Editing Macrophage (section)

=== As a host for intracellular pathogens ===
In their role as a phagocytic immune cell macrophages are responsible for engulfing pathogens to destroy them. Some pathogens subvert this process and instead live inside the macrophage. This provides an environment in which the pathogen is hidden from the immune system and allows it to replicate.{{citation needed|date=March 2023}}

Diseases with this type of behaviour include [[tuberculosis]] (caused by ''[[Mycobacterium tuberculosis]]'') and [[leishmaniasis]] (caused by ''[[Leishmania]]'' species).{{citation needed|date=March 2023}}

In order to minimize the possibility of becoming the host of an intracellular bacteria, macrophages have evolved defense mechanisms such as induction of nitric oxide and reactive oxygen intermediates,<ref>{{cite journal | vauthors = Herb M, Schramm M | title = Functions of ROS in Macrophages and Antimicrobial Immunity | journal = Antioxidants | volume = 10 | issue = 2 | page = 313 | date = February 2021 | pmid = 33669824 | pmc = 7923022 | doi = 10.3390/antiox10020313 | doi-access = free }}</ref> which are toxic to microbes. Macrophages have also evolved the ability to restrict the microbe's nutrient supply and induce [[autophagy]].<ref>{{cite journal | vauthors = Weiss G, Schaible UE | title = Macrophage defense mechanisms against intracellular bacteria | journal = Immunological Reviews | volume = 264 | issue = 1 | pages = 182–203 | date = March 2015 | pmid = 25703560 | pmc = 4368383 | doi = 10.1111/imr.12266 }}</ref>

==== Tuberculosis ====
Once engulfed by a macrophage, the causative agent of tuberculosis, ''Mycobacterium tuberculosis'',<ref name="Sherris">{{cite book|title=Sherris Medical Microbiology|publisher=McGraw Hill|year=2004|isbn=978-0-8385-8529-0|veditors=Ryan KJ, Ray CG|edition=4th}}</ref> avoids cellular defenses and uses the cell to replicate. Recent evidence suggests that in response to the pulmonary infection of ''Mycobacterium tuberculosis'', the peripheral macrophages matures into M1 phenotype. Macrophage M1 phenotype is characterized by increased secretion of pro-inflammatory cytokines (IL-1β, TNF-α, and IL-6) and increased glycolytic activities essential for clearance of infection.<ref name="NIX-mediated mitophagy regulate met"/>

==== Leishmaniasis ====
Upon phagocytosis by a macrophage, the ''Leishmania'' parasite finds itself in a phagocytic vacuole. Under normal circumstances, this phagocytic vacuole would develop into a lysosome and its contents would be digested. ''Leishmania'' alter this process and avoid being destroyed; instead, they make a home inside the vacuole.{{citation needed|date=March 2023}}

==== Chikungunya ====
Infection of macrophages in joints is associated with local inflammation during and after the acute phase of ''[[Chikungunya]]'' (caused by CHIKV or Chikungunya virus).<ref name="CHIKV persistence in human body">{{cite journal | vauthors = Dupuis-Maguiraga L, Noret M, Brun S, Le Grand R, Gras G, Roques P | title = Chikungunya disease: infection-associated markers from the acute to the chronic phase of arbovirus-induced arthralgia | journal = PLOS Neglected Tropical Diseases | volume = 6 | issue = 3 | pages = e1446 | year = 2012 | pmid = 22479654 | pmc = 3313943 | doi = 10.1371/journal.pntd.0001446 | doi-access = free }}</ref>

==== Others ====
[[Adenovirus]] (most common cause of pink eye) can remain latent in a host macrophage, with continued viral shedding 6–18 months after initial infection.{{citation needed|date=March 2023}}

''Brucella spp.'' can remain latent in a macrophage via inhibition of [[phagosome]]–[[lysosome]] fusion; causes [[brucellosis]] (undulant fever).{{citation needed|date=March 2023}}

''[[Legionella pneumophila]]'', the causative agent of [[Legionnaires' disease]], also establishes residence within macrophages.{{citation needed|date=March 2023}}