Role of integrin α11 in scleroderma or dermal fibrosis
1. Purpose of the study
In this study, we aim to better understand the involvement of integrin α11 in systematic scleroderma (SSc). SSc is one of the fibrotic diseases characterized by early inflammation and vascular injury, which results in hardening/ fibrosis of the skin and other organs. The pathological hallmark of SSc is excessive accumulation of highly cross-linked type I collagen in the affected organs which is the ligand of integrin α11β1. For this study, we will take advantage of our existing α11 KO mice, to establish dermal fibrosis models on the mice with (α11 WT) or without integrin α11 ( α11 KO). The fibrosis model will either be induced by bleomycin or breeding the α11 KO and WT mice with the Fos-related antigen 2 (Fra-2) transgenic mice which is a mouse model that spontaneous develops features resemble SSc. After SSc has developed, the skin samples will be taken for comparative analyses to investigate the role that α11 plays in dermal fibrosis in the two models.
Besides using the α11 KO and Fra-2 mice, we would also establish the ITGA11-Cre;LacZ mouse strain as an model to monitor changes of integrin α11 in skin fibrosis by LacZ reporter gene expression which is driven by a 3kb integrin α11 promoter. We therefore need to continue the breeding of both ITGA11-Cre strain and LacZ reporter strain (which has been approved before with ID6151). The fibrosis experiments on ITGA11-Cre;LacZ will be performed in our collaborator's lab in Cologne, Germany.
2. Expected harm/severity for the animals
Our α11 KO mice have been reported to have mild phenotype where main defect was the abnormal incisor which leads to dwarfism due to malnutrition. While this can be restored by giving the mice soft food. For the bleomycin-induced mouse model, we expect temporary pain for the mice when the bleomycin minipump is inserted or belomycin is injected subcutaneously (at age of 12-14w), and mild distress for the mice during the experimental period (3-4 weeks) with the dosage we use according to our previous experiences and published data.
For the Fra-2 mice, severity of SSc depends on the age of the mice. The mice develop dermal fibrosis after age12w and they may suffer from lung fibrosis after age 18w, we choose age 12w and 16w as the two time points to study the dermal fibrosis when the severity may be mild and moderate, respectively.
For ITGA11-Cre and LacZ mice, there will only be breeding from our side and we don't expect any harm to the animals (have not observed any abnormal phenotype from the two strains or offspring from the breeding based on our previous breeding experiences with these strains).
3. Expected benefit for science or society
We believe that investigating the role of integrin α11 in SSc will help us to better understand the mechanisms underlying SSc process and may shed some light on future treatment of the disease.
4. Number and kind of animals will be used (including breeding)
α11 KO strain: 600
Fr-2 Tg strain: 600
5. Compliance with the requirements for 3Rs (replacement, reduction and refinement)
- Replacement: the study requires in vivo model where the intact cell-matrix interaction is needed.
- Reduction: we have planned to make full use of the samples to minimize the amount of mice while still keep the results statistically valid.
- Refinement: both the bleomycin-induced and the Fra-2 genetic SSc model are the commonly used models to study SSc. To study the role of integrin α11, we believe it is the best and most straightforward way to have the models in the α11 KO background.
In this study, we aim to better understand the involvement of integrin α11 in systematic scleroderma (SSc). SSc is one of the fibrotic diseases characterized by early inflammation and vascular injury, which results in hardening/ fibrosis of the skin and other organs. The pathological hallmark of SSc is excessive accumulation of highly cross-linked type I collagen in the affected organs which is the ligand of integrin α11β1. For this study, we will take advantage of our existing α11 KO mice, to establish dermal fibrosis models on the mice with (α11 WT) or without integrin α11 ( α11 KO). The fibrosis model will either be induced by bleomycin or breeding the α11 KO and WT mice with the Fos-related antigen 2 (Fra-2) transgenic mice which is a mouse model that spontaneous develops features resemble SSc. After SSc has developed, the skin samples will be taken for comparative analyses to investigate the role that α11 plays in dermal fibrosis in the two models.
Besides using the α11 KO and Fra-2 mice, we would also establish the ITGA11-Cre;LacZ mouse strain as an model to monitor changes of integrin α11 in skin fibrosis by LacZ reporter gene expression which is driven by a 3kb integrin α11 promoter. We therefore need to continue the breeding of both ITGA11-Cre strain and LacZ reporter strain (which has been approved before with ID6151). The fibrosis experiments on ITGA11-Cre;LacZ will be performed in our collaborator's lab in Cologne, Germany.
2. Expected harm/severity for the animals
Our α11 KO mice have been reported to have mild phenotype where main defect was the abnormal incisor which leads to dwarfism due to malnutrition. While this can be restored by giving the mice soft food. For the bleomycin-induced mouse model, we expect temporary pain for the mice when the bleomycin minipump is inserted or belomycin is injected subcutaneously (at age of 12-14w), and mild distress for the mice during the experimental period (3-4 weeks) with the dosage we use according to our previous experiences and published data.
For the Fra-2 mice, severity of SSc depends on the age of the mice. The mice develop dermal fibrosis after age12w and they may suffer from lung fibrosis after age 18w, we choose age 12w and 16w as the two time points to study the dermal fibrosis when the severity may be mild and moderate, respectively.
For ITGA11-Cre and LacZ mice, there will only be breeding from our side and we don't expect any harm to the animals (have not observed any abnormal phenotype from the two strains or offspring from the breeding based on our previous breeding experiences with these strains).
3. Expected benefit for science or society
We believe that investigating the role of integrin α11 in SSc will help us to better understand the mechanisms underlying SSc process and may shed some light on future treatment of the disease.
4. Number and kind of animals will be used (including breeding)
α11 KO strain: 600
Fr-2 Tg strain: 600
5. Compliance with the requirements for 3Rs (replacement, reduction and refinement)
- Replacement: the study requires in vivo model where the intact cell-matrix interaction is needed.
- Reduction: we have planned to make full use of the samples to minimize the amount of mice while still keep the results statistically valid.
- Refinement: both the bleomycin-induced and the Fra-2 genetic SSc model are the commonly used models to study SSc. To study the role of integrin α11, we believe it is the best and most straightforward way to have the models in the α11 KO background.