Adipose-derived stem cells alleviate radiation-induced dermatitis by suppressing apoptosis and downregulating cathepsin F expression

Background Radiation-induced dermatitis is a serious side effect of radiotherapy, and very few effective treatments are currently available for this condition. We previously demonstrated that apoptosis is an important feature of radiation-induced dermatitis and adipose-derived stem cells (ADSCs) are one of the most promising types of stem cells that have a protective effect on acute radiation-induced dermatitis. Cathepsin F (CTSF) is a recently discovered protein that plays an important role in apoptosis. In this study, we investigated whether ADSCs affect chronic radiation-induced dermatitis, and the underlying mechanisms involved. Methods ADSCs were isolated from male Sprague-Dawley (SD) rats and characterized. For in vivo studies, rats were randomly divided into control and ADSC-treated groups, and cultured ADSCs were transplanted into radiation-induced dermatitis model rats. The effects of ADSC transplantation were determined by skin damage scoring, histopathological analysis, electron microscopy, immunohistochemical staining, and western blotting analysis of apoptosis-related proteins. To evaluate the effects of ADSCs in vitro, radiation-induced apoptotic cells were treated with ADSC culture supernatant, and apoptosis-related protein expression was investigated by TUNEL staining, flow cytometry, and western blotting. Results In the in vivo studies, skin damage, inflammation, fibrosis, and apoptosis were reduced and hair follicle and sebaceous gland regeneration were enhanced in the ADSC group compared with the control group. Further, CTSF and downstream pro-apoptotic proteins (Bid, BAX, and caspase 9) were downregulated, while anti-apoptotic proteins (Bcl-2 and Bcl-XL) were upregulated. In vitro, ADSCs markedly attenuated radiation-induced apoptosis, downregulated CTSF and downstream pro-apoptotic proteins, and upregulated anti-apoptotic proteins. Conclusion ADSCs protect against radiation-induced dermatitis by exerting an anti-apoptotic effect through inhibition of CTSF expression. ADSCs may be a good therapeutic candidate to prevent the development of radiation-induced dermatitis.

Repurposing Simeprevir, Calpain Inhibitor IV and a Cathepsin F Inhibitor Against SARS-CoV-2: A Study Using in Silico Pharmacophore Modeling and Docking Methods

The world has come to a sudden halt due to the incessant spread of a viral pneumonia dubbed COVID-19 caused by the beta-coronavirus, SARS-CoV-2. The pandemic spread of the virus has already claimed lakhs of valuable lives and has infected millions of people across the globe. The situation is further worsened by the fact that there is no approved therapeutics currently available for the treatment of the disease. The only way to handle the crisis is the rapid development of a therapeutic strategy to combat the virus. Computational biology offers resources to rapidly identify novel drug leads and to repurpose existing drugs at the expense of minimal resources and time. The main protease of SARS-CoV-2 is key to the replication and propogation of the virus in the host cells. Inhibiting the protease blocks replication and hence is an attractive therapeutic target in the virus. The crystal structures of the protein in complex with inhibitors are available in public databases. Here we describe the screening of the DrugBank database, a public repository for small molecule therapeutics, to identify approved or experimental phase drugs that can be repurposed against the main protease of SARS-CoV2. The initial screening was performed on more than 13,000 drug entries in the target database using an energy optimised pharmacophore hypothesis AARRR. A sub-set of the molecules selected based on the fitness score was further screened using molecular docking by sequentially filtering the molecules through the high throughput virtual screening, extra precision and standard precision docking modalities. The most promising hits were subjected to binding free energy estimation using the MMGBSA method. Approved drugs viz, Cobicistat, Larotrectinib and Simeprevir were identified as potential candidates for repurposing. Drugs in the discovery phase identified as inhibitors include the known cysteine protease inhibitors, Calpain inhibitor IV and an experimental cathepsin F inhibitor.

Repurposing Simeprevir, Calpain Inhibitor IV and a Cathepsin F Inhibitor Against SARS-CoV-2: A Study Using in Silico Pharmacophore Modeling and Docking Methods

The world has come to a sudden halt due to the incessant spread of a viral pneumonia dubbed COVID-19 caused by the beta-coronavirus, SARS-CoV-2. The pandemic spread of the virus has already claimed lakhs of valuable lives and has infected millions of people across the globe. The situation is further worsened by the fact that there is no approved therapeutics currently available for the treatment of the disease. The only way to handle the crisis is the rapid development of a therapeutic strategy to combat the virus. Computational biology offers resources to rapidly identify novel drug leads and to repurpose existing drugs at the expense of minimal resources and time. The main protease of SARS-CoV-2 is key to the replication and propogation of the virus in the host cells. Inhibiting the protease blocks replication and hence is an attractive therapeutic target in the virus. The crystal structures of the protein in complex with inhibitors are available in public databases. Here we describe the screening of the DrugBank database, a public repository for small molecule therapeutics, to identify approved or experimental phase drugs that can be repurposed against the main protease of SARS-CoV2. The initial screening was performed on more than 13,000 drug entries in the target database using an energy optimised pharmacophore hypothesis AARRR. A sub-set of the molecules selected based on the fitness score was further screened using molecular docking by sequentially filtering the molecules through the high throughput virtual screening, extra precision and standard precision docking modalities. The most promising hits were subjected to binding free energy estimation using the MMGBSA method. Approved drugs viz, Cobicistat, Larotrectinib and Simeprevir were identified as potential candidates for repurposing. Drugs in the discovery phase identified as inhibitors include the known cysteine protease inhibitors, Calpain inhibitor IV and an experimental cathepsin F inhibitor.

Cathepsin F of Teladorsagia circumcincta is a recently evolved cysteine protease

Parasitic cysteine proteases are involved in parasite stage transition, invasion of host tissues, nutrient uptake, and immune evasion. The cysteine protease cathepsin F is the most abundant protein produced by fourth-stage larvae (L4) of the nematode Teladorsagia circumcincta, while its transcript is only detectable in L4 and adults. T. circumcincta cathepsin F is a recently evolved cysteine protease that does not fall clearly into either of the cathepsin L or F subfamilies. This protein exhibits characteristics of both cathepsins F and L, and its phylogenetic relationship to its closest homologs is distant, including proteins of closely related nematodes of the same subfamily.