TNF-α-induced NF-κB activation promotes myofibroblast differentiation of LR-MSCs and exacerbates bleomycin-induced pulmonary fibrosis

Imbalance of dendritic cell function in pulmonary fibrosis

Pulmonary fibrosis (PF) is a chronic, irreversible interstitial lung disease. The pathogenesis of PF remains unclear, and there are currently no effective treatments or drugs that can completely cure PF. The primary cause of PF is an imbalance of inflammatory response and inappropriate repair following lung injury. Dendritic cells (DCs), as one of the immune cells in the body, play an important role in regulating immune response, immune tolerance, and promoting tissue repair following lung injury. However, the role of DCs in the PF process is ambiguous or even contradictory in the existing literature. On the one hand, DCs can secrete transforming growth factor β(TGF-β), stimulate Th17 cell differentiation, stimulate fibroblast proliferation, and promote the generation of inflammatory factors interleukin-6(IL-6) and tumor necrosis factor-α(TNF-α), thereby promoting PF. On the other hand, DCs suppress PF through mechanisms including the secretion of IL-10 to inhibit effector T cell activity in the lungs and promote the function of regulatory T cells (Tregs), as well as by expressing matrix metalloproteinases (MMPs) which facilitate the degradation of the extracellular matrix (ECM). This article will infer possible reasons for the different roles of DCs in PF and analyze possible reasons for the functional imbalance of DCs in pulmonary fibrosis from the complexity and changes of the pulmonary microenvironment, autophagy defects of DCs, and changes in the pulmonary physical environment.

Ziziphus spina-christi L. extract attenuates bleomycin-induced lung fibrosis in mice via regulating TGF-β1/SMAD pathway: LC-MS/MS Metabolic profiling, chemical composition, and histology studies

Ancient Egyptians (including Bedouins and Nubians) have long utilized Ziziphus spina-christi (L.), a traditional Arabian medicinal herb, to alleviate swellings and inflammatory disorders. It is also mentioned in Christian and Muslim traditions. Ziziphus spina-christi L. (Family: Rhamnaceae) is a plentiful source of polyphenols, revealing free radical scavenging, antioxidant, metal chelating, cytotoxic, and anti-inflammatory activities. Herein, different classes of the existing bioactive metabolites in Z. spina-christi L. were detected using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the first time. The study also aimed to assess the anti-inflammatory and antifibrotic properties of Z. spina-christi L. extract against bleomycin-induced lung fibrosis in an experimental mouse model. 32 male Swiss Albino mice were assigned into 4 groups; the first and second were the normal control group and the bleomycin positive control (single 2.5 U/kg bleomycin intratracheal dose). The third and fourth groups received 100 and 200 mg/kg/day Z. spina-christi L. extract orally for 3 weeks, 2 weeks before bleomycin, and 1 week after. The bioactive metabolites in Z. spina-christi L. extract were identified as phenolic acids, catechins, flavonoids, chalcones, stilbenes, triterpenoid acids, saponins, and sterols. The contents of total phenolic compounds and flavonoids were found to be 196.62 mg GAE/gm and 33.29 mg QE/gm, respectively. In the experimental study, histopathological examination revealed that lung fibrosis was attenuated in both Z. spina-christi L.- treated groups. Z. spina-christi L. extract downregulated the expression of nuclear factor kappa B (NF-κB) p65 and decreased levels of the inflammatory markers tumor necrosis factor-alpha (TNF-α), monocyte chemoattractant protein-1 (MCP-1), and c-Jun N-terminal kinase (JNK) in lung tissue. Z. spina-christi L. also downregulated the expression of the fibrotic parameters collagen-1, alpha-smooth muscle actin (α-SMA), transforming growth factor-beta 1 (TGF-β1), matrix metalloproteinase-9 (MMP-9) and SMAD3, with upregulation of the antifibrotic SMAD7 in lung tissue. Overall, the present study suggests a potential protective effect of Z. spina-christi L. extract against bleomycin-induced lung fibrosis through regulation of the TGF-β1/SMAD pathway.

Single-cell transcriptomics reveals CD8+ T cell structure and developmental trajectories in idiopathic pulmonary fibrosis

Immune cells in the human lung are associated with idiopathic pulmonary fibrosis. However, the contribution of different immune cell subpopulations to the pathogenesis of pulmonary fibrosis remains unclear. We used single-cell RNA sequencing data to investigate the transcriptional profiles of immune cells in the lungs of 5 IPF patients and 3 subjects with non-fibrotic lungs. In an identifiable population of immune cells, we found increased percentage of CD8+ T cells in the T cell subpopulation in IPF. Monocle analyzed the dynamic immune status and cell transformation of CD8+ T cells, as well as the cytotoxicity and exhausted status of CD8+ T cell subpopulations at different stages. Among CD8+ T cells, we found differences in metabolic pathways in IPF and Ctrl, including lipid, amino acid and carbohydrate metabolic. By analyzing the metabolites of CD8+ T cells, we found that different populations of CD8+ T cells in IPF have unique metabolic characteristics, but they also have multiple identical up-regulated or down-regulated metabolites. In IPF, signaling pathways associated with fibrosis were enriched in CD8+ T cells, suggesting that CD8+ T cells may have an important contribution to fibrosis. Finally, we analyzed the interactions between CD8+ T cells and other cells. Together, these studies highlight key features of CD8+ T cells in the pathogenesis of IPF and help to develop effective therapeutic targets.

Mesenchymal stem cells-extracellular vesicles alleviate pulmonary fibrosis by regulating immunomodulators

BACKGROUND

Pulmonary fibrosis (PF) is a chronic interstitial lung disease characterized by fibroblast proliferation and extracellular matrix formation, causing structural damage and lung failure. Stem cell therapy and mesenchymal stem cells-extracellular vesicles (MSC-EVs) offer new hope for PF treatment.

AIM

To investigate the therapeutic potential of MSC-EVs in alleviating fibrosis, oxidative stress, and immune inflammation in A549 cells and bleomycin (BLM)-induced mouse model.

METHODS

The effect of MSC-EVs on A549 cells was assessed by fibrosis markers [collagen I and α-smooth muscle actin (α-SMA), oxidative stress regulators [nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), and inflammatory regulators [nuclear factor-kappaB (NF-κB) p65, interleukin (IL)-1β, and IL-2]. Similarly, they were assessed in the lungs of mice where PF was induced by BLM after MSC-EV transfection. MSC-EVs ion PF mice were detected by pathological staining and western blot. Single-cell RNA sequencing was performed to investigate the effects of the MSC-EVs on gene expression profiles of macrophages after modeling in mice.

RESULTS

Transforming growth factor (TGF)-β1 enhanced fibrosis in A549 cells, significantly increasing collagen I and α-SMA levels. Notably, treatment with MSC-EVs demonstrated a remarkable alleviation of these effects. Similarly, the expression of oxidative stress regulators, such as Nrf2 and HO-1, along with inflammatory regulators, including NF-κB p65 and IL-1β, were mitigated by MSC-EV treatment. Furthermore, in a parallel manner, MSC-EVs exhibited a downregulatory impact on collagen deposition, oxidative stress injuries, and inflammatory-related cytokines in the lungs of mice with PF. Additionally, the mRNA sequencing results suggested that BLM may induce PF in mice by upregulating pulmonary collagen fiber deposition and triggering an immune inflammatory response. The findings collectively highlight the potential therapeutic efficacy of MSC-EVs in ameliorating fibrotic processes, oxidative stress, and inflammatory responses associated with PF.

CONCLUSION

MSC-EVs could ameliorate fibrosis in vitro and in vivo by downregulating collagen deposition, oxidative stress, and immune-inflammatory responses.

Mesenchymal stem cells-extracellular vesicles alleviate pulmonary fibrosis by regulating immunomodulators

BACKGROUND

Pulmonary fibrosis (PF) is a chronic interstitial lung disease characterized by fibroblast proliferation and extracellular matrix formation, causing structural damage and lung failure. Stem cell therapy and mesenchymal stem cells-extracellular vesicles (MSC-EVs) offer new hope for PF treatment.

AIM

To investigate the therapeutic potential of MSC-EVs in alleviating fibrosis, oxidative stress, and immune inflammation in A549 cells and bleomycin (BLM)-induced mouse model.

METHODS

The effect of MSC-EVs on A549 cells was assessed by fibrosis markers [collagen I and α-smooth muscle actin (α-SMA), oxidative stress regulators [nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), and inflammatory regulators [nuclear factor-kappaB (NF-κB) p65, interleukin (IL)-1β, and IL-2]. Similarly, they were assessed in the lungs of mice where PF was induced by BLM after MSC-EV transfection. MSC-EVs ion PF mice were detected by pathological staining and western blot. Single-cell RNA sequencing was performed to investigate the effects of the MSC-EVs on gene expression profiles of macrophages after modeling in mice.

RESULTS

Transforming growth factor (TGF)-β1 enhanced fibrosis in A549 cells, significantly increasing collagen I and α-SMA levels. Notably, treatment with MSC-EVs demonstrated a remarkable alleviation of these effects. Similarly, the expression of oxidative stress regulators, such as Nrf2 and HO-1, along with inflammatory regulators, including NF-κB p65 and IL-1β, were mitigated by MSC-EV treatment. Furthermore, in a parallel manner, MSC-EVs exhibited a downregulatory impact on collagen deposition, oxidative stress injuries, and inflammatory-related cytokines in the lungs of mice with PF. Additionally, the mRNA sequencing results suggested that BLM may induce PF in mice by upregulating pulmonary collagen fiber deposition and triggering an immune inflammatory response. The findings collectively highlight the potential therapeutic efficacy of MSC-EVs in ameliorating fibrotic processes, oxidative stress, and inflammatory responses associated with PF.

CONCLUSION

MSC-EVs could ameliorate fibrosis in vitro and in vivo by downregulating collagen deposition, oxidative stress, and immune-inflammatory responses.

Protective effects of microbial biosurfactants produced by Bacillus halotolerans and Candida parapsilosis on bleomycin-induced pulmonary fibrosis in mice: Impact of antioxidant, anti-inflammatory and anti-fibrotic properties via TGF-β1/Smad-3 pathway and miRNA-326

Idiopathic pulmonary fibrosis (IPF) is an irreversible disease which considered the most fatal pulmonary fibrosis. Pulmonary toxicity including IPF is the most severe adverse effect of bleomycin, the chemotherapeutic agent. Based on the fact that, exogenous surfactants could induce alveolar stabilization in many lung diseases, the aim of this study was to explore the effects of low cost biosurfactants, surfactin (SUR) and sophorolipids (SLs), against bleomycin-induced pulmonary fibrosis in mice due to their antioxidant, and anti-inflammatory properties. Surfactin and sophorolipids were produced by microbial conversion of frying oil and potato peel wastes using Bacillus halotolerans and Candida parapsilosis respectively. These biosurfactants were identified by FTIR, 1H NMR, and LC-MS/MS spectra. C57BL/6 mice were administered the produced biosurfactants daily at oral dose of 200 mg kg-1 one day after the first bleomycin dose (35 U/kg). We evaluated four study groups: Control, Bleomycin, Bleomycin+SUR, Bleomycin+SLs. After 30 days, lungs from each mouse were sampled for oxidative stress, ELISA, Western blot, histopathological, immunohistochemical analyses. Our results showed that the produced SUR and SLs reduced pulmonary oxidative stress and inflammatory response in the lungs of bleomycin induced mice as they suppressed SOD, CAT, and GST activities also reduced NF-κβ, TNF-α, and CD68 levels. Furthermore, biosurfactants suppressed the expression of TGF-β1, Smad-3, and p-JNK fibrotic signaling pathway in pulmonary tissues. Histologically, SUR and SLs protected against lung ECM deposition caused by bleomycin administration. Biosurfactants produced from microbial sources can inhibit the induced inflammatory and fibrotic responses in bleomycin-induced pulmonary fibrosis.

Challenges and opportunities in obesity: the role of adipocytes during tissue fibrosis

Obesity is a chronic disease that affects the energy balance of the whole body. In addition to increasing fat mass, tissue fibrosis occurred in white adipose tissue in obese condition. Fibrosis is the over-activation of fibroblasts leading to excessive accumulation of extracellular matrix, which could be caused by various factors, including the status of adipocytes. The morphology of adipocytes responds rapidly and dynamically to nutrient fluctuations. Adaptive hypertrophy of normal adipocytes protects peripheral organs from damage from lipotoxicity. However, the biological behavior of hypertrophic adipocytes in chronic obesity is abnormally altered. Adipocytes lead to fibrotic remodeling of the extracellular matrix by inducing unresolved chronic inflammation, persistent hypoxia, and increasing myofibroblast numbers. Moreover, adipocyte-induced fibrosis not only restricts the flexible expansion and contraction of adipose tissue but also initiates the development of various diseases through cellular autonomic and paracrine effects. Regarding anti-fibrotic therapy, dysregulated intracellular signaling and epigenetic changes represent potential candidate targets. Thus, modulation of adipocytes may provide potential therapeutic avenues for reversing pathological fibrosis in adipose tissue and achieving the anti-obesity purpose.

The role of epithelial cells in fibrosis: Mechanisms and treatment

Fibrosis is a pathological process that affects multiple organs and is considered one of the major causes of morbidity and mortality in multiple diseases, resulting in an enormous disease burden. Current studies have focused on fibroblasts and myofibroblasts, which directly lead to imbalance in generation and degradation of extracellular matrix (ECM). In recent years, an increasing number of studies have focused on the role of epithelial cells in fibrosis. In some cases, epithelial cells are first exposed to external physicochemical stimuli that may directly drive collagen accumulation in the mesenchyme. In other cases, the source of stimulation is mainly immune cells and some cytokines, and epithelial cells are similarly altered in the process. In this review, we will focus on the multiple dynamic alterations involved in epithelial cells after injury and during fibrogenesis, discuss the association among them, and summarize some therapies targeting changed epithelial cells. Especially, epithelial mesenchymal transition (EMT) is the key central step, which is closely linked to other biological behaviors. Meanwhile, we think studies on disruption of epithelial barrier, epithelial cell death and altered basal stem cell populations and stemness in fibrosis are not appreciated. We believe that therapies targeted epithelial cells can prevent the progress of fibrosis, but not reverse it. The epithelial cell targeting therapies will provide a wonderful preventive and delaying action.

Inhibition of bleomycin-induced pulmonary fibrosis in SD rats by sea cucumber peptides

BACKGROUND

Pulmonary fibrosis (PF) is the terminal manifestation of a type of pulmonary disease, which seriously affects the respiratory function of the body, and with no effective cure for treatment. This study evaluated the effect of sea cucumber peptides (SCP) on bleomycin-induced SD rat PF.

RESULTS

SCP can inhibit the PF induced by bleomycin. PF and SCP did not affect the food intake of rats, but PF reduced the body weight of rats, and SCP could improve the weight loss. SCP reduced lung index in PF rats in a dose-dependent manner. SCP significantly reduced IL-1β, IL-6, TNF-α, α-SMA and VIM expression levels in lung tissue (P < 0.05), significantly decreased TGF-β1 expression level in serum (P < 0.01) and the LSCP group and MSCP group had better inhibitory effects on PF than the HSCP group. Histomorphological results showed that SCP could ameliorate the structural damage of lung tissue, alveolar wall rupture, inflammatory cell infiltration, fibroblast proliferation and deposition of intercellular matrix and collagen fibers caused by PF. The improvement effect of the MSCP group was the most noteworthy in histomorphology. Metabolomics results showed that SCP significantly downregulated catechol, N-acetyl-l-histidine, acetylcarnitine, stearoylcarnitine, d-mannose, l-threonine, l-alanine, glycine, 3-guanidinopropionic acid, prostaglandin D2 and embelic acid d-(-)-β-hydroxybutyric acid expression levels in lung tissue.

CONCLUSION

SCP ameliorate bleomycin-induced SD rat PF. KEGG pathway analysis proved that SCP intervened in PF mainly via the lysosome pathway, with d-mannose as the key factor. © 2023 Society of Chemical Industry.

Identifying a survival-associated cell type based on multi-level transcriptome analysis in idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive disease with a five-year survival rate of less than 40%. There is significant variability in survival time among IPF patients, but the underlying mechanisms for this are not clear yet.

METHODS AND RESULTS

We collected single-cell RNA sequence data of 13,223 epithelial cells taken from 32 IPF patients and bulk RNA sequence data from 456 IPF patients in GEO. Based on unsupervised clustering analysis at the single-cell level and deconvolution algorithm at bulk RNA sequence data, we discovered a special alveolar type 2 cell subtype characterized by high expression of CCL20 (referred to as ATII-CCL20), and found that IPF patients with a higher proportion of ATII-CCL20 had worse prognoses. Furthermore, we uncovered the upregulation of immune cell infiltration and metabolic functions in IPF patients with a higher proportion of ATII-CCL20. Finally, the comprehensive decision tree and nomogram were constructed to optimize the risk stratification of IPF patients and provide a reference for accurate prognosis evaluation.

CONCLUSIONS

Our study by integrating single-cell and bulk RNA sequence data from IPF patients identified a special subtype of ATII cells, ATII-CCL20, which was found to be a risk cell subtype associated with poor prognosis in IPF patients. More importantly, the ATII-CCL20 cell subtype was linked with metabolic functions and immune infiltration.

The risk factors and threshold level of subchronic inhalation exposure of reclaimed water

Inhalation of reclaimed water is known to cause lung inflammation, and free endotoxins have been shown to be a major risk factor for acute exposure. Subchronic exposure has also been shown to induce inflammatory responses with visible tissue damage. However, subchronic risk factors have yet to be identified, and a threshold for the protection of occupational populations during urban reuse is necessary. In this study, potential risk factors in reclaimed water were examined by subchronic exposure with fractionated reclaimed water, and the health risk threshold was tested with a series of diluted reclaimed water. Accordingly, following a 12-week exposure, macromolecules and microorganisms were found to be two major risk factors in reclaimed water that could cause pulmonary inflammation, including increased proportion of polymorphonuclear leukocytes in bronchoalveolar fluid, formation of inducible bronchus-associated lymphoid tissue, and elevation of Immunoglobulin A levels. Moreover, inflammation persisted after a 4-week recovery period. The calculated threshold of reclaimed water exposure for mice was 31.8 Endotoxin Unit (EU)/(kg·day) under when exposed to 50% additional relative humidity from reclaimed water at 25°C for 2 hr/day. Meanwhile, the subchronic threshold estimate for humans under the same exposure conditions was found to be 12.2 EU/(kg·day), corresponding to endotoxin levels of 61.7 EU/mL in reclaimed water. The threshold level of endotoxin was lower than that in most non-potable reclaimed water. The findings of this study suggest that occupational exposure of reclaimed water can serve as a potential risk to workers.

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

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

Spatial targeting of fibrosis-promoting macrophages with nanoscale metal-organic frameworks for idiopathic pulmonary fibrosis therapy

Targeted delivery of therapeutic drugs to fibrosis-promoting macrophages (FPMs) holds promise as a challenging yet effective approach for the treatment of idiopathic pulmonary fibrosis (IPF). Here, nanocarriers composed of Mn-curcumin metal-organic frameworks (MOFs) were utilized to deliver the immune inhibitor BLZ-945 to the lungs, with the goal of depleting fibrosis-promoting macrophages (FPMs) from fibrotic lung tissues. FPM targeting was achieved by functionalizing the nanocarrier surface with an M2-like FPM binding peptide (M2pep). As a result, significant therapeutic benefits were observed through the successful depletion of approximately 80 % of the M2-like macrophages (FPMs) in a bleomycin-induced fibrosis mouse model treated with the designed M2-like FPM-targeting nanoparticle (referred to as M2NP-BLZ@Mn-Cur). Importantly, the released Mn2+ and curcumin after the degradation of M2NP-BLZ@Mn-Cur accumulated in the fibrotic lung tissue, which can alleviate inflammation and oxidative stress reactions, thereby further improving IPF therapy. This study presents a novel strategy with promising prospects for molecular-targeted fibrosis therapy. STATEMENT OF SIGNIFICANCE: Metal-organic frameworks (MOFs)- based nanocarriers equipped with both fibrosis-promoting macrophage (FPM)-specific targeting ability and therapeutic drugs are appealing for pulmonary fibrosis treatment. Here, we prepared M2pep (an M2-like FPM binding peptide)-modified and BLZ945 (a small molecule inhibitor of CSF1/CSF-1R axis)-loaded Mn-curcumin MOF nanoparticles (M2NP-BLZ@Mn-Cur) for pulmonary fibrosis therapy. The functionalized M2NP-BLZ@Mn-Cur nanoparticles can be preferentially taken up by FPMs, resulting in their depletion from fibrotic lung tissues. In addition, Mn2+and curcumin released from the nanocarriers have anti-inflammation and immune regulation effects, which further enhance the antifibrotic effect of the nanoparticles.

Promotion of myofibroblast differentiation through repeated treatment of fibroblasts to low concentrations of PM2.5

Exposure to particulate matter ≤ 2.5 µm (PM2.5) is a risk factor for many lung diseases. Although the toxicologic effects of PM2.5 on airway epithelium are well-described, the effects of PM2.5 on fibroblasts in the lung are less studied. Here, we sought to examine the effects of PM2.5 on the differentiation of fibroblasts into myofibroblasts. Although a single treatment of fibroblasts did not result in a change in collagen or the myofibroblast marker α-SMA, exposing fibroblasts to sequential treatments with PM2.5 at low concentrations caused a robust increase in these proteins. Treatment of fibroblasts with IMD0354, an inhibitor to nuclear factor κB, but not with an antagonist to aryl hydrocarbon receptor, abolished the ability of PM2.5 to induce myofibroblast differentiation. These data demonstrate that potential impact of PM2.5 to fibroblast activation and fibrosis and support the importance of utilizing low concentrations and varying exposure protocols to toxicologic studies.

Balance between Pro- and Antifibrotic Proteins in Mesenchymal Stromal Cell Secretome Fractions Revealed by Proteome and Cell Subpopulation Analysis

Multipotent mesenchymal stromal cells (MSCs) regulate tissue repair through paracrine activity, with secreted proteins being significant contributors. Human tissue repair commonly results in fibrosis, where fibroblast differentiation into myofibroblasts is a major cellular mechanism. MSCs' paracrine activity can inhibit fibrosis development. We previously demonstrated that the separation of MSC secretome, represented by conditioned medium (CM), into subfractions enriched with extracellular vesicles (EV) or soluble factors (SF) boosts EV and SF antifibrotic effect. This effect is realized through the inhibition of fibroblast-to-myofibroblast differentiation in vitro. To unravel the mechanisms of MSC paracrine effects on fibroblast differentiation, we performed a comparative proteomic analysis of MSC secretome fractions. We found that CM was enriched in NF-κB activators and confirmed via qPCR that CM, but not EV or SF, upregulated NF-κB target genes (COX2, IL6, etc.) in human dermal fibroblasts. Furthermore, we revealed that EV and SF were enriched in TGF-β, Notch, IGF, and Wnt pathway regulators. According to scRNAseq, 11 out of 13 corresponding genes were upregulated in a minor MSC subpopulation disappearing in profibrotic conditions. Thus, protein enrichment of MSC secretome fractions and cellular subpopulation patterns shift the balance in fibroblast-to-myofibroblast differentiation, which should be considered in studies of MSC paracrine effects and the therapeutic use of MSC secretome.

The causal relationship between physical activity, sedentary time and idiopathic pulmonary fibrosis risk: a Mendelian randomization study

BACKGROUND

Several observational studies have found that physical inactivity and sedentary time are associated with idiopathic pulmonary fibrosis (IPF) risk. However, the causality between them still requires further investigation. Therefore, our study aimed to investigate the causal effect of physical activity (PA) and sedentary time on the risk of IPF via two-sample Mendelian randomization (MR) analysis.

METHODS

Multiple genome-wide association study (GWAS) data involving individuals of European ancestry were analyzed. The datasets encompassed published UK Biobank data (91,105-377,234 participants) and IPF data (2018 cases and 373,064 controls) from FinnGen Biobank. The inverse variance weighting (IVW) method was the primary approach for our analysis. Sensitivity analyses were implemented with Cochran's Q test, MR-Egger regression, MR-PRESSO global test, and leave-one-out analysis.

RESULTS

Genetically predicted self-reported PA was associated with lower IPF risk [OR = 0.27; 95% CI 0.09-0.82; P = 0.02]. No causal effects of accelerometry-based PA or sedentary time on the risk of IPF were observed.

CONCLUSIONS

Our findings supported a protective relationship between self-reported PA and the risk for IPF. The results suggested that enhancing PA may be an effective preventive strategy for IPF.

Targeting the NLRP3 inflammasome and associated cytokines in scleroderma associated interstitial lung disease

SSc-ILD (scleroderma associated interstitial lung disease) is a complex rheumatic disease characterized in part by immune dysregulation leading to the progressive fibrotic replacement of normal lung architecture. Because improved treatment options are sorely needed, additional study of the fibroproliferative mechanisms mediating this disease has the potential to accelerate development of novel therapies. The contribution of innate immunity is an emerging area of investigation in SSc-ILD as recent work has demonstrated the mechanistic and clinical significance of the NLRP3 inflammasome and its associated cytokines of TNFα (tumor necrosis factor alpha), IL-1β (interleukin-1 beta), and IL-18 in this disease. In this review, we will highlight novel pathophysiologic insights afforded by these studies and the potential of leveraging this complex biology for clinical benefit.

Prolyl oligopeptidase inhibition ameliorates experimental pulmonary fibrosis both in vivo and in vitro

BACKGROUND

Pulmonary fibrosis is a progressive disease characterized by lung remodeling due to excessive deposition of extracellular matrix. Although the etiology remains unknown, aberrant angiogenesis and inflammation play an important role in the development of this pathology. In this context, recent scientific research has identified new molecules involved in angiogenesis and inflammation, such as the prolyl oligopeptidase (PREP), a proteolytic enzyme belonging to the serine protease family, linked to the pathology of many lung diseases such as pulmonary fibrosis. Therefore, the aim of this study was to investigate the effect of a selective inhibitor of PREP, known as KYP-2047, in an in vitro and in an in vivo model of pulmonary fibrosis.

METHODS

The in vitro model was performed using human alveolar A549 cells. Cells were exposed to lipopolysaccharide (LPS) 10 μg/ml and then, cells were treated with KYP-2047 at the concentrations of 1 μM, 10 μM and 50 μM. Cell viability was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) bromide colorimetric assay, while inflammatory protein expression was assessed by western blots analysis. The in vivo model was induced in mice by intra-tracheal administration of bleomycin (1 mg/kg) and then treated intraperitoneally with KYP-2047 at doses of 1, 2.5 and 5 mg/kg once daily for 12 days and then mice were sacrificed, and lung tissues were collected for analyses.

RESULTS

The in vitro results demonstrated that KYP-2047 preserved cell viability, reduced inflammatory process by decreasing IL-18 and TNF-α, and modulated lipid peroxidation as well as nitrosative stress. The in vivo pulmonary fibrosis has demonstrated that KYP-2047 was able to restore histological alterations reducing lung injury. Our data demonstrated that KYP-2047 significantly reduced angiogenesis process and the fibrotic damage modulating the expression of fibrotic markers. Furthermore, KYP-2047 treatment modulated the IκBα/NF-κB pathway and reduced the expression of related pro-inflammatory enzymes and cytokines. Moreover, KYP-2047 was able to modulate the JAK2/STAT3 pathway, highly involved in pulmonary fibrosis.

CONCLUSION

In conclusion, this study demonstrated the involvement of PREP in the pathogenesis of pulmonary fibrosis and that its inhibition by KYP-2047 has a protective role in lung injury induced by BLM, suggesting PREP as a potential target therapy for pulmonary fibrosis. These results speculate the potential protective mechanism of KYP-2047 through the modulation of JAK2/STAT3 and NF-κB pathways.

Role of the protease-activated receptor-2 (PAR2) in the exacerbation of house dust mite-induced murine allergic lung disease by multi-walled carbon nanotubes

BACKGROUND

Pulmonary exposure to multi-walled carbon nanotubes (MWCNTs) has been reported to exert strong pro-inflammatory and pro-fibrotic adjuvant effects in mouse models of allergic lung disease. However, the molecular mechanisms through which MWCNTs exacerbate allergen-induced lung disease remain to be elucidated. We hypothesized that protease-activated receptor 2 (PAR2), a G-protein coupled receptor previously implicated in the pathogenesis of various diseases including pulmonary fibrosis and asthma, may play an important role in the exacerbation of house dust mite (HDM) allergen-induced lung disease by MWCNTs.

METHODS

Wildtype (WT) male C57BL6 mice and Par2 KO mice were exposed to vehicle, MWCNTs, HDM extract, or both via oropharyngeal aspiration 6 times over a period of 3 weeks and were sacrificed 3-days after the final exposure (day 22). Bronchoalveolar lavage fluid (BALF) was harvested to measure changes in inflammatory cells, total protein, and lactate dehydrogenase (LDH). Lung protein and RNA were assayed for pro-inflammatory or profibrotic mediators, and formalin-fixed lung sections were evaluated for histopathology.

RESULTS

In both WT and Par2 KO mice, co-exposure to MWCNTs synergistically increased lung inflammation assessed by histopathology, and increased BALF cellularity, primarily eosinophils, as well as BALF total protein and LDH in the presence of relatively low doses of HDM extract that alone produced little, if any, lung inflammation. In addition, both WT and par2 KO mice displayed a similar increase in lung Cc1-11 mRNA, which encodes the eosinophil chemokine CCL-11, after co-exposure to MWCNTs and HDM extract. However, Par2 KO mice displayed significantly less airway fibrosis as determined by quantitative morphometry compared to WT mice after co-exposure to MWCNTs and HDM extract. Accordingly, at both protein and mRNA levels, the pro-fibrotic mediator arginase 1 (ARG-1), was downregulated in Par2 KO mice exposed to MWCNTs and HDM. In contrast, phosphorylation of the pro-inflammatory transcription factor NF-κB and the pro-inflammatory cytokine CXCL-1 was increased in Par2 KO mice exposed to MWCNTs and HDM.

CONCLUSIONS

Our study indicates that PAR2 mediates airway fibrosis but not eosinophilic lung inflammation induced by co-exposure to MWCNTs and HDM allergens.

A systematic review of the research progress of traditional Chinese medicine against pulmonary fibrosis: from a pharmacological perspective

Pulmonary fibrosis is a chronic progressive interstitial lung disease caused by a variety of etiologies. The disease can eventually lead to irreversible damage to the lung tissue structure, severely affecting respiratory function and posing a serious threat to human health. Currently, glucocorticoids and immunosuppressants are the main drugs used in the clinical treatment of pulmonary fibrosis, but their efficacy is limited and they can cause serious adverse effects. Traditional Chinese medicines have important research value and potential for clinical application in anti-pulmonary fibrosis. In recent years, more and more scientific researches have been conducted on the use of traditional Chinese medicine to improve or reduce pulmonary fibrosis, and some important breakthroughs have been made. This review paper systematically summarized the research progress of pharmacological mechanism of traditional Chinese medicines and their active compounds in improving or reducing pulmonary fibrosis. We conducted a systematic search in several main scientific databases, including PubMed, Web of Science, and Google Scholar, using keywords such as idiopathic pulmonary fibrosis, pulmonary fibrosis, interstitial pneumonia, natural products, herbal medicine, and therapeutic methods. Ultimately, 252 articles were included and systematically evaluated in this analysis. The anti-fibrotic mechanisms of these traditional Chinese medicine studies can be roughly categorized into 5 main aspects, including inhibition of epithelial-mesenchymal transition, anti-inflammatory and antioxidant effects, improvement of extracellular matrix deposition, mediation of apoptosis and autophagy, and inhibition of endoplasmic reticulum stress. The purpose of this article is to provide pharmaceutical researchers with information on the progress of scientific research on improving or reducing Pulmonary fibrosis with traditional Chinese medicine, and to provide reference for further pharmacological research.

Innovative Pre-Clinical Data Using Peptides to Intervene in the Evolution of Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive, relentless, and deadly disease. Little is known about its pathogenetic mechanisms; therefore, developing efficient pharmacological therapies is challenging. This work aimed to apply a therapeutic alternative using immunomodulatory peptides in a chronic pulmonary fibrosis murine model. BALB/c mice were intratracheally instilled with bleomycin (BLM) and followed for 30 days. The mice were treated with the immune modulatory peptides ToAP3 and ToAP4 every three days, starting on the 5th day post-BLM instillation. ELISA, qPCR, morphology, and respiratory function analyses were performed. The treatment with both peptides delayed the inflammatory process observed in the non-treated group, which showed a fibrotic process with alterations in the production of collagen I, III, and IV that were associated with significant alterations in their ventilatory mechanics. The ToAP3 and ToAP4 treatments, by lung gene modulation patterns, indicated that distinct mechanisms determine the action of peptides. Both peptides controlled the experimental IPF, maintaining the tissue characteristics and standard function properties and regulating fibrotic-associated cytokine production. Data obtained in this work show that the immune response regulation by ToAP3 and ToAP4 can control the alterations that cause the fibrotic process after BLM instillation, making both peptides potential therapeutic alternatives and/or adjuvants for IPF.

Inhibition of Fatty Acid Amide Hydrolase (FAAH) Regulates NF-kb Pathways Reducing Bleomycin-Induced Chronic Lung Inflammation and Pulmonary Fibrosis

The deadly interstitial lung condition known as idiopathic pulmonary fibrosis (IPF) worsens over time and for no apparent reason. The traditional therapy approaches for IPF, which include corticosteroids and immunomodulatory drugs, are often ineffective and can have noticeable side effects. The endocannabinoids are hydrolyzed by a membrane protein called fatty acid amide hydrolase (FAAH). Increasing endogenous levels of endocannabinoid by pharmacologically inhibiting FAAH results in numerous analgesic advantages in a variety of experimental models for pre-clinical pain and inflammation. In our study, we mimicked IPF by administering intratracheal bleomycin, and we administered oral URB878 at a dose of 5 mg/kg. The histological changes, cell infiltration, pro-inflammatory cytokine production, inflammation, and nitrosative stress caused by bleomycin were all reduced by URB878. Our data clearly demonstrate for the first time that the inhibition of FAAH activity was able to counteract not only the histological alteration bleomycin-induced but also the cascade of related inflammatory events.

Targeting pathogenic macrophages by the application of SHP-1 agonists reduces inflammation and alleviates pulmonary fibrosis

Idiopathic pulmonary fibrosis is a progressive fibrotic disorder with no cure that is characterized by deterioration of lung function. Current FDA-approved drugs for IPF delay the decline in lung function, but neither reverse fibrosis nor significantly improve overall survival. SHP-1 deficiency results in hyperactive alveolar macrophages accumulating in the lung, which contribute to the induction of pulmonary fibrosis. Herein, we investigated whether employing a SHP-1 agonist ameliorates pulmonary fibrosis in a bleomycin-induced pulmonary fibrosis murine model. Histological examination and micro-computed tomography images showed that SHP-1 agonist treatment alleviates bleomycin-induced pulmonary fibrosis. Reduced alveolar hemorrhage, lung inflammation, and collagen deposition, as well as enhanced alveolar space, lung capacity, and improved overall survival were observed in mice administered the SHP-1 agonist. The percentage of macrophages collected from bronchoalveolar lavage fluid and circulating monocytes in bleomycin-instilled mice were also significantly reduced by SHP-1 agonist treatment, suggesting that the SHP-1 agonist may alleviate pulmonary fibrosis by targeting macrophages and reshaping the immunofibrotic niche. In human monocyte-derived macrophages, SHP-1 agonist treatment downregulated CSF1R expression and inactivated STAT3/NFκB signaling, culminating in inhibited macrophage survival and perturbed macrophage polarization. The expression of pro-fibrotic markers (e.g., MRC1, CD200R1, and FN1) by IL4/IL13-induced M2 macrophages that rely on CSF1R signaling for their fate-determination was restricted by SHP-1 agonist treatment. While M2-derived medium promoted the expression of fibroblast-to-myofibroblast transition markers (e.g., ACTA2 and COL3A1), the application of SHP-1 agonist reversed the transition in a dose-dependent manner. Our report indicates that pharmacological activation of SHP-1 ameliorates pulmonary fibrosis via suppression of CSF1R signaling in macrophages, reduction of pathogenic macrophages, and the inhibition of fibroblast-to-myofibroblast transition. Our study thus identifies SHP-1 as a druggable target for the treatment of IPF, and suggests that the SHP-1 agonist may be developed as an anti-pulmonary fibrosis medication that both suppresses inflammation and restrains fibroblast-to-myofibroblast transition.

Protective role of baicalin in the dynamic progression of lung injury to idiopathic pulmonary fibrosis: A meta-analysis

BACKGROUND AND PURPOSE

The pathological progression of lung injury (LI) to idiopathic pulmonary fibrosis (IPF) is a common feature of the development of lung disease. At present, effective strategies for preventing this progression are unavailable. Baicalin has been reported to specifically inhibit the progression of LI to IPF. Therefore, this meta-analysis aimed to assess its clinical application and its potential as a therapeutic drug for lung disease based on integrative analysis.

METHODS

We systematically searched preclinical articles in eight databases and reviewed them subjectively. The CAMARADES scoring system was used to assess the degree of bias and quality of evidence, whereas the STATA software (version 16.0 software) was used for statistical analysis, including a 3D analysis of the effects of dosage frequency of baicalin in LI and IPF. The protocol of this meta-analysis is documented in the PROSPERO database (CRD42022356152).

RESULTS

A total of 23 studies and 412 rodents were included after several rounds of screening. Baicalin was found to reduce the levels of TNF-α, IL-1β, IL-6, HYP, TGF-β and MDA and the W/D ratio and increase the levels of SOD. Histopathological analysis of lung tissue validated the regulatory effects of baicalin, and the 3D analysis of dosage frequency revealed that the effective dose of baicalin is 10-200 mg/kg. Mechanistically, baicalin can prevent the progression of LI to IPF by modulating p-Akt, p-NF-κB-p65 and Bcl-2-Bax-caspase-3 signalling. Additionally, baicalin is involved in signalling pathways closely related to anti-apoptotic activity and regulation of lung tissue and immune cells.

CONCLUSION

Baicalin at the dose of 10-200 mg/kg exerts protective effects against the progression of LI to IPF through anti-inflammatory and anti-apoptotic pathways.

Berberine attenuates epithelial mesenchymal transition in bleomycin-induced pulmonary fibrosis in mice via activating A2aR and mitigating the SDF-1/CXCR4 signaling

AIMS

Berberine is endowed with anti-oxidant, anti-inflammatory and anti-fibrotic effects. This study explored the role of adenosine A_2a receptor (A_2aR) activation and SDF-1/CXCR4 signaling suppression in the protective effects of berberine in bleomycin-induced pulmonary fibrosis in mice.

MAIN METHODS

Pulmonary fibrosis was generated in mice by injecting bleomycin (40 U/kg, i.p.) on days 0, 3, 7, 10 and 14. Mice were treated with berberine (5 mg/kg, i.p.) from day 15 to day 28.

KEY FINDINGS

Severe lung fibrosis and increased collagen content were observed in the bleomycin-challenged mice. Pulmonary A_2aR downregulation was documented in bleomycin-induced pulmonary fibrosis animals and was accompanied by enhanced expression of SDF-1/CXCR4. Moreover, TGF-β1elevation and pSmad2/3 overexpression were reported in parallel with enhanced epithelial mesenchymal transition (EMT) markers expression, vimentin and α-SMA. Besides, bleomycin significantly elevated the inflammatory and pro-fibrogenic mediator NF-κB p65, TNF-α and IL-6. Furthermore, bleomycin administration induced oxidative stress as depicted by decreased Nrf2, SOD, GSH and catalase levels. Interestingly, berberine administration markedly ameliorated the fibrotic changes in lungs by modulating the purinergic system through the inhibition of A_2aR downregulation, mitigating EMT and effectively suppressing inflammation and oxidative stress. Strikingly, A_2aR blockade by SCH 58261, impeded the pulmonary protective effect of berberine.

SIGNIFICANCE

These findings indicated that berberine could attenuate the pathological processes of bleomycin-induced pulmonary fibrosis at least partially via upregulating A_2aR and mitigating the SDF-1/CXCR4 related pathway, suggesting A_2aR as a potential therapeutic target for the management of pulmonary fibrosis.

p53 and Myofibroblast Apoptosis in Organ Fibrosis

Organ fibrosis represents a dysregulated, maladaptive wound repair response that results in progressive disruption of normal tissue architecture leading to detrimental deterioration in physiological function, and significant morbidity/mortality. Fibrosis is thought to contribute to nearly 50% of all deaths in the Western world with current treatment modalities effective in slowing disease progression but not effective in restoring organ function or reversing fibrotic changes. When physiological wound repair is complete, myofibroblasts are programmed to undergo cell death and self-clearance, however, in fibrosis there is a characteristic absence of myofibroblast apoptosis. It has been shown that in fibrosis, myofibroblasts adopt an apoptotic-resistant, highly proliferative phenotype leading to persistent myofibroblast activation and perpetuation of the fibrotic disease process. Recently, this pathological adaptation has been linked to dysregulated expression of tumour suppressor gene p53. In this review, we discuss p53 dysregulation and apoptotic failure in myofibroblasts and demonstrate its consistent link to fibrotic disease development in all types of organ fibrosis. An enhanced understanding of the role of p53 dysregulation and myofibroblast apoptosis may aid in future novel therapeutic and/or diagnostic strategies in organ fibrosis.

Protective effects of Qing-Re-Huo-Xue formula on bleomycin-induced pulmonary fibrosis through the p53/IGFBP3 pathway

Background

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive fibrosing lung disease with high mortality. Inflammation and epithelial mesenchymal transformation (EMT) may play an important role in the occurrence and development of IPF. Qing-Re-Huo-Xue formula (QRHXF) has been used clinically by our team for half a century and has obvious therapeutic effects on lung disease. Nevertheless, the role and mechanism of QRHXF in the treatment of IPF have never been studied.

Methods

A mouse pulmonary fibrosis model was established by intratracheal injection of BLM. The effects of QRHXF on the treatment of pulmonary fibrosis were studied by pulmonary function testing, imaging examination, pathological staining, transmission electron microscopy (TEM) observation and mRNA expression. Tandem mass tag (TMT)-based quantitative proteomics was carried out to analyse the lung protein expression profiles between the control (CTL), bleomycin (BLM) and QRHXF (BLM + QRHXF) groups. Immunohistochemistry and qRT-PCR were used to verify the possible existence of drug target proteins and signalling pathways.

Results

The results of pulmonary function, lung pathology and imaging examinations showed that QRHXF could significantly alleviate BLM-induced pulmonary fibrosis in vivo. Additionally, inflammatory cell infiltration and EMT were markedly reduced in BLM-induced PF mice administered QRHXF. Proteomics detected a total of 35 proteins, of which 17 were upregulated and 18 were downregulated. A total of 19 differentially expressed proteins (DEPs) overlapped between the BLM versus CTL groups and the BLM + QRHXF versus BLM groups. The expression of p53 and IGFBP3 was reversed in the QRHXF intervention group, which was verified by immunohistochemistry and qRT-PCR.

Conclusions

QRHXF attenuated BLM-induced pulmonary fibrosis, and regulation of the p53/IGFBP3 pathway might be associated with its efficacy, which holds promise as a novel treatment strategy for pulmonary fibrosis patients.

Graphical Abstract

Inhibitory Effects of 3-Cyclopropylmethoxy-4-(difluoromethoxy) Benzoic Acid on TGF-β1-Induced Epithelial-Mesenchymal Transformation of In Vitro and Bleomycin-Induced Pulmonary Fibrosis In Vivo

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease characterized by lung inflammation and excessive deposition of extracellular matrix components. Transforming growth factor-β1 (TGF-β1) induced epithelial-mesenchymal transformation of type 2 lung epithelial cells leads to excessive extracellular matrix deposition, which plays an important role in fibrosis. Our objective was to evaluate the effects of 3-cyclopropylmethoxy-4-(difluoromethoxy) benzoic acid (DGM) on pulmonary fibrosis and aimed to determine whether EMT plays a key role in the pathogenesis of pulmonary fibrosis and whether EMT can be used as a therapeutic target for DGM therapy to reduce IPF. Firstly, stimulation of in vitro cultured A549 cells to construct EMTs with TGF-β1. DGM treatment inhibited the expression of proteins such as α-SMA, vimentin, and collagen Ⅰ and increased the expression of E-cadherin. Accordingly, Smad2/3 phosphorylation levels were significantly reduced by DGM treatment. Secondly, models of tracheal instillation of bleomycin and DGM were used to treat rats to demonstrate their therapeutic effects, such as improving lung function, reducing lung inflammation and fibrosis, reducing collagen deposition, and reducing the expression of E-cadherin. In conclusion, DGM attenuates TGF-β1-induced EMT in A549 cells and bleomycin-induced pulmonary fibrosis in rats.

Selenium Deficiency Caused Fibrosis as an Oxidative Stress-induced Inflammatory Injury in the Lungs of Mice

Selenium (Se) is a vital trace element in the regulation of inflammation and antioxidant reactions in both animals and humans. Se deficiency is rapidly affecting lung function. The present study investigated the molecular mechanism of Se deficiency aggravates reactive oxygen species (ROS)-induced inflammation, leading to fibrosis in lung. Mice fed with different concentrations of Se to establish the model. In the Se-deficient group, the ROS and malondialdehyde (MDA) was increased, and the activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), and catalase (CAT) reduced. The histopathological observation showed that Se deficiency lead to lung texture damage with varying degrees of degeneration, necrosis, shedding of some alveolar epithelial cells, and inflammatory cell infiltration. Immunohistochemistry showed that the expression of α-smooth muscle actin (α-SMA) increased. The fibrosis index was verified with Sirius red staining. The ELISA and qPCR results showed that the inflammatory cytokines (TNF-α and IL-1β) and ECM (collagen I, collagen IV, fibronectin, and laminin) were increased with ROS increasing, which was induced by Se deficiency. The results displayed that oxidative stress with Se deficiency led to an increase in tissue inhibitors of metalloproteinase (TIMPs), but a decrease in matrix metalloproteinases (MMPs). All the results indicated that Se deficiency induced excessive ROS accumulation to generate inflammation, which disrupted ECM homeostasis and aggravated fibrosis in the lung.

GRK5-mediated inflammation and fibrosis exert cardioprotective effects during the acute phase of myocardial infarction

During myocardial infarction (MI), cardiac cells at the infarcted area undergo cell death. In response, cardiac myofibroblasts, which are mainly differentiated from resident fibroblasts upon inflammation, produce extracellular matrix proteins such as collagen to fill the damaged areas of the heart to prevent cardiac rupture. In this study, we identified a cardioprotective role of G-protein-coupled receptor kinase 5 (GRK5) in MI. GRK5 expression was found to increase in the mouse heart after MI and was highly expressed in cardiac fibroblasts/myofibroblasts. In fibroblasts/myofibroblasts, GRK5 promoted the expression of inflammation-related genes through nuclear factor-κB activation, leading to an increase in the expression levels of fibrosis-related genes. Bone marrow transfer experiments confirmed that GRK5 in fibroblasts/myofibroblasts, but not in infiltrated macrophages in the infarcted area, is mainly responsible for GRK5-mediated inflammation in infarcted hearts. In addition, inflammation and fibrosis at the infarcted area were significantly suppressed in GRK5 knockout mice, resulting in increased mortality compared with that in wild-type mice. These data indicate that GRK5 in cardiac fibroblasts/myofibroblasts promotes inflammation and fibrosis to ameliorate the damage after MI.

CXCL4-RNA Complexes Circulate in Systemic Sclerosis and Amplify Inflammatory/Pro-Fibrotic Responses by Myeloid Dendritic Cells

CXCL4 is an important biomarker of systemic sclerosis (SSc), an incurable autoimmune disease characterized by vasculopathy and skin/internal organs fibrosis. CXCL4 contributes to the type I interferon (IFN-I) signature, typical of at least half of SSc patients, and its presence is linked to an unfavorable prognosis. The mechanism implicated is CXCL4 binding to self-DNA, with the formation of complexes amplifying TLR9 stimulation in plasmacytoid dendritic cells (pDCs). Here, we demonstrate that, upon binding to self-RNA, CXCL4 protects the RNA from enzymatic degradation. As a consequence, CXCL4-RNA complexes persist in vivo. Indeed, we show for the first time that CXCL4-RNA complexes circulate in SSc plasma and correlate with both IFN-I and TNF-α. By using monocyte-derived DCs (MDDCs) pretreated with IFN-α as a model system (to mimic the SSc milieu of the IFN-I signature), we demonstrate that CXCL4-RNA complexes induce MDDC maturation and increase, in particular, pro-inflammatory TNF-α as well as IL-12, IL-23, IL-8, and pro-collagen, mainly in a TLR7/8-dependent but CXCR3-independent manner. In contrast, MDDCs produced IL-6 and fibronectin independently in their CXCL4 RNA-binding ability. These findings support a role for CXCL4-RNA complexes, besides CXCL4-DNA complexes, in immune amplification via the modulation of myeloid DC effector functions in SSc and also during normal immune responses.

Interstitial lung disease in rheumatoid arthritis: A multidisciplinary problem in rheumatology and pulmonology

Rheumatoid arthritis (RA) is an immune-mediated rheumatic disease (IMRDs) characterized by chronic erosive arthritis and systemic damage to internal organs, leading to early disability and reduced life expectancy in patients. A particularly important place among the systemic manifestations of RA is occupied by interstitial lung diseases (ILD) – the most severe form of pulmonary pathology in RA, defined as RA-ILD, which is pathogenetically associated with risk factors (smoking, etc.) and autoimmune mechanisms underlying RA. RA-ILD is a subtype of RA characterized by a severe course and a poor prognosis и неблагоприятным прогнозом. The review presents new data regarding risk factors and biomarkers for RA-ILD; modern diagnostic capabilities based on the use of functional lung tests, high-resolution computed tomography, ultrasound examination of the lungs. Particular attention is paid to the efficacy and safety of pharmacotherapy, including methotrexate, biologics, JAK inhibitors, and antifibrotic therapy. An algorithm for the pharmacotherapy of RA-ILD has been proposed.

Bolstering the secretion and bioactivities of umbilical cord MSC-derived extracellular vesicles with 3D culture and priming in chemically defined media

Human mesenchymal stem cells (hMSCs)-derived extracellular vesicles (EVs) have been known to possess the features of the origin cell with nano size and have shown therapeutic potentials for regenerative medicine in recent studies as alternatives for cell-based therapies. However, extremely low production yield, unknown effects derived from serum impurities, and relatively low bioactivities on doses must be overcome for translational applications. As several reports have demonstrated the tunability of secretion and bioactivities of EVs, herein, we introduced three-dimensional (3D) culture and cell priming approaches for MSCs in serum-free chemically defined media to exclude side effects from serum-derived impurities. Aggregates (spheroids) with 3D culture dramatically enhanced secretion of EVs about 6.7 times more than cells with two-dimensional (2D) culture, and altered surface compositions. Further modulation with cell priming with the combination of TNF-α and IFN-γ (TI) facilitated the production of EVs about 1.4 times more than cells without priming (9.4 times more than cells with 2D culture without priming), and bioactivities of EVs related to tissue regenerations. Interestingly, unlike changing 2D to 3D culture, TI priming altered internal cytokines of MSC-derived EVs. Through simulating characteristics of EVs with bioinformatics analysis, the regeneration-relative properties such as angiogenesis, wound healing, anti-inflammation, anti-apoptosis, and anti-fibrosis, for three different types of EVs were comparatively analyzed using cell-based assays. The present study demonstrated that a combinatory strategy, 3D cultures and priming MSCs in chemically defined media, provided the optimum environments to maximize secretion and regeneration-related bioactivities of MSC-derived EVs without impurities for future translational applications.

L-carnosine Attenuates Bleomycin-Induced Oxidative Stress via NFκB Pathway in the Pathogenesis of Pulmonary Fibrosis

Idiopathic Pulmonary fibrosis (IPF), a chronic interstitial lung disease, has pulmonary manifestations clinically characterized by collagen deposition, epithelial cell injury, and a decline in lung function. L-carnosine, a dipeptide consisting of β-alanine and L-histidine, has demonstrated a therapeutic effect on various diseases because of its pivotal function. Despite the effect of L-carnosine in experimental IPF mice, its anti-oxidative effect and associated intercellular pathway, particularly alveolar epithelial cells, remain unknown. Therefore, we demonstrated the anti-fibrotic and anti-inflammatory effects of L-carnosine via Reactive oxygen species (ROS) regulation in bleomycin (BLM)-induced IPF mice. The mice were intratracheally injected with BLM (3 mg/kg) and L-carnosine (150 mg/kg) was orally administrated for 2 weeks. BLM exposure increased the protein level of Nox2, Nox4, p53, and Caspase-3, whereas L-carnosine treatment suppressed the protein level of Nox2, Nox4, p53, and Caspase-3 cleavage in mice. In addition, the total SOD activity and mRNA level of Sod2, catalase, and Nqo1 increased in mice treated with L-carnosine. At the cellular level, a human fibroblast (MRC-5) and mouse alveolar epithelial cell (MLE-12) were exposed to TGFβ1 following L-carnosine treatment to induce fibrogenesis. Moreover, MLE-12 cells were exposed to cigarette smoke extract (CSE). Consequently, L-carnosine treatment ameliorated fibrogenesis in fibroblasts and alveolar epithelial cells, and inflammation induced by ROS and CSE exposure was ameliorated. These results were associated with the inhibition of the NFκB pathway. Collectively, our data indicate that L-carnosine induces anti-inflammatory and anti-fibrotic effects on alveolar epithelial cells against the pathogenesis of IPF.

Defining the spatial-molecular map of fibrotic tendon healing and the drivers of Scleraxis-lineage cell fate and function

Tendon injuries heal via a scar-mediated response, and there are no biological approaches to promote more regenerative healing. Mouse flexor tendons heal through the formation of spatially distinct tissue areas: a highly aligned tissue bridge between the native tendon stubs that is enriched for adult Scleraxis-lineage cells and a disorganized outer shell associated with peri-tendinous scar formation. However, the specific molecular programs that underpin these spatially distinct tissue profiles are poorly defined. In the present study, we combine lineage tracing of adult Scleraxis-lineage cells with spatial transcriptomic profiling to define the overarching molecular programs that govern tendon healing and cell-fate decisions. Pseudotime analysis identified three fibroblast trajectories (synthetic, fibrotic, and reactive) and key transcription factors regulating these fate-switching decisions, including the progression of adult Scleraxis-lineage cells through the reactive trajectory. Collectively, this resource defines the molecular mechanisms that coordinate the temporo-spatial healing phenotype, which can be leveraged to inform therapeutic candidate selection.

Blockade of the pentraxin 3/CD44 interaction attenuates lung injury-induced fibrosis

BACKGROUND

Fibrosing interstitial lung diseases (fILD) are potentially fatal with limited therapeutic options and no effective strategies to reverse fibrogenesis. Myofibroblasts are chief effector cells in fibrosis that excessively deposit collagen in the pulmonary interstitium and lead to progressive impairment of gaseous exchange.

METHODS

Plasma and lung specimens from patients with fILD were applied for detecting pentraxin 3 (PTX3) abundance by ELISA and Immunohistochemistry. Masson's trichrome and Sirius red stains and hydroxyproline assay were performed for assessing collagen accumulation in the lungs of bleomycin-exposed conditional Ptx3-deficient and PTX3-neutralizing antibody (αPTX3i)-treated mice. Downstream effectors including signaling pathways and fibrotic genes were examined for assessing CD44-involved PTX3-induced fibrosis in HFL1 and primary mouse fibroblasts.

RESULTS

PTX3 was upregulated in the lungs and plasma of bleomycin-exposed mice and correlated with disease severity and adverse outcomes in fILD patients. Decreased collagen accumulation, attenuation of alveolar fibrosis and fibrotic markers, and improved lung function were observed in bleomycin-exposed conditional Ptx3-deficient mice. PTX3 activates lung fibroblasts to differentiate towards migrative and highly collagen-expressing myofibroblasts. Lung fibroblasts with CD44 inactivation attenuated the PI3K-AKT1, NF-κB, and JNK signaling pathways and fibrotic markers. αPTX3i mimic-based therapeutic studies demonstrated abrogation of the migrative fibroblast phenotype and myofibroblast activation in vitro. Notably, αPTX3i inhibited lung fibrosis, reduced collagen deposition, increased mouse survival, and improved lung function in bleomycin-induced pulmonary fibrosis.

CONCLUSIONS

The present study reveals new insights into the involvement of the PTX3/CD44 axis in fibrosis and suggests PTX3 as a promising therapeutic target in fILD patients.

Targeted proteomics identifies circulating biomarkers associated with active COVID-19 and post-COVID-19

The ongoing Coronavirus Disease 2019 (COVID-19) pandemic is caused by the highly infectious Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). There is an urgent need for biomarkers that will help in better stratification of patients and contribute to personalized treatments. We performed targeted proteomics using the Olink platform and systematically investigated protein concentrations in 350 hospitalized COVID-19 patients, 186 post-COVID-19 individuals, and 61 healthy individuals from 3 independent cohorts. Results revealed a signature of acute SARS-CoV-2 infection, which is represented by inflammatory biomarkers, chemokines and complement-related factors. Furthermore, the circulating proteome is still significantly affected in post-COVID-19 samples several weeks after infection. Post-COVID-19 individuals are characterized by upregulation of mediators of the tumor necrosis (TNF)-α signaling pathways and proteins related to transforming growth factor (TGF)-ß. In addition, the circulating proteome is able to differentiate between patients with different COVID-19 disease severities, and is associated with the time after infection. These results provide important insights into changes induced by SARS-CoV-2 infection at the proteomic level by integrating several cohorts to obtain a large disease spectrum, including variation in disease severity and time after infection. These findings could guide the development of host-directed therapy in COVID-19.

The mapping of mRNA alterations elucidates the etiology of radiation-induced pulmonary fibrosis

The etiology of radiation-induced pulmonary fibrosis is not clearly understood yet, and effective interventions are still lacking. This study aimed to identify genes responsive to irradiation and compare the genome expression between the normal lung tissues and irradiated ones, using a radiation-induced pulmonary fibrosis mouse model. We also aimed to map the mRNA alterations as a predictive model and a potential mode of intervention for radiation-induced pulmonary fibrosis. Thirty C57BL/6 mice were exposed to a single dose of 16 Gy or 20 Gy thoracic irradiation, to establish a mouse model of radiation-induced pulmonary fibrosis. Lung tissues were harvested at 3 and 6 months after irradiation, for histological identification. Global gene expression in lung tissues was assessed by RNA sequencing. Differentially expressed genes were identified and subjected to functional and pathway enrichment analysis. Immune cell infiltration was evaluated using the CIBERSORT software. Three months after irradiation, 317 mRNAs were upregulated and 254 mRNAs were downregulated significantly in the low-dose irradiation (16 Gy) group. In total, 203 mRNAs were upregulated and 149 were downregulated significantly in the high-dose irradiation (20 Gy) group. Six months after radiation, 651 mRNAs were upregulated and 131 were downregulated significantly in the low-dose irradiation group. A total of 106 mRNAs were upregulated and 4 downregulated significantly in the high-dose irradiation group. Several functions and pathways, including angiogenesis, epithelial cell proliferation, extracellular matrix, complement and coagulation cascades, cellular senescence, myeloid leukocyte activation, regulation of lymphocyte activation, mononuclear cell proliferation, immunoglobulin binding, and the TNF, NOD-like receptor, and HIF-1 signaling pathways were significantly enriched in the irradiation groups, based on the differentially expressed genes. Irradiation-responsive genes were identified. The differentially expressed genes were mainly associated with cellular metabolism, epithelial cell proliferation, cell injury, and immune cell activation and regulation.

The role of estrogen receptor β in fine particulate matter (PM2.5) organic extract-induced pulmonary inflammation in female and male mice

Fine particulate matter organic extract (Po) was reported to promote inflammation in the lung. Sex differences were reported in many inflammatory diseases. In this study, we investigated the effects of Po exposure on pulmonary inflammatory response and evaluated the role of sex in this process. While mice were exposed to 100 µg/m³ Po for 12 weeks by an inhalation exposure system, the lung histopathological analysis shown obvious inflammation, the cell numbers in bronchoalveolar lavage fluid (BALF) were significantly increased, and most inflammatory cytokines in BALF were upregulated. The results of factorial analysis of variance shown that there was an interaction between sex and Po exposure in the inflammatory cell numbers and the levels of tumor necrosis factor-α (TNF-α), interleukin-5 (IL-5), and growth-related oncogene/keratinocyte chemoattractant (GRO/KC). Notably, these changes and interactions were diminished while Po-exposed mice were administered with the estrogen receptor β (ERβ) antagonist. We speculated that sex might affect the levels of inflammatory indicators in BALF of Po-exposed mice and female mice were more prone to inflammation while exposed to Po. Moreover, ERβ was involved in these processes. To our knowledge, this is the first investigation about the role of sex in Po-induced adverse effects.

Tumor necrosis factor-α coordinates with transforming growth factor-β1 to induce epithelial-mesenchymal transition and migration via the NF-κB/NOX4 pathway in bronchial epithelial cells

BACKGROUND

Epithelial-to-mesenchymal transition (EMT) is the process by which epithelial cells transform into mesenchymal cells, which plays a significant role in lung fibrotic disease. Transforming growth factor-β1(TGF-β1) is considered to be the most effective EMT inducer. The purpose of this study was to investigate the effect of the proinflammatory cytokine tumor necrosis factor-α (TNF-α) on TGF-β1-induced EMT and the underlying mechanisms in the human bronchial epithelial cell line BEAS-2B.

METHODS

Human bronchial epithelial BEAS-2B cells were treated with TGF-β1 and TNF-α separately or in combination for 24 h, and qRT-PCR, western blotting, immunofluorescence staining, and migration assays were used to investigate the EMT process. Moreover, to further explore the effect of the NF-κB pathway on the EMT process, inhibitor assays (BAY-117082, NF-κB inhibitor), wound healing assays, and western blotting were performed.

RESULTS

The results showed that both cytokines enhanced the transformation of BEAS-2B cells from epithelial to mesenchymal cells. In addition, combined treatment with TNF-α and TGF-β1 further reduced E-cadherin expression, which conversely elevated α-SMA and vimentin mRNA and protein levels. Correspondingly, the migration rate of BEAS-2B cells was also increased. Furthermore, inhibiting the NF-κB signaling pathway blocked the expression of EMT-related markers and NOX4 induced by TGF-β1 and TNF-α, as well as cell migration.

CONCLUSION

Taken together, TNF-α and TGF-β1 cooperatively promoted EMT and cell migration in BEAS-2B cells through the NF-κB/NOX4 signaling pathway.

Human Lung Fibroblasts Exhibit Induced Inflammation Memory via Increased IL6 Gene Expression and Release

Fibroblasts of different origins are known to possess stromal memory after inflammatory episodes. However, there are no studies exploring human lung fibroblast memory which may predict a subsequent inflammatory response in chronic respiratory diseases and COVID-19. MRC-5 and HF19 human lung fibroblast cell lines were treated using different primary and secondary stimulus combinations: TNFα–WD–TNFα, Poly (I:C)–WD–TNFα, TNFα–WD–Poly (I:C), or LPS–WD–TNFα with a 24-h rest period (withdrawal period; WD) between the two 24-h stimulations. TLR3 and NF-κB inhibitors were used to determine pathways involved. The effect of SARS-Cov-2 spike protein to inflammatory response of lung fibroblasts was also investigated. mRNA expressions of genes and IL6 release were measured using qRT-PCR and ELISA, respectively. Statistical significance was determined by using one- or two-way ANOVA, followed by Bonferroni’s post hoc analysis for comparison of multiple groups. Preexposure with Poly (I:C) significantly increased TNFα-induced IL6 gene expression and IL6 release in both cell lines, while it affected neither gene expressions of IL1B, IL2, IL8, and MMP8 nor fibrosis-related genes: ACTA2, COL1A1, POSTN, and TGFB1. Inhibition of TLR3 or NF-κB during primary stimulation significantly downregulated IL6 release. Simultaneous treatment of MRC-5 cells with SARS-CoV-2 spike protein further increased TNFα-induced IL6 release; however, preexposure to Poly (I:C) did not affect it. Human lung fibroblasts are capable of retaining inflammatory memory and showed an augmented response upon secondary exposure. These results may contribute to the possibility of training human lung fibroblasts to respond suitably on inflammatory episodes after viral infection.

Age-Associated Changes to Lymph Node Fibroblastic Reticular Cells

The decreased proportion of antigen-inexperienced, naïve T cells is a hallmark of aging in both humans and mice, and contributes to reduced immune responses, particularly against novel and re-emerging pathogens. Naïve T cells depend on survival signals received during their circulation among the lymph nodes by direct contacts with stroma, in particular fibroblastic reticular cells. Macroscopic changes to the architecture of the lymph nodes have been described, but it is unclear how lymph node stroma are altered with age, and whether these changes contribute to reduced naïve T cell maintenance. Here, using 2-photon microscopy, we determined that the aged lymph node displayed increased fibrosis and correspondingly, that naïve T-cell motility was impaired in the aged lymph node, especially in proximity to fibrotic deposition. Functionally, adoptively transferred young naïve T-cells exhibited reduced homeostatic turnover in aged hosts, supporting the role of T cell-extrinsic mechanisms that regulate their survival. Further, we determined that early development of resident fibroblastic reticular cells was impaired, which may correlate to the declining levels of naïve T-cell homeostatic factors observed in aged lymph nodes. Thus, our study addresses the controversy as to whether aging impacts the composition lymph node stroma and supports a model in which impaired differentiation of lymph node fibroblasts and increased fibrosis inhibits the interactions necessary for naïve T cell homeostasis.

SENP1 regulates the transformation of lung resident mesenchymal stem cells and is associated with idiopathic pulmonary fibrosis progression

BACKGROUND

Lung resident mesenchymal stem cells (LR-MSCs) play an important role in idiopathic pulmonary fibrosis (IPF) by transforming into myofibroblasts, thereby losing their repair ability. Evidence suggests that key proteins of multiple signaling pathways are involved in myofibroblast differentiation of LR-MSCs, such as β-Catenin and GLI family zinc finger 1 (GLI1). These proteins are regulated by SUMO (small ubiquitin-like modifier) modification, which is a post-translational modification that promotes protein degradation, while Sumo specific protein 1 (SENP1)-mediated deSUMOylation produces the opposite biological effects. Therefore, we speculated that SENP1 might be a potential target for treating pulmonary fibrosis by preventing the myofibroblast differentiation of LR-MSCs.

METHODS

LR-MSCs were isolated from mice by using immunomagnetic beads. The extracted LR-MSCs were identified by flow cytometric analysis and multilineage differentiation assays. Lentivirus packaged shRNA silenced the expression of SENP1 in vitro and vivo. The silencing efficacy of SENP1 was verified by real-time quantitative PCR. The effect of down-regulated SENP1 on the myofibroblast differentiation of LR-MSCs was assessed by Immunofluorescence and Western blot. Immunoprecipitation was used to clarify that SENP1 was a key target for regulating the activity of multiple signaling pathways in the direction of LR-MSCs differentiation. LR-MSCs resident in the lung was analyzed with in vivo imaging system. HE and Masson staining was used to evaluate the therapeutic effect of LR-MSCs with SENP1 down-regulation on the lung of BLM mice.

RESULTS

In this study, we found that the myofibroblast differentiation of LR-MSCs in IPF lung tissue was accompanied by enhanced SENP1-mediated deSUMOylation. The expression of SENP1 increased in LR-MSCs transition of bleomycin (BLM)-induced lung fibrosis. Interfering with expression of SENP1 inhibited the transformation of LR-MSCs into myofibroblasts in vitro and in vivo and restored their therapeutic effect in BLM lung fibrosis. In addition, activation of the WNT/β-Catenin and Hedgehog/GLI signaling pathways depends on SENP1-mediated deSUMOylation.

CONCLUSIONS

SENP1 might be a potential target to restore the repair function of LR-MSCs and treat pulmonary fibrosis. Video Abstract.

Modeling Kaempferol as a Potential Pharmacological Agent for COVID-19/PF Co-Occurrence Based on Bioinformatics and System Pharmacological Tools

Objective: People suffering from coronavirus disease 2019 (COVID-19) are prone to develop pulmonary fibrosis (PF), but there is currently no definitive treatment for COVID-19/PF co-occurrence. Kaempferol with promising antiviral and anti-fibrotic effects is expected to become a potential treatment for COVID-19 and PF comorbidities. Therefore, this study explored the targets and molecular mechanisms of kaempferol against COVID-19/PF co-occurrence by bioinformatics and network pharmacology.

Methods: Various open-source databases and Venn Diagram tool were applied to confirm the targets of kaempferol against COVID-19/PF co-occurrence. Protein-protein interaction (PPI), MCODE, key transcription factors, tissue-specific enrichment, molecular docking, Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were used to clarify the influential molecular mechanisms of kaempferol against COVID-19 and PF comorbidities.

Results: 290 targets and 203 transcription factors of kaempferol against COVID-19/PF co-occurrence were captured. Epidermal growth factor receptor (EGFR), proto-oncogene tyrosine-protein kinase SRC (SRC), mitogen-activated protein kinase 3 (MAPK3), mitogen-activated protein kinase 1 (MAPK1), mitogen-activated protein kinase 8 (MAPK8), RAC-alpha serine/threonine-protein kinase (AKT1), transcription factor p65 (RELA) and phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha isoform (PIK3CA) were identified as the most critical targets, and kaempferol showed effective binding activities with the above critical eight targets. Further, anti-COVID-19/PF co-occurrence effects of kaempferol were associated with the regulation of inflammation, oxidative stress, immunity, virus infection, cell growth process and metabolism. EGFR, interleukin 17 (IL-17), tumor necrosis factor (TNF), hypoxia inducible factor 1 (HIF-1), phosphoinositide 3-kinase/AKT serine/threonine kinase (PI3K/AKT) and Toll-like receptor signaling pathways were identified as the key anti-COVID-19/PF co-occurrence pathways.

Conclusion: Kaempferol is a candidate treatment for COVID-19/PF co-occurrence. The underlying mechanisms may be related to the regulation of critical targets (EGFR, SRC, MAPK3, MAPK1, MAPK8, AKT1, RELA, PIK3CA and so on) and EGFR, IL-17, TNF, HIF-1, PI3K/AKT and Toll-like receptor signaling pathways. This study contributes to guiding development of new drugs for COVID-19 and PF comorbidities.

Endoplasmic reticulum stress modulates the fate of lung resident mesenchymal stem cell to myofibroblast via C/EBP homologous protein during pulmonary fibrosis

Background

As a fatal interstitial lung disease, idiopathic pulmonary fibrosis (IPF) was characterized by the insidious proliferation of extracellular matrix (ECM)-producing mesenchymal cells. Recent studies have demonstrated that lung resident mesenchymal/stromal cells (LR-MSC) are the source of myofibroblasts. Endoplasmic reticulum (ER) stress is prominent in IPF lung. This study sought to investigate the effects of ER stress on the behavior of LR-MSC during pulmonary fibrosis.

Methods

ER stress and myofibroblast differentiation of LR-MSC in patients with IPF were evaluated. Primary mouse LR-MSC was harvested and used in vitro for testing the effects of ER stress and C/EBP homologous protein (CHOP) on LR-MSC. Adoptive transplantation of LR-MSC to bleomycin-induced pulmonary fibrosis was done to test the in vivo behavior of LR-MSC and its influence on pulmonary fibrosis.

Results

We found that myofibroblast differentiation of LR-MSC is associated with ER stress in IPF and bleomycin-induced mouse fibrotic lung. Tunicamycin-induced ER stress impairs the paracrine, migration, and reparative function of mouse LR-MSC to injured type 2 alveolar epithelial cells MLE-12. Overexpression of the ER stress responder C/EBP homologous protein (CHOP) facilitates the TGFβ1-induced myofibroblast transformation of LR-MSC via boosting the TGFβ/SMAD signaling pathway. CHOP knockdown facilitates engraftment and inhibits the myofibroblast transformation of LR-MSC during bleomycin-induced pulmonary fibrosis, thus promoting the efficacy of adopted LR-MSC in alleviating pulmonary fibrosis.

Conclusion

Our work revealed a novel role that ER stress involved in pulmonary fibrosis by influencing the fate of LR-MSC and transformed to “crime factor” myofibroblast, during which CHOP acts as the key modulator. These results indicate that pharmacies targeting CHOP or therapies based on CHOP knockdown LR-MSC may be promising ways to treat pulmonary fibrosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02966-1.

Curcumin intervention during progressive fibrosis controls inflammatory cytokines and the fibrinolytic system in pulmonary fibrosis

Persistent injuries and chronic inflammation paired with dysregulated healing process in the lungs leads to scarring and stiffening of the tissue leading to a condition called pulmonary fibrosis. There is no efficacious therapy against the condition because of the poorly understood pathophysiology of the disease. Curcumin is well known anti-inflammatory natural compound and is shown to have beneficial effects in many diseases. It is also reported to show antifibrotic activities in pulmonary fibrosis. There are evidences that fibrinolytic system plays a crucial role in the development of pulmonary fibrosis. We aimed to see whether curcumin could regulate inflammation and fibrinolysis in murine model of pulmonary fibrosis. We prepared BLM induced pulmonary fibrosis model by administering BLM at a dose of 2 mg/ kg bodyweight. Curcumin (75 mg/kg body wt) was instilled intraperitoneally on different time points. The effect of curcumin on inflammatory cytokines and fibrinolytic system was studied using molecular biology techniques like RT-PCR, western blot and immunohistochemistry/immunofluorescence. We observed that BLM brought changes in the expressions of components in the fibrinolytic system, i.e. BLM favoured fibrin deposition by increasing the expression of PAI-1 (plasminogen activator inhibitor) and decreasing the expression of uPA (Urokinase plasminogen activator) and uPAR (Urokinase plasminogen activator receptor). We also demonstrate that curcumin could restore the normal expression of fibrinolytic components, uPA, uPAR and PAI-1. Curcumin could also minimize the expression of key enzymes in tissue remodeling in pulmonary fibrosis, MMP-2 and MMP-9, which were elevated in the BLM treated group. Our data suggest that curcumin exerts an anti-inflammatory and antifibrotic effect in lungs. We highlight curcumin as a feasible adjuvant therapy option against pulmonary fibrosis.

Current Perspectives on Nucleus Pulposus Fibrosis in Disc Degeneration and Repair

A growing body of evidence in humans and animal models indicates an association between intervertebral disc degeneration (IDD) and increased fibrotic elements in the nucleus pulposus (NP). These include enhanced matrix turnover along with the abnormal deposition of collagens and other fibrous matrices, the emergence of fibrosis effector cells, such as macrophages and active fibroblasts, and the upregulation of the fibroinflammatory factors TGF-β1 and IL-1/-13. Studies have suggested a role for NP cells in fibroblastic differentiation through the TGF-βR1-Smad2/3 pathway, inflammatory activation and mechanosensing machineries. Moreover, NP fibrosis is linked to abnormal MMP activity, consistent with the role of matrix proteases in regulating tissue fibrosis. MMP-2 and MMP-12 are the two main profibrogenic markers of myofibroblastic NP cells. This review revisits studies in the literature relevant to NP fibrosis in an attempt to stratify its biochemical features and the molecular identity of fibroblastic cells in the context of IDD. Given the role of fibrosis in tissue healing and diseases, the perspective may provide new insights into the pathomechanism of IDD and its management.

A drug-responsive multicellular human spheroid model to recapitulate drug-induced pulmonary fibrosis

Associated with a high mortality rate, pulmonary fibrosis (PF) is the end stage of several interstitial lung diseases. Although many factors are linked to PF progression, initiation of the fibrotic process remains to be studied. Current research focused on generating new strategies to gain a better understanding of the underlying disease mechanism as the animal models remain insufficient to reflect human physiology. Herein, to account complex cellular interactions within the fibrotic tissue, a multicellular spheroid (MCS) model where human bronchial epithelial cells incorporated with human lung fibroblasts was generated and treated with bleomycin (BLM) to emulate drug-induced PF. Recapitulating the epithelial-interstitial microenvironment, the findings successfully reflected the PF disease, where excessive alpha smooth muscle actin (α-SMA) and collagen type I secretion were noted along with the morphological changes in response to BLM. Moreover, increased levels of fibrotic linked COL13A1, MMP2, WNT3 and decreased expression level of CDH1 provide evidence for the model reliability on fibrosis modelling. Subsequent administration of the FDA approved nintedanib and pirfenidone anti-fibrotic drugs proved the drug-responsiveness of the model.