Macrophage lysosome and acidic intra-vesicular compartment

Macrophage lysosomes and acidic intra-vesicular compartments are specialized organelles essential for the degradation of macromolecules and the elimination of intracellular pathogens. These compartments maintain a highly acidic environment, typically with a pH between 4.5 and 5.0, which is maintained by the action of vacuolar H+-ATPases (v-ATPases) (Mindell, 2012, Annual Review of Physiology). In macrophages, these vesicles are central to the immune response, facilitating the destruction of phagocytosed bacteria and viruses and the subsequent processing of antigens for presentation to T cells (Flannagan et al., 2009, Nature Reviews Microbiology). Many pharmacological agents, particularly weak bases, act as lysosomotropic agents that selectively accumulate within these acidic spaces through a process known as ion trapping (de Duve et al., 1974, Biochemical Pharmacology). This accumulation can increase the internal pH, thereby inhibiting the activity of acid hydrolases, disrupting autophagic flux, and interfering with the replication of intracellular parasites or viral entry (Schrezenmeier & Dörner, 2020, Nature Reviews Rheumatology). While targeting these compartments is effective for treating autoimmune conditions like systemic lupus erythematosus and certain infections, chronic accumulation of drugs can lead to adverse effects such as phospholipidosis or organ-specific toxicities.

Other names

Lysosomal compartmentAcidic vesiclesPhagolysosomeEndolysosomal systemAcidic intra-vesicular organelles

Lysosomotropism and ion trapping leading to neutralization of intra-vesicular pH and inhibition of acid-dependent enzymes.