HUMAN NEUROCYSTICERCOSIS: IN VIVO EXPANSION OF PERIPHERAL REGULATORY T CELLS AND THEIR RECRUITMENT IN THE CENTRAL NERVOUS SYSTEM Laura Adalid-Peralta*, Agnes Fleury*, Teresa M. Garcı ´a-IbarraÀ, Marisela Herna ´ ndezÀ, Michael Parkhouse`, Jose ´ Carlos Crispı ´n§, Jefferson Voltaire-Proan ˜oI, Graciela Ca ´ rdenasÀ, Gladis FragosoÀ, and Edda Sciutto*À# Instituto Nacional de Neurologı ´a y Neurocirugı ´a, Insurgentes Sur 3877, Col. La Fama, Me ´ xico D.F. 14269, Me ´ xico. e-mail: edda@servidor.unam.mx ABSTRACT: Human neurocysticercosis (NC) ;< is caused by Taenia solium larvae lodged in the central nervous system. Most cases occur with no, or mild, neurological symptoms. However, in some patients, neuroinflammation is exacerbated, leading to severe forms of the disease. Considering the critical role of regulatory T cells (Tregs) in balancing inflammation in chronic diseases, their participation in restraining the inflammatory response in NC was explored in the present study. The frequency of Tregs and their relationship with the level of the proliferative response, the level of activated lymphocytes, and the cytokines expressed were determined in severe NC patients compared with those from healthy donors. Significantly increased peripheral Tregs (CD4 + CD25 high and CD4 + CD25 high FoxP3 + , CD4 + CD25 high CTLA4 + , and CD4 + CD25 high IL10 + ) and a significant decrease in activated (CD38 + and CD69 + ) T cells were observed in 19 NC patients versus 10 healthy subjects. Significantly increased Tregs in NC are accompanied by a depressed specific, and non-specific, lymphocyte proliferative response, and they negatively correlate with activated CD4 + CD69 + lymphocytes. Treg frequencies were also determined in cerebral spinal fluid for 8 of the 19 NC patients. A positive significant correlation between peripheral and local Tregs was observed. Here, we report for the first time data that support the possible contribution of local and systemic Tregs in limiting neuroinflammation in NC. Acute and chronic inflammation play a significant role in the pathogenesis of many infectious and non-infectious diseases (Zipp and Aktas, 2006; Kellum et al., 2007; Costantino et al., 2008; Infante- Duarte et al., 2008; Sgambato and Cittadini, 2010). Inflammation is the hallmark in a variety of neuropathological diseases. Human neurocysticercosis (NC), caused by Taenia solium metacestode larvae located in the central nervous system (CNS), is not an exception (Del Brutto et al., 1988; Sotelo and Del Brutto, 2002; Fleury et al., 2004). Most NC cases occur in developing countries of Latin America, Asia, and Africa (Sciutto et al., 2000; Sotelo and Del Brutto, 2002; Garcı ´a et al., 2003). However, NC prevalence has progressively increased in developed countries of North America and Europe due to immigration from areas of the world where the disease is endemic (Croker et al., 2010; Sorvillo et al., 2011). Taenia solium enters the host’s brain as migratory microscopic oncospheres, where they develop into the metacestode stage (cysticercus) in just a few months, causing neurocysticercosis (Sciutto et al., 2000; Sa ´enz et al., 2008). Cysticerci diameters are generally 1– 2 cm in the brain parenchyma and sulci, but they may exceed 5 cm at the subarachnoid basal cisterns or the Sylvian fissure. It is noteworthy to mention how often such large parasites are able to survive for years without provoking any inflammation (Dixon and Lipscomb, 1961). Neurological symptoms are observed only when an uncontrolled inflammatory response is detected in the cerebral spinal fluid (CSF) (Fleury et al., 2004; Chavarrı ´a et al., 2005). One of the factors critically involved in this heterogeneous inflammatory response is the parasite location within the CNS. Indeed, when the parasite is located in the parenchyma or in the subarachnoid space (SA) of the sulci, most patients exhibit a benign clinical presentation, with low, or almost no, inflammation in CNS. In contrast, when the parasite is located in the SA at the skull base or in the ventricles, it appears to cause severe intracranial hypertension (hydrocephalus), a life-threatening complication associated with an exacerbated inflam- matory response, or CSF mechanical obstruction (Fleury et al., 2004), which requires immediate surgical intervention (ventriculo- peritoneal shunt). Due to the strong association between inflamma- tion and NC severity, treatment often combines cysticidal drugs (albendazole, or praziquantel, or both) with corticosteroids (usually prednisone or dexamethasone) to destroy the parasite and moderate the host perilesional inflammatory response (Garcı ´a et al., 2002; Serpa et al., 2006; Jung et al., 2008). Unfortunately, these treatments sometimes fail in completely clearing cysticerci, or controlling inflammation, or both. Furthermore, severe cases sometimes become chronic and may need a prolonged treatment with high doses of corticosteroids, which may cause undesirable side effects (Jung et al., 2008). The development of an inflammatory response in the CNS and its response to treatment widely vary among patients. Several factors, i.e., immune-regulatory mechanisms and hormones, which probably depend on individual features of the affected host, may down-regulate, with differing efficacy, the immune-inflammatory response during NC. Recently, a novel mechanism to modulate the inflammatory immune response via regulatory T cells (Tregs) was proposed. These anti-inflammatory cells are generated during infectious and non-infectious diseases (Belkaid and Tarbell, 2009). These results prompted the present study, in which CSF and blood specimens from corticosteroid-treated and non-treated NC patients were studied to assess the possible participation of Tregs in controlling brain inflammation. MATERIALS AND METHODS Neurocysticercosis patients: Disease characterization and sampling Samples from 19 patients at the Instituto Nacional de Neurologı ´a y Neurocirugı ´a and Centro Me ´dico Nacional Siglo XXI in Mexico City with The Journal of Parasitology para-98-01-30.3d 6/12/11 15:09:13 1 Cust # GE-2839 Received 18 April 2011; revised 18 July 2011, 24 September2011; accepted 28 September 2011. * Unidad Perife ´rica para el Estudio de Neuroinflamacio ´ n del Instituto de Investigaciones Biome ´dicas en el Instituto Nacional de Neurologı ´a y Neurocirugı ´a, Insurgentes Sur 3877, Col. La Fama, Me ´xico D.F. 14269, Me ´xico. { Departamento de Inmunologı ´a, Instituto de Investigaciones Biome ´dicas, Universidad Nacional Auto ´ noma de Me ´xico, Me ´xico D.F. 04510, Me ´xico. { Gulbenkian Institute for Science, Rua Quinta Grande 6, P.O. Box 2780- 156, Oeiras, Portugal. } Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02115. I Medical Research Unit for Neurological Diseases, Hospital de Especialidades, Centro Me ´dico Nacional Siglo XXI, Me ´xico D.F., Me ´xico. # To whom correspondence should be addressed. DOI: 10.1645/GE-2839.1 J. Parasitol., 98(1), 2012, pp. 000–000 F American Society of Parasitologists 2012 0