Immunomodulatory potential of particular Trichinella spiralis muscle larvae excretory-secretory components.

Excretory-secretory antigens of Trichinella spiralis muscle larvae can induce the semi-matured status of rat dendritic cells. This may at least partly be the consequence of transient activation of extracellular signal-regulated kinases 1/2 (ERK1/2). Here we investigated the potential of several components of excretory-secretory antigens (native fraction containing 45, 49 and 53kDa proteins and recombinant Tsp53, representing one of the constituents of this fraction) to demonstrate previously observed effects of excretory-secretory antigens on dendritic cells in vitro, characterised by establishment of a particular phenotype (very low MHC II expression, moderate CD86 expression and significant ICAM-1 expression) and functional properties (low production of pro-inflammatory cytokine IL-12p70, and high production of IL-10 and TGF-ß). Dendritic cells activated by these components were able to provoke proliferation of naïve T cells and their polarisation towards Th2 and anti-inflammatory responses. The investigated antigens had almost the same capacity to induce IL-4 and IL-10 production from T cells as excretory-secretory antigens, but failed to induce significant TGF-ß synthesis. It could be concluded that the investigated excretory-secretory antigens components can largely reproduce the immunomodulatory effects of the complete excretory-secretory antigens and therefore may be considered as molecules important for creation of the anti-inflammatory milieu achieved by the parasite.

Differential immunological responses induced by infection with female muscle larvae and newborn larvae of Trichinella pseudospiralis.

Trichinella pseudospiralis infection can modulate the immunological response of autoimmune and allergic diseases leading to the amelioration of these diseases. The present study was undertaken to compare immunity induced by adult worms and muscle larvae. Higher eosinophilia was observed from newborn larva (NBL) infection than from adult females while higher levels of IgE were observed in adult female infections over those induced by NBL. The IgG1 response to ES antigen was more prominent in infections with adult females. The IgG2 responses to larval crude antigen were prominent against NBL. The Th2 cytokine, IL-4 cytokine was elevated in adult female infection following re-stimulation with adult crude antigen and ES. Both infections induced strong IFN-γ responses. The present study demonstrates that adult female worms induced stronger Th2 responses (IgG1, IgE and IL-4 responses) than NBL. Further examination of the mechanisms involved in immune modulation may be helpful for identifying Trichinella-derived molecules responsible for regulating autoimmune and allergic diseases.

Trichinella: what is going on during nurse cell formation?

Recent molecular studies have revealed that many genes are mobilized during nurse cell formation, including those involved in activation and proliferation of satellite cells, dedifferentiation, cell cycle re-entry and arrest, apoptosis and transformation. This article reviews the kinetics of gene expression from a cellular biology point-of-view in an effort to dissect the complex events that lead to unusual pathological changes after a Trichinella infection.

Minimally required heat doses for various tumour sizes in induction heating cancer therapy determined by computer simulation using experimental data.

PURPOSE: Although induction heating cancer therapy (IHCT) using magnetic nanoparticles can be a promising approach to treatment-less multi-nodular cancers, the objective requirement for successful clinical application has not clearly been elucidated. We intended to define objective heat doses suitable for IHCT, especially focusing on the sizes of liver cancer nodules. MATERIALS AND METHODS: Alternating magnetic fields were applied to three human pancreatic cancer cell lines, the intercellular space of those cell pellets were filled with magnetic nanoparticles, and confirmed the cytotoxic effect of IHCT. Subsequently, the temperatures of liver cancer nodules in IHCT were simulated using a computer software program and the required heat dose for various sized tumours were determined. RESULTS: Heating the cancer cells up to 50 degrees C for 10 min was sufficient for complete cell killing and the heat dose of 1.7 W/g(tumour) is required for 10 mm tumour. Larger tumours require a smaller heat dose, e.g. 20 mm and 40 mm tumours require 0.7 W/g(tumour) and 0.6 W/g(tumour), respectively, whereas smaller tumours require large amounts of heat, e.g. 5 mm and 1 mm tumours require 5.1 W/g(tumour) and 105 W/g(tumour), respectively. CONCLUSIONS: Integrating the presently available technologies, including high-quality magnetic nanoparticles (1000 W/g(material)) and effective drug delivery systems (1-2 mg(material)/g(tumour)), treatment of a 10 mm tumour seems possible. Since treatment of smaller tumours less than 5 mm require substantial heat dose, researchers involved in IHCT should target cancer nodules of 10 mm or more, and develop a heat delivery system providing a minimum of 1.7 W/g(tumour).

Hypoglycaemia induced by Trichinella infection is due to the increase of glucose uptake in infected muscle cells.

The present study investigates how Trichinella infection induces host hypoglycaemia and explores a potential relationship between infection and the insulin signalling pathway. The results showed that mice infected with Trichinella spiralis or Trichinella pseudospiralis exhibited a temporary decrease in blood glucose level between 8 and 28 days p.i. and the kinetics of the glucose levels corresponded to the process of muscle larval growth and development. Histochemical results showed that glycogen accumulation increased in infected muscle cells during the period of hypoglycaemia. Analysis of gene expression profiles with quantitative PCR demonstrated that insulin signalling pathway-related genes, such as insulin receptor (IR), insulin receptor substance 1 (IRS-1), IRS-2, phosphatidylinositol 3-kinase (PI3-K) and V-akt murine thymoma viral oncogene homologue 2 (Akt2) were up-regulated in infected muscle cells during infection and these expression changes correlated with the kinetics of blood glucose level, glycogen accumulation and the process of larval growth and development in infected muscle cells. Western blot analysis clarified that the expression of IR and Akt2 proteins increased in muscle tissues infected with both species of Trichinella. This study suggests that hypoglycaemia induced by Trichinella infection is the result of an increase in glucose uptake by infected muscle cells via up-regulation of insulin signalling pathway factors.

Genetic relationships among Trichinella pseudospiralis isolates from Australian, Nearctic, and Palearctic regions.

The study of the genetic polymorphism of pathogens is important for phylogenetic and biogeographic studies and, in the case of foodborne pathogens, to trace the origin of food infection. Since its discovery in 1972, the nonencapsulated species Trichinella pseudospiralis has been detected in mammals and birds, and human infection has occurred, in some cases resulting in death. We studied DNA polymorphism among ten T. pseudospiralis isolates from the Palearctic, Nearctic, and Australian regions, screening the sequences of nine genes [18sRNA, a random amplified polymorphism DNA derived sequence, mitochondrial cytochrome oxidase subunit I (COI), cytochrome P450, cynate lyase, epithelial fusion failure-1, and three unknown genes of Tp3, Tp8, and Tp26]. A high identity of sequence for the nine gene loci was obtained among the seven isolates from the Palearctic region and between the two isolates from the Nearctic region. Genetic identity analysis indicated the distinct polymorphism among the three geographical origins. To easily identify T. pseudospiralis genotypes, a polymerase chain reaction-restriction fragment length polymorphism analysis of COI gene was performed, and the results confirmed the DNA polymorphism within T. pseudospiralis, corresponding to the three regions of origin. We have named the three genotypes as "T. pseudospiralis Palearctic genotype" (code T4P), "Nearctic genotype" (code T4N), and "Australian genotype" (code T4A). To further investigate polymorphism among the nonencapsulated Trichinella species, the sequences of four gene loci (COI, P450, cynate lyase, and SB147D) of T. pseudospiralis, T. papuae, and T. zimbabwensis were analyzed, and the results showed high polymorphism among the three species, strongly supporting their classification as separate species.

Thermally induced and developmentally regulated expression of a small heat shock protein in Trichinella spiralis.

A cDNA encoding a small heat shock protein of Trichinella spiralis, Ts-sHsp, was cloned and expressed and is herein characterized. This cDNA encoded a predicted protein of 165 amino acids, which had a high sequence identity in alpha crystallin domain with various small heat shock proteins of other organisms. A Western blot analysis indicated that anti-Ts-sHsp recombinant antibody recognized the protein of adults and larvae migrating at about 19 kDa. An in situ localization study showed the protein to be abundantly present in the body wall muscle cells, hypodermis, stichocytes, and esophagus of muscle larvae. The Ts-sHsp recombinant protein possessed chaperone activity to suppress the thermally-induced aggregation of citrate synthase. This sHsp was expressed at various developmental stages of T. spiralis, but at different levels. A high level was observed in mature muscle larvae (infective larvae), which was much higher than the levels seen in adults, newborn larvae, or immature muscle larvae. The expression of the sHsp gene was thermal inducible, thus responding to both cold (0 degrees C) and heat shock (43 degrees C) stress; however, at different patterns. The expression of Ts-sHsp increased gradually from 3 to 72 h after cold stress, while the expression was elevated to its highest after 3 h heat stress and then decreased. These results suggest that this small heat shock protein likely plays a role in the tolerance to both chemical and physical stresses, thereby enhancing the survival ability of Trichinella muscle larvae.

Pulp ablation therapy by inductive heating: heat generation characteristics in the pulp cavity.

OBJECTIVE AND METHODS: This study was performed to clarify the usefulness of inductive heating system for the new endodontic therapy. Dextran magnetite complex (DM) suspensions were injected into the root canal of a permanent tooth, and the tooth was heated up to about 55.0 degrees C by alternating-current magnetic field. RESULTS AND CONCLUSION: The time until the temperature in the pulp cavity reached 55.0 degrees C was 328 +/- 26 s (mean +/- s.d., n = 8) in the 56 mg as Fe ml(-1) of DM concentration. The temperature in the pulp cavity could be maintained at 53.5-59.0 degrees C for 1200 s by changing the magnetic field intensity safely, while temperature elevations of the dental surface on the coronal and apical sides were 4.9 degrees and 3.7 degrees C, respectively. Thus, this inductive heating system, which has the possibility of selective heating, might be useful for eliminating residues of pulp as a new ablation therapy.

Involvement of the c-Ski oncoprotein in cell cycle arrest and transformation during nurse cell formation after Trichinella spiralis infection.

The role of c-Ski, an oncoprotein encoded by the oncogene, c-ski, in Trichinella spiralis-infected muscle tissues during nurse cell formation, was investigated by following the expression kinetics and distribution of c-Ski (both protein and mRNA) in the infected muscle cell, as well as the expression kinetics of the transforming growth factor beta (TGF-beta) signaling pathway factor genes (TGF-beta, Smad2 and Smad4) which cooperate with c-Ski. Immunohistochemical analysis using an anti-c-Ski antibody indicated that in the early stages of infection (13 and 18 days post-infection (p.i.)) the increased expression of the c-Ski protein was limited to the eosinophilic cytoplasm and not the enlarged nuclei or basophilic cytoplasm. At a later stage of infection (23 and 28 days p.i.) the c-Ski protein was limited to the enlarged nuclei in the basophilic cytoplasm, rather than the eosinophilic cytoplasm. At 48 days p.i., the c-Ski protein was barely detectable. Real-time PCR analysis showed that expression of the c-ski gene increased from 13 days p.i., reached a peak at 23-28 days p.i. and then decreased to a low level by 48 days p.i. Expression kinetics for the TGF-beta signaling pathway factor genes (TGF-beta, Smad2 and Smad4) were similar to that of c-ski. These findings provide evidence that the c-Ski protein is involved in nurse cell formation through the TGF-beta signaling pathway process in the host cell nucleus.

Molecular cloning and characterization of an Rcd1-like protein in excretory-secretory products of Trichinella pseudospiralis.

A cDNA library was constructed from muscle larvae of Trichinella pseudospiralis. A cDNA clone, designated as Tp8 contained a cDNA transcript of 1326 bp length with a single open reading frame, which encoded 303 amino acid residues (34,187 Da, estimated molecular mass). The predicted amino acid sequence of the clone had an identity of approximately 60% to the Rcd1 (Required cell differentiation 1) -like proteins among a wide range of organisms. Real-time quantitative polymerase chain reaction results showed that the transcription level of Tp8 gene reached the highest value in adult worms, and that the transcription level in muscle larvae before stichosome formation was higher than in muscle larvae after stichosome formation. The recombinant Tp8 protein migrated at 37 kDa and reacted to antibody against T. pseudospiralis excretory-secretory (E-S) products and sera from mice infected with T. pseudospiralis. An antibody against the Tp8 recombinant protein could stain proteins migrating at approximately 34 kDa (which is the expected size from the sequence) on Western blotting of E-S products from muscle larvae. An immunocytochemical study showed that the Tp8 protein was present within the stichocyte of muscle larvae and adults worms.

What is the role of p53 during the cyst formation of Trichinella spiralis ? A comparable study between knockout mice and wild type mice.

During the cyst formation of Trichinella spiralis, the infected muscle cell undergoes basophilic change and apoptosis, which results in nurse cell formation. This study revealed expression kinetics of some apoptosis genes such as p53 and its closely related genes (tumor suppressor genes p53, p53; mouse double minute 2, MDM2; cyclin-dependent kinase inhibitor p21, p21waf). RT-PCR (reverse transcription polymerase chain reaction) results showed that these genes were temporarily expressed in the infected muscles during the cyst formation period, but not in normal muscles (or very low if any), which suggested the involvement of these apoptosis genes in the nurse cell formation. Cysts and neighbouring muscle cells were separately collected and RT-PCR was performed, which suggested that p53 was expressed in the cysts. An immunocytochemical study showed that p53 was expressed in the nucleoplasm of basophilic cell in the cyst and Trichinella larvae, which suggested involvement of these apoptosis genes in the nurse cell formation. The same p53 expression kinetic study was performed on p53 knockout mice. The knockout mice did not express p53 genes, but expressed the other apoptosis genes in the same kinetics with only minor exceptions, suggesting that the expressions of these genes during the cyst formation were more or less p53-independent. There were no differences in the number and morphology of the cysts between the knockout mice and wild type mice. Thus apoptosis seen during the Trichinella cyst formation can be operated in the presence or absence of p53.

Tumor necrosis factor receptor-mediated apoptosis in Trichinella spiralis-infected muscle cells.

In order to reveal the mechanisms underlying nurse cell formation during Trichinella spiralis infection, the expression of the factors of tumor necrosis factor-alpha (TNF-alpha)/TNF receptor 1 (TNFR-1) signalling pathway mediating apoptosis was investigated. The analysed factors included TNF-alpha, TNFR-1, TNF receptor-associated death-domain (TRADD), caspase 3, caspase 8, TNF receptor associated factor-2 (TRAF2) and receptor interactive protein (RIP), all of which are involved in the TNF-alpha/TNFR-1 signalling pathway-mediated apoptosis. The quantitative RT-PCR indicated that the infected muscle tissues up-regulate the expression of pro-apoptosis genes (TNF-alpha, TNFR-1 and TRADD, caspase 3 and caspase 8), and anti-apoptosis genes (TRAF2 and RIP) at the beginning of cyst formation. The expression returned to the normal level after cyst formation. The quantitative RT-PCR analysis of mRNA from tissue samples isolated by laser capture micro-dissection confirmed that the up-regulation of these genes was restricted in infected muscle cells, was not in the inflammation cells around infected muscle cells nor in normal muscle cells. The in situ localization study of proapoptosis (TRADD, caspase 3) and anti-apoptosis gene products (TRAF2) indicated that these were expressed in the basophilic cytoplasm (infected muscle cell origin) of the nurse cells. Thus the present study suggests that the TNF-alpha/ TNFR-1 signalling pathway is involved in nurse cell formation.

A spectrum of functional genes mobilized after Trichinella spiralis infection in skeletal muscle.

Trichinella spiralis infection causes the transformation of infected muscle cells, which leads to nurse cell formation. To search for the candidate genes responsible for nurse cell formation, cDNA microarray analysis of muscle tissues was performed before and after Trichinella infection. The Atlas mouse 1.2 cDNA expression microarray revealed the expression profiles of 1176 known genes. Out of these, 311 gene expressions were detected in normal and/or infected muscles. After the infection, 184 out of the 311 genes increased in expression by more than 3-fold. These included genes responsible for cell differentiation, proliferation, cell cycle and apoptosis. Thus this study suggested candidate genes for further investigation to dissect the molecular mechanisms of nurse cell formation.

Molecular cloning and functional expression of enolase from Trichinella spiralis.

The cDNA library was constructed from muscle larvae of Trichinella spiralis, and immunoscreened with sera from mice infected with T. spiralis. A cDNA clone, designated as TsENO, encoded 2-phospho-D-glycerate hydro-lyase (enolase) that catalyzed a reversible conversion of 2-phospho-D-glyceric acid (2PGA) to phosphoenolpyruvate (PEP) in the glycolytic pathway. The recombinant TsENO protein was produced in an Escherichia coli expression system. The recombinant full-length TsENO protein had no activity in the conversion of 2PGA to PEP, but gained enolase activity after cutting off the signal peptide from the full-length protein. There was no meaningful difference in the expression level of TsENO gene at three distinct stages of T. spiralis. Also, antibody against the recombinant TsENO protein reacted with crude extract of muscle larvae, but not with the excretory and secretory products.

Trichinella pseudospiralis infection is characterized by more continuous and diffuse myopathy than T. spiralis infection.

A time course study was performed to reveal the sequence of histopathology after Trichinella spiralis or T. pseudospiralis infection in mice. A cyst was formed in the former case by about 18 days post infection and prominent myopathy was restricted within the cyst. In the latter case, however, no typical cyst was formed, and myopathy spread diffusely over the infected muscle tissues occupying half the area of muscle sections. An electron microscope observation revealed that the disintegration of muscle cells was delayed in T. pseudospiralis infection than in T. spiralis infection. Quantitative reverse transcription polymerase chain reaction (RT-PCR) showed that apoptosis-related genes were expressed for a longer term in muscles infected with T. pseudospiralis than in those with T. spiralis, although the same spectrum of genes are mobilized. Examined apoptosis-related genes included tumor suppressor genes p53, p53; mouse double minute 2, MDM2; cyclin-dependent kinase inhibitor p21 (WAF1), p21(waf) ; Bcl-2 associated protein X, BAX; apoptotic protease activating factor 1, Apaf-1; Caspase 9 and serine/ threonine protein kinase, PKB. Micro-dissection of the infected muscle tissue and subsequent RT-PCR confirmed that the expressions of these genes are restricted to tissue with myopathy. Thus, the expression of the apoptosis-related genes correlated with continuous and diffuse myopathy caused by T. pseudospiralis infection.

Reduction of a vascular endothelial growth factor receptor, fetal liver kinase-1, by antisense oligonucleotides induces motor neuron death in rat spinal cord exposed to hypoxia.

Vascular endothelial growth factor (VEGF) is reported to play a neuroprotective role through a VEGF receptor, fetal liver kinase-1 (Flk-1) in vitro. We investigated whether reduction of Flk-1 could induce motor neuron loss in rat spinal cord by inhibiting the expression of Flk-1 in rat spinal cord using antisense oligodeoxynucleotides (ODNs) against the Flk-1 receptor. Rat spinal cord was repetitively exposed to 12% hypoxia, and the change of the phosphatidylinositol 3-kinase (PI3-K)/Akt pathway and the mitogen-activated protein kinase kinase (MEK)/extracellular-signal-regulated kinase (ERK) pathway was examined. Intrathecal infusion of Flk-1 antisense ODNs for 7 days suppressed almost completely Flk-1 expression in the lumbar segment of the spinal cord and was followed by a hypoxic challenge with 12% oxygen for 1 h that was repeated for 7 more days. In the lumbar segment, we observed that reduced Flk-1 expression and hypoxic challenge for 7 days resulted in approximately 50% loss of motor neurons, in which the activation of Akt and ERK, that is, increased levels of phosphorylated-Akt and of phosphorylated-ERK by hypoxia, was markedly inhibited. In contrast, the reduction of Flk-1 expression alone did not induce motor neuron loss. These results suggest that VEGF exerts its protective effect on motor neurons against hypoxia-induced toxicity by the Flk-1 receptor through the PI3-K/Akt and the MEK/ERK signaling pathways.

Severity dependent up-regulations of LOX-1 and MCP-1 in early sclerotic changes of common carotid arteries in spontaneously hypertensive rats.

Lectin-like oxidized low-density lipoprotein receptor (LOX-1) and monocyte chemoattractant protein-1 (MCP-1) are molecules involving in the initiation and progression of atherosclerosis. In order to examine a possible difference in LOX-1 and MCP-1 expressions depending on the severity of early stage of atherosclerosis, we investigated atherosclerotic changes by exposure to hypertension and hyperlipidemia in common carotid arteries (CCAs) of stroke-prone spontaneously hypertensive rat (SHR-SP). Three rat model groups such as control [Wistar Kyoto rat (WKY) group], hypertension (SHR-SP group) and hypertension + hyperlipidemia [SHR-SP + high fat and cholesterol (HFC) group] were used. Body weights, brain weights, systolic blood pressures and serum levels of total cholesterol, low-density lipoprotein and triglyceride were measured at 0, 5, 10 and 15 days after appropriate diet. Immunohistochemistry showed that the positive area and the strength of LOX-1 and MCP-1 were larger in the SHR-SP + HFC group than in the SHR-SP group, while no immunoreactivities were found in the WKY group. Conventional RT-PCR and real-time PCR analyses showed that mRNAs of those in the SHR-SP group were higher with greater up-regulation in the SHR-SP + HFC group. LOX-1 and MCP-1 expressions were coordinately up-regulated at mRNA and protein levels in an early stage of sclerosis depending on the severity of atherosclerotic stress. Activations of LOX-1 and MCP-1 are collectively involved in the early stage of atherosclerosis.