Immune system cells called macrophages or big eaters catch bacteria and other contaminants in the skin before theyre as damaging as bacteria would befall cancer cells. Macrophages are able to detect invading bacteria and destroy them. Scientists at the Medical University of South Australia (MUSC) have shed new light on the process and could prove a key tool in battling skin cancers.

Multiple myeloid skin cancers an aggressive type of skin cancer are often a result of welter and hyper-responsive skin and they represent a leading cause of skin cancer deaths.

The new study by a team of researchers from the Australian and Canadian Institutes of Health Research the leading international collaboration advancing skin cancer research sheds fresh light on how immune cells sense harmful bacteria and destroy it. The research examined the impact of chronic UV exposure (an amount of sunlight impacting the skins surface) on skin cancer in mice.

It looked at the impact of UV on the early damage to the skin by macrophages called phagocytic macrophages in response to a smear of green and red bacteria under the skin. Skin melanocytes or melanocytes are essential to the human bodys defense against environmental exposure but skin macrophages attack our skin because they cant see damaged skin cells anymore. This damaged cell behaviour makes it difficult for the healthy skin cells to mount a robust defence against skin cancers.

The new study published in the journal Nature Immunology together with collaborators across the globe found that macrophages acted as a shield that even in the presence of UV light and in extensive UVPP macrophages are able to eradicate and destroy melanocytes.

This study has important outcomes in the forefront of immuno-oncology as it sheds light on how some diseases may have multiple etiologies and how macrophages might be an important tool to screen for and overcome in inflammatory skin diseases like psoriasis atrophic skin cancer and atopic dermatitis said Senior Research Fellow at the Australian and Canadian Institutes of Health Research Associate Professor Jin-Hua Tseng and senior author on the paper.

This study discloses the role of macrophages in parsing damage to human skin and they evidence a biological connection between chronic UV exposure and the discovery that macrophages can enter into the dermis the skins surface and destroy melanocytes. This innovative and significant study is an international collaboration of researchers from cosmopolitan Sydney McMaster University University of Melbourne and the Chinese Academy of Sciences. When mirroring macrophage responses to UV exposure the strictest level of hygiene prevents the development of residual skin damage said Associate Professor Jin-Hua Tseng.

Senior author on the paper Associate Professor Erin OConnor said mice cant remember or remember what injuries they suffered during the previous day making it difficult for them to avoid or detect further damage or disease progression. The small amounts of UV however were enough to produce enough problems in the mice. The discovery of this new role of macrophages that work as a shield against damage by skin cells underscores the importance of this research.