Serum Cytokine Biomarkers for Use in Diagnosing Pulmonary Tuberculosis versus Chronic Pulmonary Aspergillosis

Background: Aspergillus fumigatus-induced chronic pulmonary aspergillosis (CPA), the most common pulmonary tuberculosis (TB) sequela, tends to occur after pulmonary infection with the intracellular pathogen Mycobacterium tuberculosis (Mtb). Timely and accurate detection of A. fumigatus infection of pulmonary TB patients would undoubtedly greatly improve patient prognosis. Currently, the galactomannan (GM) antigen test is commonly used to detect A. fumigatus infection but has poor sensitivity that renders this assay inadequate for use in clinical practice. Design or Methods: Given the fact CPA and TB induce different host immune responses, we evaluated serum cytokine level profiles of CPA, TB patients and patients with both diseases (CPA-TB) for multiple cytokines and cytokine combinations. Results: The results revealed significantly higher serum levels of numerous proinflammatory cytokines, including IL-1 beta, IL-6, IL-8, IL-12p70, IFN-alpha, IFN-gamma and TNF-alpha, in peripheral blood of CPA-TB patients versus that of TB patients. IL-8 levels alone provided the best discriminatory performance for distinguishing between TB and either CPA-TB patients (AUC = 0.949) or CPA patients (AUC = 0.964). Moreover, both IL-8 and TNF-alpha (AUC = 0.996) levels could be used to distinguish between TB and CPA-TB patients. Likewise, IL-8, TNF-alpha and IL-6 levels together could be used to distinguish between CPA-TB and TB patients. Conclusion: In this study, multiple cytokines were identified that may serve as potential biomarkers for use in detecting TB patients with CPA. Furthermore, our results should enhance understanding of how immune system dysfunctions influence susceptibility to Mtb and/or A. fumigatus infections.

Automated summary

In this study, the levels of certain cytokines in the blood were found to differ significantly between patients with chronic pulmonary aspergillosis (CPA), tuberculosis (TB), and co-infections of the two (CPA-TB). IL-8 levels could be used to distinguish between TB, CPA, and CPA-TB patients.