MMP9 and dermatomyositis: This phenotypic shift, marked by increased expression of MMP9, IL1B, and TNF alongside reduced LYVE1 (Figure 5C), likely results in the expansion of CD14+MMP9+ cells observed in blister fluid samples of the two prototypical photosensitive diseases, CLE and DM, both of which are characterized by robust type I interferon (IFN-I) signatures (Fig. 1C).