Proteomic Profiling Identifies MARCO in Extracellular Vesicles, as a Potential Biomarker for Leishmaniasis in HIV Co-Infection

<i>Leishmania</i> is an intracellular protozoan parasite that causes leishmaniasis, a disease prevalent in 97 countries. Co-infection with HIV increases susceptibility to visceral leishmaniasis (VL), accelerating HIV's progression to AIDS. Managing VL in HIV-infected individuals is challenging due to atypical presentations and limited therapeutic responses, highlighting the need to develop new disease management strategies. Extracellular vesicles (EVs) hold great promise for this goal as they can be used for a higher understanding of biological processes and biomarker discovery. In this context, a proteomic analysis was carried out from plasma-EVs of an HIV/VL patient over two years and compared to HIV and healthy controls. The analysis confirmed classical EV markers but showed limited detection of <i>Leishmania</i> proteins. However, variations in human protein abundance related to relevant immunological processes were observed. Notably, the macrophage receptor with a collagenous structure (MARCO) was consistently detected only in the patient and not in the control groups. Significantly, the relevance of MARCO as a possible VL biomarker was confirmed using a validation cohort with five VL patients and its detection by Western Blot was possible. Although MARCO warrants further investigation as a VL related biomarker, the study of EVs confirmed their promise of being a privileged window into this disease. Future studies are needed to broaden data on EVs in infections to improve clinical management.