Taenia crassiceps-Excreted/Secreted Products Induce a Defined MicroRNA Profile that Modulates Inflammatory Properties of Macrophages.

Helminth parasites modulate immune responses in their host to prevent their elimination and to establish chronic infections. Our previous studies indicate that Taenia crassiceps-excreted/secreted antigens (TcES) downregulate inflammatory responses in rodent models of autoimmune diseases, by promoting the generation of alternatively activated-like macrophages (M2) in vivo. However, the molecular mechanisms triggered by TcES that modulate macrophage polarization and inflammatory response remain unclear. Here, we found that, while TcES reduced the production of inflammatory cytokines (IL-6, IL-12, and TNFα), they increased the release of IL-10 in LPS-induced bone marrow-derived macrophages (BMDM). However, TcES alone or in combination with LPS or IL-4 failed to increase the production of the canonical M1 or M2 markers in BMDM. To further define the anti-inflammatory effect of TcES in the response of LPS-stimulated macrophages, we performed transcriptomic array analyses of mRNA and microRNA to evaluate their levels. Although the addition of TcES to LPS-stimulated BMDM induced modest changes in the inflammatory mRNA profile, it induced the production of mRNAs associated with the activation of different receptors, phagocytosis, and M2-like phenotype. Moreover, we found that TcES induced upregulation of specific microRNAs, including miR-125a-5p, miR-762, and miR-484, which are predicted to target canonical inflammatory molecules and pathways in LPS-induced BMDM. These results suggest that TcES can modulate proinflammatory responses in macrophages by inducing regulatory posttranscriptional mechanisms and hence reduce detrimental outcomes in hosts running with inflammatory diseases.

No association of IL2, IL4, IL6, TNF, and IFNG gene polymorphisms was found with Taenia solium human infection or neurocysticercosis severity in a family-based study.

Neurocysticercosis (NC) is caused by the establishment of the metacestode stage of Taenia solium in the human central nervous system. A great heterogeneity in the susceptibility to the infection and to the disease has been reported. While the factors involved in this heterogeneity are not completely understood, clearly different immune-inflammatory profiles have been associated to each condition. This study evaluated the association of cytokine single nucleotide polymorphisms (SNPs) with susceptibility to infection and disease severity in NC patients. Blood samples from 92 NC cases and their parents (trios) were genotyped for SNPs in five cytokines relevant for the immune response: IL4 (-589C/T), IL6 (-174C/G), IFNG (+874T/A), TNF (-238G/A), and IL2 (-330G/T). Specific DNA fragments were amplified by the polymerase chain reaction, using the 5'-nuclease Taqman assay on a 7500 platform, allowing the detection of the polymorphism genotypes. No association between the polymorphisms evaluated neither with susceptibility to infection nor with disease severity was found, although previous studies reported variations in the levels of these cytokines among different NC clinical pictures. These results, nevertheless, add new elements to our understanding of the complex pathogenic mechanisms involved in susceptibility to infection by T. solium cysticerci and the severity of the ensuing disease.

Genetic variability of the 18 kDa/HP6 protective antigen in Taenia saginata and Taenia asiatica: implications for vaccine development.

Genomic characterization of the genes encoding the Taenia 18 kDa/HP6 protective antigens was carried out for Taenia saginata and T. asiatica using 42 taeniid isolates comprising 23 samples of T. saginata, 13 samples of T. asiatica and 6 samples of T. solium. The corresponding sequences from all taeniid isolates were PCR-amplified with specific primers and then sequenced. All the genes, and other described taeniid gene homologues, had the same genomic structure. Surprisingly, the T. saginata TSA18 gene showed nucleotide variability within the 23 samples analyzed. This resulted in two distinct genotypes with 96% DNA sequence similarity and deduced amino acid sequences with 21 substitutions, mainly located in the second exon which contains the fibronectin type III domain. In regards to T. asiatica, the 18 kDa gene (TASI18) was very similar to the T. saginata antigen homologues, both at the DNA and deduced amino acid sequence levels, and the TSOL18 gene was conserved among T. solium isolates as previously described. The implications of these findings on the future development of taeniid vaccines are discussed.

Differential response of antigen presenting cells from susceptible and resistant strains of mice to Taenia crassiceps infection.

Antigen presenting cells (APCs) are critically involved in the interaction between pathogens and the host immune system. Here, we examined two different populations of APCs in mice that are susceptible (BALB/c) or resistant (C57BL/6) to Taenia crassiceps cysticercosis. Bone marrow-derived dendritic cells (BMDCs) from both strains of mice were exposed to T. crassiceps excreted/secreted antigens (TcES) and, at the same time, to the Toll-like receptor (TLR) ligand LPS. BMDCs from BALB/c mice underwent a partial maturation when incubated with TcES and displayed decreased responses to TLR-dependent stimuli associated with low CD80, CD86, CD40 and CCR7 expression and impaired IL-15 production. These BMDCs-induced impaired allogenic responses. In contrast, BMDCs from C57BL/6 mice displayed normal maturation and induced strong allogenic responses. Moreover, the exposure to TcES resulted in a lower production of IL-12 and TNF-alpha by LPS-activated DCs from BALB/c mice compared to C57BL/6 DCs. Three parameters of macrophage activation were assessed during Taenia infection: LPS+IFN-gamma-induced production of IL-12, TNF-alpha and nitric oxide (NO) in vitro; infection-induced markers for alternatively activated macrophages (Arginase-1, RELM-alpha, Ym-1 and TREM-2 expression) and suppressive activity. The maximum response to LPS+IFN-gamma-induced TNF-alpha, IL-12 and NO production by macrophages from both strains of mice occurred 2 wk post-infection. However, as infection progressed, the production of these molecules by BALB/c macrophages declined. While the BALB/c macrophages displayed impaired pro-inflammatory responses, these macrophages showed strong Arginase-1, Ym-1, RELM-alpha and TREM-2 expression. By contrast, C57BL/6 macrophages maintained a pro-inflammatory profile and low transcripts for alternative activation markers. Macrophages from T. crassiceps-infected BALB/c mice showed stronger suppressive activity than those from C57BL/6 mice. These findings suggest that APC activation at both early and late time points during T. crassiceps infection is a possible mechanism that underlies the differential susceptibility to T. crassiceps infection displayed by these mouse strains.

Taeniasis and cysticercosis in Asia and the Pacific: present state of knowledge and perspectives.

Several topics on taeniasis and cysticercosis in Asia and the Pacific are overviewed. In Asia and the Pacific, three human taeniid species have been recognized: Taenia solium, Taenia saginata and Taenia asiatica. The first topic is on evolution of T. solium. Mitochondrial DNA polymorphisms of T. solium worldwide are discussed with emphasis of two specific genotypes: American-African and Asian. The second topic is recent major advances in sero- and molecular-diagnosis of T. solium cysticercosis in humans, pigs and dogs. The third is the present situation of T. solium taeniasis/cysticercosis in Papua (Irian Jaya), Indonesia. The forth is the present situation of T. solium cysticercosis and T. saginata taeniasis in Bali, Indonesia. The fifth is the present situation of T. asiatica taeniasis in Asia and the Pacific and in North Sumatra, Indonesia. The sixth is on the debate of the exact definition of T. asiatica. Because T. asiatica can not be differentiated from T. saginata morphologically, it is time to re-evaluate T. saginata in Asia and the Pacific. New and broad-based surveys across this region are necessary from epidemiological and public health perspectives, based on evidence.

Comparison of conventional techniques to differentiate between Taenia solium and Taenia saginata and an improved polymerase chain reaction-restriction fragment length polymorphism assay using a mitochondrial 12S rDNA fragment.

Given the constraints of classical diagnostic methods, i.e., morphological and isoenzymatic studies of proglottids, a polymerase chain reaction test complemented with restriction enzyme analysis has been modified by redesigning one of the primers to reduce nonspecific amplifications experienced when using field samples. The use of these new, highly cestode-specific primers and the restriction enzyme Ddel led to the development of a diagnostic assay that clearly distinguishes between Taenia saginata and T. solium proglottids in field samples. This assay confirms the presence of T. saginata in Ecuador. DNA amplification of some of these taeniids showed different patterns, suggesting the possibility that strain differences exist. These results demonstrate the need for development of useful molecular assays as reliable tools for epidemiological studies on cestodes.

Ensayo de la proliferación celular en cultivo de linfocitos de cerdo / Assay kinetics cell proliferations lymphocytes from pigs

Se reporta el cultivo de linfocitos de sangre periférica completa de cerdos sanos e infectados, para evaluar la cinética de proliferación celular; 0.5 ml de sangre fue cultivada en 6.0 ml de RPMI-11640 suplementado, en presencia de fitohemaglutinina y 5-BrdU, a 37§C. Al cabo de 48 horas de incubación se cosecharon y fueron teñidos de acuerdo a la técnica de fluorescencia más Giemsa, obteniéndose así células en diferentes etapas de diferenciación, identificándolas en primera, segunda y tercera división. La actividad proliferativa se midió bajo dos parámetros: índice mitótico e índice de replicación. Los resultados son reproducibles y se pueden diferenciar los efectos citotóxicos de los citostáticos sobre los linfocitos del huésped

Taenia taeniaeformis: cellular reconstruction of athymic mice and role of L3T4+ helper T lymphocytes in the early infection.

The role of T helper lymphocytes (L3T4+) in the early response to Taenia taeniaeformis metacestodes was investigated. Athymic BALB/c-nu/nu mice (susceptible) were inoculated intraperitoneally with the following cell populations from congenic BALB/c-nu+ + mice (resistant): (a) whole spleen single cells, (b) thymus single cell suspensions, or (c) spleen cells pretreated with anti-L3T4 monoclonal antibody before the injection. The mice were given 3 weekly injections of cells and then infected orally with 300 eggs 7 days after the last injection. Cryostat sections of the liver from the infected mice were examined at 6 days postinfection (PI) for parasite viability, the numbers of eosinophils, and L3T4+ T lymphocytes present within 100 micron of the parasite and for the presence of biotin in hepatocytes (involved in biosynthesis of fatty acids) around the parasite. The success of the cellular reconstitution of athymic mice with the lymphoid cells was measured by a T-cell mitogenic assay with concanavalin A (ConA). The cellular reconstitution of athymic mice with a mixture of lymphoid cells from the spleen and thymus of BALB/c-nu/ + mice resulted in both parasite death and eosinophil infiltration. Reconstitution with mature splenic cells alone resulted in a greater parasite killing and eosinophil infiltration as compared to reconstitution with thymic cells. The better reconstitution with splenic cells was reflected in a greater mitogenic response to ConA.(ABSTRACT TRUNCATED AT 250 WORDS)

Differences in susceptibility of rat strains to experimental infection with Taenia teaniaeformis.

Age-matched, outbred, female, Sprague-Dawley-derived rats from different commercial suppliers were compared for their susceptibility to the establishment and growth of Taenia taeniaeformis. Two of the strains, Spb:[SD] and Kng:[SD], gave very similar results, but the third, Hap:[SD]f, was considerably less receptive. Approximately one in eight of the Hap:[SD]f rats proved refractory to infection, and worm growth was slower and more variable than in Spb:[SD] rats. Male Spb:[SD] rats were not detectably different from females in susceptibility or parasite growth rate. Female rats of four different inbred lines all accepted infection, though the proportion of infective eggs giving rise to hepatic cysts differed. These differences, however, were overshadowed by variations observed in susceptibility of inbred rats of the same strain (Wistar-Lewis) purchased from different commercial suppliers. The results emphasize the need for careful standardization of laboratory procedures and rat strains for experimentation with this host-parasite system. In addition, they illustrate the dangers of extrapolation from the extensive literature of the influence of rat strain and sex on susceptibility to infection with T. taeniaeformis.