Human papillomaviruses (HPVs) and in particular cutaneous papillomaviruses affect a large part of the population. Warts appear on the skin. In very rare cases, these often benign growths can develop and cause severe forms, known as ” man-tree “.
A genetic cause
HPVs are numerous, there are more than 200, some of which cause changes in the skin promoting the appearance of common warts, generally visible on the hands or plantars. These skin changes are generally not serious unlike papillomaviruses which cause cervical cancer in women. However, they can be responsible for the syndrome of “ man-tree “, Which is a very disabling disease, which” is manifested by an uncontrolled outbreak of cutaneous horns for which surgery is not effective “. For the first time, researchers from the National Institute of Health and Medical Research (Inserm) in collaboration with the University of Paris, have succeeded in identifying the cause of this extremely rare condition. It would be genetic and linked to the mutation of the CD28 gene.
To identify the cause, Vivien Béziat, who is a research fellow at Inserm and at the Human Genetics of Infectious Diseases laboratory, studied the case of a patient of Iranian origin as well as two members of his family. The patient has the syndrome, but the other two do not. On the other hand, the latter are affected by a more moderate form, but have not developed the affection. The researcher was particularly interested in their genetic characteristics and discovered that these three people have a mutation in the CD28 gene. It turns out that this element of the chromosome plays, a priori, a key role in activating T lymphocytes, which are cells of the immune system and which are capable of destroying cells infected by the virus. Because of this genetic alteration, the body does not recognize the pathogen and is no longer able to deploy its defenses against it. Thus, the papillomavirus multiplies in the cells of the epidermis, the keratinocytes, causing an uncontrolled exponential growth of warts or cutaneous horns, as specified by Inserm.
Hope for treatment
” This is the first time that a genetic cause of the “tree man” syndrome has come to light. However, this is not the only discovery made by scientists. They also understood that the CD28 gene would ultimately not have a major role ” in the functioning of the immune system and the response of T cells “. On the other hand, it could be involved and very important in resisting skin papillomaviruses. As Vivien Béziat explains, concerning the cases he has studied, “ even if their immune response is weakened, patients defend themselves well against other pathogens “. These data are essential, as they pave the way for a potential treatment for people with the syndrome of ” man-tree ”, By means of cell therapy. Indeed, a transplant of hematopoietic stem cells, to produce blood cells and “ replace the patient’s immune system Is one solution being considered. However, this treatment is cumbersome and expensive and it is essential that research progress in order to promote access to this type of treatment, in particular for patients who live in less developed countries.
