Low levels of antibodies against E. coli and mycobacterial 65kDa heat shock proteins in patients with inflammatory bowel disease

Abstract.

Objective and design: The aim of the present study was to support and extend our initial observation, where we found low levels of antibodies against mycobacterial 65kD heat shock proteins in patients with inflammatory bowel disease (IBD). For this purpose we tested a new group of 124 patients with IBD, and beside measuring antibodies to Mycobacterium bovis 65kD heat shock protein (Hsp65) and human 60kD heat shock protein (Hsp60) as described previously, we also determined IgG antibody levels to Hsp65 from E. coli, called GroEL.

Patients and control subjects: seventy-four patients with Crohn’s disease (CD) (30 males, 44 females, 33 (27–45) years old, median (interquartile range)) and 50 patients with ulcerative colitis (UC) (22 males, 28 females, 38 (30–50) years old) were involved in the study. 110 healthy subjects (34 males, 76 females, 47 (37–53) years old) served as controls. Study subjects were consecutive patients referred to an IBD center for complex treatment of the disease.

Methods and statistical analysis: The amounts of IgG-type antibodies reacting with proteins of the chaperonin 60 family were assessed by ELISA. Since the antibody levels to heat-shock proteins as variables were not normally distributed, non-parametric Mann-Whitney test and Dunn post hoc test were used for group comparisons.

Results: Median levels of anti-GroEL (7,5 (3,5–18,3)) and anti-Hsp65 (4,8 (2,1–7,85)) were significantly (GroEL p = 0,008; and Hsp65 p < 0,001) lower in the IBD patients than in the healthy subjects (GroEL: 10,0 (5,4–31,0); Hsp65: 7,04 (4,66–12,77)). However this difference was found to be restricted to the CD patients (GroEL: 7,5 (3,7–14,2); p < 0,05; Hsp65: 4,35 (1,90–6,94); p < 0,001). We did not find difference in the concentration of anti-human Hsp60 IgG levels between patients (Hsp60: 45,5 (24,9–69,0)) and healthy controls (38,4 (21,6–69,4). Regarding the serum concentrations of each antibody tested there was no significant difference between the active and inactive stage of disease.

Conclusion: Our present findings support conclusion of our previous work, antibody levels not only for Mycobacterium bovis hsp65 but for E. coli GroEl were found to be decreased as well. In contrast no changes in the concentrations of human anti-hsp60 antibodies were observed. These findings indicate that production of antibodies to 65 kDa bacterial heat shock proteins is selectively impaired in IBD.