Taenia solium: Development of an Experimental Model of Porcine Neurocysticercosis.

Human neurocysticercosis (NC) is caused by the establishment of Taenia solium larvae in the central nervous system. NC is a severe disease still affecting the population in developing countries of Latin America, Asia, and Africa. While great improvements have been made on NC diagnosis, treatment, and prevention, the management of patients affected by extraparenchymal parasites remains a challenge. The development of a T. solium NC experimental model in pigs that will allow the evaluation of new therapeutic alternatives is herein presented. Activated oncospheres (either 500 or 1000) were surgically implanted in the cerebral subarachnoid space of piglets. The clinical status and the level of serum antibodies in the animals were evaluated for a 4-month period after implantation. The animals were sacrificed, cysticerci were counted during necropsy, and both the macroscopic and microscopic characteristics of cysts were described. Based on the number of established cysticerci, infection efficiency ranged from 3.6% (1000 oncospheres) to 5.4% (500 oncospheres). Most parasites were caseous or calcified (38/63, 60.3%) and were surrounded by an exacerbated inflammatory response with lymphocyte infiltration and increased inflammatory markers. The infection elicited specific antibodies but no neurological signs. This novel experimental model of NC provides a useful tool to evaluate new cysticidal and anti-inflammatory approaches and it should improve the management of severe NC patients, refractory to the current treatments

Macroscopic examination of cysticerci recovered after implantation of activated oncospheres in brain and muscle (Experiment 2).

<p>SA: subarachnoid. IM: intramuscular. Co/Cs: colloidal/caseous.</p><p>Macroscopic examination of cysticerci recovered after implantation of activated oncospheres in brain and muscle (Experiment 2).</p

Expression of inflammatory cell markers in brain tissues.

<p>Six-micrometer sections of pig brain tissues proximal to installed parasites and sections of an equivalent region from sham-operated pigs (40X) were incubated with antibodies against inflammatory cell markers (CD106, CD80, CD54, and CD69). Non-immunized rabbit serum (control) showed no reaction. Arrows indicate regions where inflammatory markers are expressed. CD106 was expressed in brain microvessels, while CD80 was expressed in microglia cells.</p

Microscopic examination (HE, 4x) of a cysticercus recovered from brain.

<p>Lymphocyte Aggregates are observed in the parasite periphery. Parasite structures are not visible. A grade-4 inflammatory reaction is shown.</p

Expression of inflammatory and non-inflammatory cytokines.

<p>Six-micrometer sections of pig brain tissues proximal to installed parasites and sections of an equivalent region from sham-operated pigs (40X) were incubated with antibodies against inflammatory cytokines (IL-17, TNF-α, and IL6), the non-inflammatory cytokine IL-10 and a Th2-prototype cytokine. Arrows indicate regions where cytokines were expressed.</p

Expression of vimentin.

<p>The immunohistochemical analysis of vimentin expression showed that immature astrocytes were more frequently found in areas proximal to the parasite (A) than in tissues distal to the parasite (B) (40X).</p

Expression of GFAP, NeuN, and nestin.

<p>(Line A) Parasite and brain tissue adjacent to it. (Line B) Tissue adjacent to the parasite. (Line C) Brain tissue distal to the parasite (40X).</p

Histopathological classification of the inflammatory reaction (Experiment 2).

<p>SA: subarachnoid. IM: intramuscular.</p><p>Histopathological classification of the inflammatory reaction (Experiment 2).</p

Kinetics of serum anti-cysticercal antibodies and HP10 secretion antigen levels after implantation of activated oncospheres in pigs.

<p>Two doses of activated oncospheres (500 or 1000) were surgically implanted in the subarachnoid space (SA) of the brain or in muscular tissues (IM). Two pigs were not infected (control). (A): Serum antibody levels. (B): Serum HP10 secretion antigen levels.</p

Macroscopic aspect of cysticerci recovered from brain.

<p>Vesicular (white arrows) and colloidal/caseous (black arrows) parasites are shown.</p