Abstract
Background Understanding immune mechanisms, particularly the
role of innate immune markers during latent TB infection remains
elusive. The main objective of this study was to evaluate mRNA gene
expression patterns of toll-like receptors (TLRs) as correlates of
immunity during latent TB infection and further infer their roles as
potential diagnostic biomarkers. Methods Messenger RNA (mRNA)
were analysed in a total of 64 samples collected from apparently healthy
children and adolescents, who were latently infected with tuberculosis
(n=32) or non-infected (n=32) and were selected using purposive sampling
to compare the relative expressions of selected TLRs (TLR-1, TLR-2,
TLR-4, TLR-6 and TLR-9), using quantitative real-time polymerase chain
reaction (qRT-PCR). Specific primers and florescent labelled probes were
used to detect the expression of these markers in peripheral blood; a
comparative threshold cycle method was used to describe fold change in
the relative expression of TLR genes. Data were analysed using Graph-Pad
Prism 7.01 for Windows and a p-value less than 0.05 was considered
statistically significant. Results An increased mean fold
change in the relative expression of TLR-2 and TLR-6 mRNA was observed
in LTBI groups relative to non-LTBI groups (p < 0.05), whereas
a slight fold decrease was observed for TLR-1 gene. Conclusions
An increased mRNA expression of TLR-2 and TLR-6 was observed in latently
infected individuals relative to those non-infected, possibly indicating
the roles these biomarkers play in sustenance of the steady state
interaction between the dormant TB bacilli and host immunity.