Calpain 9 as a therapeutic target in TGFβ-induced mesenchymal transition and fibrosis

lncRNA CDKN2B-AS1 regulates collagen expression

The long noncoding RNA CDKN2B-AS1 harbors a major coronary artery disease risk haplotype, which is also associated with progressive forms of the oral inflammatory disease periodontitis as well as myocardial infarction (MI). Despite extensive research, there is currently no broad consensus on the function of CDKN2B-AS1 that would explain a common molecular role of this lncRNA in these diseases. Our aim was to investigate the role of CDKN2B-AS1 in gingival cells to better understand the molecular mechanisms underlying the increased risk of progressive periodontitis. We downregulated CDKN2B-AS1 transcript levels in primary gingival fibroblasts with LNA GapmeRs. Following RNA-sequencing, we performed differential expression, gene set enrichment analyses and Western Blotting. Putative causal alleles were searched by analyzing associated DNA sequence variants for changes of predicted transcription factor binding sites. We functionally characterized putative functional alleles using luciferase-reporter and antibody electrophoretic mobility shift assays in gingival fibroblasts and HeLa cells. Of all gene sets analysed, collagen biosynthesis was most significantly upregulated (Padj=9.7 × 10- 5 (AUC > 0.65) with the CAD and MI risk gene COL4A1 showing strongest upregulation of the enriched gene sets (Fold change = 12.13, Padj = 4.9 × 10- 25). The inflammatory "TNFA signaling via NFKB" gene set was downregulated the most (Padj=1 × 10- 5 (AUC = 0.60). On the single gene level, CAPNS2, involved in extracellular matrix organization, was the top upregulated protein coding gene (Fold change = 48.5, P < 9 × 10- 24). The risk variant rs10757278 altered a binding site of the pathogen responsive transcription factor STAT1 (P = 5.8 × 10- 6). rs10757278-G allele reduced STAT1 binding 14.4% and rs10757278-A decreased luciferase activity in gingival fibroblasts 41.2% (P = 0.0056), corresponding with GTEx data. CDKN2B-AS1 represses collagen gene expression in gingival fibroblasts. Dysregulated collagen biosynthesis through allele-specific CDKN2B-AS1 expression in response to inflammatory factors may affect collagen synthesis, and in consequence tissue barrier and atherosclerotic plaque stability.

Gonadotropin upregulates intraovarian calpains-1 and -2 during ovarian follicular recruitment in the SD rat model

Calpain role has been shown in the cumulus cell-oocyte complexes and, corpus luteum. We investigated the association of calpains-1 and -2 in ovarian folliculogenesis using the Sprague-Dawley (SD) rat model and steroidogenesis in the human granulosa cells (hGCs). We induced PCOS in 42-day-old SD rats by letrozole oral gavage for 21 days. Premature ovarian failure (POF) was induced in 21-day-old SD rats by 4-vinylcyclohexene diepoxide (VCD). Ovulation and ovarian hyperstimulatory (OHS) syndrome were induced by pregnant mare gonadotropin (PMSG) + human chorionic gonadotropin (hCG) treatments in 21 days SD rats, respectively. Steroidogenesis is stimulated in human granulosa cells (hGCs) by forskolin and the response of 17-beta-estradiol (E2) on calpains expression was checked in hGCs. The protein expression by immunoblotting and activity by biochemical assay of calpains-1 and -2 showed an oscillating pattern in the ovarian cycle. PMSG-induced follicular recruitment showed upregulation of calpains-1 and -2, but with no change during ovarian function cessation (POF). Upregulated calpain-2 expression and calpain activity was found in the hCG +PMSG-induced ovulation. Letrozole-induced PCOS showed downregulation of calpain-1, but upregulation of calpain-2. PMSG+hCG-induced OHS led to the upregulation of calpain-1. Letrozole and metformin separately increased the expression level of calpains-1 and -2 in the hGCs during luteinization. In conclusion, the expression levels of calpains -1 and -2 are increased with ovarian follicular recruitment by PMSG and calpain-1 is decreased in the PCOS condition, and letrozole and metformin upregulate the expression of calpains-1 and -2 during luteinization in the hGCs possibly via E2 action.

Alpinetin ameliorates bleomycin-induced pulmonary fibrosis by repressing fibroblast differentiation and proliferation

OBJECTIVE

Idiopathic pulmonary fibrosis (IPF) is a progressive and irreversible interstitial lung disease with a poor prognosis. Alpinetin (ALP), derived from Alpinia katsumadai Hayata, has shown potential as a therapeutic measure of various diseases. However, the utilization of ALP in managing pulmonary fibrosis and its underlying mechanisms are still not fully understood.

METHODS

A well-established mouse model of pulmonary fibrosis induced by bleomycin (BLM) was used in this study. The antifibrotic effects of ALP on histopathologic manifestations and expression levels of fibrotic markers were examined. Subsequently, the impact of ALP on fibroblast differentiation, proliferation, apoptosis, and associated signaling pathways was investigated to elucidate the underlying mechanisms.

RESULTS

In the present study, we observed that ALP effectively mitigated BLM-induced pulmonary fibrosis in mice, as evidenced by histopathological manifestations and the expression levels of fibrotic markers. Furthermore, the in vitro experiments demonstrated that ALP treatment attenuated the ability of fibroblasts to differentiate into myofibroblasts. Mechanically, our findings provided evidence that ALP suppressed fibroblast-to-myofibroblast differentiation by repressing TGF-β/ALK5/Smad signaling pathway. ALP was found to possess the capability of inhibiting fibroblast proliferation and promoting apoptosis of fibroblasts induced by TGF-β.

CONCLUSION

In general, ALP may exert therapeutic effects on pulmonary fibrosis by modulating the differentiation, proliferation, and apoptosis of fibroblasts. Although its safety has been demonstrated in mice, further studies are required to investigate the efficacy of ALP in treatment of patients with IPF.

Unveiling Vaginal Fibrosis: A Novel Murine Model Using Bleomycin and Epithelial Disruption

Objective

Develop, validate, and characterize a fibrotic murine vaginal wound healing model using bleomycin instillations and epithelial disruption.

Approach

We tested the effect of repeated bleomycin instillations with mucosal layer disruption on induction of vaginal fibrosis. Tissue samples collected at various time points were analyzed for fibrosis-related gene expression changes and collagen content.

Results

Low (1.5U/kg) and high-dose (2.5U/kg) bleomycin instillations alone did not induce fibrosis, but when high-dose bleomycin was combined with epithelial disruption, increased pro-fibrotic gene expression and trichrome staining were observed. To evaluate spatial and temporal changes in the ECM structure and gene expression, tissue samples were collected at 1 day, 3 weeks, and 6 weeks after bleomycin and epithelial disruption. Data analyses revealed a significant decrease in matrix metabolizing genes and an increase in pro-fibrotic genes and inhibitors of matrix metabolizing genes in the bleomycin plus epithelial disruption group at 3 weeks. Elevated levels of the profibrotic genes Acta2 , Col1a1 , and Col3a were exclusively detected in this group at 3 weeks, and trichrome staining confirmed increased collagen content after 3 weeks. Hydroxyproline levels showed a tendency towards elevation at 3 weeks (p=0.12) and 6 weeks (p=0.14), indicating fibrosis manifestation at 3 weeks and resolution by 6 weeks post-instillation and epithelial disruption.

Innovation

We combined bleomycin instillations with epithelial disruption to induce fibrosis and understand the mechanisms of the vaginal repair process.

Conclusions

Epithelial disruption combined with bleomycin induces murine vaginal fibrosis within three weeks, characterized by increased collagen synthesis. Remarkably, the vaginal tissue fully recovers within six weeks, elucidating the regenerative capacity of the vagina.

Expression profiling of luminal B breast tumor in Indian women

PURPOSE

In this study, we aimed at profiling of luminal B breast cancer specific gene expression pattern in Indian women using mRNA-seq and validation based on TCGA expression data.

METHODS

RNA isolated from luminal B tumor and adjacent normal tissues was used for library construction and sequencing. Reference-based assemblies of these reads were used for differential gene expression analysis using DeSeq2. The DEGs were evaluated using TCGA expression data. Kaplan-Meier survival method was used to evaluate association between genes showing luminal B specific differential expression pattern and breast cancer prognosis and statistical significance was assessed using log-rank test. Alternate splicing analysis was done using rmats.

RESULTS

Differential expression analysis identified 2371 differentially expressed genes (DEGs) in luminal B breast tumors in comparison with adjacent normal tissues of Indian Women. Of them, 1692 DEGs were validated using TCGA luminal B paired samples. Integration of this data with the DEGs obtained by comparative analysis of unpaired luminal B with luminal A unpaired samples from TCGA resulted in 291 DEGs showing luminal B specific expression pattern. Further, 26 genes of prognostic value were identified. Differential splicing analysis between luminal B tumors and adjacent normal tissues in our cohort led to the identification of 687 genes showing significant differential alternate splicing events.

CONCLUSION

This study profiled gene expression pattern of luminal B tumors of Indian women and identified 26 key genes of prognostic value for luminal B breast cancer. This study also profiled differential alternate splicing and identified important alternate splicing events in luminal B breast cancer.

Calpain: the regulatory point of myocardial ischemia-reperfusion injury

Calpain is a conserved cysteine protease readily expressed in several mammalian tissues, which is usually activated by Ca²⁺ and with maximum activity at neutral pH. The activity of calpain is tightly regulated because its aberrant activation will nonspecifically cleave various proteins in cells. Abnormally elevation of Ca²⁺ promotes the abnormal activation of calpain during myocardial ischemia-reperfusion, resulting in myocardial injury and cardiac dysfunction. In this paper, we mainly reviewed the effects of calpain in various programmed cell death (such as apoptosis, mitochondrial-mediated necrosis, autophagy-dependent cell death, and parthanatos) in myocardial ischemia-reperfusion. In addition, we also discussed the abnormal activation of calpain during myocardial ischemia-reperfusion, the effect of calpain on myocardial repair, and the possible future research directions of calpain.

Identification of potential biomarkers for idiopathic pulmonary fibrosis and validation of TDO2 as a potential therapeutic target

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease with a high mortality rate. On this basis, exploring potential therapeutic targets to meet the unmet needs of IPF patients is important.

AIM

To explore novel hub genes for IPF therapy.

METHODS

Here, we used public datasets to identify differentially expressed genes between IPF patients and healthy donors. Potential targets were considered based on multiple bioinformatics analyses, especially the correlation between hub genes and carbon monoxide diffusing capacity of carbon monoxide, forced vital capacity, and patient survival rate. The mRNA levels of the hub genes were determined through quantitative real-time polymerase chain reaction.

RESULTS

We found that TDO2 was upregulated in IPF patients and predicted poor prognosis. Surprisingly, single-cell RNA sequencing data analysis revealed significant enrichment of TDO2 in alveolar fibroblasts, indicating that TDO2 may participate in the regulation of proliferation and survival. Therefore, we verified the upregulated expression of TDO2 in an experimental mouse model of transforming growth factor-β (TGF-β)-induced pulmonary fibrosis. Furthermore, the results showed that a TDO2 inhibitor effectively suppressed TGF-β-induced fibroblast activation. These findings suggest that TDO2 may be a potential target for IPF treatment. Based on transcription factors-microRNA prediction and scRNA-seq analysis, elevated TDO2 promoted the IPF proliferation of fibroblasts and may be involved in the P53 pathway and aggravate ageing and persistent pulmonary fibrosis.

CONCLUSION

We provided new target genes prediction and proposed blocking TGF-β production as a potential treatment for IPF.

Motor neurons transplantation alleviates neurofibrogenesis during chronic degeneration by reversibly regulating Schwann cells epithelial-mesenchymal transition

A novel understanding of peripheral nerve injury is epithelial-mesenchymal transition (EMT), which characterizes the process of dedifferentiation and transformation of Schwann cells after nerve injury. Despite being regarded as an important mechanism for healing nerve injuries, long-term EMT is the primary cause of fibrosis in other tissue organs. The potential mechanism promoting neurofibrosis in the process of chronic degeneration of nerve injury and the effects of motor neurons (MNs) transplantation on neurofibrosis and repair of nerve injury were studied by transcriptome sequencing and bioinformatics analysis, which were confirmed by in vivo and in vitro experiments. Even 3 months after nerve injury, the distal nerve maintained high levels of transforming growth factor β-1 (TGFβ-1) and Snail family transcriptional repressor 2 (Snai2). The microenvironment TGFβ-1, Snai2 and endogenous TGFβ-1 formed a positive feedback loop in vivo and in vitro, which may contribute to the sustained EMT state and neurofibrogenesis in the distal injured nerve. Inhibiting TGFβ-1 and Snai2 expression and reversing EMT can be achieved by transferring MNs to distal nerves, and the removal of transplanted MNs is capable of reactivating EMT and promoting the growth of proximal axons. In conclusion, EMT persisting can be an explanation for distal neurofibrosis and a potential therapeutic target. By reversibly regulating EMT, MNs transplantation can alleviate neurofibrogenesis of distal nerve in chronic degeneration.

Inhibition of calpain9 attenuates peritoneal dialysis-related peritoneal fibrosis

Aim: Peritoneal dialysis is a common renal replacement method for end-stage renal disease. Long-term peritoneal dialysis leads to peritoneal dialysis-related peritoneal fibrosis, which leads to a cessation of treatment. Calpain is a protein belonging to calcium-dependent endopeptidase family and plays an important role in extracellular matrix remodeling. Here, we evaluated the effect of calpain in peritoneal dialysis-related peritoneal fibrosis.

Methods: We established two animal models of peritoneal fibrosis and inhibited the activity of Calpain, and then collected peritoneal tissue to evaluate the progress of fibrosis and the changes of Calpain and β-catenin. We obtained Rat peritoneal mesothelial cells and Human peritoneal mesothelial cell line and stimulated with TGF-β to produce extracellular matrix. Next we inhibited Calpain activity or reduced Calpain9 expression, and then assessed changes in extracellular matrix and β-catenin.

Results: Inhibition of calpain activity attenuated chlorhexidine glucose and peritoneal dialysis-induced peritoneal thickening and β-catenin expression in mice. In addition, compared with the control group, when primary rat peritoneal mesothelial cells or human peritoneal mesothelial cells were treated with transforming growth factor beta, down-regulation of calpain activity inhibited the expression of Fibronectin and Collagen I, and increased the expression of E-cadherin. These changes could be adjusted after silencing calpain9. Finally, calpain9 deficiency was associated with down-regulation of Fibronectin and β-catenin in human peritoneal mesothelial cells.

Conclusion: Our results suggest that calpain9 may be a key molecule in mediating peritoneal dialysis-related peritoneal fibrosis.

Therapeutic use of calpeptin in COVID-19 infection

This perspective considers the benefits of the potential future use of the cell permeant calpain inhibitor, calpeptin, as a drug to treat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Recent work has reported calpeptin’s capacity to inhibit entry of the virus into cells. Elsewhere, several drugs, including calpeptin, were found to be able to inhibit extracellular vesicle (EV) biogenesis. Unsurprisingly, because of similarities between viral and EV release mechanisms, calpeptin has also been shown to inhibit viral egress. This approach, identifying calpeptin, through large-scale screening studies as a candidate drug to treat COVID-19, however, has not considered the longer term likely benefits of calpain inhibition, post-COVID-19. This perspective will reflect on the capacity of calpeptin for treating long COVID by inhibiting the overproduction of neutrophil extracellular traps potentially damaging lung cells and promoting clotting, together with limiting associated chronic inflammation, tissue damage and pulmonary fibrosis. It will also reflect on the tolerated and detrimental in vivo side-effects of calpain inhibition from various preclinical studies.

Autologous Skin Fibroblast-Based PLGA Nanoparticles for Treating Multiorgan Fibrosis

Fibrotic diseases remain a substantial health burden with few therapeutic approaches. A hallmark of fibrosis is the aberrant activation and accumulation of myofibroblasts, which is caused by excessive profibrotic cytokines. Conventional anticytokine therapies fail to undergo clinical trials, as simply blocking a single or several antifibrotic cytokines cannot abrogate the profibrotic microenvironment. Here, biomimetic nanoparticles based on autologous skin fibroblasts are customized as decoys to neutralize multiple fibroblast-targeted cytokines. By fusing the skin fibroblast membrane onto poly(lactic-co-glycolic) acid cores, these nanoparticles, termed fibroblast membrane-camouflaged nanoparticles (FNPs), are shown to effectively scavenge various profibrotic cytokines, including transforming growth factor-β, interleukin (IL)-11, IL-13, and IL-17, thereby modulating the profibrotic microenvironment. FNPs are sequentially prepared into multiple formulations for different administration routines. As a proof-of-concept, in three independent animal models with various organ fibrosis (lung fibrosis, liver fibrosis, and heart fibrosis), FNPs effectively reduce the accumulation of myofibroblasts, and the formation of fibrotic tissue, concomitantly restoring organ function and indicating that FNPs are a potential broad-spectrum therapy for fibrosis management.

Myeloid cell-specific deletion of Capns1 prevents macrophage polarization toward the M1 phenotype and reduces interstitial lung disease in the bleomycin model of systemic sclerosis

Background

Calpains are a family of calcium-dependent thiol proteases that participate in a wide variety of biological activities. In our recent study, calpain is increased in the sera of scleroderma or systemic sclerosis (SSc). However, the role of calpain in interstitial lung disease (ILD) has not been reported. ILD is a severe complication of SSc, which is the leading cause of death in SSc. The pathogenesis of SSc-related ILD remains incompletely understood. This study investigated the role of myeloid cell calpain in SSc-related ILD.

Methods

A novel line of mice with myeloid cell-specific deletion of Capns1 (Capns1-ko) was created. SSc-related ILD was induced in Capns1-ko mice and their wild-type littermates by injection 0.l mL of bleomycin (0.4 mg/mL) for 4 weeks. In a separate experiment, a pharmacological inhibitor of calpain PD150606 (Biomol, USA, 3 mg/kg/day, i.p.) daily for 30 days was given to mice after bleomycin injection on daily basis. At the end of the experiment, the animals were killed, skin and lung tissues were collected for the following analysis. Inflammation, fibrosis and calpain activity and cytokines were assessed by histological examinations and ELISA, and immunohistochemical analyses, western blot analysis and Flow cytometry analysis.

Results

Calpain activities increased in SSc-mouse lungs. Both deletion of Capns1 and administration of PD150606 attenuated dermal sclerosis as evidenced by a reduction of skin thickness and reduced interstitial fibrosis and inflammation in bleomycin model of SSc mice. These effects of reduced calpain expression or activity were associated with prevention of macrophage polarization toward M1 phenotype and consequent reduced production of pro-inflammatory cytokines including TNF-α, IL-12 and IL-23 in lung tissues of Capns1-ko mice with bleomycin model of SSc. Furthermore, inhibition of calpain correlated with an increase in the protein levels of PI3K and phosphorylated AKT1 in lung tissues of the bleomycin model of SSc mice.

Conclusions

This study for the first time demonstrates that the role of myeloid cell calpain may be promotion of macrophage M1 polarization and pro-inflammatory responses related PI3K/AKT1 signaling. Thus, myeloid cell calpain may be a potential therapeutic target for bleomycin model of SSc-related ILD.

Cytoskeletal protein degradation in brain death donor kidneys associates with adverse posttransplant outcomes

In brain death, cerebral injury contributes to systemic biological dysregulation, causing significant cellular stress in donor kidneys adversely impacting the quality of grafts. Here, we hypothesized that donation after brain death (DBD) kidneys undergo proteolytic processes that may deem grafts susceptible to posttransplant dysfunction. Using mass spectrometry and immunoblotting, we mapped degradation profiles of cytoskeletal proteins in deceased and living donor kidney biopsies. We found that key cytoskeletal proteins in DBD kidneys were proteolytically cleaved, generating peptide fragments, predominantly in grafts with suboptimal posttransplant function. Interestingly, α-actinin-4 and talin-1 proteolytic fragments were detected in brain death but not in circulatory death or living donor kidneys with similar donor characteristics. As talin-1 is a specific proteolytic target of calpain-1, we investigated a potential trigger of calpain activation and talin-1 degradation using human ex vivo precision-cut kidney slices and in vitro podocytes. Notably, we showed that activation of calpain-1 by transforming growth factor-β generated proteolytic fragments of talin-1 that matched the degradation fragments detected in DBD preimplantation kidneys, also causing dysregulation of the actin cytoskeleton in human podocytes; events that were reversed by calpain-1 inhibition. Our data provide initial evidence that brain death donor kidneys are more susceptible to cytoskeletal protein degradation. Correlation to posttransplant outcomes may be established by future studies.

Aggravation of pulmonary fibrosis after knocking down the Aryl hydrocarbon receptor in the Insulin-like growth factor 1 receptor pathway

BACKGROUND AND PURPOSE

Idiopathic pulmonary fibrosis (IPF) is a devastating disease with multiple contributing factors. Insulin-like growth factor 1 receptor (IGF1R), with a reciprocal function to Aryl hydrocarbon receptor (AhR), is known to be involved in the development of airway inflammation. However, the exact relationship between IGF1R and AhR in lung fibrogenesis is unclear. This study aimed to investigate the cascade pathway involving IGF1R and AhR in IPF.

EXPERIMENTAL APPROACH

The AhR and IGF1R expressions were determined in the lungs of IPF patients and in a rodent fibrosis model. Pulmonary fibrosis was evaluated in bleomycin (BLM)-induced lung injury in wild type and AhR knockout (AhR^-/- ) mice. The effects of IGF1R inhibition and AhR activation in vitro on TGF-β1-induced epithelial-mesenchymal transition (EMT) in Beas2B cells and in vivo on BLM-exposed mice were also examined.

KEY RESULTS

There were increased IGF1R levels but diminished AhR expression in the lung tissues of IPF patients and BLM-induced mice. Knockout of AhR aggravated lung fibrosis, while the use of IGF1R inhibitor and AhR agonist significantly attenuated such effects and inhibited TGF-β1-induced EMT in Beas2B cells. Both TGF-β1 and BLM markedly suppressed AhR expression through endoplasmic reticulum (ER) stress and consequently, IGF1R activation. The IGF1R inhibitor and specific knockdown of IGF1R reversed the activation of the TGF-β1 signal pathway.

CONCLUSION AND IMPLICATIONS

In the development of IPF, AhR and IGF1R play opposite roles via the TGF-β/Smad/STAT signaling cascade. The AhR/IGF1R axis is a potential target for the treatment of lung injury and fibrosis.

Tranilast inhibits angiotensin II-induced myocardial fibrosis through S100A11/ transforming growth factor-β (TGF-β1)/Smad axis

Tranilast has an ameliorative effect on myocardial fibrosis (MF), but the specific mechanism has not been studied. S100A11 is a key regulator of collagen expression in MF. In this paper, we will study the regulatory roles of Tranilast and S100A11 in MF. After the introduction of angiotensin II (AngII) to Human cardiac fibroblasts (HCF), Tranilast was administered. CCK-8 kit was used to detect cell viability. Wound Healing assay detected cell migration, and Western blot was used to detect the expression of migration-related proteins and proteins related to extracellular matrix synthesis. The expression of α-SMA was detected by immunofluorescence (IF). The expression of S100A11 was detected by qPCR and Western blot, and then S100A11 was overexpressed by cell transfection technology, so as to explore the mechanism by which Tranilast regulated MF. In addition, the expression of TGF-β1/Smad pathway related proteins was detected by Western blot. Tranilast inhibited Ang II–induced over-proliferation, migration and fibrosis of human cardiac fibroblasts (HCF), and simultaneously significantly decreased S100A11 expression was observed. Overexpression of S100A11 reversed the inhibition of Tranilast on AngII–induced over-proliferation, migration, and fibrosis in HCF, accompanied by activation of the TGF-β1/Smad pathway. Overall, Tranilast inhibits angiotensin II-induced myocardial fibrosis through S100A11/TGF-β1/Smad axis.

Pro-inflammatory immunity supports fibrosis advancement in epidermolysis bullosa: intervention with Ang-(1-7)

Recessive dystrophic epidermolysis bullosa (RDEB), a genetic skin blistering disease, is a paradigmatic condition of tissue fragility-driven multi-organ fibrosis. Here, longitudinal analyses of the tissue proteome through the course of naturally developing disease in RDEB mice revealed that increased pro-inflammatory immunity associates with fibrosis evolution. Mechanistically, this fibrosis is a consequence of altered extracellular matrix organization rather than that of increased abundance of major structural proteins. In a humanized system of disease progression, we targeted inflammatory cell fibroblast communication with Ang-(1-7)-an anti-inflammatory heptapeptide of the renin-angiotensin system, which reduced the fibrosis-evoking aptitude of RDEB cells. In vivo, systemic administration of Ang-(1-7) efficiently attenuated progression of multi-organ fibrosis and increased survival of RDEB mice. Collectively, our study shows that selective down-modulation of pro-inflammatory immunity may mitigate injury-induced fibrosis. Furthermore, together with published data, our data highlight molecular diversity among fibrotic conditions. Both findings have direct implications for the design of therapies addressing skin fragility and fibrosis.

Finding Solutions for Fibrosis: Understanding the Innate Mechanisms Used by Super-Regenerator Vertebrates to Combat Scarring

Soft tissue fibrosis and cutaneous scarring represent massive clinical burdens to millions of patients per year and the therapeutic options available are currently quite limited. Despite what is known about the process of fibrosis in mammals, novel approaches for combating fibrosis and scarring are necessary. It is hypothesized that scarring has evolved as a solution to maximize healing speed to reduce fluid loss and infection. This hypothesis, however, is complicated by regenerative animals, which have arguably the most remarkable healing abilities and are capable of scar-free healing. This review explores the differences observed between adult mammalian healing that typically results in fibrosis versus healing in regenerative animals that heal scarlessly. Each stage of wound healing is surveyed in depth from the perspective of many regenerative and fibrotic healers so as to identify the most important molecular and physiological variances along the way to disparate injury repair outcomes. Understanding how these powerful model systems accomplish the feat of scar-free healing may provide critical therapeutic approaches to the treatment or prevention of fibrosis.

A bilirubin-derived nanomedicine attenuates the pathological cascade of pulmonary fibrosis

Pulmonary fibrosis is an irreparable and life-threatening disease with only limited therapeutic options. The recent outbreak of COVID-19 has caused a sharp rise in the incidence of pulmonary fibrosis owing to SARS-CoV-2 infection-mediated acute respiratory distress syndrome (ARDS). The considerable oxidative damage caused by locally infiltrated immune cells plays a crucial role in ARDS, suggesting the potential use of antioxidative therapeutics. Here, we report the therapeutic potential of nanoparticles derived from the endogenous antioxidant and anti-inflammatory bile acid, bilirubin (BRNPs), in treating pulmonary fibrosis in a bleomycin-induced mouse model of the disease. Our results demonstrate that BRNPs can effectively reduce clinical signs in mice, as shown by histological, disease index evaluations, and detection of biomarkers. Our findings suggest that BRNPs, with their potent antioxidant and anti-inflammatory effects, long blood circulation half-life, and preferential accumulation at the inflamed site, are potentially a viable clinical option for preventing Covid-19 infection-associated pulmonary fibrosis.

[Calpain activation promotes dialysis-associated peritoneal fibrosis in rats]

OBJECTIVE

To explore the role of calpain activation in the progression of peritoneal fibrosis.

OBJECTIVE

Twenty-four male Sprague-Dawley rats were randomized equally into control group, MDL28170 (a calpain inhibitor)+normal saline group, peritoneal dialysis (PD) model group and PD + MDL28170 group. In the latter two groups, the rats received daily intraperitoneal injections of 100 mL/kg of 4.25% glucose PD solution, and those in PD+MDL28170 group and MDL28170 saline group received daily infusion of 4 mg/kg MDL28170 every other day. Eight weeks later, the rats were euthanized for pathological examination of the parietal peritoneum, and the visceral peritoneum was used for examining the activation status of calpain and the expressions of fibronectin (FN) and collagen I (COL-I). Calpain activation and expressions of FN, COL-I and α-SMA were also examined using Western blotting and immunofluorescence assay in primary cultures of rat peritoneal mesothelial cells treated with MDL28170, transforming growth factor-β (TGF-β), or both.

OBJECTIVE

Compared with the control rats, the rats in PD model group showed significantly increased peritoneal peritoneum thickness, calpain activation in the peritoneal tissue, and expressions of FN and COL-I (P < 0.05). Treatment with MDL28170 significantly alleviated associated peritoneal fibrosis, decreased the thickness of the peritoneum (P < 0.05), and reduced the expressions of FN and COL-I in the rats with daily PD (P < 0.05). In the in vitro experiment, the expressions of FN and COL-I were also significantly lower in rat peritoneal mesothelial cells treated with both MDL28170 and TGF-β than in the cells treated with TGF-β alone (P < 0.05).

OBJECTIVE

Peritoneal calpain activity and expressions FN and COL-I all increase significantly in rat models of PD-associated peritoneal fibrosis. Calpain activation can promote peritoneal fibrosis, and inhibition of calpain can alleviate peritoneal fibrosis.

Biomimetic lipid Nanocomplexes incorporating STAT3-inhibiting peptides effectively infiltrate the lung barrier and ameliorate pulmonary fibrosis

Activation of signal transducer and activator of transcription 3 (STAT3) under conditions of inflammation plays a crucial role in the pathogenesis of life-threatening pulmonary fibrosis (PF), initiating pro-fibrotic signaling following its phosphorylation. While there have been attempts to interfere with STAT3 activation and associated signaling as a strategy for ameliorating PF, potent inhibitors with minimal systemic toxicity have yet to be developed. Here, we assessed the in vitro and in vivo therapeutic effectiveness of a cell-permeable peptide inhibitor of STAT3 phosphorylation, designated APTstat3-9R, for ameliorating the indications of pulmonary fibrosis. Our results demonstrate that APTstat3-9R formulated with biomimetic disc-shaped lipid nanoparticles (DLNPs) markedly enhanced the penetration of pulmonary surfactant barrier and alleviated clinical symptoms of PF while causing negligible systemic cytotoxicity. Taken together, our findings suggest that biomimetic lipid nanoparticle-assisted pulmonary delivery of APTstat3-9R may be a feasible therapeutic option for PF in the clinic, and could be applied to treat other fibrotic diseases.

Precision therapeutic targets for COVID-19

Beginning in late 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged as a novel pathogen that causes coronavirus disease 2019 (COVID-19). SARS-CoV-2 has infected more than 111 million people worldwide and caused over 2.47 million deaths. Individuals infected with SARS-CoV-2 show symptoms of fever, cough, dyspnea, and fatigue with severe cases that can develop into pneumonia, myocarditis, acute respiratory distress syndrome, hypercoagulability, and even multi-organ failure. Current clinical management consists largely of supportive care as commonly administered treatments, including convalescent plasma, remdesivir, and high-dose glucocorticoids. These have demonstrated modest benefits in a small subset of hospitalized patients, with only dexamethasone showing demonstrable efficacy in reducing mortality and length of hospitalization. At this time, no SARS-CoV-2-specific antiviral drugs are available, although several vaccines have been approved for use in recent months. In this review, we will evaluate the efficacy of preclinical and clinical drugs that precisely target three different, essential steps of the SARS-CoV-2 replication cycle: the spike protein during entry, main protease (MPro) during proteolytic activation, and RNA-dependent RNA polymerase (RdRp) during transcription. We will assess the advantages and limitations of drugs that precisely target evolutionarily well-conserved domains, which are less likely to mutate, and therefore less likely to escape the effects of these drugs. We propose that a multi-drug cocktail targeting precise proteins, critical to the viral replication cycle, such as spike protein, MPro, and RdRp, will be the most effective strategy of inhibiting SARS-CoV-2 replication and limiting its spread in the general population.

Effects of functionally diverse calpain system on immune cells

Calpains are a family of nonlysosomal cysteine proteases, which play important roles in numerous physiological and pathological processes. Locations of them dictates the functions so that they are classified as ubiquitously expressed calpains and tissue-specific calpains. Recent studies are mainly focused on conventional calpains (calpain-1,2) in development and diseases, and increasing people pay attention to other subtypes of calpains but may not been summarized appropriately. Growing evidence suggests that calpains are also involved in immune regulation. However, seldom articles review the regulation of calpains on immune cells. The aim of this article is to review the research progress of each calpain isozyme and the effect of calpains on immune cells, especially the promotion effect of calpains on the immune response of macrophage, neutrophils, dendritic cells, mast cells, natural killed cells, and lymphocytes. These effects would hold great promise for the clinical application of calpains as a practicable therapeutic option in the treatment of immune related diseases.

TGFβ-Directed Therapeutics: 2020

The transforming growth factor-beta (TGFβ) pathway is essential during embryo development and in maintaining normal homeostasis. During malignancy, the TGFβ pathway is co-opted by the tumor to increase fibrotic stroma, to promote epithelial to mesenchymal transition increasing metastasis and producing an immune-suppressed microenvironment which protects the tumor from recognition by the immune system. Compelling preclinical data demonstrate the therapeutic potential of blocking TGFβ function in cancer. However, the TGFβ pathway cannot be described as a driver of malignant disease. Two small molecule kinase inhibitors which block the serine-threonine kinase activity of TGFβRI on TGFβRII, a pan-TGFβ neutralizing antibody, a TGFβ trap, a TGFβ antisense agent, an antibody which stabilizes the latent complex of TGFβ and a fusion protein which neutralizes TGFβ and binds PD-L1 are in clinical development. The challenge is how to most effectively incorporate blocking TGFβ activity alone and in combination with other therapeutics to improve treatment outcome.

Necrostatin-1, RIP1/RIP3 inhibitor, relieves transforming growth factor β-induced wound-healing process in formation of hypertrophic scars

BACKGROUND

Hypertrophic scars (HS) are common pathologic processes emerged during wound-healing process. The receptor-interacting protein kinase (RIP) might participate in keloid formation.

AIMS

This study aimed to investigate Necrostatin-1 (Nec-1), a RIP1/RIP3 inhibitor, in the formation of hypertrophic scar.

METHODS

Human hypertrophic scar fibroblasts (HSF) were extracted from patients with hypertrophic scar. Transforming growth factor-β1 (TGF-β1) was performed to induce wound-healing process including cell proliferation (CCK-8, Flow cytometry, and Western blot), migration (Transwell assay, Western blot), collagen production (Western blot), and extracellular matrix dysfunction (Western blotting and immunofluorescence).

RESULTS

Our results reported that Nec-1 inhibited TGF-β1-induced cell proliferation and promoted G0/G1 phase arrest in HSF. In addition, Nec-1 attenuated TGF-β1-induced cell migration and inhibited the expression of MMP2 and MMP9 in TGF-β1-induced HSF. Besides, Nec-1 also reduced TGF-β1-induced collagen production and α-smooth muscle actin expression in HSF.

CONCLUSIONS

The present data in this study showed the potential role of Nec-1 as a novel treatment for HS.

Human pluripotent stem cell-derived cardiac stromal cells and their applications in regenerative medicine

Coronary heart disease is one of the leading causes of death in the United States. Recent advances in stem cell biology have led to the development and engineering of human pluripotent stem cell (hPSC)-derived cardiac cells and tissues for application in cellular therapy and cardiotoxicity studies. Initial studies in this area have largely focused on improving differentiation efficiency and maturation states of cardiomyocytes. However, other cell types in the heart, including endothelial and stromal cells, play crucial roles in cardiac development, injury response, and cardiomyocyte function. This review discusses recent advances in differentiation of hPSCs to cardiac stromal cells, identification and classification of cardiac stromal cell types, and application of hPSC-derived cardiac stromal cells and tissues containing these cells in regenerative and drug development applications.

Celastrol exerts anti-inflammatory effect in liver fibrosis via activation of AMPK-SIRT3 signalling

Celastrol, a pentacyclic tritepene extracted from Tripterygium Wilfordi plant, showing potent liver protection effects on several liver-related diseases. However, the anti-inflammatory potential of celastrol in liver fibrosis and the detailed mechanisms remain uncovered. This study was to investigate the anti-inflammatory effect of celastrol in liver fibrosis and to further reveal mechanisms of celastrol-induced anti-inflammatory effects with a focus on AMPK-SIRT3 signalling. Celastrol showed potent ameliorative effects on liver fibrosis both in activated hepatic stellate cells (HSCs) and in fibrotic liver. Celastrol remarkably suppressed inflammation in vivo and inhibited the secretion of inflammatory factors in vitro. Interestingly, celastrol increased SIRT3 promoter activity and SIRT3 expression both in fibrotic liver and in activated HSCs. Furthermore, SIRT3 silencing evidently ameliorated the anti-inflammatory potential of celastrol. Besides, we found that celastrol could increase the AMPK phosphorylation. Further investigation showed that SIRT3 siRNA decreased SIRT3 expression but had no obvious effect on phosphorylation of AMPK. In addition, inhibition of AMPK by employing compound C (an AMPK inhibitor) or AMPK1α siRNA significantly suppressed SIRT3 expression, suggesting that AMPK was an up-stream protein of SIRT3 in liver fibrosis. We further found that depletion of AMPK significantly attenuated the inhibitory effect of celastrol on inflammation. Collectively, celastrol attenuated liver fibrosis mainly through inhibition of inflammation by activating AMPK-SIRT3 signalling, which makes celastrol be a potential candidate compound in treating or protecting against liver fibrosis.