Serum interleukin-1β, interleukin-8 and anti-heat shock 60 Chlamydia trachomatis antibodies as markers of ectopic pregnancy

Abstract

Anti-Chlamydial trachomatis (anti-CT) responses, particularly anti-heat shock 60 (Hsp60), antibodies confer a higher risk of ectopic pregnancy. With emerging evidence supporting the pivotal role of interleukin-1β (IL-1β) and IL-8 in the immunopathogenesis of CT-specific tubal obstruction, we determined anti-CT Hsp60 antibody reactivity and serum concentrations of IL-1β and IL-8 in failed pregnancies consisting of 30 consecutive ectopic pregnancies and 30 missed abortions, with 32 viable intrauterine pregnancies tested as normal controls. ELISAs were utilised to measure IgA or IgG anti-CT major outer membrane outer protein (MOMP) antibodies, IgG anti-CT Hsp60 antibodies and IL-1β and IL-8. IgG anti-CT Hsp60 antibodies were more prevalent in ectopic pregnancy cases (43.3%, 13/30) than in intrauterine pregnancies (16%, 5/32, p=0.016). All 13 ectopic pregnancy anti-CT Hsp60-positive cases had anti-CT MOMP antibodies. CT-specific antibodies were more frequent in merged ectopic pregnancy and missed abortions cases (35%, 21/60) than in intrauterine pregnancies (16%, p=0.049). The median (range) levels of IL-1β in ectopic pregnancy, missed abortions and normal intrauterine pregnancies were 1.74 (0.2-8.7), 1.14 (0.2-16) and 1.22 (0.2-16.2) pg/ml, respectively (p>0.05, for all). Serum IL-8 levels were comparable amongst groups: ectopic pregnancy (median [range]: 25.1 [18.3-1000]); missed abortions (32.9 [15.39-1000]); and intrauterine pregnancies (25.11 [18.3-1000] pg/ml). Anti-CT antibody-positive ectopic pregnancy had significantly lower IL-1β levels (1.29 [0.2-2.93]) pg/ml than sero-negative ectopic pregnancy cases (2.09 [1.10-8.70]) pg/ml, (p=0.022), but IL-8 did not differ. Our data demonstrate that anti-CT Hsp60 immunity is a predominant feature of ectopic pregnancy. We conclude that neither IL-1β nor IL-8 can be considered markers of failed pregnancy, although lower levels of the former cytokine are associated with CT-related ectopic pregnancy.