The use of sirius red in assessing dermal collagen reorganisation in mice lacking α11β1 integrins

Elucidation of a potential role in vivo of α11β1-integrins for the control of collagen fibril arrangement would increase the understanding on the mechanisms of fibrillogenesis and may reveal a possible therapeutic target in the management of fibrotic diseases (1; 2). In order to answer this question, here, we analysed the overall organisation of the dermal collagen network in samples of back skin of α11β1-integrin-deficient mice (KO). Collagen remodelling was assessed light microscopically (n=4) on paraffin sections after Sirius red staining. Traditionally, the use of Sirius Red staining is associated to study of collagen fibre bundle thickness using circularly polarized light. Here Sirius red stained sections were imaged at the structure light microscope and analysed fluorescently. Following acquiring at the structured light microscope images were evaluated by Image J for fractal dimension and lacunarity, which express the level of complexity of the network and network heterogeneity respectively. The results showed increase in fractal dimension (1.40±0.06 in α11 KO mice vs 1.24±0.05 of control mice, p=0.009), and reduction in lacunarity (0.78±0.06 in α11 KO mice 0.97±0.02 of control mice p=0.002) in KO mice. These differences indicate an overall re-organisation of dermal collagen network in skin devoid of integrins α11β1. This study show that sirius red staining is a suitable method to evaluate the overall oragnisation of demal collagen and that α11β1-integrins are involved in the control of skin biomechanics by influencing the overall organisation of the dermal collagen network.