High-Mobility Group Box 1 Mediates Fibroblast Activity via RAGE-MAPK and NF-κB Signaling in Keloid Scar Formation

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.

Aligned electrospun fibers of different diameters for improving cell migration capacity

Electrospun fibers have gained significant attention as scaffolds in skin tissue engineering due to their biomimetic properties, which resemble the fibrous extracellular matrix. The morphological characteristics of electrospun fibers play a crucial role in determining cell behavior. However, the effects of electrospun fibers' arrangement and diameters on human skin fibroblasts (HSFs) remain elusive. Here, we revealed the impact of electrospun fiber diameters (700 nm, 2000 nm, and 3000 nm) on HSFs' proliferation, migration, and functional expression. The results demonstrated that all fibers exhibited good cytocompatibility. HSFs cultured on nanofibers (700 nm diameter) displayed a more dispersed and elongated morphology. Conversely, fibers with a diameter of 3000 nm exhibited a reduced specific surface area and lower adsorption of adhesion proteins, resulting in enhanced cell migration speed and effective migration rate. Meanwhile, the expression levels of migration-related genes and proteins were upregulated at 48 h for the 3000 nm fibers. This study demonstrated the unique role of fiber diameters in controlling the physiological functions of cells, especially decision-making and navigating migration in complex microenvironments of aligned electrospun fibers, and highlights the utility of these bioactive substitutes in skin tissue engineering applications.

Insights into How Plant-Derived Extracts and Compounds Can Help in the Prevention and Treatment of Keloid Disease: Established and Emerging Therapeutic Targets

Keloid is a disease in which fibroblasts abnormally proliferate and synthesize excessive amounts of extracellular matrix, including collagen and fibronectin, during the healing process of skin wounds, causing larger scars that exceed the boundaries of the original wound. Currently, surgical excision, cryotherapy, radiation, laser treatment, photodynamic therapy, pressure therapy, silicone gel sheeting, and pharmacotherapy are used alone or in combinations to treat this disease, but the outcomes are usually unsatisfactory. The purpose of this review is to examine whether natural products can help treat keloid disease. I introduce well-established therapeutic targets for this disease and various other emerging therapeutic targets that have been proposed based on the phenotypic difference between keloid-derived fibroblasts (KFs) and normal epidermal fibroblasts (NFs). We then present recent studies on the biological effects of various plant-derived extracts and compounds on KFs and NFs. Associated ex vivo, in vivo, and clinical studies are also presented. Finally, we discuss the mechanisms of action of the plant-derived extracts and compounds, the pros and cons, and the future tasks for natural product-based therapy for keloid disease, as compared with existing other therapies. Extracts of Astragalus membranaceus, Salvia miltiorrhiza, Aneilema keisak, Galla Chinensis, Lycium chinense, Physalis angulate, Allium sepa, and Camellia sinensis appear to modulate cell proliferation, migration, and/or extracellular matrix (ECM) production in KFs, supporting their therapeutic potential. Various phenolic compounds, terpenoids, alkaloids, and other plant-derived compounds could modulate different cell signaling pathways associated with the pathogenesis of keloids. For now, many studies are limited to in vitro experiments; additional research and development are needed to proceed to clinical trials. Many emerging therapeutic targets could accelerate the discovery of plant-derived substances for the prevention and treatment of keloid disease. I hope that this review will bridge past, present, and future research on this subject and provide insight into new therapeutic targets and pharmaceuticals, aiming for effective keloid treatment.

Interleukin-10-Modified Adipose-Derived Mesenchymal Stem Cells Prevent Hypertrophic Scar Formation via Regulating the Biological Characteristics of Fibroblasts and Inflammation

Hypertrophic scar causes serious functional and cosmetic problem, but no treatment method is known to achieve a satisfactory therapeutic effect. However, mesenchymal stem cells show a possible cure prospect. Here, we investigated the effect of interleukin-10-modified adipose-derived mesenchymal stem cells (IL-10-ADMSC) on the formation of hypertrophic scar. In vitro, IL-10-ADMSC could highly express IL-10 and exhibited stronger inhibition of hypertrophic scar fibroblasts (HSFs) proliferation, migration, and extracellular matrix synthesis (the expression of collagen I, collagen III, FN, and α-SMA protein) than ADMSC. In vivo, we found that IL-10-ADMSC speeded up wound healing time and reduced scar area and scar outstanding height. Same as in vitro, IL-10-ADMSC also exhibited stronger inhibition of extracellular matrix synthesis (the expression of collagen I, collagen III protein) in wound than ADMSC. In addition, we also found that IL-10-ADMSC is also a stronger inhibitory effect on inflammation in wound than ADMSC, and IL-10-ADMSC inhibited TGF-β/Smads and NF-κB pathway. In conclusion, IL-10-ADMSC demonstrated the ability to prevent hypertrophic scar formation. And its possible molecular mechanism might be related to IL-10-ADMSC inhibiting the proliferation and migration of the synthesis of extracellular matrix of HSFs, and IL-10-ADMSC inhibited the inflammation during the wound healing.

Identification and validation of HOXD3 and UNC5C as molecular signatures in keloid based on weighted gene co-expression network analysis

BACKGROUND

Keloid is a benign proliferative disease characterized by excessive deposition of extracellular matrix collagen during skin wound healing. The mechanisms of keloid formation have not been fully elucidated, and the current treatment methods are not effective for all keloid patients. Therefore, there is an urgent need to find more effective therapies, and our research focused on identifying characteristic molecular signatures of keloid to explore potential therapeutic targets.

METHODS

Gene expression profiles of keloid and control group samples were retrieved from the GEO database. Taking the GSE113619 dataset as the training set, the dataset collected skin tissues from non-lesion sites of healthy and keloid-prone individuals, denoted as Day0. The second sampling was performed 42 days later at the original sampling site of control and keloid groups, denoted as Day42.The 'limma' package and Venn diagram identified differentially expressed genes (DEGs) specific to keloid day42 versus day0 samples. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Reactome pathway functional enrichment, and annotation of the characteristic genes were conducted on the Metascape website. Ingenuity canonical pathways, disease & function enrichment analysis and gene interaction network were performed and predicted in Ingenuity Pathway Analysis (IPA) software. Key module genes related to keloid were filtered out by Weighted Gene Co-expression Network Analysis (WGCNA). We utilized the Least Absolute Shrinkage and Selection Operator (LASSO) algorithm to screen the characteristic genes in keloid by the 'glmnet' package. The area under the curve (AUC) of receiver operating characteristic (ROC) was utilized to determine the effectiveness of potential signatures in discriminating keloid samples from normal samples and performed by using the 'pROC' package. The enrich scores of 24 immune cells in each sample were calculated by the single-sample gene set enrichment analysis (ssGSEA) algorithm， and then the Gene Set Variation Analysis (GSVA) was performed. Finally, RNA from 4 normal and 6 keloid samples was extracted, and RT-qPCR and Western Blot validated the expression of characteristic genes.

RESULTS

A total of 640 DEGs specific to keloid day42 versus day0 samples were detected. 69 key module genes were uncovered and implicated in 'NCAM signaling for neurite out-growth', 'oncogenic MAPK signaling', 'transmission across chemical synapses' pathways, and the mitotic cell cycle-related processes. Five characteristic genes (MTUS1, UNC5C, CEP57, NAA35, and HOXD3) of keloid were identified by LASSO, and among which UNC5C and HOXD3 were validated by ROC plot in external dataset, RT-qPCR and Western Blot in validation samples. The result of ssGSEA indicated that the infiltration of neutrophils showed a relatively higher abundance and natural killer cells with relatively low enrichment in the keloid group compared to the control group. UNC5C was correlated with more immune cells compared with other characteristic genes.

CONCLUSION

In this study, characteristic genes associated with keloid were identified by bioinformatic approaches and verified in clinical validation samples, providing potential targets for the diagnosis and treatment of keloid.

High-mobility group box 1 (HMGB1) in COVID-19: extrapolation of dangerous liaisons

High-mobility group box 1 (HMGB1), a multifunctional nuclear protein, exists mainly within the nucleus of all mammal eukaryotic cells. It is actively secreted by the necrotic cells as a response to the inflammatory signaling pathway. HMGB1 binds to receptor ligands as RAGE, and TLR and becomes a pro-inflammatory cytokine with a robust capacity to trigger inflammatory response. It is a critical mediator of the pathogenesis of systemic inflammation in numerous inflammatory disorders. Release of HMGB1 is associated with different viral infections and strongly participates in the regulation of viral replication cycles. In COVID-19 era, high HMGB1 serum levels were observed in COVID-19 patients and linked with the disease severity, development of cytokine storm (CS), acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). SARS-CoV-2-induced cytolytic effect may encourage release of HMGB1 due to nuclear damage. Besides, HMGB1 activates release of pro-inflammatory cytokines from immune cells and up-regulation of angiotensin I-converting enzyme 2 (ACE2). Therefore, targeting of the HMGB1 pathway by anti-HMGB1 agents, such as heparin, resveratrol and metformin, may decrease COVID-19 severity. HMGB1 signaling pathway has noteworthy role in the pathogenesis of SARS-CoV-2 infections and linked with development of ALI and ARDS in COVID-19 patients. Different endogenous and exogenous agents may affect release and activation of HMGB1 pathway. Targeting of HMGB1-mediated TLR2/TLR4, RAGE and MAPK signaling, might be a new promising drug candidate against development of ALI and/or ARDS in severely affected COVID-19 patients.

Grape-Seed-Derived Procyanidin Attenuates Chemotherapy-Induced Cognitive Impairment by Suppressing MMP-9 Activity and Related Blood–Brain-Barrier Damage

(1) Background: Chemotherapy-induced cognitive impairment (CICI) is often observed in cancer patients and impairs their life quality. Grape-seed-orientated procyanidin has been shown to have anti-inflammatory and neuroprotective effects, yet its effects in preventing CICI have not been investigated. (2) Method: Adult male mice received 2.3 mg/kg cisplatin or saline injections for three cycles consisting of five daily injections followed by 5 days of rest. Procyanidin or saline was administered 1 h prior to cisplatin treatment. Cognitive testing, gelatin zymography, and blood–brain-barrier (BBB) penetration tests were performed after treatment cessation. RAW264.7 cells were treated by stimulated supernatant of SHSY5Y cells. In addition, high-mobility group protein B1 (HMGB1) expression and MMP-9 activity were tested. (3) Results: Repeated cisplatin treatment increased BBB penetration, MMP-9 activity, impaired performance in contextual fear conditioning, and novel object recognition tasks. The knockout of MMP-9 rescues cognitive impairment and cisplatin-induced upregulation of HMGB1 in SHSY5Y cells. HMGB1/TLR4/IP3K/AKT signaling contributes to the increased MMP-9 activity in RAW264.7 cells. Procyanidin treatment attenuates MMP-9 activity, BBB damage, and CICI. (4) Conclusions: The results indicated that MMP-9 activation and BBB disruption is involved in CICI. Procyanidin may effectively alleviate the harmful effects of cisplatin.

Arsenic-induced lung inflammation and fibrosis in a rat model: Contribution of the HMGB1/RAGE, PI3K/AKT, and TGF-β1/SMAD pathways

An increasing number of studies have shown that arsenic exposure increases the risk of lung cancer as well as a variety of non-malignant respiratory diseases, including bronchitis and tracheobronchitis. HMGB1 is widely expressed in a variety of tissues and cells and is involved in the pathological processes of many lung diseases through binding to the corresponding receptors and activating the downstream signaling pathways. However, the exact role of HMGB1/RAGE in arsenic-induced lung injury remains unknown. The aim of this study was to investigate whether HMGB1/RAGE and its activated downstream pathways are involved in the process of arsenic exposure-induced lung injury in rats. In this study, an animal model of oral exposure to arsenic was induced using 2.5, 5 and 10 mg/kg NaAsO2. The results showed that capillary permeability (LDH, TP, ACP, and AKP) was increased in the arsenic exposure groups, resulting in cell damage; this was accompanied by acute inflammation marked by significant neutrophil infiltration. Meanwhile, obvious histopathological damage, including thickening of the lung epithelium, increased infiltration of inflammatory cells, rupture of the alveolar wall, swelling of the mitochondria, and chromatin agglutination was observed by H&E staining and transmission electron microscopy. Furthermore, the results confirmed that the expressions of HMGB1 and RAGE in lung tissue were enhanced, and protein expression of PI3K, p-AKT, IL-1β, IL-18, and MMP-9 was increased in lung homogenates from the arsenic-exposed groups compared to the control group. Finally, Masson's staining results revealed arsenic-induced fibrosis and collagen deposition. Moreover, a significant increase in key fibrosis factors, including TGF-β1, p-SMAD2, p-SMAD3, and SMAD4 was observed in the lung homogenates in arsenic-exposed groups. In conclusion, the current study demonstrates that sub-chronic arsenic exposure triggers the inflammatory response and collagen fiber deposition in rat lung tissue. The potential mechanism may be closely related to activation of the pro-inflammatory-related HMGB1/RAGE pathway and initiation of the PI3K/AKT and TGF-β1/SMAD pathways.

Methylglyoxal-Derived Advanced Glycation End Products (AGE4) Promote Cell Proliferation and Survival in Renal Cell Carcinoma Cells through the RAGE/Akt/ERK Signaling Pathways

Advanced glycation end products (AGEs) are the products formed through a non-enzymatic reaction of reducing sugars with proteins or lipids. There is a potential for toxicity in the case of AGEs produced through glycation with dicarbonyl compounds including methylglyoxal, glyoxal, and 3-deoxyglucosone. The AGEs bind the receptor for advanced glycation end products (RAGE) and stimulate the mitogen-activated protein (MAP) kinase signaling pathway that can increase the production of matrix metalloproteinases (MMPs). In addition, AGE-induced protein kinase B (Akt) signaling can promote cancer cell proliferation and contribute to many diseases such as kidney cancer. In light of the lack of extensive study of the relationship between methylglyoxal-induced AGEs (AGE4) and renal cancer, we studied the proliferous and anti-apoptotic effects of AGE4 on renal cell carcinoma (RCC) in this study. AGE4 treatment was involved in the proliferation and migration of RCC cells in vitro by upregulating proliferating cell nuclear antigen (PCNA) and MMPs while suppressing apoptotic markers such as Bax and caspase 3. Moreover, Akt and extracellular-signal-regulated kinase (ERK) were phosphorylated in RCC cells with AGE4 treatment. As a result, this study demonstrated that AGE4-RAGE axis can promote the growth ability of RCC by inducing PCNA, MMPs, and inhibiting apoptosis in RCC via the Akt and ERK signaling pathways.

HMGB1 is a key factor for tamoxifen resistance and has the potential to predict the efficacy of CDK4/6 inhibitors in breast cancer

Breast cancer is the leading cause of cancer death in women. Hormone‐receptor‐positive breast cancer (HR + BC) is the most common pathological type of breast cancer, of which the main treatment method is endocrine therapy. Unfortunately, primary or acquired drug resistance greatly limits its efficacy. In recent years, the newly launched CDK4/6 inhibitors could effectively reverse endocrine resistance in breast cancer. However, considering their expensive price and side effects, it is particularly important to find out effective biomarkers and screen sensitive patients. Here, we found through bioinformatics analysis that high mobility group box 1 (HMGB1) expression increased in endocrine‐resistant HR + BC. In clinical specimens, the higher expression of HMGB1 was associated with shorter progression‐free survival (PFS) for HR + BC patients with endocrine therapy after surgery. For endocrine‐resistant breast cancer, compared with HMGB1‐negative patients, HMGB1‐positive patients who received CDK4/6 inhibitors treatment benefited more in PFS. Moreover, we demonstrated that HMGB1 promoted tamoxifen resistance by combining with the Toll‐like receptor 4 (TLR4) and activating nuclear factor kappa B (NF‐κB) pathway. CDK4/6 inhibitors could downregulate the expression of HMGB1 and suppress the TLR4‐NF‐κB pathway, and in turn reverse tamoxifen resistance. These results illuminated the critical role of HMGB1 in the process of tamoxifen resistance, explained the mechanism of CDK4/6 inhibitors reversing tamoxifen resistance, and suggested the feasibility of HMGB1 as a potential biomarker for screening sensitive patients receiving CDK4/6 inhibitors.

The effects of baicalin on piglets challenged with Glaesserella parasuis

Glaesserella parasuis (G. parasuis) causes porcine vascular inflammation and damage. Baicalin is reported to have antioxidant and anti-inflammatory functions. However, whether baicalin protects piglets against G. parasuis challenge and the potential protective mechanism have not been investigated. Therefore, in this study, we comprehensively examined the protective efficacy of baicalin in piglets challenged with G. parasuis and the possible protective mechanism. Our results show that baicalin attenuated the release of the inflammation-related cytokines interleukin (IL) 1β, IL6, IL8, IL10, and tumour necrosis factor α (TNF-α) and reduced high mobility group box 1 (HMGB1) production and cell apoptosis in piglets infected with G. parasuis. Baicalin also inhibited the activation of the mitogen-activated protein kinase (MAPK) signalling pathway and protected piglets against G. parasuis challenge. Taken together, our data suggest that baicalin could protect piglets from G. parasuis by reducing HMGB1 release, attenuating cell apoptosis, and inhibiting MAPK signalling activation, thereby alleviating the inflammatory response induced by the bacteria. Our results suggest that baicalin has utility as a novel therapeutic drug to control G. parasuis infection.

The cytotoxicity of advanced glycation end products was attenuated by UCMSCs in human vaginal wall fibroblasts by inhibition of an inflammatory response and activation of PI3K/AKT/PTEN

Pelvic organ prolapse (POP) occurs when the pelvic organs (bladder, bowel or uterus) herniate into the vagina, causing incontinence, voiding, and bowel and sexual dysfunction, negatively impacting upon a woman's quality of life. Intermediate intermolecular cross-links and advanced glycation cross-links increase in prolapsed tissue. Stem cells are able to participate in tissue repair due to their ability to differentiate into multiple lineages, and thus into various types of connective tissue cells, so they therefore hold great promise for treating pelvic floor dysfunction. The current study found that advanced glycation end products (AGEs) inhibited the viability and proliferation of human vaginal wall fibroblasts (VWFs), were cytotoxic to VWFs, and also induced the apoptosis of VWFs. In contrast, umbilical cord-derived mesenchymal stem cells (UCMSCs) secreted anti-inflammation cytokines to protect against the cytotoxic effects of fibroblasts induced by AGEs and attenuated the cytotoxic effect of AGE on fibroblasts by activation of the PI3K/Akt-PTEN pathway. This study demonstrated that UCMSCs inhibited the cytotoxic effect of AGE in cells from patients with POP by inducing an anti-inflammatory reaction and activating the PI3K/AKT/PTEN signaling pathway. The current results provide important insights into use of stem cells to treat POP.

Cross talk between Hsp72, HMGB1 and RAGE/ERK1/2 signaling in the pathogenesis of bronchial asthma in obese patients

BACKGROUND

The incidence of obesity-related asthma has shown a remarkable increase.

OBJECTIVES

We aimed to explore the role of heat shock protein 72 (Hsp72) and receptor for advanced glycation end products (RAGE) axis with its downstream signaling in the pathogenesis of obesity-related asthma.

METHODS

We enrolled a total of 55 subjects and divided them into three groups. Groups I and II included healthy, normal weight (n = 15) and obese (n = 15) subjects, respectively. Twenty-five obese asthmatics (group III) were subdivided into group IIIa (10 patients with mild to moderate asthma) and group IIIb (15 patients with severe asthma). High mobility group box 1 (HMGB1), interleukin 8 (IL-8), monocyte chemoattractant protein 1 (MCP-1), extracellular signal-regulated protein kinases 1 and 2 (ERK1/2), and urinary Hsp72 were immunoassayed. Hydrogen peroxide (H₂O₂) and free fatty acids (FFAs) levels were photometrically measured. RAGE mRNA expression was relatively quantified by real-time PCR.

RESULTS

We found significant elevations of serum HMGB1, IL-8, MCP1, ERK1/2, FFAs, and H₂O₂ levels as well as urinary Hsp72 levels in obese subjects compared to healthy control. These were more evident in patients with severe asthma (group IIIb). Multivariate regression analysis identified Hsp72 and ERK1/2 as independent predictors of bronchial asthma severity. Receiver operating characteristic (ROC) curve analysis revealed that areas under the curve (AUC) for Hsp72 and ERK1/2 were 0.991 and 0.981, respectively, which denotes a strong predictive value for identifying the severity of bronchial asthma in obese patients.

CONCLUSION

The current study highlights the role of Hsp72 and HMGB1/RAGE/ERK1/2 signaling cascade in the pathogenesis of bronchial asthma and its link to obesity, which could be reflected on monitoring, severity grading, and management of this disease.

Alternatively activated macrophages are associated with the α2AP production that occurs with the development of dermal fibrosis : The role of alternatively activated macrophages on the development of fibrosis

Background

Fibrotic diseases are characterized by tissue overgrowth, hardening, and/or scarring because of the excessive production, deposition, and contraction of the extracellular matrix (ECM). However, the detailed mechanisms underlying these disorders remain unclear. It was recently reported that α2-antiplasmin (α2AP) is elevated in fibrotic tissue and that it is associated with the development of fibrosis. In the present study, we examined the mechanism underlying the production of α2AP on the development of fibrosis.

Methods

To clarify the mechanism underlying the production of α2AP on the development of fibrosis, we focused on high-mobility group box 1 (HMGB1), which is associated with the development of fibrosis. The mouse model of bleomycin-induced fibrosis was used to evaluate the production of α2AP on the development of fibrosis.

Results

We found that HMGB1 induced the production of α2AP through receptor for advanced glycation end products (RAGE) in fibroblasts. Next, we showed that macrophage reduction by a macrophage-depleting agent, clodronate, attenuated the progression of fibrosis and the production of α2AP and HMGB1 in the bleomycin-induced mice. We also showed that IL-4-stimulated alternatively activated macrophages induced the production of HMGB1, that IL-4-stimulated alternatively activated macrophage conditioned media (CM) induced pro-fibrotic changes and α2AP production, and that the inhibition of HMGB1 and RAGE attenuated these effects in fibroblasts. Furthermore, the blockade of IL-4 signaling by IL-4Rα neutralizing antibodies attenuated the progression of fibrosis and the production of α2AP and HMGB1 in the bleomycin-induced mice.

Conclusion

These findings suggest that alternatively activated macrophage-derived HMGB1 induced the production of α2AP through RAGE and that these effects are associated with the development of fibrosis. Our findings may provide a clinical strategy for managing fibrotic disorders.

Two Different Missense C1S Mutations, Associated to Periodontal Ehlers-Danlos Syndrome, Lead to Identical Molecular Outcomes

Ehlers-Danlos syndromes (EDS) are clinically and genetically heterogeneous disorders characterized by soft connective tissue alteration like joint hypermobility and skin hyper-extensibility. We previously identified heterozygous missense mutations in the C1R and C1S genes, coding for the complement C1 proteases, in patients affected by periodontal EDS, a specific EDS subtype hallmarked by early severe periodontitis leading to premature loss of teeth and connective tissue alterations. Up to now, there is no clear molecular link relating the nominal role of the C1r and C1s proteases, which is to activate the classical complement pathway, to these heterogeneous symptoms of periodontal EDS syndrome. We aim therefore to elucidate the functional effect of these mutations, at the molecular and enzymatic levels. To explore the molecular consequences, a set of cell transfection experiments, recombinant protein purification, mass spectroscopy and N-terminal analyses have been performed. Focusing on the results obtained on two different C1S variants, namely p.Val316del and p.Cys294Arg, we show that HEK293-F cells stably transfected with the corresponding C1s variant plasmids, unexpectedly, do not secrete the full-length mutated C1s, but only a truncated Fg40 fragment of 40 kDa, produced at very low levels. Detailed analyses of the Fg40 fragments purified for the two C1s variants show that they are identical, which was also unexpected. This suggests that local misfolding of the CCP1 module containing the patient mutation exposes a novel cleavage site, between Lys353 and Cys354, which is not normally accessible. The mutation-induced Fg40 fragment contains the intact C-terminal serine protease domain but not the N-terminal domain mediating C1s interaction with the other C1 subunits, C1r, and C1q. Thus, Fg40 enzymatic activity escapes the normal physiological control of C1s activity within C1, potentially providing a loss-of-control. Comparative enzymatic analyses show that Fg40 retains the native esterolytic activity of C1s, as well as its cleavage efficiency toward the ancillary alarmin HMGB1 substrate, for example, whereas the nominal complement C4 activation cleavage is impaired. These new results open the way to further molecular explorations possibly involving subsidiary C1s targets.

Modeling Progressive Fibrosis with Pluripotent Stem Cells Identifies an Anti-fibrotic Small Molecule

Progressive organ fibrosis accounts for one-third of all deaths worldwide, yet preclinical models that mimic the complex, progressive nature of the disease are lacking, and hence, there are no curative therapies. Progressive fibrosis across organs shares common cellular and molecular pathways involving chronic injury, inflammation, and aberrant repair resulting in deposition of extracellular matrix, organ remodeling, and ultimately organ failure. We describe the generation and characterization of an in vitro progressive fibrosis model that uses cell types derived from induced pluripotent stem cells. Our model produces endogenous activated transforming growth factor β (TGF-β) and contains activated fibroblastic aggregates that progressively increase in size and stiffness with activation of known fibrotic molecular and cellular changes. We used this model as a phenotypic drug discovery platform for modulators of fibrosis. We validated this platform by identifying a compound that promotes resolution of fibrosis in in vivo and ex vivo models of ocular and lung fibrosis.

High-Mobility Group Box 1 (HMGB1) Induces Migration of Endothelial Progenitor Cell via Receptor for Advanced Glycation End-Products (RAGE)-Dependent PI3K/Akt/eNOS Signaling Pathway

BACKGROUND High-mobility group box1 (HMGB1) is a cytokine that has been demonstrated to have an important role in inducing migration and homing of endothelial progenitor cells (EPCs) in the process of neovascularization during wound healing, but its specific mechanism remains elusive. The aim of this study was to investigate the effects of the HMGB-RAGE axis in EPC migration, as well as the underlying molecular mechanism responsible for these effects. MATERIAL AND METHODS EPCs were isolated from the mice and identified using flow cytometry and fluorescence staining. The effect of HMGB1 on the activity of EPCs was detected using the Cell Counting Kit-8 (CCK-8). Then, the migration of EPCs was detected by scratch wound-healing and cell migration assay. NO levels were analyzed by ELISA. The expression of p-PI3K, p-Akt, and p-eNOS was determined by Western blot analysis. RAGE expression was measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot analysis. F-actin was assessed by fluorescent staining. RESULTS The results showed that HMGB1 induced a concentration-dependent migration of EPCs, and the migration was RAGE-dependent. The migration could be almost completely blocked by PI3K inhibitors and eNOS inhibitor. HMGB1-RAGE upregulated the expression of p-Akt, p-eNOS, and p-ERK. We also demonstrated that the MEK/ERK signaling pathway is not involved in the EPC migration induced by HMGB1-RAGE. CONCLUSIONS These data demonstrate that HMGB1 activates RAGE and induces PI3K/Akt/eNOS signaling transduction pathway activation to promote EPC migration. Therefore, the HMGB1-RAGE axis plays an important role in the EPC migration process and may become a potential target in wound healing.

HMGB1 enhances mechanical stress-induced cardiomyocyte hypertrophy in vitro via the RAGE/ERK1/2 signaling pathway

Pressure overload-induced cardiac hypertrophy is associated with a complex spectrum of pathophysiological mechanisms, including the inflammation response. High mobility group box-1 (HMGB1), a pro-inflammatory cytokine, is not only increased in myocardium under pressure overload, but also exacerbates pressure overload-induced cardiac hypertrophy and dysfunction; however, the underlying mechanisms have remained elusive. In the present study, cultured cardiomyocytes were stimulated by mechanical stress and/or HMGB1 for various durations to examine the role of HMGB1 in cardiomyocyte hypertrophy, and to detect the expression of receptor for advanced glycation end products (RAGE), toll-like receptor 4 (TLR-4) and the activation status of mitogen-activated protein kinases (MAPKs) and Janus kinase 2 (JAK2)/STAT3. The results indicated that HMGB1 aggravated mechanical stress-induced cardiomyocyte hypertrophy. Furthermore, mechanical stress and HMGB1 stimulation activated extracellular signal-regulated kinase 1/2 (ERK1/2), P38 and JAK2/STAT3 signaling in cardiomyocytes, but an additive effect of the combined stimuli was only observed on the activation of ERK1/2. In addition, mechanical stress caused a prompt upregulation of the expression of RAGE and TLR-4 in cardiomyocytes, while the activation of ERK1/2 by HMGB1 was inhibited by blockage of RAGE, but not by blockage of TLR-4. In summary, the present results indicated that extracellular HMGB1 enhanced mechanical stress-induced cardiomyocyte hypertrophy in vitro, at least partially via the RAGE/ERK1/2 signaling pathway.

Hypoxia-Induced Epithelial-To-Mesenchymal Transition Mediates Fibroblast Abnormalities via ERK Activation in Cutaneous Wound Healing

Previous studies described the involvement of extracellular signal-related kinase (ERK) in systemic fibrotic diseases, but the role of ERK in cutaneous scarring is unknown. Although hypoxia drives tissue fibrosis by activating hypoxia-inducible factor-1α (HIF-1α), the specific roles of hypoxia and associated ERK phosphorylation in abnormal fibroblast activity during cutaneous scarring are unclear. Here, we investigated whether pathologic myofibroblast-like keloid fibroblast activity is promoted by hypoxia-induced epithelial-mesenchymal transition mediated by ERK activation. ERK phosphorylation was significantly increased in keloid tissue and fibroblasts. Human dermal fibroblasts cultured under hypoxia (1% O₂) expressed phosphorylated ERK and exhibited activation of p38 mitogen-activated protein kinase signaling. Hypoxic human dermal fibroblasts showed increased protein and mRNA levels of epithelial-mesenchymal transition markers. Furthermore, administration of an ERK inhibitor (SCH772984) reduced the hypoxia-induced elevation of collagen type I levels in human dermal fibroblasts. Therefore, ERK may be a promising therapeutic target in profibrogenic diseases.

PARP1 Inhibition as a Novel Therapeutic Target for Keloid Disease

Objective: Inactivation of poly(ADP-ribose) polymerase 1 (PARP1) has been found to have protective effect in several fibrotic diseases. But the effect is not studied yet in keloids. Herein, we evaluated the therapeutic effect of PARP1 inhibitor, rucaparib, for keloids.

Approach: The protein expressions of PARP1 and smad3 were evaluated with western blotting in keloids and controls. The effect of rucaparib was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and migration assay. We further analyzed the effect of rucaparib on patient-derived keloid xenograft murine model.

Results: The protein expressions of PARP1 and smad3 were significantly higher in keloid tissue. Rucaparib (20 μM) significantly suppressed the proliferation of keloid fibroblasts. Moreover, the combination of rucaparib (20 μM) and triamcinolone (50 μM) showed additive suppressive effect on keloid fibroblasts. Migration assay showed that rucaparib (10 μM) significantly suppressed the migration of keloid fibroblasts. Fibrosis markers in keloid fibroblasts significantly decreased after rucaparib treatment (20 μM). In patient-derived keloid xenograft model, rucaparib significantly reduced the size of keloid tissue.

Innovation and Conclusion: The study data suggest PARP1 might be a novel therapeutic target for keloid disease. PARP1 inhibitor, rucaparib, might be a promising therapeutic drug for the treatment of keloid disease.

Protective effects of febuxostat against paraquat-induced lung toxicity in rats: Impact on RAGE/PI3K/Akt pathway and downstream inflammatory cascades

AIMS

The herbicide paraquat causes fatal lung toxicity by induction of xanthine oxidase, production of free radicals and inflammation. Febuxostat, a xanthine oxidase inhibitor and anti-gout has recently shown anti-inflammatory activity. Accordingly, this study was carried out to investigate whether febuxostat may attenuate paraquat-induced lung toxicity and to explore the possible underlying mechanisms.

MAIN METHODS

Rats were administered either vehicle, a single dose of paraquat (30 mg/kg, i.p.), febuxostat (15 mg/kg, oral), or both for 14 successive days. Serum LDH and sRAGE were estimated. Lung tissue xanthine oxidase activity, SOD, TAC, MDA, and RAGE, HMGB1 gene expression, PI3K/Akt and β-catenin protein expression, MMP-9, IL-8, VEGF and COX-2 gene expression were estimated.

KEY FINDINGS

Results showed that paraquat induced lung injury characterized by enhanced oxidative stress and inflammation, upregulated RAGE, HMGB1 gene expression, PI3K/Akt and β-catenin protein expression. Administration of febuxostat inhibited the deleterious effects of paraquat on lung through inhibition of xanthine oxidase activity and related oxidative stress, downregulation of RAGE/PI3K/Akt pathway, and suppression of β-catenin protein expression and its downstream inflammatory mediators.

SIGNIFICANCE

The present study showed that febuxostat may abrogate paraquat-induced lung toxicity and demonstrated a novel mechanism for its ameliorative effects.

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

High-mobility group box 1 (HMGB1) protein acts as a DNA chaperone for nuclear homeostasis. It translocates into the cytosol and is secreted into extracellular spaces, triggering proinflammatory cytokines and acting as a mediator in fibrosis. We determined whether HMGB1 plays a role in normal dermal fibrosis and keloid, and is involved with transforming growth factor β. We investigated the translocation and active release of HMGB1 from normal dermal fibroblasts under lipopolysaccharide stimuli, and the redistribution of nuclear HMGB1 into the cytoplasm of keloid fibroblasts. HMGB1 and its effector toll-like receptors and receptors for advanced glycation end product proteins are actively expressed in keloid tissues. Exogenous HMGB1 can induce the proliferation of human dermal fibroblasts, and could act as a profibrogenic molecule to produce collagen, decrease MMP-1, and increase TIMP-1 mRNA expression. Moreover, administration of HMGB1 increased the expression level of TGF-β1 and internal signaling molecules, such as Smad 2 and 3, phosphorylated Smad 2/3 complex, Erk 1/2, Akt, and NF-κB. Collectively, we demonstrate that HMGB1 treatment increases the expression level of collagen types I and III, elastin, and fibronectin in dermal spheroid cultures, thus making HMGB1 a promising therapeutic target for treatment of profibrogenic diseases.