Suppression of von Hippel-Lindau Protein in Fibroblasts Protects against Bleomycin-Induced Pulmonary Fibrosis

DNA methyltransferase 3A induces the occurrence of oral submucous fibrosis by promoting the methylation of the von Hippel-Lindau

BACKGROUND

Oral submucous fibrosis (OSF) is associated with malignant disorders. DNA methyltransferase 3A (DNMT3A) is a DNA methylesterase reported to be upregulated in multiple organs and shown to inhibit fibrosis. However, the detailed effect of DNMT3A on OSF remains unclear.

METHODS

To mimic OSF in vitro, oral fibroblasts were exposed to arecoline and molecular biological experiments were performed to detect the function of DNMT3A in OSF.

RESULTS

We found that von Hippel-Lindau (VHL) was downregulated and highly methylated in OSF. Arecoline remarkably increased the viability, invasiveness, and migration of oral fibroblasts, but upregulation of VHL partially reversed these effects. DNMT3A induces DNA hypermethylation in the VHL promoter, and VHL markedly inhibits the level of tenascin-C (TNC) by inducing the ubiquitination of TNC. TNC reversed the inhibitory effect of VHL upregulation on the differentiation of oral fibroblasts into myofibroblasts.

CONCLUSION

DNMT3A induces OSF by promoting methylation of the VHL promoter. Hence, our study provides novel insights into the discovery of novel strategies that can be employed against OSF.

Idiopathic interstitial pneumonia in a patient with von Hippel-Lindau syndrome: a first case

Although the mechanisms are not known, this is a case of progressive interstitial lung involvement, with a NSIP radiological pattern, evolving in pulmonary fibrosis in a patient with von Hippel-Lindau syndrome, without extrapulmonary fibrosis. https://bit.ly/3QlNStu.

Secretome of Mesenchymal Stromal Cells Prevents Myofibroblasts Differentiation by Transferring Fibrosis-Associated microRNAs within Extracellular Vesicles

Fibroblasts differentiation into myofibroblasts is a central event of tissue fibrosis. Multipotent mesenchymal stromal cells (MSCs) secretome can interfere with fibrosis development; despite precise underlying mechanisms remain unclear. In this study, we tested the hypothesis that MSC secretome can affect fibroblast’ differentiation into myofibroblasts by delivering regulatory RNAs, including microRNAs to these cells. Using the model of transforming growth factor-beta (TGFbeta)-induced fibroblast differentiation into myofibroblasts, we tested the activity of human MSC secretome components, specifically extracellular vesicles (MSC-EV). We showed that MSC-EV down-regulated secretion of extracellular matrix proteins by fibroblasts as well as suppressed their contractility resulting in prevention as well as reversion of fibroblasts differentiation to myofibroblasts. High-throughput sequencing of RNAs extracted from MSC-EV has revealed many fibrosis-associated microRNAs. Fibroblast treatment with MSC-EV led to direct transfer of microRNAs, which resulted in the elevation of most prominent fibrosis-associated microRNAs, including microRNA-21 and microRNA-29c. Using MSC-EV transfection by antagomirs to these microRNAs we demonstrated their involvement in the suppression of fibroblast differentiation in our model. Taken together, MSC secretome can suppress fibrosis by prevention of fibroblast differentiation into myofibroblasts as well as induce de-differentiation of the latter by direct transfer of specific microRNAs.

HIF1A up-regulates the ADORA2B receptor on alternatively activated macrophages and contributes to pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a deadly chronic lung disease. Extracellular accumulation of adenosine and subsequent activation of the ADORA2B receptor play important roles in regulating inflammation and fibrosis in IPF. Additionally, alternatively activated macrophages (AAMs) expressing ADORA2B have been implicated in mediating adenosine's effects in IPF. Although hypoxic conditions are present in IPF, hypoxia's role as a direct modulator of macrophage phenotype and identification of factors that regulate ADORA2B expression on AAMs in IPF is not well understood. In this study, an experimental mouse model of pulmonary fibrosis and lung samples from patients with IPF were used to examine the effects and interactions of macrophage differentiation and hypoxia on fibrosis. We demonstrate that hypoxia-inducible factor 1-α (HIF1A) inhibition in late stages of bleomycin-induced injury attenuates pulmonary fibrosis in association, with reductions in ADORA2B expression in AAMs. Additionally, ADORA2B deletion or pharmacological antagonism along with HIF1A inhibition disrupts AAM differentiation and subsequent IL-6 production in cultured macrophages. These findings suggest that hypoxia, through HIF1A, contributes to the development and progression of pulmonary fibrosis through its regulation of ADORA2B expression on AAMs, cell differentiation, and production of profibrotic mediators. These studies support a potential role for HIF1A or ADORA2B antagonists in the treatment of IPF.-Philip, K., Mills, T. W., Davies, J., Chen, N.-Y., Karmouty-Quintana, H., Luo, F., Molina, J. G., Amione-Guerra, J., Sinha, N., Guha, A., Eltzschig, H. K., Blackburn, M. R. HIF1A up-regulates the ADORA2B receptor on alternatively activated macrophages and contributes to pulmonary fibrosis.

Analysis of a Mouse Skin Model of Tuberous Sclerosis Complex

Tuberous Sclerosis Complex (TSC) is an autosomal dominant tumor suppressor gene syndrome in which patients develop several types of tumors, including facial angiofibroma, subungual fibroma, Shagreen patch, angiomyolipomas, and lymphangioleiomyomatosis. It is due to inactivating mutations in TSC1 or TSC2. We sought to generate a mouse model of one or more of these tumor types by targeting deletion of the Tsc1 gene to fibroblasts using the Fsp-Cre allele. Mutant, Tsc1^ccFsp-Cre+ mice survived a median of nearly a year, and developed tumors in multiple sites but did not develop angiomyolipoma or lymphangioleiomyomatosis. They did develop a prominent skin phenotype with marked thickening of the dermis with accumulation of mast cells, that was minimally responsive to systemic rapamycin therapy, and was quite different from the pathology seen in human TSC skin lesions. Recombination and loss of Tsc1 was demonstrated in skin fibroblasts in vivo and in cultured skin fibroblasts. Loss of Tsc1 in fibroblasts in mice does not lead to a model of angiomyolipoma or lymphangioleiomyomatosis.

Comparative Proteomic Analysis of Bleomycin-induced Pulmonary Fibrosis Based on Isobaric Tag for Quantitation

BACKGROUND

Pulmonary fibrosis (PF) is a destructive pulmonary disease and the molecular mechanisms underlying PF are unclear. This study investigated differentially expressed proteins associated with the occurrence and development of PF in rat lung tissue with bleomycin-induced PF.

METHODS

Sixteen Sprague-Dawley rats were randomly divided into 2 groups: the PF model group (n = 8) and the control group (n = 8). After successfully establishing the rat PF model induced by bleomycin, the differentially expressed proteins in the 2 groups were identified through isobaric tag for relative and absolute quantitation coupled with liquid chromatography-mass spectrometry and bioinformatics analysis.

RESULTS

A total of 146 differentially expressed proteins were identified; 88 of which displayed increased abundance and 58 were downregulated in the PF rat model group. Most functional proteins were associated with extracellular matrix, inflammation, damage response, vitamin A synthesis and metabolism. Critical proteins related to PF development and progression was identified, such as type V collagen-3, arachidonic acid 12-lipoxygenase, arachidonic acid 15-lipoxygenase and cytochrome P4501A1. Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that these differentially expressed proteins were enriched in extracellular matrix receptor interaction pathway, renin-angiotensin system and metabolic pathway of retinol.

CONCLUSIONS

The proteins expressed in bleomycin-induced PF rat model provide important data for further functional analysis of proteins involved in PF.