyp-derived fibroblasts (NPDF) the effect of hypoxia on the differentiation of myofibroblasts, the role of ROS, the major Nox homolog mediating myofibroblast differentiation, and the role of TGF-ß(1). METHODS: Eight primary cultures of NPDF were established from nasal polyps, which were incubated under hypoxic conditions. Reverse transcription polymerase chain reaction for αSMA, Nox1, Nox3, Nox4, Nox5, and fibronectin mRNA was performed. Western blotting for α-SMA and fibronectin was done. ROS production was detected using a fluorometer. NPDF were pretreated with ROS scavengers and transfected with siNox4. The TGF-ß(1) protein level was measured by ELISA. The effect of treatment with TGF-ß(1) type I tyrosine kinase inhibitor SB431542 on myofibroblast differentiation was observed. RESULTS: Hypoxic stimulation of NPDF significantly increased α-SMA and fibronectin mRNA and protein expression. ROS production was increased by hypoxia, and ROS scavengers inhibited myofibroblast differentiation. Nox4 mRNA was the only Nox homolog increased by hypoxia. Transfection with siNox4 inhibited myofibroblast differentiation. TGF-ß(1) was secreted endogenously by hypoxic NPDF. SB431542 significantly inhibited myofibroblast differentiation. CONCLUSIONS: Hypoxia induces myofibroblast differentiation of NPDF through a signaling pathway involving Nox4-dependent ROS generation and TGF-ß(1). Therapies targeting Nox4 may be effective against remodeling of nasal polyps.

Role of reactive oxygen species in transforming growth factor beta1-induced alpha smooth-muscle actin and collagen production in nasal polyp-derived fibroblasts.

BACKGROUND: Myofibroblasts are detected in nasal polyps and are involved in nasal polyp formation by inducing extracellular matrix accumulation. Reactive oxygen species (ROS) are released during the differentiation of fibroblasts to myofibroblasts. The purpose of this study was to investigate ROS production and nicotinamide adenine dinucleotide phosphate oxidase (NOX) expression in nasal polyp-derived fibroblasts (NPDFs) and to evaluate whether ROS from NOX mediates transforming growth factor (TGF)-ß1-induced production of alpha smooth-muscle actin (α-SMA) and collagen production. METHODS: NPDFs were incubated and treated with TGF-ß1. The mRNA expression of NOXs, α-SMA, and collagen type I and IV was determined by reverse transcription-polymerase chain reaction, and the expression of α-SMA protein was determined by immunofluorescence microscopy. The amount of total soluble collagen production was analyzed by the SirCol assay. The ROS generation of cells was investigated using the 2',7'-dichlorfluorescein-diacetate. The fluorescence was captured by fluorescent microscope and measured using a fluorometer. RESULTS: Stimulation with TGF-ß1 increased ROS production by NPDFs compared with NPDFs not treated with TGF-ß1. Stimulation with TGF-ß1 increased the expression of NOX4 mRNA most potently among various Nox enzymes. siNOX4 was able to decrease the level of ROS production. Myofibroblast differentiation and the production of collagen in NPDFs were prevented by inhibition of ROS generation with diphenyliodonium, N-acetylcysteine, ebselen, and siNox4. CONCLUSIONS: This study showed that NOX4 and ROS have a role in myofibroblast differentiation and collagen production of TGF-ß1-induced NPDFs and that these processes are inhibited by the elimination of ROS.

Inhibitory effect of prostaglandin E(2) on the migration of nasal fibroblasts.

BACKGROUND: Fibroblast migration is crucial for normal wound repair after sinonasal surgery. Prostaglandin E2 (PGE2) is a potent inhibitor of fibroblast functions including chemotaxis, proliferation, and matrix production. The purpose of this study was to determine whether PGE2 affects the migration of nasal fibroblasts and to investigate the mechanism of action of PGE2 on nasal fibroblasts. METHODS: Primary cultures of nasal fibroblasts were established from inferior turbinate samples. Fibroblast migration was evaluated with scratch assays. Reverse-transcription polymerase chain reaction was performed for E prostanoid (EP) 1, EP2, EP3, and EP4 receptors. EP receptor-selective agonists and antagonists were used to evaluate receptor functions. Stimulatory G (Gs) proteins were activated to evaluate mechanisms. Intracellular cyclic adenosine monophosphate (cAMP) levels were measured by ELISA, and fibroblast cytoskeletal structures were visualized with immunocytochemistry. RESULTS: PGE2 significantly reduced the migration of nasal fibroblasts. Agonists selective for the EP2 and EP4 receptors significantly reduced the nasal fibroblast migration. Antagonists of the EP2 and EP4 receptors inhibited the effect of PGE2 on nasal fibroblast migration. Activation of Gs protein and adenyl cyclase reduced nasal fibroblast migration. CONCLUSION: PGE2 inhibited the migration of nasal fibroblasts via the EP2 and EP4 receptors, and this inhibition was mediated by cAMP elevation. Targeting specific EP receptors could offer therapeutic opportunities for conditions such as delayed wound healing after nasal surgery.

Effect of prostaglandin e2 on vascular endothelial growth factor production in nasal polyp fibroblasts.

PURPOSE: Angiogenesis is involved in the pathogenesis of chronic rhinosinusitis with nasal polyps. We aimed to investigate the effects of prostaglandin E2 (PGE2) on vascular endothelial growth factor (VEGF) production, the role of E-prostanoid (EP) 4 receptors, and the signal transduction pathway mediating VEGF production in nasal polyp-derived fibroblasts (NPDFs). METHODS: Eight primary NPDF cultures were established from nasal polyps, which were incubated with or without PGE2. Reverse transcription-polymerase chain reaction amplification of EP receptors (EP1, EP2, EP3, and EP4) and immunofluorescence staining for VEGF production were performed. VEGF production via the cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) and phosphatidylinositol 3-kinase (PI3K) pathways was evaluated by enzyme-linked immunosorbent assay. RESULTS: All EP receptors were expressed in NPDFs. PGE2 significantly increased VEGF production concentration- and time dependently, and VEGF production was regulated by an EP4 receptor. Activation of intracellular cAMP regulated VEGF production. VEGF production was decreased by PKA and PI3K inhibitors via intracellular cAMP. CONCLUSIONS: PGE2 stimulates VEGF production via the EP4 receptor in NPDFs. These results indicate that PGE2-induced VEGF production is mediated, at least partially, through cAMP-dependent signaling pathways. Therapies targeting the EP4 receptor may be effective in inhibiting the development of nasal polyps.

Effects of histone deacetylase inhibitor on extracellular matrix production in human nasal polyp organ cultures.

BACKGROUND: Nasal polyposis is associated with a chronic inflammatory condition of the sinonasal mucosa and involves myofibroblast differentiation and extracellular matrix (ECM) accumulation. Epigenetic modulation by histone deacetylase (HDAC) inhibitors including trichostatin A (TSA) has been reported to have inhibitory effects on myofibroblast differentiation in lung and renal fibroblasts. The purpose of this study was to investigate the inhibitory effect of TSA on myofibroblast differentiation and ECM production in nasal polyp organ cultures. METHODS: Nasal polyp tissues from 18 patients were acquired during endoscopic sinus surgery. After organ culture, nasal polyps were stimulated with TGF-beta1 and then treated with TSA. Alpha-smooth muscle actin (α-SMA), fibronectin, and collagen type I expression levels were examined by reverse transcription-polymerase chain reaction (PCR), real-time PCR, Western blot, and immunofluorescent staining. HDAC2, HDAC4, and acetylated H4 expression levels were assayed by Western blot. Cytotoxicity was analyzed by the terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling assay. RESULTS: The expression levels of α-SMA, fibronectin, and collagen type 1 were increased in nasal polyp after transforming growth factor (TGF) beta1 treatment. TSA-inhibited TGF-beta1 induced these gene and protein expression levels. Furthermore, TSA suppressed protein expression levels of HDAC2 and HDAC4. However, TSA induced hyperacetylation of histones H4. Treatment with TGF-beta1 with or without TSA did not have cytotoxic effect. CONCLUSION: These findings provide novel insights into the epigenetic regulation in myofibroblast differentiation and ECM production of nasal polyp. TSA could be a candidate of a therapeutic agent for reversing the TGF-beta1-induced ECM synthesis that leads to nasal polyp development.

Inhibitory effect of ginsenoside Rg1 on extracellular matrix production via extracellular signal-regulated protein kinase/activator protein 1 pathway in nasal polyp-derived fibroblasts.

Nasal polyps are associated with chronic inflammation of the sinonasal mucosa and are involved in myofibroblast differentiation and extracellular matrix (ECM) accumulation. Ginsenoside Rg1, a compound derived from Panax ginseng, shows antifibrotic and anticancer effects. However, the molecular effects of Rg1 on myofibroblast differentiation and ECM production remain unknown. The aims of this study were to investigate the effect of Rg1 on transforming growth factor (TGF)-ß1-induced myofibroblast differentiation and ECM production and to determine the molecular mechanism of Rg1 in nasal polyp-derived fibroblasts (NPDFs). NPDFs were isolated from nasal polyps of seven patients who had chronic rhinosinusitis with nasal polyp. NPDFs were exposed to TGF-ß1 with or without Rg1. Expression levels of α-smooth muscle actin (SMA), fibronectin and collagen type Iα1 were determined by reverse transcription polymerase chain reaction, Western blot and immunofluorescent staining. TGF-ß1 signaling molecules, including Smad2/3, extracellular signal-regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 were analyzed by Western blotting. Transcription factors involved with TGF-ß1 signaling, nuclear factor (NF)-κB and activator protein 1 (AP-1) were also assessed by Western blot. The cytotoxic effect of Rg1 was measured by an established viability assay. The mRNA and protein expression levels of α-SMA, fibronectin and collagen type Iα1 were increased in TGF-ß1-induced NPDFs. Rg1 inhibited these effects. The inhibitory molecular mechanism of Rg1 was involved in the ERK pathway. Rg1 inhibited the transcription factor activation of AP-1. Rg1 itself was not cytotoxic. The ginsenoside Rg1 has inhibitory effects on myofibroblast differentiation and ECM production. The inhibitory mechanism of Rg1 is involved with the ERK and AP-1 signaling pathways. Rg1 may be useful as an inhibitor of ECM deposition, and has potential to be used as a novel treatment option for nasal polyps.

Increased expression of intelectin-1 in nasal polyps.

BACKGROUND: Intelectin-1 is a new type of Ca(2+)-dependant soluble lectin in humans that has affinity for galactofuranose in carbohydrate chains of bacterial cell walls, indicating that intelectin-1 may play a role in immune defense against bacteria. The purpose of the current study was to determine the expression of intelectin-1 mRNA and protein and to localize intelectin-1 protein in nasal polyps and tissues from control subjects. METHODS: Normal sphenoid sinus mucosa was obtained from 10 patients undergoing surgery for pituitary tumor. Nasal polyp samples were obtained from 10 patients undergoing endoscopic sinus surgery for chronic polypoid rhinosinusitis. Real-time polymerase chain reaction (PCR) was performed for intelectin-1 mRNA. Immunofluorescent staining was done for localization of intelectin-1 and quantitatively analyzed using computer-based image analysis. Western blot analysis was performed. RESULTS: Real-time PCR and Western blot analysis showed that intelectin-1 expression in nasal polyps was increased compared with normal sinus mucosa. Using immunofluorescent staining, intelectin-1 was strongly stained in epithelium and submucosa of nasal polyps, and faint staining was found in normal sinus mucosa. CONCLUSIONS: Intelectin-1 is expressed in human sinus mucosa and is increased in patients with nasal polyps. These results suggest a possible contribution for intelectin-1 in the pathophysiology of nasal polyps.

Effect of [6]-gingerol on myofibroblast differentiation in transforming growth factor beta 1-induced nasal polyp-derived fibroblasts.

BACKGROUND: [6]-Gingerol is one of the major pungent principles of ginger and has diverse effects, including anti-inflammatory, and antioxidative effects. Reactive oxygen species (ROS) are released during the phenotypic transformation of fibroblasts to myofibroblasts, a process that is involved in the growth of nasal polyps by inducing extracellular matrix (ECM) accumulation. The purpose of this study was to determine the effect of [6]-gingerol on myofibroblast differentiation and collagen production of nasal polyp-derived fibroblasts (NPDFs) and to determine if the effect of [6]-gingerol is linked to an antioxidant effect. METHODS: NPDFs were incubated and treated with transforming growth factor (TGF) beta 1. The ROS generated by NPDFs were determined using 2″,7″-dichlorfluorescein-diacetate. The fluorescence was captured by a fluorescent microscope and measured using a fluorometer. The expression of alpha-smooth muscle actin (SMA) and collagen type IV mRNA was determined by a reverse transcription-polymerase chain reaction, and the expression of α-SMA protein and pSmad2/3 was determined by immunofluorescence microscopy and or Western blotting. The amount of total soluble collagen production was analyzed by the SirCol collagen dye-binding assay. RESULTS: TGF-beta 1 stimulation increased ROS production by NPDFs. [6]-Gingerol decreased the production of ROS in TGF-beta 1-induced NPDFs. Myofibroblast differentiation, collagen production, and phosphorylation of Smad2/3 were prevented by [6]-gingerol and inhibition of ROS generation with antioxidant such as diphenyliodonium, N-acetylcysteine, and ebselen. CONCLUSION: These results suggest the possibility that [6]-gingerol may play an important role in inhibiting the production of the ECM in the development of nasal polyps through an antioxidant effect.

Effect of simvastatin on transforming growth factor beta-1-induced myofibroblast differentiation and collagen production in nasal polyp-derived fibroblasts.

BACKGROUND: Statins are the most commonly prescribed drugs for the treatment of hypercholesterolemia. Statins exert not only lipid-lowering but also other cellular effects, including antifibrotic properties. The purpose of this study was to determine the effect of simvastatin on transforming growth factor (TGF)-beta-1-induced myofibroblast differentiation and collagen production in nasal polyp-derived fibroblasts (NPDFs) and to verify the mechanism of the effect of simvastatin in TGF-beta-1-induced myofibroblast differentiation in NPDFs. METHODS: NPDFs were pretreated with simvastatin with or without mevalonate or Y-27643 for 2 hours before induction by TGF-beta-1. The expression of alpha-smooth muscle actin (SMA) and collagen type IV mRNA was determined by a reverse transcription-polymerase chain reaction, and the expression of alpha-SMA protein was determined by immunofluorescent cytochemical staining. Total soluble collagen production was analyzed by the SirCol collagen dye-binding assay (Biocolor, Belfast, U.K.). Phosphorylation of Smad 2/3 was evaluated by Western blot analysis. RESULTS: In TGF-beta-1-induced NPDFs, simvastatin significantly inhibited the expressions of α-SMA and collagen type IV mRNA and reduced alpha-SMA and collagen protein levels. Pretreatment with mevalonate reversed the effect of simvastatin. The expression of alpha-SMA mRNA and protein was significantly decreased by pretreatment with Y-27632. The TGF-beta-1-induced expression of pSmad 2/3 protein was notably decreased by pretreatment with simvastatin. CONCLUSION: We showed that simvastatin inhibits TGF-beta-1-induced myofibroblast differentiation (expression of alpha-SMA) and collagen production in NPDFs and Rho/Rock and TGF-ß/Smad signaling is involved as an underlying mechanism. The results of our study suggest that simvastatin is a possible candidate for the suppression of nasal polyp formation.