Background Mycobacterium tuberculosis (Mtb) is the major causal pathogen of human tuberculosis (TB).
Autophagy is a highly conserved cytosolic pathway influencing the immune responses and the
elimination of intracellular pathogens including Mtb.
Objective To evaluate the effect of Mtb on autophagy flux with autophagy related genes of LC3I and LC3II,
beside the evaluation of serum interferon-gamma (IFN-γ) level in patients with pulmonary TB.
Methods A total of 50 blood samples were collected from patients with pulmonary TB, besides 30 as healthy
control. The real-time polymerase chain reaction (PCR) method was determined the measuring of
mRNA expression of autophagy-related genes of LC3I and LC3II. Serum IFN-γ protein concentration
was measured using sandwich Enzyme Linked ImmunoSorbant assay.
Results The present study showed an increasing in LC3-I level in newly-diagnosed pulmonary TB patients
rather than in the control group despite statistically non-significant P˃0.05, while LC3-II showed
decreasing in all pulmonary TB groups but statistically non-significant P˃0.05. Autophagy flux ratio
of LC3-I and LC3-II genes showed a statistically significant decrease in pulmonary TB groups
especially in newly- diagnosed (p value=0.02) rather than control groups. Moreover, the study of
the serum level of IFN-γ showed an increase in the level of IFN-γ with p=0.0001 in pulmonary TB
patients in comparison with the control group. In addition, the correlation between autophagyrelated
genes and IFN-γ have been shown a positive significant correlation (p value =0.013) in the
multidrug-resistant (MDR) TB group.
Conclusion Autophagy flux ratio showed a statistically significant decrease in pulmonary TB groups particularly
in newly-diagnosed TB patients rather than control groups, this indicates the different modulation
factors that may affect the process of autophagy. The only positive correlation within biomarkers of
the present study has been shown that LC3-II is a dependent factor on IFN-γ in MDR group.
Keywords Pulmonary tuberculosis, autophagy flux, LC3-I, LC3-II, diagnosis, IFN-γ
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