Construction of rabbit animal model of lesion of central nervous system induced by Campylobacter jejuni

Huaijun LIU; Wei CHEN; Ruichun LIU; Chunyan LI; Yong WANG; Linfang LI

ABSTRACT

BACKGROUND:

It has been found that central nervous system is involved in Guillain-Barre syndrome and Miller-Fisher syndrome, and the involved sites include optic nerve, brain stem and cerebellum. Abnormal signal of MRI can be observed in the brainstem and spinocerebellar tract of patients with Miller-Fisher syndrome. To establish an animal model of encephalitis after infection of Campylobacter jejuni, and investigate the mechanism of formation by means of imaging, immunology and pathology.

OBJECTIVE:

To construct an animal model of lesion of central nervous system after infection of Campylobacter jejuni Penner 4.

DESIGN:

A randomized grouping designed, controlled animal experiment.

SETTING:

Department of Imaging and Department of Neurology, Second Hospital of Hebei Medical University.MATERIALS The experiment was carried out in the Laboratory of Molecular Imaging, the Second Hospital of Hebei Medical University between August and December 2003. Fifteen healthy flap-eared rabbits were randomly divided into experimental group (n=10) and control group (n=5).

METHODS:

In the experimental group, Campylobacter jejuni inactivated bacteria liquor was completely emulsified with complete Freund adjuvant (CFA) of the same volume in week 1, and then the rabbits were immunized with subcutaneous injection at multiple points of bilateral axilla, bilateral groins and side of back spine, 1 mL for each site, and 5 mL for each rabbit; The rabbits were further immunized with intraperitoneal injection of simple Campylobacterjejuni inactivated bacteria liquor in the following every two weeks, 5 mL for each time in each rabbit for 5 times. In the control group, the Campylobacter jejuni inactivated bacteria liquor was replaced by saline of the same volume, the injected method and time were all the same as those in the experimental group. Evaluative

methods:

①Symptoms and physical signs their mental status, conditions of diet, urine and excrement, and activities of limbs were observed; ② Serological examination the contents of anti-Campylobacterjejuni antibody, anti-IgG GM1 antibody and myelin basic protein (MBP) were detected with enzyme-linked immunoadsorbent assay (ELISA); ③ MRI examination was applied to the randomly selected rabbits before every immunization with Toshiba 1.5 T MRI instrument. The scanning sequence included spin-echo T1-weighted image with the scanning parameter of 500/15 ms (TR/TE); rapid spin-echo T2-weighted image, 4 000/108 ms (TR/TE); fluid attented inversion recovery (Flair) sequence, the parameter was 10 000/120 ms (TR/TE), inversion angle was 90°. The thickness of scanning layer was 4.0 mm, and the layer space was 0.8 mm. ④ Histological examination At 4 weeks after the first immunization, the attacked animals were induced to death by cardiac perfusion, and the skull was opened immediately to remove optic nerve, part white matter, hippocampus, brainstem, cerebellum and spinal cords of neck, chest and waist, which were fixed with formaldehyde solution (40 g/L),and hematoxylin-eosin (HE) staining, fast blue staining and MBP immunohistochemical staining were performed respectively. At 10 weeks after immunization, 5 randomly selected rabbits in the experimental group and the 5 rabbits in the control group were treated with the same methods to obtain the histological samples.MAIN OUTCOME

MEASURES:

The symptoms and physical signs,contents of anti-Campylobacterjejuni antibody, anti-IgG GM1 antibody and MBP, imaging observation and histological examination were mainly observed.

RESULTS:

Fifteen animals were enrolled, 14 were involved in the analysis of results, 1 rabbit in the experimental group died at 4 weeks after immunization. ① Mental symptoms and disorder of limb's activity occurred in 1 rabbit in the experimental group at 2 weeks after immunization. ② In the experimental group, titre of anti-Campylobacterjejuni-IgG antibody in serum reach the peak at 2-4 weeks. From week 2, the serum A value was significantly higher in the experimental group than in the control group (1.923±0.403, 0.973±0.633, P ＜ 0.05). The IgG type GM1 (A value) was obviously elevated at week 8, but insignificantly different from that in the control group (0.115±0.042, 0.097±0.039, P ＞ 0.05). The MBP content (Avalue) in serum was significantly elevated at the 8th week (0.134±0.041).③ The imaging examination showed that abnormal MRI signal of different degree occurred at 2-4 weeks after immunization in the experimental group. ④ The histological changes showed that there was swelling of myelin sheath at the sites of brainstem, medulla oblongata, cervical spinal cord, thoracic spinal cord and lumbar spinal cord in the experimental group, no inflammatory cell infiltration and deletion of myelin sheath were observed. No obvious changes at the above site were observed in the contro1 group.

CONCLUSION:

Campylobacterjejuni Penner 4 can induce lesion of central nervous system.