Serum apoptosis inhibitor of macrophage is associated with radiologic severity in pulmonary Mycobacterium avium complex disease.

BACKGROUND

Pulmonary Mycobacterium avium complex disease (MAC-PD) is a chronic infection with variable severity and treatment responses. It lacks blood biomarkers that reflect disease burden and early treatment-related biological activity. We evaluated whether serum apoptosis inhibitor of macrophage (AIM), a macrophage-derived soluble protein, is associated with radiologic severity and changes during treatment in MAC-PD.

METHODS

This prospective observational pilot study included 18 female patients with MAC-PD who received guideline-based therapy for at least 6 months. Serum AIM levels were measured at baseline and 6 months. Radiologic severity and symptom burden were assessed using Nodules-Infiltration-Cavities-Ectasis (NICE) score and Chronic Obstructive Pulmonary Disease Assessment Test (CAT), respectively. C-reactive protein, Krebs von den Lungen-6, surfactant protein D, and albumin levels were analyzed as comparator markers.

RESULTS

Serum AIM was associated with the NICE score at baseline (Spearman's ρ = 0.648, 95% CI 0.260-0.856, p = 0.004) and after 6 months (ρ = 0.701, 95% CI 0.348-0.880, p = 0.001). AIM levels decreased after treatment (median, 420.1-331.7 ng/mL; p = 0.015). NICE scores decreased (median, 9-8; p = 0.077), but the change did not reach statistical significance. CAT scores decreased (median, 11-6; p = 0.007). The percentage change in AIM was not significantly associated with absolute changes in CAT or NICE scores.

CONCLUSIONS

Serum AIM was associated with radiologic disease burden in patients with MAC-PD at baseline and 6 months and decreased during the first 6 months of GBT. Larger studies are needed to further evaluate its clinical utility.