Determination of the concentration of cathepsin B by SPRI biosensor in children with appendicitis, and its correlation with proteasomes.

BACKGROUND: Cathepsin B (CatB) belongs to a family of lysosomal cysteine proteases and plays an important role in intracellular proteolysis.

OBJECTIVES: The concentration of CatB and 20S proteasome was evaluated in the serum of children with appendicitis, before and after surgery, on a basis of an innovative method for determining biomolecules concentration - surface plasmon resonance imaging (SPRI) biosensor.

MATERIAL AND METHODS: Forty-two children with acute appendicitis, who were treated at the Department of Pediatric Surgery (Medical University of Bialystok, Poland), were randomly included into the study (age: 5-17 years, mean age: 11.5 ±1 year). There were 15 girls and 27 boys in the study group. Eighteen healthy, age-matched subjects, admitted for planned surgeries, served as controls. Exclusion criteria were the following: severe preexisting infections, immunological or cardiovascular diseases that required longterm medication, and complicated cases of appendicitis with perforation of the appendix and/or peritonitis.

RESULTS: The CatB concentrations in the blood plasma of patients with acute appendicitis were elevated before surgery, they were the highest 24 h after surgery, and were above the range of concentrations measured in controls; the difference was statistically significant. The CatB concentration measured 72 h after the operation was decreased, but still did not reach the normal range when compared with the concentration measured in controls (p < 0.05).

CONCLUSIONS: Cathepsin B concentration may reflect the metabolic response to acute state of inflammation, surgical intervention in the abdominal cavity and the process of gradual ebbing of the inflammation. The method of operation - classic open appendectomy or laparoscopic appendectomy - does not influence the general trend in the CatB concentration in children with appendicitis. There is a strong positive correlation between the CatB and 20S proteasome concentrations 24 h after surgery. The SPRI method can be successfully used for determining the concentration of active forms of enzymes presented in lysosomes in the diagnosis of inflammatory conditions in the abdominal cavity.