50 Years of Myofibroblasts: How the Myofibroblast Concept Evolved

Development and dysfunction of structural cells in eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a disorder characterized by dysfunction and chronic local inflammation of the esophagus. The incidence and prevalence of EoE are increasing worldwide. The mechanisms responsible are poorly understood, and effective treatment options are limited. From the lumen outward, the esophagus comprises stratified squamous epithelium, lamina propria, and muscle. The tissue-specific nature of EoE strongly suggests that structural cells in the esophagus are involved in the EoE diathesis. Epithelial basal cell hyperplasia and dilated intercellular spaces are cardinal features of EoE. Some patients with EoE develop lamina propria fibrosis, strictures, or esophageal muscle dysmotility. Clinical symptoms of EoE are only weakly correlated with peak eosinophil count, implying that other cell types contribute to EoE pathogenesis. Epithelial, endothelial, muscle, and fibroblast cells can each initiate inflammation and repair, regulate tissue resident immune cells, recruit peripheral leukocytes, and tailor adaptive immune cell responses. A better understanding of how structural cells maintain tissue homeostasis, respond to cell-intrinsic and cell-extrinsic stressors, and exacerbate and/or resolve inflammatory responses in the esophagus is needed. This knowledge will facilitate the development of more efficacious treatment strategies for EoE that can restore homeostasis of both hematopoietic and structural elements in the esophagus.

Neurological, cardiac, musculoskeletal, and renal manifestations of scleroderma along with insights into its genetics, pathophysiology, diagnostic, and therapeutic updates

Background

Scleroderma, also referred to as systemic sclerosis, is a multifaceted autoimmune condition characterized by abnormal fibrosis and impaired vascular function. Pathologically, it encompasses the persistent presence of inflammation, abnormal collagen buildup, and restructuring of blood vessels in various organs, resulting in a wide range of clinical symptoms. This review incorporates the most recent scientific literature on scleroderma, with a particular emphasis on its pathophysiology, clinical manifestations, diagnostic approaches, and treatment options.

Methodology

A comprehensive investigation was carried out on numerous databases, such as PubMed, MEDLINE, Scopus, Web of Science, and Google Scholar, to collect pertinent studies covering diverse facets of scleroderma research.

Results

Scleroderma presents with a range of systemic manifestations, such as interstitial lung disease, gastrointestinal dysmotility, Raynaud's phenomenon, pulmonary arterial hypertension, renal complications, neurological symptoms, and cardiac abnormalities. Serological markers, such as antinuclear antibodies, anti-centromere antibodies, and anti-topoisomerase antibodies, are important for classifying diseases and predicting their outcomes.

Discussion

The precise identification of scleroderma is crucial for promptly and correctly implementing effective treatment plans. Treatment approaches aim to improve symptoms, reduce complications, and slow down the progression of the disease. An integrated approach that combines pharmacological agents, including immunosuppressants, endothelin receptor antagonists, and prostanoids, with nonpharmacological interventions such as physical and occupational therapy is essential for maximizing patient care.

Conclusion

Through the clarification of existing gaps in knowledge and identification of emerging trends, our goal is to improve the accuracy of diagnosis, enhance the effectiveness of therapeutic interventions, and ultimately enhance the overall quality of life for individuals suffering from scleroderma. Ongoing cooperation and creative research are necessary to advance the field and achieve improved patient outcomes and new therapeutic discoveries.

Impact of TRP Channels on Extracellular Matrix Remodeling: Focus on TRPV4 and Collagen

Disturbed remodeling of the extracellular matrix (ECM) is frequently observed in several high-prevalence pathologies that include fibrotic diseases of organs such as the heart, lung, periodontium, liver, and the stiffening of the ECM surrounding invasive cancers. In many of these lesions, matrix remodeling mediated by fibroblasts is dysregulated, in part by alterations to the regulatory and effector systems that synthesize and degrade collagen, and by alterations to the functions of the integrin-based adhesions that normally mediate mechanical remodeling of collagen fibrils. Cell-matrix adhesions containing collagen-binding integrins are enriched with regulatory and effector systems that initiate localized remodeling of pericellular collagen fibrils to maintain ECM homeostasis. A large cadre of regulatory molecules is enriched in cell-matrix adhesions that affect ECM remodeling through synthesis, degradation, and contraction of collagen fibrils. One of these regulatory molecules is Transient Receptor Potential Vanilloid-type 4 (TRPV4), a mechanically sensitive, Ca2+-permeable plasma membrane channel that regulates collagen remodeling. The gating of Ca2+ across the plasma membrane by TRPV4 and the consequent generation of intracellular Ca2+ signals affect several processes that determine the structural and mechanical properties of collagen-rich ECM. These processes include the synthesis of new collagen fibrils, tractional remodeling by contractile forces, and collagenolysis. While the specific mechanisms by which TRPV4 contributes to matrix remodeling are not well-defined, it is known that TRPV4 is activated by mechanical forces transmitted through collagen adhesion receptors. Here, we consider how TRPV4 expression and function contribute to physiological and pathological collagen remodeling and are associated with collagen adhesions. Over the long-term, an improved understanding of how TRPV4 regulates collagen remodeling could pave the way for new approaches to manage fibrotic lesions.

Inhibition of Integrin-Associated Kinases FAK and ILK on the In Vitro Model of Skin Wound Healing

Dermal fibroblasts are essential cells of skin tissue responsible for its normal functioning. In skin wounds, the differentiation of resident fibroblasts into myofibroblasts occurs, which is accompanied by the rearrangement of actin cytoskeleton with the expression of alpha-smooth muscle actin. This transformation is a prerequisite for a successful wound healing. At the same time, different studies indicate that extracellular matrix may be involved in regulation of this process. Since the connection between cells and matrix is provided by transmembrane integrin receptors, this work was aimed at studying the dynamics of signaling pathways associated with integrins on an in vitro model of wound healing using human skin fibroblasts. It was shown that the healing of simulated wound was accompanied by a change in the level of integrins as well as integrin-associated kinases ILK (integrin-linked kinase) and FAK (focal adhesion kinase). Pharmacological inhibition of ILK and FAK caused the suppression of p38 and Akt which proteins are involved in regulation of the actin cytoskeleton. Moreover, it resulted in an inefficient wound closure in vitro. The results of this study support the involvement of integrin-associated kinases in regulation of fibroblast-to-myofibroblast transition during wound healing.

Fibroblast Activation Protein Alpha (FAPα) in Fibrosis: Beyond a Perspective Marker for Activated Stromal Cells?

The development of tissue fibrosis is a complex process involving the interaction of multiple cell types, which makes the search for antifibrotic agents rather challenging. So far, myofibroblasts have been considered the key cell type that mediated the development of fibrosis and thus was the main target for therapy. However, current strategies aimed at inhibiting myofibroblast function or eliminating them fail to demonstrate sufficient effectiveness in clinical practice. Therefore, today, there is an unmet need to search for more reliable cellular targets to contribute to fibrosis resolution or the inhibition of its progression. Activated stromal cells, capable of active proliferation and invasive growth into healthy tissue, appear to be such a target population due to their more accessible localization in the tissue and their high susceptibility to various regulatory signals. This subpopulation is marked by fibroblast activation protein alpha (FAPα). For a long time, FAPα was considered exclusively a marker of cancer-associated fibroblasts. However, accumulating data are emerging on the diverse functions of FAPα, which suggests that this protein is not only a marker but also plays an important role in fibrosis development and progression. This review aims to summarize the current data on the expression, regulation, and function of FAPα regarding fibrosis development and identify promising advances in the area.

A Multidisciplinary Approach as a Goal for the Management of Complications in Systemic Scleroderma: A Literature Review and Case Scenario

Systemic sclerosis (also known as scleroderma) is a chronic fibrosing autoimmune disease with both skin and multisystem organ involvement. Scleroderma has the highest mortality among all rheumatic diseases. The pathophysiology mechanism of systemic sclerosis is a progressive self-amplifying process, which involves widespread microvascular damage, followed by a dysregulation of innate and adaptive immunity and inflammation and diffuse fibrosis of the skin and visceral organs. Fibrosis of internal organs is a hint for systemic sclerosis, moreover associated with interstitial lung disease (SSc-ILD) is a complex process. In order to correlate scientific data from the literature with clinical experience, we present the case of a 56-year-old woman who was diagnosed with systemic sclerosis 16 years ago. The association of numerous comorbidities characterized by a considerable level of seriousness characterizes this case: the highly extensive systemic damage, the cardiovascular impact of the illness, and the existence of severe pulmonary arterial hypertension. The systemic and clinical manifestations, respiratory functional tests, radiological features, and specific therapy are discussed.

Kinin receptors regulate skeletal muscle regeneration: differential effects for B1 and B2 receptors

OBJECTIVE AND DESIGN

After traumatic skeletal muscle injury, muscle healing is often incomplete and produces extensive fibrosis. Bradykinin (BK) reduces fibrosis in renal and cardiac damage models through the B2 receptor. The B1 receptor expression is induced by damage, and blocking of the kallikrein-kinin system seems to affect the progression of muscular dystrophy. We hypothesized that both kinin B1 and B2 receptors could play a differential role after traumatic muscle injury, and the lack of the B1 receptor could produce more cellular and molecular substrates for myogenesis and fewer substrates for fibrosis, leading to better muscle healing.

MATERIAL AND METHODS

To test this hypothesis, tibialis anterior muscles of kinin receptor knockout animals were subjected to traumatic injury. Myogenesis, angiogenesis, fibrosis, and muscle functioning were evaluated.

RESULTS

Injured B1KO mice showed a faster healing progression of the injured area with a larger amount of central nucleated fiber post-injury when compared to control mice. In addition, they exhibited higher neovasculogenic capacity, maintaining optimal tissue perfusion for the post-injury phase; had higher amounts of myogenic markers with less inflammatory infiltrate and tissue destruction. This was followed by higher amounts of SMAD7 and lower amounts of p-SMAD2/3, which resulted in less fibrosis. In contrast, B2KO and B1B2KO mice showed more severe tissue destruction and excessive fibrosis. B1KO animals had better results in post-injury functional tests compared to control animals.

CONCLUSIONS

We demonstrate that injured skeletal muscle tissues have a better repair capacity with less fibrosis in the presence of B2 receptor and absence of B1 receptor, including better performances in functional tests.

The Role of Myofibroblasts in Physiological and Pathological Tissue Repair

Myofibroblasts are the construction workers of wound healing and repair damaged tissues by producing and organizing collagen/extracellular matrix (ECM) into scar tissue. Scar tissue effectively and quickly restores the mechanical integrity of lost tissue architecture but comes at the price of lost tissue functionality. Fibrotic diseases caused by excessive or persistent myofibroblast activity can lead to organ failure. This review defines myofibroblast terminology, phenotypic characteristics, and functions. We will focus on the central role of the cell, ECM, and tissue mechanics in regulating tissue repair by controlling myofibroblast action. Additionally, we will discuss how therapies based on mechanical intervention potentially ameliorate wound healing outcomes. Although myofibroblast physiology and pathology affect all organs, we will emphasize cutaneous wound healing and hypertrophic scarring as paradigms for normal tissue repair versus fibrosis. A central message of this review is that myofibroblasts can be activated from multiple cell sources, varying with local environment and type of injury, to either restore tissue integrity and organ function or create an inappropriate mechanical environment.

The Immunological Microenvironment and the Emerging Role of Stem Cells Therapy in Peyronie's Disease: A Systematic Narrative Review

Current literature has indicated that Peyronie's disease (PD) could be initiated by microtrauma and the subsequent inflammation episodes that follow. PD could be sorted into acute or chronic status, and it can differ when selecting the clinical therapeutics. PD would cause pain and penile deformity to diseased men and impair their erectile function. Occasionally, surgical revision of the penis might be needed to correct the penile curvature. We find that there are limited effective options of intra-lesion injections for the PD plaques. By searching the databases and screening the literature with the PRISMA 2020 guideline, we observed that several preclinical studies that applied stem cell therapy in treating PD were fruitful in the acute phase. Although in the chronic phase of PD, erectile parameters were not significantly improved, and therefore, future studies might be better elevated in certain aspects, such as the sites selected for harvesting stem cells or changing the centrifugation forces. In this review, we concluded the contemporary understanding of inflammatory microenvironments in PD, the stem cell therapy in PD, and our perspectives on future studies. We concluded that there may be great potential in stem cell therapy for treating both acute and chronic phases PD.

Pathophysiology of systemic sclerosis (scleroderma)

Systemic sclerosis (scleroderma) is an autoimmune-triggered chronic fibrosing disease that affects the skin and many other organs. Its pathophysiology is complex and involves an early endothelial damage, an inflammatory infiltrate and a resulting fibrotic reaction. Based on a predisposing genetic background, an altered balance of the acquired and the innate immune system leads to the release of many cytokines and chemokines as well as autoantibodies, which induce the activation of fibroblasts with the formation of myofibroblasts and the deposition of a stiff and rigid connective tissue. A curative treatment is still not available but remarkable progress has been made in the management of organ complications. In addition, several breakthroughs in the pathophysiology have led to new therapeutic concepts. Based on these, many new compounds have been developed during the last years, which target these different pathways and offer specific therapeutic approaches.