Human cerebral cysticercosis: Immunolocalization of a sodium-dependent glucose cotransporter (SGLT) in larval and adult tapeworms

Light microscopic immunocytochemistry was used to examine human brain cysti cerci resected from the fourth ventricles of patients who had not been trea ted with anthelminthic drugs. Tissues were examined from 3 different patien ts undergoing surgery for treatment of hydrocephalus. A rabbit polyclonal a ntiserum to the peptide corresponding to amino acids 564-575 unique to the rabbit sodium-dependent, SGLT1 glucose cotransporter labeled with immunoper oxidase, localized immunoreactive SGLT epitopes. This antibody localizes SG LT1 in the apical brush borders of human enterocytes, but is negative in cy toplasm, as well as lateral and basal enterocyte membranes. Taenia solium n eurocysticerci were SGLT positive; transporter protein was highly expressed on the surface microvilli of the external cyst wall. The well-developed ne twork of small and larger osmoregulatory ducts within racemose larval cystc erci displayed high expression of SGLT cotransporter, consistent with a res orptive function for this system of tubules. Because water is cotransported with glucose molecules by the SGLT protein, its high expression in neurocy sticerci may contribute to the expansive growth of these larvae in subarach noid and intraventricular sites. The SGLT epitopes were also immunolocalize d in gravid proglottids of Taenia saginata, indicating that cotransporter e xpression persisted in intestinal-dwelling, adult tapeworms. Cotransporter antibody was abundantly localized at the proglottid tegumentary surface and in the lateral osmoregulatory ducts, analogous to the SGLT localization in cysticerci. Furthermore, high expression of this cotransporter was seen in the branches of the uterus, suggesting that SGLT-mediated absorption of gl ucose and water has an important functional role within the reproductive sy stem of adult tapeworms.