Profibrogenic effect of high-mobility group box protein-1 in human dermal fibroblasts and its excess in keloid tissues

Targeting HMGB1 and Its Interaction with Receptors: Challenges and Future Directions

High mobility group box 1 (HMGB1) is a nonhistone chromatin protein predominantly located in the nucleus. However, under pathological conditions, HMGB1 can translocate from the nucleus to the cytoplasm and subsequently be released into the extracellular space through both active secretion and passive release mechanisms. The distinct cellular locations of HMGB1 facilitate its interaction with various endogenous and exogenous factors, allowing it to perform diverse functions across a range of diseases. This Perspective provides a comprehensive overview of the structure, release mechanisms, and multifaceted roles of HMGB1 in disease contexts. Furthermore, it introduces the development of both small molecule and macromolecule inhibitors targeting HMGB1 and its interaction with receptors. A detailed analysis of the predicted pockets is also presented, aiming to establish a foundation for the future design and development of HMGB1 inhibitors.

The Effect of Metformin on Radiation-Induced Lung Fibrosis in Mice

Introduction: Radiation-induced lung fibrosis (RILF) is a common complication of thoracic radiotherapy. Metformin has been suggested to have a radioprotective effect. Objective: This study explored the radioprotective effects of metformin on RILF and its mechanisms. Methods: C57BL/6J mice were randomly divided into control, ionizing radiation (IR), low-dose metformin (L-Met), and high-dose metformin (H-Met) groups. The IR, L-Met, and H-Met groups received 15 Gy chest irradiation. The L-Met and H-Met groups were administrated 100 or 200 mg/kg metformin from 3 days before irradiation and continued for 6 months. The mice were then sacrificed, and samples were collected for further analysis. Results: RILF was induced in the irradiated mice. Metformin improved lung pathology, inhibited collagen deposition, and reduced inflammatory factors such as high mobility group box 1 (HMGB1), interleukin-1 beta, interleukin-6, tumor necrosis factor alpha in lung tissue, lavage fluid, and serum. Western blot and quantitative real-time PCR analyses revealed that metformin downregulated HMGB1, toll-like receptor 4 (TLR4), and nuclear factor kappaB (NF-κB) expression. Additionally, metformin reversed the irradiation-induced reduction in the abundance of Lactobacillus and Lachnospiraceae at the genus level. Conclusion: Our findings indicated that metformin ameliorates RILF by downregulating the inflammatory-related HMGB1/TLR4/NF-κB pathway and improving intestinal flora disorder.

High mobility group box 1 (HMGB1) is a potential disease biomarker in cell and mouse models of Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a progressive muscle wasting disorder affecting 1:3500 male births and is associated with myofiber degeneration, regeneration, and inflammation. Glucocorticoid treatments have been the standard of care due to immunomodulatory/immunosuppressive properties but novel genetic approaches, including exon skipping and gene replacement therapy, are currently being developed. The identification of additional biomarkers to assess DMD-related inflammatory responses and the potential efficacy of these therapeutic approaches are thus of critical importance. The current study uses RNA sequencing of skeletal muscle from two mdx mouse models to identify high mobility group box 1 (HMGB1) as a candidate biomarker potentially contributing to DMD-related inflammation. HMGB1 protein content was increased in a human iPSC-derived skeletal myocyte model of DMD and microdystrophin treatment decreased HMGB1 back to control levels. In vivo, HMGB1 protein levels were increased in vehicle treated B10-mdx skeletal muscle compared to B10-WT and significantly decreased in B10-mdx animals treated with adeno-associated virus (AAV)-microdystrophin. However, HMGB1 protein levels were not increased in D2-mdx skeletal muscle compared to D2-WT, demonstrating a strain-specific difference in DMD-related immunopathology.

Post-Excision Soft X-Ray Radiotherapy for Keloids: Experience in a Tertiary Referral Center

INTRODUCTION

Keloid is an abnormal proliferation of scar tissue that grows beyond the original margins of the injury. Even after complete resection, recurrences are common and pose a poorly understood challenge in dermatology. There is lack of large prospective clinical trials; thus, treatment recommendations are based on retrospective analyses and small cohort studies. Superficial radiotherapy is recommended in recurrent keloids; however, the successful treatment rates vary greatly. The aim of this study was to evaluate the keloid recurrence rate after post-excision soft X-ray radiotherapy and the associated factors.

METHODS

We reviewed retrospective data of all patients, treated with adjuvant post-excision soft X-ray radiotherapy with 12 Gy in 6 sessions at the tertiary referral center, Department of Dermatology, University Hospital Zurich, Switzerland, between 2005 and 2018. We analyzed individual keloids as separate cases. Successful treatment was defined as no sign of recurrence within 2 years.

RESULTS

Of the 200 identified patients, 90 met the inclusion criteria and were included in the final analysis. In 90 patients, 104 cases of treated keloids were analyzed. Keloids were mainly located on the trunk (49%) and were mostly caused by previous surgery (52.2%). 50% of the keloids did not relapse within 2 years after therapy. A significant factor leading to recurrence was the presence of previous therapy, with prior topical therapies, such as steroid injections or 5-fluorouracil, leading to most relapses. 69.2% of keloid cases who relapsed were pretreated. Soft X-ray radiotherapy was well tolerated, with posttreatment hyperpigmentation noted in 34% of patients, particularly in patients with non-Caucasian origin (61.3%).

CONCLUSION

Treatment of refractory keloids is difficult. Post-excision radiotherapy is an established adjuvant treatment option; nevertheless, recurrence rates are high, especially in pretreated keloids. Prospective studies determining the exact dosage and fraction of post-excisional radiotherapy are needed to determine the optimal radiation parameters.

Ethyl Pyruvate Decreases Collagen Synthesis and Upregulates MMP Activity in Keloid Fibroblasts and Keloid Spheroids

Keloids, marked by abnormal cellular proliferation and excessive extracellular matrix (ECM) accumulation, pose significant therapeutic challenges. Ethyl pyruvate (EP), an inhibitor of the high-mobility group box 1 (HMGB1) and TGF-β1 pathways, has emerged as a potential anti-fibrotic agent. Our research evaluated EP's effects on keloid fibroblast (KF) proliferation and ECM production, employing both in vitro cell cultures and ex vivo patient-derived keloid spheroids. We also analyzed the expression levels of ECM components in keloid tissue spheroids treated with EP through immunohistochemistry. Findings revealed that EP treatment impedes the nuclear translocation of HMGB1 and diminishes KF proliferation. Additionally, EP significantly lowered mRNA and protein levels of collagen I and III by attenuating TGF-β1 and pSmad2/3 complex expression in both human dermal fibroblasts and KFs. Moreover, metalloproteinase I (MMP-1) and MMP-3 mRNA levels saw a notable increase following EP administration. In keloid spheroids, EP induced a dose-dependent reduction in ECM component expression. Immunohistochemical and western blot analyses confirmed significant declines in collagen I, collagen III, fibronectin, elastin, TGF-β, AKT, and ERK 1/2 expression levels. These outcomes underscore EP's antifibrotic potential, suggesting its viability as a therapeutic approach for keloids.

Fibrosis in burns: an overview of mechanisms and therapies

Scar development remains a common occurrence and a major healthcare challenge affecting the lives of millions of patients annually. Severe injuries to the skin, such as burns can lead to pathological wound healing patterns, often characterized by dermal fibrosis or excessive scarring, and chronic inflammation. The two most common forms of fibrotic diseases following burn trauma are hypertrophic scars (HSCs) and keloids, which severely impact the patient's quality of life. Although the cellular and molecular mechanisms are similar, HSC and keloids have several distinct differences. In this review, we discuss the different forms of fibrosis that occur postburn injury, emphasizing how the extent of burn influences scar development. Moreover, we highlight how a systemic response induced by a burn injury drives wound fibrosis, including both the role of the inflammatory response, as well as the fate of fibroblast during skin healing. Finally, we list potential therapeutics aimed at alleviating pathological scar formation. An understanding of the mechanisms of postburn fibrosis will allow us to effectively move studies from bench to bedside.

HMGB1 in depression: An overview of microglial HMBG1 in the pathogenesis of depression

Depression is a prevalent psychiatric disorder with elusive pathogenesis. Studies have proposed that enhancement and persistence of aseptic inflammation in the central nervous system (CNS) may be closely associated with the development of depressive disorder. High mobility group box 1 (HMGB1) has obtained significant attention as an evoking and regulating factor in various inflammation-related diseases. It is a non-histone DNA-binding protein that can be released as a pro-inflammatory cytokine by glial cells and neurons in the CNS. Microglia, as the immune cell of the brain, interacts with HMGB1 and induces neuroinflammation and neurodegeneration in the CNS. Therefore, in the current review, we aim to investigate the role of microglial HMGB1 in the pathogenetic process of depression.

Review: The role of HMGB1 in spinal cord injury

High mobility group box 1 (HMGB1) has dual functions as a nonhistone nucleoprotein and an extracellular inflammatory cytokine. In the resting state, HMGB1 is mainly located in the nucleus and regulates key nuclear activities. After spinal cord injury, HMGB1 is rapidly expressed by neurons, microglia and ependymal cells, and it is either actively or passively released into the extracellular matrix and blood circulation; furthermore, it also participates in the pathophysiological process of spinal cord injury. HMGB1 can regulate the activation of M1 microglia, exacerbate the inflammatory response, and regulate the expression of inflammatory factors through Rage and TLR2/4, resulting in neuronal death. However, some studies have shown that HMGB1 is beneficial for the survival, regeneration and differentiation of neurons and that it promotes the recovery of motor function. This article reviews the specific timing of secretion and translocation, the release mechanism and the role of HMGB1 in spinal cord injury. Furthermore, the role and mechanism of HMGB1 in spinal cord injury and, the challenges that still need to be addressed are identified, and this work will provide a basis for future studies.

Activation of the NLRP3 inflammasome by HMGB1 through inhibition of the Nrf2/HO-1 pathway promotes bleomycin-induced pulmonary fibrosis after acute lung injury in rats

OBJECTIVE

Acute lung injury (ALI) is a common complication of critical diseases with high morbidity and mortality. This study explored the regulatory role and mechanism of high mobility histone box 1 protein (HMGB1) on pulmonary fibrosis (PF) after ALI in rats through nucleotide oligomerization domain-like receptor protein-3 (NLRP3) inflammasome.

METHODS

PF rat models after ALI were established by induction of bleomycin. Degree of fibrosis was assessed by Masson staining and Ashcroft scoring. Hydroxyproline (Hyp) contents in lung tissues and rat lung tissue morphology were detected by enzyme-linked-immunosorbent serologic assay (ELISA) and hematoxylin and eosin staining. The levels of NLRP3, major proteins of NLRP3 inflammasome (NLRP3/ASC/caspase-1), and downstream inflammatory cytokines interleukin (IL)-1 and IL-18 were determined using immunohistochemistry, Western blotting analysis, and ELISA. The nuclear/cytoplasmic nuclear factor erythroid 2-related factor 2 (Nrf2) levels and HO-1 levels were measured by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blotting analysis. Rats was injected with lentivirus carrying short hairpin (sh)-HMGB1 and zinc protoporphyria (ZNPP) (HO-1 inhibitor) to assess the effects of HMGB1 and HO-1 on PF and NLRP3 inflammasome activation.

RESULTS

Bleomycin induced PF after ALI in rats, manifested as patchy fibrosis, atelectasis, and excessive expansion, and increased Aschcroft score and Hyp content. Bleomycin treatment enhanced levels of NLRP3, ASC, caspase-1, IL-1, and IL-18 in rat lung tissues, which promoted activation of NLRP3 inflammasome. HMGB1 was up-regulated in bleomycin-induced rats. HMGB1 knockdown partially reversed NLRP3 inflammasome activation and PF progression. HMGB1 knockdown promoted Nrf2 nuclear translocation and up-regulated HO-1. Suppression of HO-1 partially reversed inhibition of HMGB1 knockdown on NLRP3 inflammasome activation and PF.

CONCLUSION

HMGB1 can activate NLRP3 inflammasomes and promote PF by inhibiting the Nrf2/HO-1 pathway.

Spatially resolved deconvolution of the fibrotic niche in lung fibrosis

A defining pathological feature of human lung fibrosis is localized tissue heterogeneity, which challenges the interpretation of transcriptomic studies that typically lose spatial information. Here we investigate spatial gene expression in diagnostic tissue using digital profiling technology. We identify distinct, region-specific gene expression signatures as well as shared gene signatures. By integration with single-cell data, we spatially map the cellular composition within and distant from the fibrotic niche, demonstrating discrete changes in homeostatic and pathologic cell populations even in morphologically preserved lung, while through ligand-receptor analysis, we investigate cellular cross-talk within the fibrotic niche. We confirm findings through bioinformatic, tissue, and in vitro analyses, identifying that loss of NFKB inhibitor zeta in alveolar epithelial cells dysregulates the TGFβ/IL-6 signaling axis, which may impair homeostatic responses to environmental stress. Thus, spatially resolved deconvolution advances understanding of cell composition and microenvironment in human lung fibrogenesis.

Inhibition of p38 mitogen-activated protein kinases may attenuate scar proliferation after cleft lip surgery in rabbits via Smads signaling pathway

Background

Cleft lip repair surgery always results in visible scarring. It has been proved that scar formation can be reduced by inhibiting the p38 mitogen-activated protein kinases (p38MAPKs) signaling pathway. However, the interaction between p38MAPK and Smads in scar formation is still controversial.

Methods

This study was designed to investigate whether inhibition of p38MAPK reduces postoperative scar formation of cleft lips on rabbits via the Smads signaling pathway. Scar models in rabbits after cleft lip surgery were created and their fibroblasts were extracted. Then the expression of p38MAPK was disturbed by adenovirus in vitro and Vivo. The scar thickness was measured and scar tissues were excised for Sirius red staining and immunohistochemistry to detect the expression of type I collagen (col I), type III collagen (col III), and α-smooth muscle actin (α-SMA). The underlying mechanisms of p38MAPK knockdown on the extracellular matrix and Smad signaling pathway were invested in vitro using the EdU assay, Western blot, RT PCR, and immunofluorescence.

Results

p38MAPK knockdown suppresses the expression of p-smad3 and p-smad2 in fibroblasts, modulating the expression of its target genes, such as α-SMA, col I, and col III. When Ad-P38MAPK-1 was injected into lip scar, it reduced the expression of scar-related genes and scar thickness when compared to the negative control groups.

Conclusions

In rabbits, inhibiting p38MAPK expression prevents scar proliferation through inhibiting the Smad signaling pathway after cleft lip surgery.

Evaluation of different methodologies for primary human dermal fibroblast spheroid formation: automation through 3D Bioprinting technology

Cell spheroids have recently emerged as an effective tool to recapitulate native microenvironments of living organisms in an in vitro scenario, increasing the reliability of the results obtained and broadening their applications in regenerative medicine, cancer research, disease modeling and drug screening. In this study the generation of spheroids containing primary human dermal fibroblasts (dHFs) was approached using the two-widely employed methods: hanging-drop (HD) and U-shape low adhesion plate (LA-plate). Moreover, extrusion-based 3D bioprinting was introduced to achieve a standardized and scalable production of cell spheroids, decreasing considerably the possibilities of human error. This was ensured when U-shape LA-plates were used, showing an 85% formation efficiency, increasing up to a 98% when it was automatized using the 3D bioprinting technologies. However, sedimentation effect within the cartridge led to a reduction of 20% in size of the spheroid during the printing process. Hyaluronic acid (HA) was chosen as viscosity enhancer to supplement the bioink and overcome cell sedimentation within the cartridge due to the high viability values exhibited by the cells - around 80% - at the used conditions. Finally, ANCOVA analysis of spheroid size over time for different printing conditions stand out HA 0.4% (w/v) 60 kDa as the viscosity-improved bioink that exhibit the highest cell viability and spheroid formation percentages. Besides, not only did it ensure cell spheroid homogeneity over time, reducing cell sedimentation effects, but also wider spheroid diameters over time with less variability, outperforming significantly manual loading.

Circular RNA HECTD1 knockdown inhibits transforming growth factor-beta/ small mothers against decapentaplegic (TGF-β/Smad) signaling to reduce hypertrophic scar fibrosis

Scars are nearly impossible to avoid after a skin injury, but despite advancements in the treatment modalities, they remain a clinical problem, especially hypertrophic scars (HS). Many studies include the mechanism of formation and inhibition of HS, but it is not fully understood yet. Circular RNA HECTD1 (circHECTD1), for the first time, has been found to have roles in HS physiology. We determined the relative circHECTD1 levels in HS fibrous cells and tissues by RT-qPCR. Afterward, the effect of circHECTD1 knockdown on the proliferation, migration, invasion, fibrosis, and Transforming Growth Factor-beta/small mothers against decapentaplegic (TGF-β/Smad) signaling was studied using CCK-8, wound healing, Transwell, and western blot assays. After the role of circHECTD1 was clarified, its targeted micro RNA (miR) was predicted using the Starbase database, and we constructed a miR-142-3p mimic to study the details of its regulation mechanism. We used the TargetScan database to predict the downstream target high mobility group box 1 (HMGB1) of miR-142-3p, and the luciferase report assay verified the binding, and then its effect was determined by RT-qPCR. circHECTD1 is highly expressed in HS tissues and human skin hypertrophic scar fibroblasts (HSF); its loss of function inhibits cell proliferation, migration, invasion, fibrosis, and TGF-β/Smad signaling. However, miR-142-3p inhibitor reverses the effect of circHECTD1 on all the above-mentioned aspects, including HMGB1 expression. In conclusion, circHECTD1 knockdown interrupts TGF-β/Smad signaling through miR-142-3p/HMGB1 and suppresses scar fibrosis.

The mechanism of HMGB1 secretion and release

High mobility group box 1 (HMGB1) is a nonhistone nuclear protein that has multiple functions according to its subcellular location. In the nucleus, HMGB1 is a DNA chaperone that maintains the structure and function of chromosomes. In the cytoplasm, HMGB1 can promote autophagy by binding to BECN1 protein. After its active secretion or passive release, extracellular HMGB1 usually acts as a damage-associated molecular pattern (DAMP) molecule, regulating inflammation and immune responses through different receptors or direct uptake. The secretion and release of HMGB1 is fine-tuned by a variety of factors, including its posttranslational modification (e.g., acetylation, ADP-ribosylation, phosphorylation, and methylation) and the molecular machinery of cell death (e.g., apoptosis, pyroptosis, necroptosis, alkaliptosis, and ferroptosis). In this minireview, we introduce the basic structure and function of HMGB1 and focus on the regulatory mechanism of HMGB1 secretion and release. Understanding these topics may help us develop new HMGB1-targeted drugs for various conditions, especially inflammatory diseases and tissue damage.

A nuclear protein that gets released after cell death or is actively secreted by immune cells offers a promising therapeutic target for treating diseases linked to excessive inflammation. Daolin Tang from the University of Texas Southwestern Medical Center in Dallas, USA, and colleagues review how cellular stresses can trigger the accumulation of HMGB1, a type of alarm signal protein that promotes the recruitment and activation of inflammation-promoting immune cells. The researchers discuss various mechanisms that drive both passive and active release of HMGB1 into the space around cells. These processes, which include enzymatic modifications of the HMGB1 protein, cell–cell interactions and molecular pathways of cell death, could be targeted by drugs to lessen tissue damage and inflammatory disease caused by HMGB1-induced immune responses

Emerging insights into the immunological aspects of keloids

A special kind of scar, keloid, sometimes grows huge, disturbing patients in different ways. We discussed the pathogenesis of keloids and found researches about fibroblasts and collagen disorders, with little emphasis on immunity. Coupled with few effective treatments in keloid at present, we have focused on the immunological mechanisms of keloids with an aim to unravel some new therapeutic approaches in the future. In this review, the immunological processes are separately illustrated by the classification of different immune cells. In addition, we also discuss possible reasons for the repeated recurrence of keloids, the phenomenon of cell talks, and inflammation-related signal pathways involved in the pathogenesis of keloids.

Verbascoside inhibits the epithelial-mesenchymal transition of prostate cancer cells through high-mobility group box 1/receptor for advanced glycation end-products/TGF-β pathway

INTRODUCTION

Prostate cancer has significant mortality and metastasis rate in the male. Unfortunately, effective treatment for patients with advanced prostate cancer is still lacking. Verbascoside, a phenylethanoid glycoside, displays various pharmacological properties, such as the anti-cancer activities. The present study aimed to evaluate the effects of purified verbascoside on human prostate cancer and the associated molecular mechanisms.

MATERIALS AND METHODS

The human prostate cancer cell lines, Du-145 and PC-3, were treated with various concentrations of verbascoside (0.1, 1, 10 μM) for 24 h followed by the examination of cell viability using MTT and trypan blue exclusion assays. Cell migration and invasion capacities were assessed by wound healing assay and transwell system. Western blot and immunofluorescence staining were used to detect the expression of epithelial-mesenchymal transition (EMT)-associated factors, components of transforming growth factor (TGF-β)/Smad signaling, and high-mobility group box (HMGB)/receptor for advanced glycation end-products (RAGE) axis.

RESULTS

Verbascoside treatment significantly inhibited cell proliferation, migration, and invasion abilities of Du-145 and PC-3 cells. We showed that verbascoside decreased the expression of EMT promotors, Snail and Slug, and increased the expression of E-cadherin. Moreover, the expression level of alpha-smooth muscle actin was downregulated by verbascoside as well. Besides, we found that the TGF-β pathway was suppressed, which was demonstrated by the diminished expression of type I and II TGF-β receptors and phosphorylated Smad2/3 along with the upregulated Smad7. Our data suggested that this downregulation of TGF-β signaling was mediated by repression of HMGB 1 (HMGB1)/RAGE axis.

CONCLUSION

Verbascoside mitigated the cell proliferation and aggressiveness of prostate cancer via downregulation of TGF-β-associated EMT progression through HMGB1/RAGE suppression. Collectively, our findings revealed that verbascoside may be a beneficial dietary supplement for prostate cancer patients.

Adiponectin, but Not TGF-β1, CTGF, IL-6 or TNF-α, May Be a Potential Anti-Inflammation and Anti-Fibrosis Factor in Keloid

INTRODUCTION

Numerous studies have elucidated adiponectin as a negative impact on inflammation and tissue fibrosis. However, little is known about the relevance between adiponectin and inflammatory factors in keloid.

METHODS

To clarify whether adiponectin plays a role in the inflammation and fibrosis of keloid, 50 patients with keloid and 50 healthy subjects were enrolled, We examined the serum and mRNA expression levels of adiponectin, TGF-β1, CTGF, IL-6 and TNF-α in normal skin tissues and keloid tissues by ELISA and qPCR, respectively. Correlation analysis between serum concentration of adiponectin with Vancouver Scar Scale (VSS) scores and the age of patients with keloid was evaluated, and the adiponectin concentrations in patients with keloid between different genders were measured. We further examined the effects of adiponectin on TGF-β1 mediated expression of collagen I, FN and MMP-1 in normal fibroblasts (NFs) and keloid fibroblasts (KFs).

RESULTS

We discovered that lower serum concentration and mRNA expression of adiponectin, but higher TGF-β1, CTGF, IL-6 and TNF-α levels were measured in patients with keloid compared with those in normal controls. Furthermore, there was a strong inverse correlation between the serum adiponectin levels and VSS scores in patients with keloid, but not in ages, and there was no statistically difference between different genders. Moreover, adiponectin attenuated TGF-β1 mediated expression of collagen I and FN, and upregulated the expression level of MMP-1 in KFs, but not in NFs. In addition, the inhibitory effect of adiponectin on TGF-β1 was attenuated by AMPK inhibitor Compound C, but not PI3K/Akt inhibitor LY294002.

DISCUSSION

Adiponectin may exert an anti-inflammation and anti-fibrosis role in the development of keloid. One of the underlying mechanisms may be the activation of the AMPK signaling pathway.

The puzzling pathophysiology of frozen shoulders - a scoping review

Purpose

The pathophysiology of frozen shoulders is a complex and multifactorial process. The purpose of this review is to scope the currently available knowledge of the pathophysiology of frozen shoulders.

Methods

A systematic search was conducted in Medline, Embase and the Cochrane library. Original articles published between 1994 and October 2020 with a substantial focus on the pathophysiology of frozen shoulders were included.

Results

Out of 827 records, 48 original articles were included for the qualitative synthesis of this review. Glenohumeral capsular biopsies were reported in 30 studies. Fifteen studies investigated were classified as association studies. Three studies investigated the pathophysiology in an animal studies. A state of low grade inflammation, as is associated with diabetes, cardiovascular disease and thyroid disorders, predisposes for the development of frozen shoulder. An early immune response with elevated levels of alarmins and binding to the receptor of advance glycation end products is present at the start of the cascade. Inflammatory cytokines, of which transforming growth factor-β1 has a prominent role, together with mechanical stress stimulates Fibroblast proliferation and differentiation into myofibroblasts. This leads to an imbalance of extracellular matrix turnover resulting in a stiff and thickened glenohumeral capsule with abundance of type III collagen.

Conclusion

This scoping review outlines the complexity of the pathophysiology of frozen shoulder. A comprehensive overview with background information on pathophysiologic mechanisms is given. Leads are provided to progress with research for clinically important prognostic markers and in search for future interventions.

Level of evidence

Level V.

Indirect regulation of HMGB1 release by gasdermin D

The protein high-mobility group box 1 (HMGB1) is released into the extracellular space in response to many inflammatory stimuli, where it is a potent signaling molecule. Although research has focused on downstream HMGB1 signaling, the means by which HMGB1 exits the cell is controversial. Here we demonstrate that HMGB1 is not released from bone marrow-derived macrophages (BMDM) after lipopolysaccharide (LPS) treatment. We also explore whether HMGB1 is released via the pore-forming protein gasdermin D after inflammasome activation, as is the case for IL-1β. HMGB1 is only released under conditions that cause cell lysis (pyroptosis). When pyroptosis is prevented, HMGB1 is not released, despite inflammasome activation and IL-1β secretion. During endotoxemia, gasdermin D knockout mice secrete HMGB1 normally, yet secretion of IL-1β is completely blocked. Together, these data demonstrate that in vitro HMGB1 release after inflammasome activation occurs after cellular rupture, which is probably inflammasome-independent in vivo.

High-mobility group box 1 promotes epithelial-to-mesenchymal transition in crystalline silica induced pulmonary inflammation and fibrosis

Silicosis is an inflammatory and fibrotic lung disease caused by prolonged inhalation of silica. The potential role of high-mobility group box-1 (HMGB-1) and its underlying mechanisms in silicosis remain unclear. In this study, intratracheal instillation of a silica suspension was used to establish silicosis in male C57BL/6 mice. To elucidate the effects of HMGB-1 on the pathogenesis of silicosis, we used HMGB-1 neutralizing antibody (anti-HMGB-1) and recombinant HMGB-1 (rmHMGB-1) to abrogate or increase the HMGB-1 levels, respectively. At days 7, 28, and 84, the accumulation of macrophages and neutrophils decreased by anti-HMGB-1 treatment. The expression levels of interleukin-6 and tumor necrosis factor-α in lung increased in response to silica exposure across three time points; anti-HMGB-1 could alleviate those expressions at day 28 and 84. In contrast, rmHMGB-1 aggravated this process. At days 28 and 84, the protein expression of fibronectin and col1a1 decreased in the silica + anti-HMGB-1 groups but increased in silica + rmHMGB-1 groups compared to mice with silica alone. Further study suggested that HMGB-1-mediated epithelial-mesenchymal transition participated in the development of silicosis. In conclusion, the findings demonstrate that HMGB-1 participates in the pathogenesis of silicosis and may represent a potential therapeutic target for the treatment of silicosis.

Contribution of TGF-Beta-Mediated NLRP3-HMGB1 Activation to Tubulointerstitial Fibrosis in Rat With Angiotensin II-Induced Chronic Kidney Disease

Fibrosis is a common phenotype that often leads to the progression of blood pressure-induced chronic kidney disease (CKD). TGF-beta plays an important role in promoting pathogenesis, and NLRP3 is a critical mediator in the progression of blood pressure-induced CKD. However, the pathophysiological roles of the TGF-beta-mediated NLRP3 pathway in modulating fibrosis in blood pressure-induced CKD have not been elucidated. The present study aims to investigate the contribution of TGF-beta-mediated NLRP3 inflammasome to renal fibrosis in rats with high blood pressure. By treating rats with angiotensin II (Ang II) for 14 days, we observed the development of fibrosis, characterized by epithelial-mesenchymal transition (EMT) markers [alpha-smooth muscle actin (alpha-SMA), MMP-2, and MMP-9]. Immunohistochemical analysis further revealed that TGF-beta and NLRP3 inflammasome activation [high-mobility group box 1 (HMGB1), IL-1beta, and NLRP3] were significantly upregulated in the kidney of rats with Ang II-induced hypertension. Interestingly, we observed that Ang II could not increase the production of NLRP3 proteins, but TGF-beta could induce NLRP3 protein expression in cultured NRK-52E cells. Furthermore, we speculated that TGF-beta played a pathogenic role in Ang II-induced CKD because TGF-beta induced the activation of NLRP3 inflammasomes and Gasdermin D cleavage expression. We also proved that the pharmacological inhibition of NLRP3 by ISO caused a decrease in TGF-beta-induced NLRP3 inflammasome activation and the expression of EMT markers (alpha-SMA and CollagenI) and Gasdermin D cleavage. Collectively, these results suggest that TGF-beta-mediated NLRP3 inflammasome activation may cause the release of HMGB1 and an increase in Gasdermin D cleavage in NRK-52E, thereby contributing to renal fibrosis in Ang II-induced CKD. These findings provide novel insights into the pathogenic role of NLRP3 in CKD associated with high blood pressure.

Raltegravir Attenuates Experimental Pulmonary Fibrosis In Vitro and In Vivo

Raltegravir, an inhibitor of human immunodeficiency virus-1 (HIV-1) integrase, has been used to treat HIV/acquired immunodeficiency syndrome; however, its therapeutic effects on pulmonary fibrosis have not been investigated. In this study, the in vitro effects of raltegravir (RAV) on transforming growth factor beta 1 (TGF-β1)-induced pulmonary fibrosis on L929 mouse fibroblasts were investigated. In addition, the effects of RAV on an in vivo pulmonary fibrosis model induced by intratracheal instillation of bleomycin were investigated. The proliferation of L929 cells was inhibited after RAV treatment. Meanwhile, the in vitro and in vivo protein expression of nucleotide-binding oligomerization domain-like receptor 3 (NLRP3), high-mobility group box 1 (HMGB1), toll-like receptor 4 (TLR4), prolyl hydroxylase domain protein 2, phosphorylated nuclear factor-κB (p-NF-κB), hypoxia-inducible factor-1α (HIF-1α), collagens I and III was reduced relative to TGF-β1 or the bleomycin group. Raltegravir ameliorated pulmonary fibrosis by reducing the pathology score, collagen deposition, and expression of α-smooth muscle actin, NLRP3, HMGB1, TLR4, inhibitor of kappa B, p-NF-κB, HIF-1α, collagen I, and collagen III. The results of this study demonstrate that RAV attenuated experimental attenuates pulmonary fibrosis by inhibiting NLRP3 activation.

Dual regulatory roles of HMGB1 in inflammatory reaction of chondrocyte cells and mice

Osteoarthritis (OA) is one of the most common bone diseasesas it is reported that the impact of knee osteoarthritis symptomatic form is estimated at 240/100,000 people per year. The inflammation of articular cartilageis thought to be the pathologic drive for development of this disease. HMGB1(high mobility group box-1), a regulatory factor for gene transcription, could stimulate inflammation response. However, theexact regulatory role of HMGB1 in the inflammation of articular cartilage still need to be elucidated. In the current study, we used Quantitative Real-Time PCR(Q-PCR) to detect them RNA levels of Collagen Type II Alpha 1(Col2a1), Aggrecan, MMP3(Matrix Metallopeptidase 3), MMP13, ADAMTs4 and ADAMTs5; Enzyme-Linked Immunosorbent Assay(ELISA) was used to detect the content of IL-1β and calpain protein; Cell apoptosis was evaluated by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling(TUNEL) assay and flow cytometryanalysis; Western blot and immunofluorescence assays were applied to assess the expression of HMGB1; Lastly autophagic activity was mainly verified by monodansylcadaverine (MDC) staining. Our data revealed that in the early stage of chondrocyte inflammation(3 and 6 h of LPS stimulation), cytosolic HMGB1 attenuated inflammation response by facilitating cell autophagy and preventing cell apoptosis. While in the late stage (24 and 48 h of LPS stimulation), the extracellular HMGB1 stimulated inflammation reaction and contributed to the cartilage destruction in OA.

Coacervate-mediated exogenous growth factor delivery for scarless skin regeneration

Although there are numerous medical applications to recover damaged skin tissue, scarless wound healing is being extensively investigated to provide a better therapeutic outcome. The exogenous delivery of therapeutic growth factors (GFs) is one of the engineering strategies for skin regeneration. This study presents an exogenous GF delivery platform developed using coacervates (Coa), a tertiary complex of poly(ethylene argininyl aspartate diglyceride) (PEAD) polycation, heparin, and cargo GFs (i.e., transforming growth factor beta 3 (TGF-β3) and interleukin 10 (IL-10)). Coa encompasses the advantage of high biocompatibility, facile preparation, protection of cargo GFs, and sustained GF release. We therefore speculated that coacervate-mediated dual delivery of TGF-β3/IL-10 would exhibit synergistic effects for the reduction of scar formation during physiological wound healing. Our results indicate that the exogenous administration of dual GF via Coa enhances the proliferation and migration of skin-related cells. Gene expression profiles using RT-PCR revealed up-regulation of ECM formation at early stage of wound healing and down-regulation of scar-related genes at later stages. Furthermore, direct injection of the dual GF Coa into the edges of damaged skin in a rat skin wound defect model demonstrated accelerated wound closure and skin regeneration after 3 weeks. Histological evaluation and immunohistochemical staining also revealed enhanced formation of the epidermal layer along with facilitated angiogenesis following dual GF Coa delivery. Based on these results, we conclude that polycation-mediated Coa fabrication and exogenous dual GF delivery via the Coa platform effectively augments both the quantity and quality of regenerated skin tissues without scar formation. STATEMENT OF SIGNIFICANCE: This study was conducted to develop a simple administration platform for scarless skin regeneration using polycation-based coacervates with dual GFs. Both in vitro and in vivo studies were performed to confirm the therapeutic efficacy of this platform toward scarless wound healing. Our results demonstrate that the platform developed by us enhances the proliferation and migration of skin-related cells. Sequential modulation in various gene expression profiles suggests a balanced collagen-remodeling process by dual GFs. Furthermore, in vivo histological evaluation demonstrates that our technique enhances clear epidermis formation with less scab and thicker woven structure of collagen bundle, similar to that of a normal tissue. We propose that simple administration of dual GFs with Coa has the potential to be applied as a clinical approach for fundamental scarless skin regeneration.

Molecular Mechanisms and Potential Therapeutic Targets in Incisional Hernia

The pathophysiology underlying the formation, progression, and surgical healing of incisional hernia (IH) that develops as a major complication associated with abdominal laparotomy is poorly understood. The proposed mechanisms include the switch of collagen phenotype and the proliferation of abnormal fibroblasts after surgery. The focus of this article was to critically review the cellular, biochemical, and potential molecular events associated with the development of IH. The disturbance in collagen homeostasis with alterations in the expression of collagen subtypes, including type 1, type 3, type 4, and type 5, and impairment in the transdifferentiation of fibroblasts to myofibroblasts are discussed. The phenotype switch of wound-repair fibroblasts results in mechanically compromised extracellular matrix that triggers the proliferation of abnormal fibroblasts. High-mobility group box 1 could be involved in wound progression, whereas signaling events mediated by tumor necrosis factor β1, connective tissue growth factor, lysyl oxidase, and hypoxia-inducible factor 1 play significant role in the wound healing response. Thus, the ratio of tumor necrosis factorβ1: high-mobility group box 1 could be a critical determinant of the underlying pathology. Potential target sites for therapeutic intervention in the management of IH are recognized.