Phagosome proteomics to study Leishmania's intracellular niche in macrophages

Exploring the paradox of defense between host and Leishmania parasite

Leishmaniasis, a neglected tropical disease, still remains a global concern for the healthcare sector. The primary causative agents of the disease comprise diverse leishmanial species, leading to recurring failures in disease diagnosis and delaying the initiation of appropriate chemotherapy. Various species of the Leishmania parasite cause diverse clinical manifestations ranging from skin ulcers to systemic infections. Therefore, host immunity in response to different forms of infecting species of Leishmania becomes pivotal in disease progression or regression. Thus, understanding the paradox of immune arsenals during host and parasite interface becomes crucial to eliminate this deadly disease. In the present review, we have elaborated on the immunological perspectives of the disease and discussed primary host immune cells that form a defense line to counteract parasite infection. Furthermore, we also have shed light on the immune cells and effector molecules responsible for parasite survival in host lethal milieu/ environment. Next, we have highlighted recent molecules/compounds showing potent leishmanicidal activities pertaining to their pro-oxidant and immuno-modulatory mechanisms. This review addresses an immuno-biological overview of the factors influencing the parasitic disease, as this knowledge can aid in the unraveling/ identification of potential biomarkers, novel therapeutics, and vaccine candidates against leishmaniasis.

Functional aspects, phenotypic heterogeneity, and tissue immune response of macrophages in infectious diseases

Macrophages are a functionally heterogeneous group of cells with specialized functions depending not only on their subgroup but also on the function of the organ or tissue in which the cells are located. The concept of macrophage phenotypic heterogeneity has been investigated since the 1980s, and more recent studies have identified a diverse spectrum of phenotypic subpopulations. Several types of macrophages play a central role in the response to infectious agents and, along with other components of the immune system, determine the clinical outcome of major infectious diseases. Here, we review the functions of various macrophage phenotypic subpopulations, the concept of macrophage polarization, and the influence of these cells on the evolution of infections. In addition, we emphasize their role in the immune response in vivo and in situ, as well as the molecular effectors and signaling mechanisms used by these cells. Furthermore, we highlight the mechanisms of immune evasion triggered by infectious agents to counter the actions of macrophages and their consequences. Our aim here is to provide an overview of the role of macrophages in the pathogenesis of critical transmissible diseases and discuss how elucidation of this relationship could enhance our understanding of the host-pathogen association in organ-specific immune responses.