Lichen sclerosus is a relatively common chronic inflammatory skin disease that predominantly affects the anogenital area. Accumulating evidence indicates that lichen sclerosus in women may be associated with other autoimmune disease, whereas this association seems to lack in male patients. We retrospectively evaluated the prevalence of autoimmune diseases and serological parameters indicative for autoimmunity in male and female patients with lichen sclerosus. Of the 532 patients (396 women, 136 men; 500 adults, 32 children; mean age: 49 years; range 1-89 years; female:male ratio 3:1), 452 (85%) had genital and 80 (15%) had extragenital disease. In women, lichen sclerosus was significantly more often associated with at least one autoimmune disease as compared to men (odds ratio [OR] 4.3, 95% confidence interval [CI] 1.9-9.6; p<0.0001). Moreover, female patients with lichen sclerosus had sinificantly more often associated autoimmune thyroid diseases (OR 4.7, 95% CI 1.8-11.9; p<0.0002), antithyroid-antibodies (OR 2.7, 95% CI 1.1-6.5; p=0.023), and elevated autoantibodies (OR 4.1, 95% CI 1.9-9.3; p<0.0001) as compared to male patients. This observation is suggestive for a different pathogenetic background in male and female patients.

Tumor-associated macrophages (TAMs) are the most abundant immune cells in the tumor microenvironment, promoting tumor initiation, growth, progression, metastasis, and immune evasion. Recently it was shown that cancer cell-derived exosomes induce a tumor-promoting phenotype in TAMs. Exosome-loaded proteins, DNA, and RNAs may contribute to the macrophage reprogramming. However, the exact mediators and mechanisms, particularly in melanoma, are not known. In this study we examined the effects of cutaneous melanoma-derived exosomes on macrophage function and the underlying mechanisms. First, we showed that exposure to melanoma exosomes induces a tumor-promoting TAM phenotype in macrophages. Sequencing revealed enrichment for several miRNAs including miR-125b-5p in cutaneous melanoma exosomes. We showed that miR-125b-5p is delivered to macrophages by melanoma exosomes and partially induces the observed tumor-promoting TAM phenotype. Finally, we showed that miR-125b-5p targets the lysosomal acid lipase A (LIPA) in macrophages, which in turn contributes to their phenotype switch and promotes macrophage survival. Thus, our data show for the first time that miR-125b-5p transferred by cutaneous melanoma-derived exosomes induces a tumor-promoting TAM phenotype in macrophages.

Surgical treatment as well as radiation and chemotherapy may improve survival in selected cases but probably have their value much more in terms of local disease control and improvement life quality of patients who probably already suffer from an aggressive systemic disease at time of nodal involvement.

clinicaltrials.gov Identifier: NCT01400022.