Role of cytokines in Trypanosoma brucei-induced anaemia: A review of the literature|
Musaya, J.; Matovu, E.; Nyirenda, M. & Chisi, J.
Anaemia is an important complication of trypanosomiasis. The
mechanisms through which trypanosomal infection leads to anaemia
are poorly defined. A number of studies have implicated inflammatory
cytokines, but these data are limited and inconsistent. In this article, we
reviewed the published literature on cytokines associated with Trypanosoma brucei infections and their role in the immunopathology leading to anaemia.
Articles were searched in PubMed through screening of titles and abstracts
with no limitation on date of publishing and study design. Articles
in English were searched using keywords “African trypanosomiasis”,
“sleeping sickness”, “Trypanosoma brucei”, in all possible combinations with
“anaemia” and/or “cytokines”.
Twelve articles examining cytokines and their role in trypanosomeinduced
anaemia were identified out of 1095 originally retrieved from
PubMed. None of the articles identified were from human-based studies.
A total of eight cytokines were implicated, with four cytokines (IFN-γ,
IL-10, TNF-α, IL-12) showing an association with anaemia. These articles
reported that mice lacking TNF-α were able to control anaemia, and
that IFN-γ was linked to severe anaemia given its capacity to suppress
erythropoiesis, while IL-10 was shown to regulate IFN-γ and TNF-α,
providing a balance that was associated with severity of anaemia. IFN-γ
and TNF-α have also been reported to work in concert with other factors
such as nitric oxide and iron in order to induce anaemia.
IFN-γ, IL-10, and TNF-α were the three major cytokines identified to be
heavily involved in anaemia caused by Trypanosoma brucei infection. The
anti-inflammatory cytokine, IL-10, was shown to counter the effects of
proinflammatory cytokines in order to balance the severity of anaemia.
The mechanism of anaemia is multifactorial and therefore requires
further, more elaborate research. Data from human subjects would also
shed more light.