Diagnosing Deep Endometriosis Using Transvaginal Elastosonography

Progressively Diminished Prostaglandin E2 Signaling in Concordance with Increasing Fibrosis in Ectopic Endometrium

The prostaglandin E2 (PGE2) signaling has traditionally been viewed to play a pivotal role in endometriosis, linking inflammation and hyperestrogenism. We have previously reported that asectopic endometrium becomes more fibrotic, the expression of both COX-2 and PGE2 receptors (EP2 and EP4) are reduced. This study further investigatedwhether the expression levels of genes involved in the biosynthesis and metabolism of PGE2in ectopic endometrium diminish in concordance with increasing lesional fibrosis. We performed immunohistochemistry analyses of COX-2, mPGES-1, mPGES-2, cPGES, 15-PGDH, EP2 and EP4 and Masson trichrome staining for ovarian endometrioma (OE), adenomyosis (AD), and deep endometriosis (DE) tissue samples and control endometrial tissue samples (CT). Gene and protein expression analyses were performed by real-time RT-PCR and Western blotting, respectively. We found that as the extent of lesional fibrosis increased, immunoexpression of COX-2, mPGES-1/2, cPGES, EP2 and EP4 in OE lesions was increased but no change in these genes/proteins in DE lesions as compared with CT. Immunoexpression of COX-2 was found to be reduced while that of 15-PGDH was found to be elevated in DE lesions. In AD lesions, only EP2 and COX-2 were overexpressed. Thus, our data indicate that when the extent of lesional fibrosis is high, the PGE2 signaling pathway is depressed, manifesting as reduced COX-2 expression and elevated expression of 15-PGDH. They underscore the fact that not all ectopic endometria are the same and equal, and highlight the importance of the extracellular matrix in shaping the lesional behavior and response to drug treatment.

The role of fibrosis in endometriosis: a systematic review

BACKGROUND

Fibrosis is an important pathological feature of endometriotic lesions of all subtypes. Fibrosis is present in and around endometriotic lesions, and a central role in its development is played by myofibroblasts, which are cells derived mainly after epithelial-to-mesenchymal transition (EMT) and fibroblast-to-myofibroblast transdifferentiation (FMT). Transforming growth factor-β (TGF-β) has a key role in this myofibroblastic differentiation. Myofibroblasts deposit extracellular matrix (ECM) and have contracting abilities, leading to a stiff micro-environment. These aspects are hypothesized to be involved in the origin of endometriosis-associated pain. Additionally, similarities between endometriosis-related fibrosis and other fibrotic diseases, such as systemic sclerosis or lung fibrosis, indicate that targeting fibrosis could be a potential therapeutic strategy for non-hormonal therapy for endometriosis.

OBJECTIVE AND RATIONALE

This review aims to summarize the current knowledge and to highlight the knowledge gaps about the role of fibrosis in endometriosis. A comprehensive literature overview about the role of fibrosis in endometriosis can improve the efficiency of fibrosis-oriented research in endometriosis.

SEARCH METHODS

A systematic literature search was performed in three biomedical databases using search terms for 'endometriosis', 'fibrosis', 'myofibroblasts', 'collagen', and 'α-smooth muscle actin'. Original studies were included if they reported about fibrosis and endometriosis. Both preclinical in vitro and animal studies, as well as research concerning human subjects were included.

OUTCOMES

Our search yielded 3441 results, of which 142 studies were included in this review. Most studies scored a high to moderate risk of bias according to the bias assessment tools. The studies were divided in three categories: human observational studies, experimental studies with human-derived material, and animal studies. The observational studies showed details about the histologic appearance of fibrosis in endometriosis and the co-occurrence of nerves and immune cells in lesions. The in vitro studies identified several pro-fibrotic pathways in relation to endometriosis. The animal studies mainly assessed the effect of potential therapeutic strategies to halt or regress fibrosis, for example targeting platelets or mast cells.

WIDER IMPLICATIONS

This review shows the central role of fibrosis and its main cellular driver, the myofibroblast, in endometriosis. Platelets and TGF-β have a pivotal role in pro-fibrotic signaling. The presence of nerves and neuropeptides is closely associated with fibrosis in endometriotic lesions, and is likely a cause of endometriosis-associated pain. The process of fibrotic development after EMT and FMT shares characteristics with other fibrotic diseases, so exploring similarities in endometriosis with known processes in diseases like systemic sclerosis, idiopathic pulmonary fibrosis or liver cirrhosis is relevant and a promising direction to explore new treatment strategies. The close relationship with nerves appears rather unique for endometriosis-related fibrosis and is not observed in other fibrotic diseases.

REGISTRATION NUMBER

N/A.

Ultrasound Elastography in Benign Gynecology: A Scoping Review

OBJECTIVE

To perform a scoping review of the literature in which ultrasound elastography (UE) has been used in benign gynecology and identify avenues for its use in future research and clinical implementations.

METHODS

A structured search of EMBASE, Medline and Cochrane databases was conducted (last search date April 15th, 2022). Eligible studies included adult participants with female pelvic anatomy. English language papers focusing on the utility of ultrasound elastography applied to benign gynecology were included. Narrative reviews, conference abstracts, and letters to the editor were excluded. Two independent reviewers screened titles and abstracts for inclusion, a third reviewer was consulted in cases of disagreement. Study quality was assessed by a checklist for study implementation and elastography technique. Extracted data included elastography technology, gynecologic application, opportunities for clinical implementation, and strengths and limitations.

RESULTS

The search returned 2026 studies. A total of 40 studies, published between 2013 and 2022, were retained for data extraction. Studies most frequently used shear wave elastography as the method of UE (n = 23), followed by strain elastography (n = 13) and acoustic radiation force impulse (n = 4). Most common clinical applications for UE were the diagnosis of adenomyosis and uterine fibroids (27.5%), assessment of pelvic floor muscle function (22.5%), and describing the elastic properties of polycystic ovaries (17.5%) and the uterine cervix (15.0%). Limitations of the technology were identified as the lack of published reference values for gynecologic organs and difficulties in assessing tissues deep to the transducer.

CONCLUSION

Future research is needed to validate the use of ultrasound elastography in gynecology under both normal and pathologic conditions.

Endometriosis: Improvements and challenges in diagnosis and symptom management

Endometriosis is a chronic disorder with debilitating symptoms that is difficult to diagnose and treat. Advances in imaging technologies and strategies for the management of symptoms are improving the quality of life of patients by reducing the time taken for diagnosis and offering a more balanced approach to therapy.

Noninvasive diagnostic imaging for endometriosis part 1: a systematic review of recent developments in ultrasound, combination imaging, and artificial intelligence

Endometriosis affects 1 in 9 women and those assigned female at birth. However, it takes 6.4 years to diagnose using the conventional standard of laparoscopy. Noninvasive imaging enables a timelier diagnosis, reducing diagnostic delay as well as the risk and expense of surgery. This review updates the exponentially increasing literature exploring the diagnostic value of endometriosis specialist transvaginal ultrasound (eTVUS), combinations of eTVUS and specialist magnetic resonance imaging, and artificial intelligence. Concentrating on literature that emerged after the publication of the IDEA consensus in 2016, we identified 6192 publications and reviewed 49 studies focused on diagnosing endometriosis using emerging imaging techniques. The diagnostic performance of eTVUS continues to improve but there are still limitations. eTVUS reliably detects ovarian endometriomas, shows high specificity for deep endometriosis and should be considered diagnostic. However, a negative scan cannot preclude endometriosis as eTVUS shows moderate sensitivity scores for deep endometriosis, with the sonographic evaluation of superficial endometriosis still in its infancy. The fast-growing area of artificial intelligence in endometriosis detection is still evolving, but shows great promise, particularly in the area of combined multimodal techniques. We finalize our commentary by exploring the implications of practice change for surgeons, sonographers, radiologists, and fertility specialists. Direct benefits for endometriosis patients include reduced diagnostic delay, better access to targeted therapeutics, higher quality operative procedures, and improved fertility treatment plans.

The Benefit of Transvaginal Elastography in Detecting Deep Endometriosis: A Feasibility Study

OBJECTIVES

This study aimed to evaluate elastography features of deep infiltrating endometriosis (DIE), and to define whether this technique may discriminate lesions from surrounding non-endometriotic tissue.

METHODS

This was an exploratory observational study on women affected by DIE treated in a third-level academic hospital gynaecology outpatient facility between 2020 and 2021. Strain elastography (SE) was conducted via transvaginal probe. Tissue deformation of DIE and surrounding tissue was expressed as percentage tissue deformation or as subjective colour score (CS; from blue=stiff to red=soft, assigned numerical values from 0 to 3). Ratios of normal tissue/DIE were compared to ratio of normal tissue/stiffer normal tissue area.

RESULTS

Evaluations were performed on 46 DIE nodules and surrounding tissue of the uterosacral ligaments (n=21), parametrium (n=7), rectum (n=14), and recto-vaginal septum (n =4). Irrespective of location, DIE strain ratio (3.09, IQR 2.38-4.14 vs. 1.25, IQR 1.11-1.48; p<0.001) and CS ratio (4.62, IQR 3.83-6.94 vs. 1.13, IQR 1.06-1.29; p<0.001) was significantly higher than that of normal tissue. ROC AUC of CS ratio was higher than ROC AUC of strain ratio (99.76%, CI.95 99.26-100% vs. 91.35%, CI.95 85.23-97.47%; p=0.007), and best ROC threshold for CS ratio was 1.82, with a sensitivity of 97.83% (CI.95 93.48-100%) and a specificity of 100% (CI.95 100-100%).

CONCLUSIONS

Both strain and CS ratios accurately distinguish DIE nodules at various locations. Applications of elastography in improving the diagnosis DIE, in distinguishing different DIE lesions and in monitoring DIE evolution can be envisioned and are worthy of further evaluation.

Deep endometriosis muscular infiltration of the bowel wall: correlation between MRI and histopathology

AIM

To assess the correlation between magnetic resonance imaging (MRI) and histopathology for predicting muscular infiltration of endometriosis in the bowel wall in patients undergoing colorectal resection.

MATERIALS AND METHODS

All consecutive patients who underwent colorectal surgery for deep endometriosis (DE) with a preoperative MRI in a single tertiary care referral hospital between 2001 and 2019 were included in a prospective cohort. MRI images were revised by a single blinded radiologist. The MRI results regarding the infiltration depth (serosal, muscular, submucosal, or mucosal) and lesion expansion of DE were compared to histopathology.

RESULTS

A total of 84 patients were eligible for evaluation. A sensitivity of 89% and positive predictive value of 97% was shown for predicting muscular involvement of the bowel wall.

CONCLUSION

This study showed that MRI is valuable in predicting the involvement of the muscular layer of the colorectal wall. Therefore, in patients with symptomatic pelvic bowel endometriosis MRI is a useful tool in guiding the extent of colorectal surgery.

Prevention of Uterine Fibroids: molecular mechanisms and potential clinical application

Uterine fibroids (UFs; leiomyoma) are the most common benign neoplastic threat to women worldwide, exacting an immense personal burden on female health and a monetary expense to the healthcare system estimated in the hundreds of billions of dollars every year globally. With no long-term non-invasive treatment option currently available to treat UFs, deeper insights regarding tumor etiology are the key for developing newer therapies. Accordingly, in this review, we discuss new mechanistic paradigm to explain UF tumor development through an exquisite model involving developmental reprogramming of myometrial stem cells due to early life endocrine disruptors exposure, inflammation, fibrosis, DNA damage, and eventually tissue stiffness. Further, we propose to utilize shear wave elastography as a potential screening tool for the early identification of women at risk for developing UFs who can benefit from several simple preventive strategies, including the consumption of natural compounds such as vitamin D and green tea as a safe fertility friendly non-hormonal modality to delay or even arrest or reverse UF progression.

Ultrasound Elastography for the Diagnosis of Endometriosis and Adenomyosis: A Systematic Review with Meta-analysis

Elastography is capable of measuring tissue mechanical properties and elasticity. It is used to help diagnose various diseases, although its use in pelvic endometriosis remains to be established. A systematic review and meta-analysis were conducted to assess transvaginal ultrasound elastography for the diagnosis of different manifestations of endometriosis and adenomyosis. PRISMA guidelines were used for a Medline, PubMed, Embase, BVS/Bireme, Scopus, Cochrane Library and Escudos database search. Studies indexed until March 2021 that evaluated elastography compared with histopathological results (gold standard), ultrasound or magnetic resonance imaging for diagnosis of pelvic endometriosis and adenomyosis were eligible. The Rayyan platform was used to select studies. Sensitivity (S), specificity (Ps), positive and negative predictive values and receiver operating characteristic curves were calculated for elastographic diagnosis of endometriosis. A meta-analysis using Review Manager 5 and Open Meta Analyst was performed. Bias risk in the studies was analyzed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-2 tool. This systematic review was prospectively registered in the PROSPERO database: CRD42021244555. Among the 163 identified citations, 10 studies were eligible for review (5 for diagnosis of adenomyosis, 2 for endometrioma, 3 for deep intestinal endometriosis and rectovaginal septum [deep pelvic endometriosis], N = 744 women). In deep pelvic endometriosis, lesions diagnosed by elastography were found to correlate with histopathology results. Increased "stiffness" (elastography) was associated with a higher fibrotic component, with S = 78%-100% and Ps = 100%, according to the authors. On elastography, endometriomas were stiffer than hemorrhagic cysts (S = 82%, Ps = 79%) and malignant tumors (S = 86%, Ps = 100%). For these lesions, a meta-analysis could not be performed because the small number of studies and insufficient data. In adenomyosis, meta-analysis and receiver operating characteristic curve analysis revealed that elastography had good sensitivity and specificity. Studies indicated a low bias risk by QUADAS-2. Elastography had high sensitivity and specificity for deep pelvic endometriosis diagnosis, and its findings correlated with histopathology results. For adenomyosis, the meta-analysis confirmed the sensitivity and specificity results of the studies. Given these results, elastography may be a promising imaging test, contributing to non-invasive diagnosis of endometriosis and adenomyosis.

Aberrant expression of histone deacetylase 8 in endometriosis and its potential as a therapeutic target

Purpose

To screen Zn2+-dependent histone deacetylase (HDAC) 1-11 in endometriotic cells and then evaluated the HDACs identified from the screening in ovarian endometrioma (OE) and deep endometriotic (DE) lesions, and to evaluate the therapeutic potential of HDAC8 inhibition in mice.

Methods

Quantification of gene and protein expression levels of HDAC1-11 in endometriotic cells stimulated by TGF-β1, and immunohistochemistry analysis of Class I HDACs and HDAC6 in OE/DE lesion samples. The therapeutic potential of HDAC8 inhibition was evaluated by a mouse model of deep endometriosis.

Results

The screening identified Class I HDACs and HDAC6 as targets of interest. Immunohistochemistry analysis found a significant elevation in HDAC8 immunostaining in both OE and DE lesions, which was corroborated by gene and protein expression quantification. For other Class I HDACs and HDAC6, their lesional expression was more subtle and nuanced. HDAC1 and HDAC6 staining was significantly elevated in DE lesions while HDAC2 and HDAC3 staining was reduced in DE lesions. Treatment of mice with induced deep endometriosis with an HDAC8 inhibitor resulted in significantly longer hotplate latency, a reduction of lesion weight by nearly two-thirds, and significantly reduced lesional fibrosis.

Conclusions

These findings highlight the progression-dependent nature of specific HDAC aberrations in endometriosis, and demonstrate, for the first titme, the therapeutic potential of suppressing HDAC8.

In Search of an Imaging Classification of Adenomyosis: A Role for Elastography?

Adenomyosis is a complex and poorly understood gynecological disease. It used to be diagnosed exclusively by histology after hysterectomy; today its diagnosis is carried out increasingly by imaging techniques, including transvaginal ultrasound (TVUS) and magnetic resonance imaging (MRI). However, the lack of a consensus on a classification system hampers relating imaging findings with disease severity or with the histopathological features of the disease, making it difficult to properly inform patients and clinicians regarding prognosis and appropriate management, as well as to compare different studies. Capitalizing on our grasp of key features of lesional natural history, here we propose adding elastographic findings into a new imaging classification of adenomyosis, incorporating affected area, pattern, the stiffest value of adenomyotic lesions as well as the neighboring tissues, and other pathologies. We argue that the tissue stiffness as measured by elastography, which has a wider dynamic detection range, quantitates a fundamental biologic property that directs cell function and fate in tissues, and correlates with the extent of lesional fibrosis, a proxy for lesional "age" known to correlate with vascularity and hormonal receptor activity. With this new addition, we believe that the resulting classification system could better inform patients and clinicians regarding prognosis and the most appropriate treatment modality, thus filling a void.

Cracking the enigma of adenomyosis: an update on its pathogenesis and pathophysiology

In brief

Traditionally viewed as enigmatic and elusive, adenomyosis is a fairly common gynecological disease but is under-recognized and under-researched. This review summarizes the latest development on the pathogenesis and pathophysiology of adenomyosis, which have important implications for imaging diagnosis of the disease and for the development of non-hormonal therapeutics.

Abstract

Traditionally considered as an enigmatic disease, adenomyosis is a uterine disease that affects many women of reproductive age and is a contributing factor for pelvic pain, heavy menstrual bleeding (HMB), and subfertility. In this review, the new development in the pathogenesis and pathophysiology of adenomyosis has been summarized, along with their clinical implications. After reviewing the progress in our understanding of the pathogenesis and describing the prevailing theories, in conjunction with their deficiencies, a new hypothesis, called endometrial-myometrial interface disruption (EMID), which is backed by extensive epidemiologic data and demonstrated by a mouse model, is reviewed, along with recent data implicating the role of Schwann cells in the EMI area in the genesis of adenomyosis. Additionally, the natural history of adenomyotic lesions is elaborated and underscores that, in essence, adenomyotic lesions are fundamentally wounds undergoing repeated tissue injury and repair (ReTIAR), which progress to fibrosis through epithelial-mesenchymal transition, fibroblast-to-myofibroblast transdifferentiation, and smooth muscle metaplasia. Increasing lesional fibrosis propagates into the neighboring EMI and endometrium. The increased endometrial fibrosis, with ensuing greater tissue stiffness, results in attenuated prostaglandin E2, hypoxia signaling and glycolysis, impairing endometrial repair and causing HMB. Compared with adenomyosis-associated HMB, the mechanisms underlying adenomyosis-associated pain are less understood but presumably involve increased uterine contractility, hyperinnervation, increased lesional production of pain mediators, and central sensitization. Viewed through the prism of ReTIAR, a new imaging technique can be used to diagnose adenomyosis more accurately and informatively and possibly help to choose the best treatment modality.

Changing prostaglandin E2 (PGE2) signaling during lesional progression and exacerbation of endometriosis by inhibition of PGE2 receptor EP2 and EP4

Purpose

We investigated the change, if any, in prostaglandin E2 (PGE₂) signaling in endometriotic lesions of different developmental stages in mouse. In addition, we evaluated the effect of treatment of mice with induced deep endometriosis (DE) with inhibitors of PGE₂ receptor subtypes EP2 and EP4 and metformin.

Methods

Three mouse experimentations were conducted. In Experiment 1, female Balb/C mice were induced with endometriosis or DE and were serially sacrificed after induction. Experiments 2 and 3 evaluated the effect of treatment with EP2 and EP4 inhibitors and metformin, respectively, in mice with induced DE. Immunohistochemistry analysis of COX-2, EP2, and EP4, along with the extent of lesional fibrosis, was evaluated.

Results

The immunostaining of COX-2, EP2, and EP4 turned from activation to a stall as lesions progressed. Treatment with EP2/EP4 inhibitors in DE mice exacerbated endometriosis-associated hyperalgesia and promoted fibrogenesis in lesions even though it suppressed the PGE₂ signaling dose-dependently. In contrast, treatment with metformin resulted in increased PGE₂ signaling, concomitant with improved hyperalgesia, and retarded lesional fibrogenesis.

Conclusions

The PGE₂ signaling diminishes as endometriotic lesions progress. Treatment with EP2/EP4 inhibitors in DE mice exacerbates endometriosis, but metformin appears to be promising seemingly through the induction of the PGE₂ signaling.

Higher fibrotic content of endometriotic lesions is associated with diminished prostaglandin E2 signaling

Purpose

While the prevailing view holds that the prostaglandin E2 (PGE₂) signaling plays a vital role in endometriosis, PGE₂ also is known to be anti-fibrotic. We investigated the immunostaining of COX-2, EP2, and EP4, along with fibrotic content in ovarian endometrioma (OE) and deep endometriosis (DE) lesions, and in OE lesions from adolescent and adult patients. In addition, we evaluated the effect of substrate stiffness on the expression of COX-2, EP2, and EP4 in endometrial stromal cells.

Methods

Immunohistochemistry analysis of COX-2, EP2, and EP4, along with the quantification of lesional fibrosis, was conducted for OE and DE lesion samples and also OE lesion samples from adolescent and adult patients. The effect of substrate rigidity on fibroblast-to-myofibroblast transdifferentiation (FMT) and the expression of COX-2, EP2, and EP4, with or without TGF-β1 stimulation, were investigated.

Results

The immunostaining of COX-2, EP2, and EP4 was substantially reduced in endometriotic lesions as lesions became more fibrotic. Both TGF-β1 stimulation and stiff substrates induced FMT and reduced the expression of COX-2, EP2, and EP4.

Conclusions

Since fibrosis is a common feature of endometriosis, our results thus cast doubts on the use of therapeutics that suppresses the PGE₂ signaling pathway, either by inhibiting COX-2 or EP2/EP4.

Platelets and Regulatory T Cells May Induce a Type 2 Immunity That Is Conducive to the Progression and Fibrogenesis of Endometriosis

Endometriosis is a hormonal disease, as well as a chronic inflammatory disease. While various immune cells are documented to be involved in endometriosis, there is a wanton lack of a bigger picture on how these cells are coordinated to work concertedly. Since endometriotic lesions experience cyclical bleeding, they are fundamentally wounds that undergo repeated tissue injury and repair (ReTIAR). In this study, we attempted to characterize the role of platelets and regulatory T cells (Tregs) in modulating the lesional immune microenvironment and its subsequent effects on lesional progression and fibrogenesis. Through two mouse experiments, we show that, by disrupting predominantly a type 2 immune response in lesional microenvironment, both platelets and Tregs depletion decelerated lesional progression and fibrogenesis, likely through the suppression of the TGF-β1/Smad3 and PDGFR-β/PI3K/Akt signaling pathways. In particular, platelet depletion resulted in significantly reduced lesional expression of thymic stromal lymphopoietin (TSLP), leading to reduced aggregation of macrophages and alternatively activated (M2) macrophages, and of Tregs, T helper 2 (Th2) and Th17 cells but increased aggregation of Th1 cells, in lesions, which, in turn, yields retarded fibrogenesis. Similarly, Tregs depletion resulted in suppression of platelet aggregation, and reduced aggregation of M2 macrophages, Th2 and Th17 cells but increased aggregation of Th1 cells, in lesions. Thus, both platelet and Tregs depletion decelerated lesional progression and fibrogenesis by disrupting predominantly a type 2 immunity in lesional microenvironment. Taken together, this suggests that both platelets and Tregs may induce a type 2 immunity in lesional microenvironment that is conducive to lesional progression and fibrogenesis.

Mesothelial Cells Participate in Endometriosis Fibrogenesis Through Platelet-Induced Mesothelial-Mesenchymal Transition

CONTEXT

While fibrosis in endometriosis has recently loomed prominently, the sources of myofibroblasts, the principal effector cell in fibrotic diseases, remain largely obscure. Mesothelial cells (MCs) can be converted into myofibroblasts through mesothelial-mesenchymal transition (MMT) in many fibrotic diseases and adhesion.

OBJECTIVE

To evaluate whether MCs contribute to the progression and fibrogenesis in endometriosis through MMT.

SETTING, DESIGN, PATIENTS, INTERVENTION, AND MAIN OUTCOME MEASURES

Dual immunofluorescence staining and immunohistochemistry using antibodies against calretinin, Wilms' tumor-1 (WT-1), and α-smooth muscle actin (α-SMA) were performed on lesion samples from 30 patients each with ovarian endometrioma (OE) and deep endometriosis (DE), and 30 normal endometrial (NE) tissue samples. Human pleural and peritoneal MCs were co-cultured with activated platelets or control medium with and without neutralization of transforming growth factor β1 (TGF-β1) and/or platelet-derived growth factor receptor (PDGFR) and their morphology, proliferation, and expression levels of genes and proteins known to be involved in MMT were evaluated, along with their migratory and invasive propensity, contractility, and collagen production.

RESULTS

The number of calretinin/WT-1 and α-SMA dual-positive fibroblasts in OE/DE lesions was significantly higher than NE samples. The extent of lesional fibrosis correlated positively with the lesional α-SMA staining levels. Human MCs co-cultured with activated platelets acquire a morphology suggestive of MMT, concomitant with increased proliferation, loss of calretinin expression, and marked increase in expression of mesenchymal markers. These changes coincided with functional differentiation as reflected by increased migratory and invasive capacity, contractility, and collagen production. Neutralization of TGF-β1 and PDGFR signaling abolished platelet-induced MMT in MCs.

CONCLUSIONS

MCs contribute to lesional progression and fibrosis through platelet-induced MMT.