Identification of serum biomarker associated with pulmonary mycobacterium tuberculosis in HIV infected individuals
Background: Accurate active tuberculosis (TB) diagnosis remains a challenge in clinical practice, especially in HIV infected patients. The aim of the study was to determine the serum markers that are associated with pulmonary Mycobacterium tuberculosis among HIV infected febrile individuals. Methods: The study compared HIV infected people with and without pulmonary tuberculosis and asymptomatic HIV infected individuals for inflammatory makers CRP and leptin levels, and the activation markers IP 10 and β2 microglobulin. Markers were tested on previously collected frozen serum samples. Serum markers CRP, Leptin and β2- microglobulin were measured using the enzyme-linked immunosorbent assays in 20 cases with pulmonary Mycobacterium tuberculosis, 20 suspects (control1) with B symptoms but without Mycobacterium tuberculosis and 20 (control 2) asymptomatic HIV infected individuals. The IP 10 was measured using the Bio-plex Pro assay. The assays were performed according to the manufacturers‟ instructions. Statistical analysis was performed using the Graph Pad prism program (version 6, Graphpad software, USA). Mann Whitney u test was used to compare for non-parametric variables among the three groups i.e. the HIV positive pulmonary TB positive cases, the negative pulmonary TB suspects and the asymptomatic HIV infected individuals and p values<0.05 were considered statistically significantly. Results: HIV positive pulmonary cases had elevated levels of IP 10, β2- microglobulin and CRP with a mean of 19566pg/ml (p=0.0001), 33.9ng/ml (p=0.023) and 1.77mg/ml (p=0.05) respectfully. There was negative correlation of the clinical characteristics with the serum levels of leptin and β2-microglobulin; however CRP had a positive correlation (r =0.086) fever weeks and (r = 0.143) cough weeks. The asymptomatic individuals had elevated leptin levels with a mean of 102.4, (p=0.01) but the leptin levels had no correlation with the weight of both controls. Conclusion: IP10, β2- microglobulin and CRP marker levels were higher among active TB pulmonary cases compared to negative Tb HIV positive individuals and asymptomatic HIV positive individuals. The serum markers levels had no correlation with the clinical characteristics.