Interleukin-1β attenuates myofibroblast formation and extracellular matrix production in dermal and lung fibroblasts exposed to transforming growth factor-β1

Interleukin-1α inhibits transforming growth factor-β1 and β2-induced extracellular matrix production, remodeling and signaling in human lung fibroblasts: Master regulator in lung mucosal repair

BACKGROUND

Lung fibroblasts play a central role in maintaining lung homeostasis and facilitating repair through the synthesis and organization of the extracellular matrix (ECM). This study investigated the cross-talk between interleukin-1 alpha (IL-1α) and transforming growth factor-β (TGF-β) signaling, two key regulators in tissue repair and fibrosis, in the context of lung fibroblast repair in the healthy lung.

RESULTS

Stimulation of lung fibroblasts with TGF-β1 and TGF-β2 induced collagen-I and fibronectin protein expression (p < 0.05), a response inhibited with co-treatment with IL-1α (p < 0.05). Additionally, TGF-β1 and TGF-β2 induced myofibroblast differentiation, and collagen-I gel contraction, which were both suppressed by IL-1α (p < 0.05). In contrast, interleukin (IL)-6, IL-8 and thymic stromal lymphopoietin induced by IL-1α, were unaffected by TGF-β1 or TGF-β2. Mechanistically, IL-1α administration led to the suppression of TGF-β1 and TGF-β2 signaling, through downregulation of mRNA and protein for TGF-β receptor II and the downstream adaptor protein TRAF6, but not through miR-146a that is known to be induced by IL-1α.

DISCUSSION

IL-1α acts as a master regulator, modulating TGF-β1 and TGF-β2-induced ECM production, remodeling, and myofibroblast differentiation in human lung fibroblasts, playing a vital role in balancing tissue repair versus fibrosis. Further research is required to understand the dysregulated cross-talk between IL-1α and TGF-β signaling in chronic lung diseases and the exploration of therapeutic opportunities.

METHODS

Primary human lung fibroblasts (PHLF) were treated with media control, or 1 ng/ml IL-1α with or without 50 ng/ml TGF-β1 or TGF-β2 for 1, 6 and 72 h. Cell lysates were assessed for the expression of ECM proteins and signaling molecules by western blot, miRNA by qPCR, mRNA by RNA sequencing and cell supernatants for cytokine production by ELISA. PHLFs were also seeded in non-tethered collagen-I gels to measure contraction, and myofibroblast differentiation using confocal microscopy.

Mitochondrial DNA mutations attenuate Bleomycin-induced dermal fibrosis by inhibiting differentiation into myofibroblasts

Post-mitotic, non-proliferative dermal fibroblasts have crucial functions in maintenance and restoration of tissue homeostasis. They are involved in essential processes such as wound healing, pigmentation and hair growth, but also tumor development and aging-associated diseases. These processes are energetically highly demanding and error prone when mitochondrial damage occurs. However, mitochondrial function in fibroblasts and the influence of mitochondrial dysfunction on fibroblast-specific demands are still unclear. To address these questions, we created a mouse model in which accelerated cell-specific mitochondrial DNA (mtDNA) damage accumulates. We crossed mice carrying a dominant-negative mutant of the mitochondrial replicative helicase Twinkle (RosaSTOP system) with mice that express fibroblast-specific Cre Recombinase (Collagen1A2 CreERT) which can be activated by Tamoxifen (TwinkleFIBRO). Thus, we are able to induce mtDNA deletions and duplications in specific cells, a process which resembles the physiological aging process in humans, where this damage accumulates in all tissues. Upon proliferation in vitro, Tamoxifen induced Twinkle fibroblasts deplete most of their mitochondrial DNA which, although not disturbing the stoichiometry of the respiratory chain complexes, leads to reduced ROS production and mitochondrial membrane potential as well as an anti-inflammatory and anti-fibrotic profile of the cells. In Sodium Azide treated wildtype fibroblasts, without a functioning respiratory chain, we observe the opposite, a rather pro-inflammatory and pro-fibrotic signature. Upon accumulation of mitochondrial DNA mutations in vivo the TwinkleFIBRO mice are protected from fibrosis development induced by intradermal Bleomycin injections. This is due to dampened differentiation of the dermal fibroblasts into α-smooth-muscle-actin positive myofibroblasts in TwinkleFIBRO mice. We thus provide evidence for striking differences of the impact that mtDNA mutations have in contrast to blunted mitochondrial function in dermal fibroblasts and skin homeostasis. These data contribute to improved understanding of mitochondrial function and dysfunction in skin and provide mechanistic insight into potential targets to treat skin fibrosis in the future.

NLRP3 inflammasome activation contributes to the development of the pro-fibrotic phenotype of lung fibroblasts

Idiopathic pulmonary fibrosis (IPF) is an irreversible progressive interstitial lung disease of unknown cause. The poorly understood pathophysiology of IPF poses substantial challenges to the development of effective anti-lung fibrotic drugs. The NLRP3 inflammasome, a key component of the innate immune system, has recently been linked to the pathogenesis of lung fibrosis. However, the specific contributions of NLRP3 inflammasomes to determination of the pro-fibrotic phenotype of lung fibroblasts, which play a central role in the production of extracellular matrix protein, remain to be investigated. Therefore, the present study was performed to elucidate the involvement of NLRP3 inflammasome signalling pathways in modulation of lung fibroblast proliferation and differentiation. We found that activation of NLRP3 inflammasomes increased in lung fibroblasts derived from individuals with pulmonary fibrosis and in normal lung fibroblasts stimulated with transforming growth factor β and platelet-derived growth factor. Importantly, blockage of NLRP3 inflammasome signalling, either by gene silencing of NLRP3 or using pharmacological inhibitors of NLRP3, caspase-1, or IL-1 receptor, inhibited the proliferation, differentiation, and extracellular matrix protein synthesis of activated lung fibroblasts. Moreover, induction of the reactive oxygen species/thioredoxin-interacting protein axis, an upstream signalling pathway of NLRP3 inflammasomes, was essential for maintenance of the pro-fibrotic phenotype of lung fibroblasts. Interestingly, treatments with pharmacological inhibitors of NLRP3 inflammasomes prevented the progression of bleomycin-induced pulmonary fibrosis in mice. Collectively, these findings suggest that aberrant activation of NLRP3 inflammasomes is a critical event in the pathogenesis of IPF and that targeting NLRP3 inflammasomes may serve as a therapeutic strategy for IPF.

Activin A Is a Master Regulator of Phenotypic Switch in Adipose Stromal Cells Initiated by Activated Immune Cell-Secreted Interleukin-1β

Prolonged tissue ischemia and inflammation lead to organ deterioration and are often accompanied by microvasculature rarefaction, fibrosis, and elevated systemic Activin A (ActA), the level of which frequently correlates with disease severity. Mesenchymal stromal cells are prevalent in the perivascular niche and are likely involved in tissue homeostasis and pathology. This study investigated the effects of inflammatory cells on modulation of phenotype of adipose mesenchymal stromal cells (ASC) and the role of ActA in this process. Peripheral blood mononuclear cells were activated with lipopolysaccharide (activated peripheral blood mononuclear cells [aPBMC]) and presented to ASC. Expression of smooth muscle/myofibroblast markers, ActA, transforming growth factors beta 1-3 (TGFβ1-3), and connective tissue growth factor (CTGF) was assessed in ASC. Silencing approaches were used to dissect the signaling cascade of aPBMC-induced acquisition of myofibroblast phenotype by ASC. ASC cocultured with aPBMC or exposed to the secretome of aPBMC upregulated smooth muscle cell markers alpha smooth muscle actin (αSMA), SM22α, and Calponin I; increased contractility; and initiated expression of ActA. Interleukin (IL)-1β was sufficient to replicate this response, whereas blocking IL-1β eliminated aPBMC effects. ASC-derived ActA stimulated CTGF and αSMA expression in ASC; the latter independent of CTGF. Induction of αSMA in ASC by IL-1β or ActA-enriched media relied on extracellular enzymatic activity. ActA upregulated mRNA levels of several extracellular matrix proteins in ASC, albeit to a lesser degree than TGFβ1, and marginally increased cell contractility. In conclusion, the study suggests that aPBMC induce myofibroblast phenotype with weak fibrotic activity in perivascular progenitors, such as ASC, through the IL-1β-ActA signaling axis, which also promotes CTGF secretion, and these effects require ActA extracellular enzymatic processing.

Mini review on collagens in normal skin and pathological scars: current understanding and future perspective

Pathological scar tissues are characterized by the presence of overabundant collagens whose structure and organization are also different from those in unwounded skin. This causes scar tissues to lose some functions performed by normal skin, and currently, there are no effective measures to prevent scar formation. Inflammation has been shown to modulate fibroblast proliferation, differentiation, and function, hence collagen production and organization. In this minireview, we provide an overview of the current understanding of collagen, specifically collagen type I and III which are main collagens in skin, structure and fibre formation and highlight their differences between normal skin and pathological scars. We discuss the role that cytokines play in modulating fibroblast function. We also identify some potential research directions which could help to further our understanding of the complex and dynamic wound healing and scar formation process.

Cell Cross-Talk in Alveolar Microenvironment: From Lung Injury to Fibrosis

Alveoli are complex microenvironments composed of various cell types, including epithelial, fibroblast, endothelial, and immune cells, which work together to maintain a delicate balance in the lung environment, ensuring proper growth, development, and an effective response to lung injuries. However, prolonged inflammation or aging can disrupt normal interactions among these cells, leading to impaired repair processes and a substantial decline in lung function. Therefore, it is essential to understand the key mechanisms underlying the interactions among the major cell types within the alveolar microenvironment. We explored the key mechanisms underlying the interactions among the major cell types within the alveolar microenvironment. These interactions occur through the secretion of signaling factors and play crucial roles in the response to injury, repair mechanisms, and the development of fibrosis in the lungs. Specifically, we focused on the regulation of alveolar type 2 cells by fibroblasts, endothelial cells, and macrophages. In addition, we explored the diverse phenotypes of fibroblasts at different stages of life and in response to lung injury, highlighting their impact on matrix production and immune functions. Furthermore, we summarize the various phenotypes of macrophages in lung injury and fibrosis as well as their intricate interplay with other cell types. This interplay can either contribute to the restoration of immune homeostasis in the alveoli or impede the repair process. Through a comprehensive exploration of these cell interactions, we aim to reveal new insights into the molecular mechanisms that drive lung injury toward fibrosis and identify potential targets for therapeutic intervention.

Glycyrrhetinic acid loaded in milk-derived extracellular vesicles for inhalation therapy of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and life-threatening lung disease for which treatment options are limited. Glycyrrhetinic acid (GA) is a triterpenoid with multiple biological effects, such as anti-inflammatory and anti-fibrotic properties. Herein, inhalable milk-derived extracellular vesicles (mEVs) encapsulating GA (mEVs@GA) were screened and evaluated for IPF treatment. The results indicated that the loading efficiency of GA in mEVs@GA was 8.65%. Therapeutic effects of inhalable mEVs@GA were investigated in vitro and in vivo. The mEVs@GA demonstrated superior anti-inflammatory effects on LPS-stimulated MHS cells. Furthermore, repeated noninvasive inhalation delivery of mEVs@GA in bleomycin-induced IPF mice could decrease the levels of transforming growth factors β1 (TGF-β1), Smad3 and inflammatory cytokines IL-6, IL-1β and TNF-α. The mEVs@GA effectively diminished the development of fibrosis and improved pulmonary function in the IPF mice model at a quarter of the dose compared with the pirfenidone oral administration group. Additionally, compared to pirfenidone-loaded mEVs, mEVs@GA demonstrated superior efficacy at the same drug concentration in the pharmacodynamic study. Overall, inhaled mEVs@GA have the potential to serve as an effective therapeutic option in the treatment of IPF.

Macrophage phenotype is determinant for fibrosis development in keloid disease

Keloid refers to a fibroproliferative disorder characterized by an accumulation of extracellular matrix (ECM) components at the dermis level, overgrowth beyond initial wound, and formation of tumor-like nodule areas. Treating keloid is still an unmet clinical need and the lack of an efficient therapy is clearly related to limited knowledge about keloid etiology, despite the growing interest of the scientific community in this pathology. In past decades, keloids were often studied in vitro through the sole prism of fibroblasts considered as the major effector of ECM deposition. Nevertheless, development of keloids results from cross-interactions of keloid fibroblasts (KFs) and their surrounding microenvironment, including immune cells such as macrophages. Our study aimed to evaluate the effect of M1 and M2 monocyte-derived macrophages on KFs in vitro. We focused on the effects of the macrophage secretome on fibrosis-related criteria in KFs, including proliferation, migration, differentiation, and ECM synthesis. First, we demonstrated that M2-like macrophages enhanced the fibrogenic profile of KFs in culture. Then, we surprisingly founded that M1-like macrophages can have an anti-fibrogenic effect on KFs, even in a pro-fibrotic environment. These results demonstrate, for the first time, that M1 and M2 macrophage subsets differentially impact the fibrotic fate of KFs in vitro, and suggest that restoring the M1/M2 balance to favor M1 in keloids could be an efficient therapeutic lever to prevent or treat keloid fibrosis.

AMPK signaling inhibits the differentiation of myofibroblasts: impact on age-related tissue fibrosis and degeneration

Disruption of the extracellular matrix (ECM) and an accumulation of fibrotic lesions within tissues are two of the distinctive hallmarks of the aging process. Tissue fibroblasts are mesenchymal cells which display an impressive plasticity in the regulation of ECM integrity and thus on tissue homeostasis. Single-cell transcriptome studies have revealed that tissue fibroblasts exhibit a remarkable heterogeneity with aging and in age-related diseases. Excessive stress and inflammatory insults induce the differentiation of fibroblasts into myofibroblasts which are fusiform contractile cells and abundantly secrete the components of the ECM and proteolytic enzymes as well as many inflammatory mediators. Detrimental stresses can also induce the transdifferentiation of certain mesenchymal and myeloid cells into myofibroblasts. Interestingly, many age-related stresses, such as oxidative and endoplasmic reticulum stresses, ECM stiffness, inflammatory mediators, telomere shortening, and several alarmins from damaged cells are potent inducers of myofibroblast differentiation. Intriguingly, there is convincing evidence that the signaling pathways stimulated by the AMP-activated protein kinase (AMPK) are potent inhibitors of myofibroblast differentiation and accordingly AMPK signaling reduces fibrotic lesions within tissues, e.g., in age-related cardiac and pulmonary fibrosis. AMPK signaling is not only an important regulator of energy metabolism but it is also able to control cell fate determination and many functions of the immune system. It is known that AMPK signaling can delay the aging process via an integrated signaling network. AMPK signaling inhibits myofibroblast differentiation, e.g., by suppressing signaling through the TGF-β, NF-κB, STAT3, and YAP/TAZ pathways. It seems that AMPK signaling can alleviate age-related tissue fibrosis and degeneration by inhibiting the differentiation of myofibroblasts.

Inhibiting JAK1, not NF-κB, reverses the effect of pro-inflammatory cytokines on engineered human ligament function

The role of inflammation in chronic tendon/ligament injury is hotly debated. There is less debate about inflammation following acute injury. To better understand the effect of acute inflammation, in this study we developed a multi-cytokine model of inflammatory tendinitis. The combined treatment with TNF-α, IL-1β, and IL-6, at dosages well below what are routinely used in vitro, decreased the mechanical properties and collagen content of engineered human ligaments. Treatment with this cytokine mixture resulted in an increase in phospho-NF-κB and MMP-1, did not affect procollagen production, and decreased STAT3 phosphorylation relative to controls. Using this more physiologically relevant model of acute inflammation, we inhibited NF-κB or JAK1 signaling in an attempt to reverse the negative effects of the cytokine mixture. Surprisingly, NF-κB inhibition led to an even greater decrease in mechanical function and collagen content. By contrast, inhibiting JAK1 led to an increase in mechanical properties, collagen content and thermal stability concomitant with a decrease in MMP-1. Our results suggest that inhibition of JAK1, not NF-κB, reverses the negative effects of pro-inflammatory cytokines on collagen content and mechanics in engineered human ligaments.

Roles of lipid metabolism and its regulatory mechanism in idiopathic pulmonary fibrosis: A review

Idiopathic pulmonary fibrosis is a progressive lung disease of unknown etiology characterized by distorted distal lung architecture, inflammation, and fibrosis. Several lung cell types, including alveolar epithelial cells and fibroblasts, have been implicated in the development and progression of fibrosis. However, the pathogenesis of idiopathic pulmonary fibrosis is still incompletely understood. The latest research has found that dysregulation of lipid metabolism plays an important role in idiopathic pulmonary fibrosis. The changes in the synthesis and activity of fatty acids, cholesterol and other lipids seriously affect the regenerative function of alveolar epithelial cells and promote the transformation of fibroblasts into myofibroblasts. Mitochondrial function is the key to regulating the metabolic needs of a variety of cells, including alveolar epithelial cells. Sirtuins located in mitochondria are essential to maintain mitochondrial function and cellular metabolic homeostasis. Sirtuins can maintain normal lipid metabolism by regulating respiratory enzyme activity, resisting oxidative stress, and protecting mitochondrial function. In this review, we aimed to discuss the difference between normal and idiopathic pulmonary fibrosis lungs in terms of lipid metabolism. Additionally, we highlight recent breakthroughs on the effect of abnormal lipid metabolism on idiopathic pulmonary fibrosis, including the effects of sirtuins. Idiopathic pulmonary fibrosis has its high mortality and limited therapeutic options; therefore, we believe that this review will help to develop a new therapeutic direction from the aspect of lipid metabolism in idiopathic pulmonary fibrosis.

Clinical and laboratory characterization of patients with localized scleroderma and response to UVA-1 phototherapy: In vivo and in vitro skin models

BACKGROUND/PURPOSE

Localized scleroderma (LS) is a rare disease leading to progressive hardening and induration of the skin and subcutaneous tissues. LS is responsive to UVA-1 phototherapy, though its exact mechanism of action dermal fibrosis is yet to be fully elucidated. We aimed to investigate the molecular changes induced by UVA-1 rays in human primary fibroblasts cultures.

METHODS

A total of 16 LS patients were treated with medium-dose UVA-1 phototherapy. At baseline, during and after therapy, Localized Scleroderma Assessment Tool, Dermatology Life Quality Index and lesions' staging and mapping were performed along with high-frequency ultrasound (HFUS) examination for dermal thickness assessment. Gene expression analysis for 23 mRNA transcripts, in vitro UVA-1 irradiation and viability tests were realized on lesional fibroblasts' primary cultures, before and 3 months after therapy.

RESULTS

The dermal thickness, the LoSCAT and the DLQI progressively decreased starting from the last phototherapy session up to the 6 and 9 month follow-ups (-57% and -60%, respectively). Molecular gene analysis (rt-PCR) revealed that UVA-1 phototherapy exerts multiple effects: the activation of specific anti-fibrotic pathways (e.g., overexpression of CTHRC1 and metalloproteases 1, 2, 7, 8, 9, 12, suppression of TIMP-1), the downregulation of peculiar pro-fibrotic pathways (e.g., downregulation of TGF-ß, TGF-ßrII, Grb2, SMAD 2/3, TNRSF12A, CTGF) through a significant overexpression of IL-1ß; the stabilization of collagen synthesis acting on genes COL1A1, COL3A1, COL8A1, COL10A1, COL12A1.

CONCLUSION

UVA-1 phototherapy adds significant benefits in local tissue remodeling, rebalancing the alteration between pro-fibrotic and anti-fibrotic pathways; these changes can be well monitored by HFUS.

An open microfluidic coculture model of fibroblasts and eosinophils to investigate mechanisms of airway inflammation

Interactions between fibroblasts and immune cells play an important role in tissue inflammation. Previous studies have found that eosinophils activated with interleukin-3 (IL-3) degranulate on aggregated immunoglobulin G (IgG) and release mediators that activate fibroblasts in the lung. However, these studies were done with eosinophil-conditioned media that have the capacity to investigate only one-way signaling from eosinophils to fibroblasts. Here, we demonstrate a coculture model of primary normal human lung fibroblasts (HLFs) and human blood eosinophils from patients with allergy and asthma using an open microfluidic coculture device. In our device, the two types of cells can communicate via two-way soluble factor signaling in the shared media while being physically separated by a half wall. Initially, we assessed the level of eosinophil degranulation by their release of eosinophil-derived neurotoxin (EDN). Next, we analyzed the inflammation-associated genes and soluble factors using reverse transcription quantitative polymerase chain reaction (RT-qPCR) and multiplex immunoassays, respectively. Our results suggest an induction of a proinflammatory fibroblast phenotype of HLFs following the coculture with degranulating eosinophils, validating our previous findings. Additionally, we present a new result that indicate potential impacts of activated HLFs back on eosinophils. This open microfluidic coculture platform provides unique opportunities to investigate the intercellular signaling between the two cell types and their roles in airway inflammation and remodeling.

The Inflammasome NLR Family Pyrin Domain-Containing Protein 3 (NLRP3) as a Novel Therapeutic Target for Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a dramatic disease without cure. The US Food and Drug Administration-approved drugs, pirfenidone and nintedanib, only slow disease progression. The clinical investigation of novel therapeutic approaches for IPF is an unmet clinical need. Nucleotide-binding oligomerization domain-like receptor or NOD-like receptors are pattern recognition receptors capable of binding a large variety of stress factors. NLR family pyrin domain-containing protein 3 (NLRP3), once activated, promotes IL-1β, IL-18 production, and innate immune responses. Multiple reports indicate that the inflammasome NLRP3 is overactivated in IPF patients, leading to increased production of class I IL and collagens. Similarly, data from animal models of pulmonary fibrosis confirm the role of NLRP3 in the development of chronic lung injury and pulmonary fibrosis. This report provides a review of the evidence of NLRP3 activation in IPF and of NLRP3 inhibition in different animal models of fibrosis, and highlights the recent advances in direct and indirect NLRP3 inhibitors.

The Mechanism and Regulation of the NLRP3 Inflammasome during Fibrosis

Fibrosis is often the end result of chronic inflammation. It is characterized by the excessive deposition of extracellular matrix. This leads to structural alterations in the tissue, causing permanent damage and organ dysfunction. Depending on the organ it effects, fibrosis can be a serious threat to human life. The molecular mechanism of fibrosis is still not fully understood, but the NLRP3 (NOD-, LRR- and pyrin–domain–containing protein 3) inflammasome appears to play a significant role in the pathogenesis of fibrotic disease. The NLRP3 inflammasome has been the most extensively studied inflammatory pathway to date. It is a crucial component of the innate immune system, and its activation mediates the secretion of interleukin (IL)-1β and IL-18. NLRP3 activation has been strongly linked with fibrosis and drives the differentiation of fibroblasts into myofibroblasts by the chronic upregulation of IL-1β and IL-18 and subsequent autocrine signaling that maintains an activated inflammasome. Both IL-1β and IL-18 are profibrotic, however IL-1β can have antifibrotic capabilities. NLRP3 responds to a plethora of different signals that have a common but unidentified unifying trigger. Even after 20 years of extensive investigation, regulation of the NLRP3 inflammasome is still not completely understood. However, what is known about NLRP3 is that its regulation and activation is complex and not only driven by various activators but controlled by numerous post-translational modifications. More recently, there has been an intensive attempt to discover NLRP3 inhibitors to treat chronic diseases. This review addresses the role of the NLRP3 inflammasome in fibrotic disorders across many different tissues. It discusses the relationships of various NLRP3 activators to fibrosis and covers different therapeutics that have been developed, or are currently in development, that directly target NLRP3 or its downstream products as treatments for fibrotic disorders.

Study of Interleukin-1Beta Expression in Acne Vulgaris and Acne Scars

BACKGROUND

Acne vulgaris is a multifactorial disease that mostly heals by scarring. Interleukin-1 beta (IL-1β) is a proinflammatory cytokine, suggested to play a key role in acne pathogenesis.

OBJECTIVE

To study the immunohistochemical (IHC) expression of IL1β in acne vulgaris and acne scars to evaluate its possible role in their pathogenesis and to study the relation between expression of IL1β and the clinicopathological parameters.

PATIENTS AND METHODS

This study was conducted on sixty subjects (twenty patients with acne vulgaris and twenty patients with acne scars), and twenty healthy volunteers as controls. Skin biopsies were taken from patients and controls for routine histopathological examination with Hematoxylin and Eosin (H&E) stain and IHC staining of IL-1β.

RESULTS

There was a statistically significant increase in expression of IL-1β in acne vulgaris compared to post-acne scars and controls, (p<0.001) for both. IL-1β expression was significantly positively correlated with both clinical severity of acne vulgaris (p=0.022) and severity of histopathological inflammation (p=0.011).

CONCLUSION

IL-1β expression was associated with acne vulgaris and post acne scars with significant positive correlation to clinical and histopathological severity of acne vulgaris. Thus IL-1β could be a key player cytokine in acne pathogenesis, its severity and development of post acne scars.

Therapeutic and diagnostic targeting of fibrosis in metabolic, proliferative and viral disorders

Fibrosis is a common denominator in many pathologies and crucially affects disease progression, drug delivery efficiency and therapy outcome. We here summarize therapeutic and diagnostic strategies for fibrosis targeting in atherosclerosis and cardiac disease, cancer, diabetes, liver diseases and viral infections. We address various anti-fibrotic targets, ranging from cells and genes to metabolites and proteins, primarily focusing on fibrosis-promoting features that are conserved among the different diseases. We discuss how anti-fibrotic therapies have progressed over the years, and how nanomedicine formulations can potentiate anti-fibrotic treatment efficacy. From a diagnostic point of view, we discuss how medical imaging can be employed to facilitate the diagnosis, staging and treatment monitoring of fibrotic disorders. Altogether, this comprehensive overview serves as a basis for developing individualized and improved treatment strategies for patients suffering from fibrosis-associated pathologies.

Comparison of Cellular Responses to TGF-β1 and BMP-2 Between Healthy and Torn Tendons

BACKGROUND

Tendons heal by fibrotic repair, increasing the likelihood of reinjury. Animal tendon injury and overuse models have identified transforming growth factor beta (TGF-β) and bone morphogenetic proteins (BMPs) as growth factors actively involved in the development of fibrosis, by mediating extracellular matrix synthesis and cell differentiation.

PURPOSE

To understand how TGF-β and BMPs contribute to fibrotic processes using tendon-derived cells isolated from healthy and diseased human tendons.

STUDY DESIGN

Controlled laboratory study.

METHODS

Tendon-derived cells were isolated from patients with a chronic rotator cuff tendon tear (large to massive, diseased) and healthy hamstring tendons of patients undergoing anterior cruciate ligament repair. Isolated cells were incubated with TGF-β1 (10 ng/mL) or BMP-2 (100 ng/mL) for 3 days. Gene expression was measured by real-time quantitative polymerase chain reaction. Cell signaling pathway activation was determined by Western blotting.

RESULTS

TGF-β1 treatment induced ACAN mRNA expression in both cell types but less in the diseased compared with healthy cells (P < .05). BMP-2 treatment induced BGN mRNA expression in healthy but not diseased cells (P < .01). In the diseased cells, TGF-β1 treatment induced increased ACTA2 mRNA expression (P < .01) and increased small mothers against decapentaplegic (SMAD) signaling (P < .05) compared with those of healthy cells. Moreover, BMP-2 treatment induced ACTA2 mRNA expression in the diseased cells only (P < .05).

CONCLUSION

Diseased tendon-derived cells show reduced expression of the proteoglycans aggrecan and biglycan in response to TGF-β1 and BMP-2 treatments. These same treatments induced enhanced fibrotic differentiation and canonical SMAD cell signaling in diseased compared with healthy cells.

CLINICAL RELEVANCE

Findings from this study suggest that diseased tendon-derived cells respond differently than healthy cells in the presence of TGF-β1 and BMP-2. The altered responses of diseased cells may influence fibrotic repair processes during tendon healing.

Cytokine-mediated induction of human xylosyltransferase-I in systemic sclerosis skin fibroblasts

Systemic sclerosis (SSc) is an inflammatory fibrotic disease characterized by an excessive extracellular matrix deposition in the skin and internal organs. One fibrotic key event remains the fibroblast-to-myofibroblast differentiation that is controlled by a combination of mechanical and soluble factors, such as transforming growth factor-β1 (TGF-β1) and interleukin-1β (IL-1β). One important myofibroblast biomarker is human xylosyltransferase-I (XT-I), the initial enzyme in proteoglycan biosynthesis. Increased serum XT activity was quantified in SSc, but the underlying cellular mechanisms remain elusive. This study aims to determine the cellular basis of XT-I induction in SSc by using a myofibroblast cell culture model with SSc fibroblasts (SScF) and healthy control fibroblasts. We found that SScF exhibit a higher extracellular XT-I activity compared to control fibroblasts. This increased XT-I activity in SScF was demonstrated to be mediated by an enhanced autocrine TGF-β signaling. Upon IL-1β treatment, SScF showed an increased mRNA expression level of XT-I and TGF-β receptor II (TGFBR2), while healthy control fibroblasts did not, pointing towards an involvement of IL-1β in the cytokine-mediated XT-I induction. Performing microRNA (miRNA) inhibition experiments in the presence of TGF-β1, we showed that the pro-fibrotic effect of IL-1β may be mediated by a miRNA-21/TGF-β receptor II axis, enhancing the autocrine TGF-β signaling in SScF. Taken together, this study improves the mechanistic understanding of fibrotic XT-I induction in SSc by identifying a hitherto unknown IL-1β-mediated miRNA-21/TGFBR2 regulation contributing to the enhanced XYLT1 expression and XT-I activity in SScF.

Albumin inhibits the nuclear translocation of Smad3 via interleukin-1beta signaling in hepatic stellate cells

Activation of quiescent hepatic stellate cells (HSCs) to myofibroblasts plays a key role in liver fibrosis. We had previously shown that albumin and its derivative, R-III (a retinol-binding protein—albumin domain III fusion protein), inhibited HSC activation by sequestering retinoic acid (RA) and that R-III administration reduced carbon tetrachloride (CCl₄)-induced liver fibrosis. In this study, we aimed to elucidate the mechanism of action of albumin downstream of RA sequestration. Nuclear factor-κB p65 was evenly distributed in the cytoplasm in activated mouse HSCs, whereas albumin expression or R-III treatment (albumin/R-III) caused the nuclear translocation of p65, probably via RA sequestration, resulting in a dramatic increase in interleukin-1beta (IL-1β) expression. Albumin/R-III in turn induced the phosphorylation of Smad3 at the linker region, inhibiting its nuclear import in an IL-1β-dependent manner. Consistent with the in vitro results, the level of IL-1β mRNA expression was higher in CCl₄/R-III-treated livers than in CCl₄-treated livers. These findings reveal that albumin/R-III inhibits the transforming growth factor-β-Smad3 signaling as well as the retinoic acid receptor-mediated pathway, which probably contributes to the inhibition of HSC activation, and suggest that R-III may be an anti-fibrotic drug candidate.

Pro-inflammatory cytokines suppress HYBID (hyaluronan (HA) -binding protein involved in HA depolymerization/KIAA1199/CEMIP) -mediated HA metabolism in human skin fibroblasts

In the skin, the metabolism of hyaluronan (HA) is highly regulated. Aging leads to chronic low-grade inflammation, which is characterized by elevated levels of pro-inflammatory cytokines; however, the relationship between inflammation and HA metabolism is not clear. Herein, we investigated the effects of a mixture of pro-inflammatory cytokines containing TNF-α, IL-1β, and IL-6 on HA metabolism in human skin fibroblasts. Treatment with the cytokine mixture for 24 h suppressed HA depolymerization via downregulation of HYBID (HA-binding protein involved in HA depolymerization/KIAA1199/CEMIP) and promoted HA synthesis via upregulation of HAS2 in human skin fibroblasts. Moreover, HAS2-dependent HA synthesis was driven mainly by IL-1β with partial contribution from TNF-α. Transmembrane protein 2 (TMEM2/CEMIP2), which was previously reported as a candidate hyaluronidase, was upregulated by the cytokine mixture, suggesting that TMEM2 might not function as a hyaluronidase in human skin fibroblasts. Furthermore, the effects of the cytokine mixture on HA metabolism were observed in fibroblasts after 8 days of treatment with cytokines during three passages. Thus, we have shown that HYBID-mediated HA metabolism is negatively regulated by the pro-inflammatory cytokine mixture, providing novel insights into the relationship between inflammation and HA metabolism in the skin.

Interleukin-1β Modulation of the Mechanobiology of Primary Human Pulmonary Fibroblasts: Potential Implications in Lung Repair

Pro-inflammatory cytokines like interleukin-1β (IL-1β) are upregulated during early responses to tissue damage and are expected to transiently compromise the mechanical microenvironment. Fibroblasts are key regulators of tissue mechanics in the lungs and other organs. However, the effects of IL-1β on fibroblast mechanics and functions remain unclear. Here we treated human pulmonary fibroblasts from control donors with IL-1β and used Atomic Force Microscopy to unveil that IL-1β significantly reduces the stiffness of fibroblasts concomitantly with a downregulation of filamentous actin (F-actin) and alpha-smooth muscle (α-SMA). Likewise, COL1A1 mRNA was reduced, whereas that of collagenases MMP1 and MMP2 were upregulated, favoring a reduction of type-I collagen. These mechanobiology changes were functionally associated with reduced proliferation and enhanced migration upon IL-1β stimulation, which could facilitate lung repair by drawing fibroblasts to sites of tissue damage. Our observations reveal that IL-1β may reduce local tissue rigidity by acting both intracellularly and extracellularly through the downregulation of fibroblast contractility and type I collagen deposition, respectively. These IL-1β-dependent mechanical effects may enhance lung repair further by locally increasing pulmonary tissue compliance to preserve normal lung distension and function. Moreover, our results support that IL-1β provides innate anti-fibrotic protection that may be relevant during the early stages of lung repair.

Inflammatory Responses in Oro-Maxillofacial Region Expanded Using Anisotropic Hydrogel Tissue Expander

OBJECTIVE

Reconstruction of oral and facial defects often necessitate replacement of missing soft tissue. The purpose of tissue expanders is to grow healthy supplementary tissue under a controlled force. This study investigates the inflammatory responses associated with the force generated from the use of anisotropic hydrogel tissue expanders.

METHODS

Sprague Dawley rats (n = 7, body weight = 300 g ± 50 g) were grouped randomly into two groups-control (n = 3) and expanded (n = 4). Anisotropic hydrogel tissue expanders were inserted into the frontal maxillofacial region of the rats in the expanded group. The rats were sacrificed, and skin samples were harvested, fixed in formalin, and embedded in paraffin wax for histological investigation. Hematoxylin and eosin staining was performed to detect histological changes between the two groups and to investigate the inflammatory response in the expanded samples. Three inflammatory markers, namely interleukin (IL)-1α, IL-6, and tumor necrosis factor-α (TNF-α), were analyzed by immunohistochemistry.

RESULT

IL-1-α expression was only observed in the expanded tissue samples compared to the controls. In contrast, there was no significant difference in IL-6, and TNF-α production. Histological analysis showed the absence of inflammatory response in expanded tissues, and a negative non-significant correlation (Spearman's correlation coefficient) between IL-1-α immune-positive cells and the inflammatory cells (r = -0.500). In conclusion, tissues that are expanded and stabilized using an anisotropic self-inflating hydrogel tissue expander might be useful for tissue replacement and engraftment as the expanded tissue does not show any sign of inflammatory responses. Detection of IL-1-α in the expanded tissues warrants further investigation for its involvement without any visible inflammatory response.

Emerging therapies for right ventricular dysfunction and failure

Therapeutic options for right ventricular (RV) dysfunction and failure are strongly limited. Right heart failure (RHF) has been mostly addressed in the context of pulmonary arterial hypertension (PAH), where it is not possible to discern pulmonary vascular- and RV-directed effects of therapeutic approaches. In part, opposing pathomechanisms in RV and pulmonary vasculature, i.e., regarding apoptosis, angiogenesis and proliferation, complicate addressing RHF in PAH. Therapy effective for left heart failure is not applicable to RHF, e.g., inhibition of adrenoceptor signaling and of the renin-angiotensin system had no or only limited success. A number of experimental studies employing animal models for PAH or RV dysfunction or failure have identified beneficial effects of novel pharmacological agents, with most promising results obtained with modulators of metabolism and reactive oxygen species or inflammation, respectively. In addition, established PAH agents, in particular phosphodiesterase-5 inhibitors and soluble guanylate cyclase stimulators, may directly address RV integrity. Promising results are furthermore derived with microRNA (miRNA) and long non-coding RNA (lncRNA) blocking or mimetic strategies, which can target microvascular rarefaction, inflammation, metabolism or fibrotic and hypertrophic remodeling in the dysfunctional RV. Likewise, pre-clinical data demonstrate that cell-based therapies using stem or progenitor cells have beneficial effects on the RV, mainly by improving the microvascular system, however clinical success will largely depend on delivery routes. A particular option for PAH is targeted denervation of the pulmonary vasculature, given the sympathetic overdrive in PAH patients. Finally, acute and durable mechanical circulatory support are available for the right heart, which however has been tested mostly in RHF with concomitant left heart disease. Here, we aim to review current pharmacological, RNA- and cell-based therapeutic options and their potential to directly target the RV and to review available data for pulmonary artery denervation and mechanical circulatory support.

Microengineered 3D pulmonary interstitial mimetics highlight a critical role for matrix degradation in myofibroblast differentiation

Fibrosis, characterized by aberrant tissue scarring from activated myofibroblasts, is often untreatable. Although the extracellular matrix becomes increasingly stiff and fibrous during disease progression, how these physical cues affect myofibroblast differentiation in 3D is poorly understood. Here, we describe a multicomponent hydrogel that recapitulates the 3D fibrous structure of interstitial tissue regions where idiopathic pulmonary fibrosis (IPF) initiates. In contrast to findings on 2D hydrogels, myofibroblast differentiation in 3D was inversely correlated with hydrogel stiffness but positively correlated with matrix fibers. Using a multistep bioinformatics analysis of IPF patient transcriptomes and in vitro pharmacologic screening, we identify matrix metalloproteinase activity to be essential for 3D but not 2D myofibroblast differentiation. Given our observation that compliant degradable 3D matrices amply support fibrogenesis, these studies demonstrate a departure from the established relationship between stiffness and myofibroblast differentiation in 2D, and provide a new 3D model for studying fibrosis and identifying antifibrotic therapeutics.

What Have In Vitro Co-Culture Models Taught Us about the Contribution of Epithelial-Mesenchymal Interactions to Airway Inflammation and Remodeling in Asthma?

As the lung develops, epithelial-mesenchymal crosstalk is essential for the developmental processes that drive cell proliferation, differentiation, and extracellular matrix (ECM) production within the lung epithelial-mesenchymal trophic unit (EMTU). In asthma, a number of the lung EMTU developmental signals have been associated with airway inflammation and remodeling, which has led to the hypothesis that aberrant activation of the asthmatic EMTU may lead to disease pathogenesis. Monoculture studies have aided in the understanding of the altered phenotype of airway epithelial and mesenchymal cells and their contribution to the pathogenesis of asthma. However, 3-dimensional (3D) co-culture models are needed to enable the study of epithelial-mesenchymal crosstalk in the setting of the in vivo environment. In this review, we summarize studies using 3D co-culture models to assess how defective epithelial-mesenchymal communication contributes to chronic airway inflammation and remodeling within the asthmatic EMTU.

Dose-dependent pro- or anti-fibrotic responses of endometriotic stromal cells to interleukin-1β and tumor necrosis factor α

Endometriosis are characterized by dense fibrous tissue. Numerous studies have investigated roles of inflammation on the pathophysiology of endometriosis. However, the interplay of inflammation and fibrosis remains to be clarified. Here we show that low levels of interleukin-1β (IL-1β) and tumor necrosis factor-alpha (TNFα) promoted a fibrotic phenotype, whereas high levels of IL-1β and TNFα inactivated the fibrotic phenotype of endometriotic stromal cells (Ectopic-ES). IL-1β 10 pg/mL and TNFα 100 and 1,000 pg/mL had minimal effects, whereas the highest dose of IL-1β (100 pg/mL) significantly decreased collagen gel contraction in Ectopic-ES. Furthermore, in Ectopic-ES, low levels of IL-1β (1 pg/mL) and/or TNFα 10 pg/mL significantly increased Col I mRNA expression, whereas higher doses of IL-1β (10 and/or 100 pg/mL) and/or TNFα (100 and/or 1,000 pg/mL) significantly decreased Col I and/or αSMA mRNA expression and the percentage of cells with Col I + and/or αSMA + stress fibers. In contrast, in either menstrual endometrial stromal cells of patients with endometriosis or those of healthy women, varying doses of IL-1β and/or TNFα had no significant effects on either Col I or αSMA mRNA/protein expression. The present findings bring into question whether we should still continue to attempt anti-inflammatory treatment strategies for endometriosis.

Epithelial-interleukin-1 inhibits collagen formation by airway fibroblasts: Implications for asthma

In asthma, the airway epithelium has an impaired capacity to differentiate and plays a key role in the development of airway inflammation and remodeling through mediator release. The study objective was to investigate the release of (IL)-1 family members from primary airway epithelial-cells during differentiation, and how they affect primary airway fibroblast (PAF)-induced inflammation, extracellular matrix (ECM) production, and collagen I remodeling. The release of IL-1α/β and IL-33 during airway epithelial differentiation was assessed over 20-days using air-liquid interface cultures. The effect of IL-1 family cytokines on airway fibroblasts grown on collagen-coated well-plates and 3-dimensional collagen gels was assessed by measurement of inflammatory mediators and ECM proteins by ELISA and western blot, as well as collagen fiber formation using non-linear optical microscopy after 24-hours. The production of IL-1α is elevated in undifferentiated asthmatic-PAECs compared to controls. IL-1α/β induced fibroblast pro-inflammatory responses (CXCL8/IL-8, IL-6, TSLP, GM-CSF) and suppressed ECM-production (collagen, fibronectin, periostin) and the cell’s ability to repair and remodel fibrillar collagen I via LOX, LOXL1 and LOXL2 activity, as confirmed by inhibition with β-aminopropionitrile. These data support a role for epithelial-derived-IL-1 in the dysregulated repair of the asthmatic-EMTU and provides new insights into the contribution of airway fibroblasts in inflammation and airway remodeling in asthma.

Current perspectives on the role of interleukin-1 signalling in the pathogenesis of asthma and COPD

Asthma and chronic obstructive pulmonary disease (COPD) cause significant morbidity and mortality worldwide. In the context of disease pathogenesis, both asthma and COPD involve chronic inflammation of the lung and are characterised by the abnormal release of inflammatory cytokines, dysregulated immune cell activity and remodelling of the airways. To date, current treatments still only manage symptoms and do not reverse the primary disease processes. In recent work, interleukin (IL)-1α and IL-1β have been suggested to play important roles in both asthma and COPD. In this review, we summarise overwhelming pre-clinical evidence for dysregulated signalling of IL-1α and IL-1β contributing to disease pathogenesis and discuss the paradox of IL-1 therapeutic studies in asthma and COPD. This is particularly important given recent completed and ongoing clinical trials with IL-1 biologics that have had varying degrees of failure and success as therapeutics for disease modification in asthma and COPD.

A Review of Last Decade Developments on Epiretinal Membrane Pathogenesis

Epiretinal membrane (ERM) is a pathologic tissue that develops at the vitreoretinal interface. ERM is responsible for pathological changes of vision with varying degrees of clinical significance. It is either idiopathic or secondary to a wide variety of diseases such as proliferative diabetic retinopathy (PDR) and proliferative vitreoretinopathy (PVR). A great variation in the prevalence of idiopathic ERM among different ethnic groups proposed that genetic and lifestyle factors may play a role in ERM occurrence. Histopathological studies demonstrate that various cell types including retinal pigment epithelium (RPE) cells, fibrocytes, fibrous astrocytes, myofibroblast-like cells, glial cells, endothelial cells (ECs) and macrophages, as well as trophic and transcription factors, including transforming growth factor (TGF), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF) etc., are directly or indirectly involved in the pathogenesis of idiopathic or secondary ERMs. These processes are driven (on the last count) by more than 50 genes, such as Tumor Necrosis Factor (TNF), CCL2 (chemokine (C-C motif) ligand )), Metastasis Associated Lung Adenocarcinoma Transcript 1 )MALAT1(, transforming growth factor (TGF)-β1, TGF-β2, Interleukin-6 (IL-6), IL-10, VEGF and glial fibrillary acidic protein (GFAP), some of which have been studied more intensely than others. The present paper tried to summarize, highlight and cross-correlate the major findings made in the last decade on the function of these genes and their association with different types of cells, genes and gene expression products in the ERM formation.

Regulation of connexin 43 by interleukin 1β in adult rat cardiac fibroblasts and effects in an adult rat cardiac myocyte: fibroblast co-culture model

Connexin 43 expression (Cx43) is increased in cardiac fibroblasts (CFs) following myocardial infarction. Here, potential mediators responsible for increasing Cx43 expression and effects of differential CF phenotype on cardiac myocyte (CM) function were investigated. Stimulating adult rat CFs with proinflammatory mediators revealed that interleukin 1β (IL-1β) significantly enhanced Cx43 levels through the IL-1β pathway. Additionally, IL-1β reduced mRNA levels of the myofibroblast (MF) markers: (i) connective tissue growth factor (CTGF) and (ii) α smooth muscle actin (αSMA), compared to control CFs. A co-culture adult rat CM:CF model was utilised to examine cell-to-cell interactions. Transfer of calcein from CMs to underlying CFs suggested functional gap junction formation. Functional analysis revealed contraction duration (CD) of CMs was shortened in co-culture with CFs, while treatment of CFs with IL-1β reduced this mechanical effect of co-culture. No effect on action potential rise time or duration of CMs cultured with control or IL-1β-treated CFs was observed. These data demonstrate that stimulating CFs with IL-1β increases Cx43 and reduces MF marker expression, suggesting altered cell phenotype. These changes may underlie the reduced mechanical effects of IL-1β treated CFs on CD of co-cultured CMs and therefore have an implication for our understanding of heterocellular interactions in cardiac disease.

Multiscale Coupling of an Agent-Based Model of Tissue Fibrosis and a Logic-Based Model of Intracellular Signaling

Wound healing and fibrosis following myocardial infarction (MI) is a dynamic process involving many cell types, extracellular matrix (ECM), and inflammatory cues. As both incidence and survival rates for MI increase, management of post-MI recovery and associated complications are an increasingly important focus. Complexity of the wound healing process and the need for improved therapeutics necessitate a better understanding of the biochemical cues that drive fibrosis. To study the progression of cardiac fibrosis across spatial and temporal scales, we developed a novel hybrid multiscale model that couples a logic-based differential equation (LDE) model of the fibroblast intracellular signaling network with an agent-based model (ABM) of multi-cellular tissue remodeling. The ABM computes information about cytokine and growth factor levels in the environment including TGFβ, TNFα, IL-1β, and IL-6, which are passed as inputs to the LDE model. The LDE model then computes the network signaling state of individual cardiac fibroblasts within the ABM. Based on the current network state, fibroblasts make decisions regarding cytokine secretion and deposition and degradation of collagen. Simulated fibroblasts respond dynamically to rapidly changing extracellular environments and contribute to spatial heterogeneity in model predicted fibrosis, which is governed by many parameters including cell density, cell migration speeds, and cytokine levels. Verification tests confirmed that predictions of the coupled model and network model alone were consistent in response to constant cytokine inputs and furthermore, a subset of coupled model predictions were validated with in vitro experiments with human cardiac fibroblasts. This multiscale framework for cardiac fibrosis will allow for systematic screening of the effects of molecular perturbations in fibroblast signaling on tissue-scale extracellular matrix composition and organization.

Activated Human Lung Fibroblasts Produce Extracellular Vesicles with Antifibrotic Prostaglandins

The differentiation of interstitial lung fibroblasts into contractile myofibroblasts that proliferate and secrete excessive extracellular matrix is critical for the pathogenesis of pulmonary fibrosis. Certain lipid signaling molecules, such as prostaglandins (PGs), can inhibit myofibroblast differentiation. However, the sources and delivery mechanisms of endogenous PGs are undefined. Activated primary human lung fibroblasts (HLFs) produce PGs such as PGE₂. We report that activation of primary HLFs with IL-1β inhibited transforming growth factor β-induced myofibroblast differentiation in both the IL-1β-treated cells themselves (autocrine signal) and adjacent naive HLFs in cocultures (paracrine signal). Additionally, we demonstrate for the first time that at least some of the antifibrotic effect of activated fibroblasts on nearby naive fibroblasts is carried by exosomes and other extracellular vesicles that contain several PGs, including high levels of the antifibrotic PGE₂. Thus, activated fibroblasts communicate with surrounding cells to limit myofibroblast differentiation and maintain homeostasis. This work opens the way for future research into extracellular vesicle-mediated intercellular signaling in the lung and may inform the development of novel therapies for fibrotic lung diseases.

Naringenin potentiated β-sitosterol healing effect on the scratch wound assay

In the present investigation scratch wound assay was used to study the ability of several combinations of each flavonoid (chrysin, naringenin or resveratrol) with β-sitosterol to heal wounds in vitro. MTT test was performed to determine if the combination of flavonoid with β-sitosterol was toxic to fibroblasts or not. Also, superoxide dismutase (SOD) activity and interleukin-1β (IL-1β) concentrations were measured. The best closure rates were obtained with β-sitosterol combined with naringenin and β-sitosterol combined with resveratrol. The combination that produced the best closure rate namely β-sitosterol with naringenin increased SOD activity significantly. However, this combination was not better than naringenin or β-sitosterol alone in reducing IL-β concentration. The results of MTT test indicated that the combination as well as β-sitosterol alone or naringenin alone has no toxic effect on fibroblasts. In conclusion, the combination of β-sitosterol and naringenin exerted a synergistic effect on wound closure without decreasing the viability of fibroblasts, increased antioxidant defense mechanism and decreased IL-β.

IL-1 receptor blockade skews inflammation towards Th2 in a mouse model of systemic sclerosis

The interleukin (IL)-1 family of cytokines is strongly associated with systemic sclerosis (SSc) and pulmonary involvement, but the molecular mechanisms are poorly understood. The aim of this study was to assess the role of IL-1α and IL-1β in pulmonary vascular and interstitial remodelling in a mouse model of SSc.

IL-1α and IL-1β were localised in lungs of SSc patients and in the fos-related antigen-2 (Fra-2) transgenic (TG) mouse model of SSc. Lung function, haemodynamic parameters and pulmonary inflammation were measured in Fra-2 TG mice with or without 8 weeks of treatment with the IL-1 receptor antagonist anakinra (25 mg·kg⁻¹·day⁻¹). Direct effects of IL-1 on pulmonary arterial smooth muscle cells (PASMCs) and parenchymal fibroblasts were investigated in vitro.

Fra-2 TG mice exhibited increased collagen deposition in the lung, restrictive lung function and enhanced muscularisation of the vasculature with concomitant pulmonary hypertension reminiscent of the changes in SSc patients. Immunoreactivity of IL-1α and IL-1β was increased in Fra-2 TG mice and in patients with SSc. IL-1 stimulation reduced collagen expression in PASMCs and parenchymal fibroblasts via distinct signalling pathways. Blocking IL-1 signalling in Fra-2 TG worsened pulmonary fibrosis and restriction, enhanced T-helper cell type 2 (Th2) inflammation, and increased the number of pro-fibrotic, alternatively activated macrophages.

Our data suggest that blocking IL-1 signalling as currently investigated in several clinical studies might aggravate pulmonary fibrosis in specific patient subsets due to Th2 skewing of immune responses and formation of alternatively activated pro-fibrogenic macrophages.

IL-1 dampens collagen production of lung structural cells and balances pro-fibrotic actions of the immune system. Blockade of IL-1 signalling in Fra-2 TG mice worsens lung function by increased Th2 inflammation and collagen production in the lung.http://bit.ly/2IVUGLX

Pirfenidone activates cannabinoid receptor 2 in a mouse model of bleomycin-induced pulmonary fibrosis

Inflammation serves an important role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). Cannabinoid receptor 2 (CB2R) is a receptor predominantly expressed in the immune system. CB2R agonists can be used to treat a wide range of inflammation-related diseases. Pirfenidone has been demonstrated to be effective for IPF treatment. The aim of present study was to investigate whether CB2R activation mediates the antifibrotic effect of pirfenidone. For that purpose, mice were intravenously injected with bleomycin (BLM; 5 mg/kg/day). pirfenidone (300 mg/kg/day) was then orally administered for 15 days. Lung pathological alterations in the mice were evaluated by Masson's trichrome staining. The mRNA and protein levels of CB2R in lung tissues were measured by reverse transcription-quantitative PCR and western blotting. The levels of inflammatory factors were determined by ELISA. The effect of pirfenidone on WI38 cell viability was evaluated by MTT assay. The results demonstrated that CB2R protein and mRNA levels increased with increasing fibrosis in mice with BLM-induced IPF. Pirfenidone administration significantly ameliorated IPF and reduced the serum levels of inflammatory factors induced by BLM. Pirfenidone also inhibited fibroblast cell proliferation and decreased the levels of inflammatory factors in vitro, which could be reversed by the CB2R antagonist SR144528, suggesting that CB2R was activated by pirfenidone. In conclusion, pirfenidone attenuated and activated CB2R in BLM-treated mice. In addition, pirfenidone inhibited fibroblast cell proliferation in vitro. These effects could be reversed by the CB2R antagonist SR144528. Thus, activation of CB2R may be considered a mechanism of the antifibrotic effects of pirfenidone.

Endogenous viable cells in lyopreserved amnion retain differentiation potential and anti-fibrotic activity in vitro

Human amniotic membrane (AM) has intrinsic anti-inflammatory, anti-fibrotic and antimicrobial properties. Tissue preservation methods have helped to overcome the short shelf life of fresh AM allowing "on demand" use of AM grafts. Cryopreserved AM that retains all native tissue components, including viable cells, has clinical benefits in treating chronic wounds. However, cryopreservation requires ultra-low temperature storage, limiting the use of cryopreserved products. To overcome this limitation, a new lyopreservation method has been developed for ambient storage of living tissues. The goal of this study was to investigate the viability and functionality of AM cells following lyopreservation. Fresh AM and devitalized lyopreserved AM (DLAM) served as positive and negative controls, respectively. Using live/dead staining, we confirmed the presence of living cells in viable lyopreserved AM (VLAM) and showed that these cells persisted up to 21 days in culture medium. The functionality of cells in VLAM was assessed by their differentiation potential and anti-fibrotic activity in vitro. With osteogenic induction, cells in VLAM deposited calcium within the membrane, a marker of osteogenic cells, in a time-dependent manner. The migration of human lung fibrotic fibroblasts in a scratch wound assay was reduced significantly in the presence of VLAM-derived conditioned medium. Quantitative PCR analyses indicated that VLAM reduced the expression of pro-fibrotic factors such as type I collagen and increased the expression of anti-fibrotic factors such as hepatocyte growth factor and anti-fibrotic microRNA in fibrotic fibroblasts. Taken together, these results demonstrate that endogenous cells in VLAM remain viable and functional post-lyophilization. STATEMENT OF SIGNIFICANCE: This study, for the first time, provides direct evidence showing that tissue viability and functional cells can be preserved by lyophilization. Similar to fresh amniotic membrane (AM), viable lyopreserved AM (VLAM) retains viable cells for extended periods of time. More importantly, these cells are functional and maintain their osteogenic differentiation potential and anti-fibrotic activity. Our results confirmed that the novel lyophilization method preserves tissue viability.

Interplay between EZH2 and G9a Regulates CXCL10 Gene Repression in Idiopathic Pulmonary Fibrosis

Selective repression of the antifibrotic gene CXCL10 contributes to tissue remodeling in idiopathic pulmonary fibrosis (IPF). We have previously reported that histone deacetylation and histone H3 lysine 9 (H3K9) methylation are involved in CXCL10 repression. In this study, we explored the role of H3K27 methylation and the interplay between the two histone lysine methyltransferases enhancer of zest homolog 2 (EZH2) and G9a in CXCL10 repression in IPF. By applying chromatin immunoprecipitation, Re-ChIP, and proximity ligation assays, we demonstrated that, like G9a-mediated H3K9 methylation, EZH2-mediated histone H3 lysine 27 trimethylation (H3K27me3) was significantly enriched at the CXCL10 promoter in fibroblasts from IPF lungs (F-IPF) compared with fibroblasts from nonfibrotic lungs, and we also found that EZH2 and G9a physically interacted with each other. EZH2 knockdown reduced not only EZH2 and H3K27me3 but also G9a and H3K9me3, and G9a knockdown reduced not only G9 and H3K9me3 but also EZH2 and H3K27me3. Depletion and inhibition of EZH2 and G9a also reversed histone deacetylation and restored CXCL10 expression in F-IPF. Furthermore, treatment of fibroblasts from nonfibrotic lungs with the profibrotic cytokine transforming growth factor-β1 increased EZH2, G9a, H3K27me3, H3K9me3, and histone deacetylation at the CXCL10 promoter, similar to that observed in F-IPF, which was correlated with CXCL10 repression and was prevented by EZH2 and G9a knockdown. These findings suggest that a novel and functionally interdependent interplay between EZH2 and G9a regulates histone methylation-mediated epigenetic repression of the antifibrotic CXCL10 gene in IPF. This interdependent interplay may prove to be a target for epigenetic intervention to restore the expression of CXCL10 and other antifibrotic genes in IPF.

Regeneration of Dermis: Scarring and Cells Involved

There are many studies on certain skin cell specifications and their contribution to wound healing. In this review, we provide an overview of dermal cell heterogeneity and their participation in skin repair, scar formation, and in the composition of skin substitutes. The papillary, reticular, and hair follicle associated fibroblasts differ not only topographically, but also functionally. Human skin has a number of particular characteristics that are different from murine skin. This should be taken into account in experimental procedures. Dermal cells react differently to skin wounding, remodel the extracellular matrix in their own manner, and convert to myofibroblasts to different extents. Recent studies indicate a special role of papillary fibroblasts in the favorable outcome of wound healing and epithelial-mesenchyme interactions. Neofolliculogenesis can substantially reduce scarring. The role of hair follicle mesenchyme cells in skin repair and possible therapeutic applications is discussed. Participation of dermal cell types in wound healing is described, with the addition of possible mechanisms underlying different outcomes in embryonic and adult tissues in the context of cell population characteristics and extracellular matrix composition and properties. Dermal white adipose tissue involvement in wound healing is also overviewed. Characteristics of myofibroblasts and their activity in scar formation is extensively discussed. Cellular mechanisms of scarring and possible ways for its prevention are highlighted. Data on keloid cells are provided with emphasis on their specific characteristics. We also discuss the contribution of tissue tension to the scar formation as well as the criteria and effectiveness of skin substitutes in skin reconstruction. Special attention is given to the properties of skin substitutes in terms of cell composition and the ability to prevent scarring.

Current and upcoming therapies to modulate skin scarring and fibrosis

Skin is the largest organ of the human body. Being the interface between the body and the outer environment, makes it susceptible to physical injury. To maintain life, nature has endowed skin with a fast healing response that invariably ends in the formation of scar at the wounded dermal area. In many cases, skin remodelling may be impaired, leading to local hypertrophic scars or keloids. One should also consider that the scarring process is part of the wound healing response, which always starts with inflammation. Thus, scarring can also be induced in the dermis, in the absence of an actual wound, during chronic inflammatory processes. Considering the significant portion of the population that is subject to abnormal scarring, this review critically discusses the state-of-the-art and upcoming therapies in skin scarring and fibrosis.

Quantitative proteomic profiling of extracellular matrix and site-specific collagen post-translational modifications in an in vitro model of lung fibrosis

Lung fibrosis is characterized by excessive deposition of extracellular matrix (ECM), in particular collagens, by fibroblasts in the interstitium. Transforming growth factor-β1 (TGF-β1) alters the expression of many extracellular matrix (ECM) components produced by fibroblasts, but such changes in ECM composition as well as modulation of collagen post-translational modification (PTM) levels have not been comprehensively investigated. Here, we performed mass spectrometry (MS)-based proteomics analyses to assess changes in the ECM deposited by cultured lung fibroblasts from idiopathic pulmonary fibrosis (IPF) patients upon stimulation with transforming growth factor β1 (TGF-β1). In addition to the ECM changes commonly associated with lung fibrosis, MS-based label-free quantification revealed profound effects on enzymes involved in ECM crosslinking and turnover as well as multiple positive and negative feedback mechanisms of TGF-β1 signaling. Notably, the ECM changes observed in this in vitro model correlated significantly with ECM changes observed in patient samples. Because collagens are subject to multiple PTMs with major implications in disease, we implemented a new bioinformatic platform to analyze MS data that allows for the comprehensive mapping and site-specific quantitation of collagen PTMs in crude ECM preparations. These analyses yielded a comprehensive map of prolyl and lysyl hydroxylations as well as lysyl glycosylations for 15 collagen chains. In addition, site-specific PTM analysis revealed novel sites of prolyl-3-hydroxylation and lysyl glycosylation in type I collagen. Interestingly, the results show, for the first time, that TGF-β1 can modulate prolyl-3-hydroxylation and glycosylation in a site-specific manner. Taken together, this proof of concept study not only reveals unanticipated TGF-β1 mediated regulation of collagen PTMs and other ECM components but also lays the foundation for dissecting their key roles in health and disease.

The proteomic data has been deposited to the ProteomeXchange Consortium via the MassIVE partner repository with the data set identifier MSV000082958.

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Quantitative proteomics of TGF-β-induced changes in ECM composition and collagen PTM in pulmonary fibroblasts

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TGF-β promotes crosslinking and turnover as well as complex feedback mechanisms that alter fibroblast ECM homeostasis.

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A novel bioinformatic workflow for MS data analysis enabled global mapping and quantitation of known and novel collagen PTMs

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Quantitative assessment of prolyl-3-hydroxylation site occupancy and lysine-O-glycosylation microheterogeneity

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TGF-β1 modulates collagen PTMs in a site-specific manner that may favor collagen accumulation in lung fibrosis

A systems pharmacology workflow with experimental validation to assess the potential of anakinra for treatment of focal and segmental glomerulosclerosis

Focal and Segmental Glomerulosclerosis (FSGS) is a severe glomerulopathy that frequently leads to end stage renal disease. Only a subset of patients responds to current therapies, making it important to identify alternative therapeutic options. The interleukin (IL)-1 receptor antagonist anakinra is beneficial in several diseases with renal involvement. Here, we evaluated the potential of anakinra for FSGS treatment. Molecular process models obtained from scientific literature data were used to build FSGS pathology and anakinra mechanism of action models by exploiting information on protein interactions. These molecular models were compared by statistical interference analysis and expert based molecular signature matching. Experimental validation was performed in Adriamycin- and lipopolysaccharide (LPS)-induced nephropathy mouse models. Interference analysis (containing 225 protein coding genes and 8 molecular process segments) of the FSGS molecular pathophysiology model with the drug mechanism of action of anakinra identified a statistically significant overlap with 43 shared molecular features that were enriched in pathways relevant in FSGS, such as plasminogen activating cascade, inflammation and apoptosis. Expert adjudication of molecular signature matching, focusing on molecular process segments did not suggest a high therapeutic potential of anakinra in FSGS. In line with this, experimental validation did not result in altered proteinuria or significant changes in expression of the FSGS-relevant genes COL1A1 and NPHS1. In summary, an integrated bioinformatic and experimental workflow showed that FSGS relevant molecular processes can be significantly affected by anakinra beyond the direct drug target IL-1 receptor type 1 (IL1R1) context but might not counteract central pathophysiology processes in FSGS. Anakinra is therefore not suggested for extended preclinical trials.

Development and validation of a novel phonomimetic bioreactor

Vocal fold fibroblasts (VFF) constitute the main cell type of the vocal fold’s lamina propria, produce the extracellular matrix and thereby determine the tissue characteristics. To study VFF behavior under in vitro conditions it is important to mimic the dynamic environment of the in vivo state. The aim of our study was to develop and validate a novel phonomimetic bioreactor system mainly based on commercially available components. The use of cell culture dishes with flexible silicone bottoms in combination with a suitable loudspeaker made it possible to expose the cells to various kinds of phonatory stimuli. The fundamental vibration characteristics of silicone membranes were investigated with and without cell culture medium by laser Doppler vibrometry. Human VFF were seeded in flexible-bottomed plates and placed in a custom-made housing containing a loudspeaker. After the cells were exposed to a predefined audio stimulation protocol, cell viability was assessed and gene as well as protein expression levels were compared to static controls. Laser Doppler vibrometry revealed that addition of cell culture medium changed the resonance frequencies of vibrating membranes. Gene expression of hyaluronan synthase 2, collagen III, fibronectin and TGFβ-1 was significantly upregulated in VFF exposed to vibration, compared to static control. Vibration also significantly upregulated collagen I gene and protein expression. We present a new type of phonomimetic bioreactor. Compared to previous models, our device is easy to assemble and cost-effective, yet can provide a wide spectrum of phonatory stimuli based on the entire dynamic range of the human voice. Gene expression data of VFF cultured in our phonomimetic bioreactor show a significant effect of vibration on ECM metabolism, which illustrates the efficacy of our device.

Carbon nanotubes and crystalline silica stimulate robust ROS production, inflammasome activation, and IL-1β secretion in macrophages to induce myofibroblast transformation

Pulmonary exposure to inhaled particulates elicits complex inflammatory and fibrotic responses that may progress to chronic fibrosis. The fibrogenic potentials of respirable particulates are influenced by their physicochemical properties and their interactions with major pathways to drive fibrotic development in the lung. Macrophages were exposed to six carbon nanotubes (CNTs) of varying dimensions, crystalline silica, or carbon black (CB), with lipopolysaccharide (LPS) and transforming growth factor (TGF)-β1 as positive controls. Macrophage-conditioned media was collected and applied to cultures of human pulmonary fibroblast line WI38-VA13 to induce myofibroblast transformation. Multi-walled and single-walled CNTs (MWCNTs and SWCNTs, respectively) and silica, but not CB, stimulated robust myofibroblast transformation through macrophage-conditioned media. On an equal weight basis, MWCNTs induced higher induction than SWCNTs. High induction was observed for MWCNTs with a long and slender or a short and rigid shape, and silica, at levels comparable to those by LPS and TGF-β1. Fibrogenic particulates induced high levels of IL-1β mRNA expression and protein secretion that are required for macrophage-guided myofibroblast transformation. Induction of IL-1β is dependent on the activation of the NLRP3 (NOD-like receptor family, pyrin domain containing 3) inflammasome and ROS (reactive oxygen species) production in macrophages, as inhibition of NLRP3 by MCC950 and reduction of ROS production by N-acetylcysteine blocked NLRP3 activation, IL-1β induction, and fibroblast activation and differentiation. Therefore, fibrogenic CNTs and silica, but not CB, elicit robust macrophage-guided myofibroblast transformation, which depends on the induction of IL-1β through the NLRP3 inflammasome pathway and the increased production of ROS in macrophages.

Different response of human chondrocytes from healthy looking areas and damaged regions to IL1β stimulation under different oxygen tension

Due to its avascular nature, articular cartilage is relatively hypoxic. The aim of this study was to elucidate the functional changes of macroscopically healthy looking areas chondrocytes (MHC) and macroscopically damaged regions chondrocytes (MDC) at a cellular level in response to the inflammatory cytokine IL1β under different oxygen tension levels. In this study, two-dimensional (2-D) expanded MHC and MDC were redifferentiated in 3-D pellet cultures in chondrogenic differentiation medium, supplemented with or without IL1β at conventional culture (normoxia) or 2.5% O₂ (hypoxia) for 3 weeks. qPCR, immunohistochemistry and ELISA were used to detect the expression of anabolic and catabolic gene expression. Alcian blue/Safranin O staining and GAG assay were used to measure cartilage matrix production. Cell proliferation and apoptosis were assessed by EdU staining and TUNEL assay, respectively. The results showed that hypoxia enhanced matrix production in both MHC and MDC and this effect was stronger on MDC. Under normoxia, MHC showed higher expression of cartilage markers and lower catabolic genes expression than MDC. Interestingly, hypoxia diminished the difference between MHC and MDC. IL1β potently induced MMPs expression regardless of cell population and oxygen tension. The fold induction of these MMPs in hypoxia was however much higher than in normoxia. In addition, hypoxia promoted the expression of HIF1α and HIF2α in MHC, while it only enhanced HIF1α expression but decreased the HIF2α expression in MDC. We concluded that hypoxia stimulated the redifferentiation of cultured chondrocytes, particularly in MDC derived from macroscopically diseased cartilage. Oxygen tension may profoundly and differentially influence inflammation-associated cartilage injury and diseases by regulating the expression of HIF1α and HIF2α. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 9999:XX-XX, 2018.

YAP activation promotes the transdifferentiation of cardiac fibroblasts to myofibroblasts in matrix remodeling of dilated cardiomyopathy

Yes-associated protein (YAP) is an important regulator of cellular proliferation and transdifferentiation. However, little is known about the mechanisms underlying myofibroblast transdifferentiation in dilated cardiomyopathy (DCM). We investigated the role of YAP in the pathological process of cardiac matrix remodeling. A classic model of DCM was established in BALB/c mice by immunization with porcine cardiac myosin. Cardiac fibroblasts were isolated from neonatal Sprague-Dawley rats by density gradient centrifugation. The expression levels of α-smooth muscle actin (α-SMA) and collagen volume fraction (CVF) were significantly increased in DCM mice. Angiotensin II (Ang II)-mediated YAP activation promoted the proliferation and transdifferentiation of neonatal rat cardiac fibroblasts, and this effect was significantly suppressed in the shRNA YAP + Ang II group compared with the shRNA Control + Ang II group in vitro (2.98±0.34 ×10⁵vs 5.52±0.82 ×10⁵, P<0.01). Inhibition of endogenous Ang II-stimulated YAP improved the cardiac function by targeting myofibroblast transdifferentiation to attenuate matrix remodeling in vivo. In the valsartan group, left ventricular ejection fraction and fractional shortening were significantly increased compared with the DCM group (52.72±5.51% vs 44.46±3.01%, P<0.05; 34.84±3.85% vs 26.65±3.12%, P<0.01). Our study demonstrated that YAP was a regulator of cardiac myofibroblast differentiation, and regulation of YAP signaling pathway contributed to improve cardiac function of DCM mice, possibly in part by decreasing myofibroblast transdifferentiation to inhibit matrix remodeling.

Unraveling SSc Pathophysiology; The Myofibroblast

Systemic sclerosis (SSc) is a severe auto-immune disease, characterized by vasculopathy and fibrosis of connective tissues. SSc has a high morbidity and mortality and unfortunately no disease modifying therapy is currently available. A key cell in the pathophysiology of SSc is the myofibroblast. Myofibroblasts are fibroblasts with contractile properties that produce a large amount of pro-fibrotic extracellular matrix molecules such as collagen type I. In this narrative review we will discuss the presence, formation, and role of myofibroblasts in SSc, and how these processes are stimulated and mediated by cells of the (innate) immune system such as mast cells and T helper 2 lymphocytes. Furthermore, current novel therapeutic approaches to target myofibroblasts will be highlighted for future perspective.

Origin and Consequences of Necroinflammation

When cells undergo necrotic cell death in either physiological or pathophysiological settings in vivo, they release highly immunogenic intracellular molecules and organelles into the interstitium and thereby represent the strongest known trigger of the immune system. With our increasing understanding of necrosis as a regulated and genetically determined process (RN, regulated necrosis), necrosis and necroinflammation can be pharmacologically prevented. This review discusses our current knowledge about signaling pathways of necrotic cell death as the origin of necroinflammation. Multiple pathways of RN such as necroptosis, ferroptosis, and pyroptosis have been evolutionary conserved most likely because of their differences in immunogenicity. As the consequence of necrosis, however, all necrotic cells release damage associated molecular patterns (DAMPs) that have been extensively investigated over the last two decades. Analysis of necroinflammation allows characterizing specific signatures for each particular pathway of cell death. While all RN-pathways share the release of DAMPs in general, most of them actively regulate the immune system by the additional expression and/or maturation of either pro- or anti-inflammatory cytokines/chemokines. In addition, DAMPs have been demonstrated to modulate the process of regeneration. For the purpose of better understanding of necroinflammation, we introduce a novel classification of DAMPs in this review to help detect the relative contribution of each RN-pathway to certain physiological and pathophysiological conditions.