Significant elevation of plasma cathepsin B and cystatin C in patients with community-acquired pneumonia.

BACKGROUND

We identified the relationship between plasma level changes of cathepsin B and cystatin C before and after antibiotic treatment in hospitalized adult patients with community-acquired pneumonia (CAP).

METHODS

We collected blood specimens from 61 adult patients with CAP before and after antibiotic treatment and from 60 healthy controls and measured the plasma concentrations of cathepsin B and cystatin C expression using the enzyme-linked immunosorbent assay (ELISA). The APACHE II, CURB-65, and Pneumonia Severity Index (PSI) scores were determined to assess CAP severity in patients upon initial hospitalization.

RESULTS

The results showed a decline in the number of WBCs and neutrophils, with decreases in the concentrations of CRP, cathepsin B, cystatin C, and the cathepsin B/cystatin C ratio being observed after antibiotic treatment. The plasma concentration of cathepsin B correlated with severity of CAP with the PSI score (r=0.290, p=0.025) and the CURB-65 score (r=0.258, p=0.047), respectively. The plasma concentration of cystatin C correlated with the APACHE II score (r=0.523, p<0.001), severity of CAP in the PSI score (r=0.721, p<0.001) and the CURB-65 score (r=0.609, p<0.001), respectively.

CONCLUSIONS

Cathepsin B and cystatin C may play a role in the diagnosis and clinical assessment of the severity of CAP, which could potentially guide the development of treatment strategies.