TITLE:
The Role of Neutrophils in the Interaction with Leishmania: Far beyond a Simple Trojan Horse?
AUTHORS:
João Carlos Araujo Carreira, Alba Valéria Machado da Silva
KEYWORDS:
Neutrophils, Leishmania, Reverse Transmigration
JOURNAL NAME:
Open Journal of Animal Sciences,
Vol.11 No.3,
June
25,
2021
ABSTRACT: Neutrophils are the most numerous leukocyte in mammals and normally they
are the first phagocyte observed in recently damaged or infected tissues. They
play a key role in the innate immune responses to Leishmania and several other microorganisms, nonetheless
an exacerbated neutrophils activity can generate a harmful response to the
host, therefore its turnover rate is very important to maintain the homeostasis
and averts the host tissue damage. Both apoptosis followed by phagocytosis by
mononuclear phagocytes (eferocytosis) and reverse transmigration have been
considered the main processes for the clearance of neutrophils from injured or
infected tissues. However, the interaction with Leishmania and other microbes, as well as molecules
produced by arthropod vectors such as sandflies saliva can modify the behavior
of neutrophils, causing immediate lysis to prolong their life. In fact, as a
result of a long course of coevolution, several microorganisms have developed skills
to avoid neutrophil effector mechanisms and take advantage of neutrophil
clearance pathways to promote their spread in the host’s body. Leishmania, Chlamydia pneumoniae and Yersinia pestis for example
use the efferocytic Trojan horse process for their dissemination and immune
protection, in a different way vaccinia Ankara virus and Toxoplasma gondii exploit the
neutrophil reverse transmigration for the same reason. Here we present an
overview of some characteristics of neutrophils and their different
destinations after interaction with several microorganisms, with an emphasis on Leishmania species. It was also suggested the probable role of neutrophils reverse
transmigration as another possible route for the spreading of Leishmania in the visceral leishmaniasis.