Studies of macrophage function during Trichinella spiralis infection in mice.

Studies were made to investigate the quantitative and functional changes which occur in peritoneal macrophage populations obtained from mice infected orally with Trichinella spiralis larvae. C57BL/6 mice infected with T. spiralis larvae became parasitized with adult worms which were rejected from the intestine from 14 to 20 days after infection. Infected mice developed a striking increase in peritoneal exudate cells, composed largely of macrophages, which was maximal at from 16 to 18 days after infection. T. spiralis larvae and eosinophils were not seen in the peritoneal exudates. Macrophages from mice infected more than 11 days earlier inhibited DNA synthesis of syngeneic and allogeneic tumour cells, a property atributed to activated macrophages. In addition, macrophages from T. spiralis-infected mice had the functional ability to kill EL-4 tumour cells as measured by 51Cr release. Unlike activated macrophages, however, macrophages from infected mice did not develop the ability to inhibit multiplication of the intracellular pathogen Toxoplasma gondii. These studies demonstrate that T. spiralis infection in mice induces changes in macrophage function that differ from changes associated with infections by intracellular pathogens.     

旋毛虫对三硝基苯磺酸诱导的实验性小鼠肠炎模型的干预研究

目的 研究旋毛虫对三硝基苯磺酸（TNBS）诱导的实验性小鼠肠炎模型的影响及其免疫作用机制。方法观察感染和未感染旋毛虫小鼠于TNBS诱导肠炎后3d及7d不同指标的变化，包括小鼠生存率、疾病活动指数（DAI）、结肠大体损伤和病理损伤评分、炎症指标髓过氧化物酶（MPO）活性检测，结肠细胞因子IFN-γ和IL-4 mRNA的表达量分析。结果 预先感染旋毛虫后诱导TNBS模型组小鼠在造模后3d及7d与单纯模型组相比小鼠生存率升高（P〈0．05），DAI、结肠大体损伤和病理损伤评分及MPO活性下降（P〈0．05），结肠中IFN-γmRNA的表达量下调（P〈0．05），而IL-4 mRNA的表达量增加（P〈0．05）。结论 旋毛虫对TNBS诱导的实验性小鼠肠炎具有良好的干预作用，其免疫作用机制可能是通过下调炎症性肠病过度的．TH1型免疫反应、上调TH2型免疫反应而实现的。     

Trichinella spiralis: changes in leucocytes during infection

Rats infected with Trichinella spiralis were examined during the course of infection for various changes in the leucocytic population. In each experiment rats were divided into three groups: Group A, inoculated with Escherichia coli B-5-lipopolysaccharide (LPS) administered four days before each experiment; Group B, infected with Trichinella spiralis; and Group C, untreated controls.     

Interleukin-10 limits local and body cavity inflammation during infection with muscle-stage Trichinella spiralis

The aim of this study was to characterize cellular responses to muscle-stage Trichinella spiralis. From its intracellular habitat in muscle, T. spiralis secretes potent glycoprotein antigens that elicit a strong systemic host immune response. Despite the magnitude and prolonged nature of this response, nurse cells are rarely destroyed by infiltrating cells. We tested the hypothesis that the anti-inflammatory cytokine interleukin-10 (IL-10) moderates cellular responses to muscle-stage parasites. Trichinella larvae colonize the diaphragm in large numbers, prompting us to evaluate regional responses in body cavities in addition to local responses in muscle. Mice deficient in IL-10 demonstrated an exaggerated inflammatory response around nurse cells and in the pleural cavity. The effect of IL-10 was most evident 20 days following muscle infection. The increased intensity of the response in IL-10-deficient mice did not affect parasite establishment or survival. Between 20 and 50 days postinfection, the inflammatory response was diminished in both wild-type and IL-10-deficient mice. Muscle infection also elicited an antibody response, characterized initially by mixed isotypes directed at somatic larval antigens and changing to an immunoglobulin G1-dominated response directed at tyvelose-bearing excreted or secreted antigens. We conclude that IL-10 limits local and regional inflammation during the early stages of muscle infection but that chronic inflammation is controlled by an IL-10-independent mechanism that is coincident with a Th2 response.     

Response of intestinal globule leucocytes in the mouse during a Trichinella spiralis infection and its independence of intestinal mast cells.

We have previously reported that intestinal mast cells represent a separate population of mast cells which is thymus- (T-) dependent. In this paper we examine whether the appearance of these cells is dependent on thymus-dependent antibodies or thymus serum factor(s). The response of intestinal mast cells and globule leucocytes to a Trichinella spiralis infection was therefore studied in congenitally athymic (nude) mice after treatment with specific anti-T. spiralis hyperimmune serum or normal mouse serum from thymus-bearing litter-mates. However, transfer of both types of serum did not lead to an intestinal mast cell response. It was concluded that the presence of an intact thymus or T-dependent cellular reactions and/or their products are essential for appearance of intestinal mast cells. In contrast infected athymic mice reacted with a minor reponse of globule leucocytes irrespective of the serum transfer. Occasionally metachromatic intra-epithelially located cells with toluidine-blue-positive granules, believed to be globule leucocytes, showed mitotic figures. Metachromatic cells were observed occasionally within the lumen of the gut. These data were interpreted as supporting the idea that the globule leucocyte is a cell sui generis and independent of the intestinal mast cell.     

Taurine drinking attenuates the burden of intestinal adult worms and muscle larvae in mice with Trichinella spiralis infection

The parasitic nematode Trichinella spiralis can cause trichinellosis, which leads to pathological processes in the intestine and muscle. The intestinal invasion determines the development, subsequent course, and consequences of the disease. Gastrointestinal nematode infection, including with T. spiralis, is accompanied by a rapid and reversible expansion of mucosal mast cell and goblet cell in the intestinal epithelium, which play important roles in the host immune response to parasite and worm expulsion from the intestine. Taurine and its derivatives have anti-infection and anti-inflammatory properties. We investigated whether taurine supplementation in mice could influence the development and pathological processes of infection with T. spiralis. Supplementing 1 % taurine in drinking water in mice infected with T. spiralis could alleviate the burden of intestinal adult worms on days 7 and 10 postinfection (all p?<?0.01) and the formation of infective muscle larvae in striated muscle during T. spiralis infection (p?<?0.01). As compared with T. spiralis infection alone, taurine treatment increased the number of goblet cells on days 7, 10, and 15 (p?<?0.01 and p?<?0.05) and alleviated intestinal mucosal mast cell hyperplasia on days 10 and 15 (all p?<?0.01). So taurine supplementation in drinking water increased infection-induced intestinal goblet cell hyperplasia and ameliorated mucosal mastocytosis. Thus, taurine can ameliorate the pathological processes of trichinellosis and may be of great value for the treatment and prevention of infection with T. spiralis and other gastrointestinal nematodes.     

Effect of Trichinella spiralis infection on passive cutaneous anaphylaxis in mice.

Infection of CFW mice with Trichinella spiralis induced a state of relative unresponsiveness to passive cutaneous anaphylaxis (PCA) induced with hen egg albumin and its corresponding antibodies. The unresponsiveness was to PCA produced either with immunoglobulin G1 (IgG1) or IgE type of antibodies, but was more pronounced with the latter. As few as 25 larvae given by stomach tube 20 days before induced this resistance, although 400 larvae induced a greater resistance. When 400 to 600 larvae were fed to mice, the refractoriness of these mice to PCA was noticed 15 days later. The sera of infected mice had the ability to inhibit mainly PCA induced by IgE. This inhibitory property of sera from infected mice was more pronounced 35 days after infection than 10 months later, when only weak inhibitory activity was detected. Purified rat IgE inhibited the PCA reactions induced in both mice and rats with mouse IgE-type antibody. At high concentrations, evidence of inhibition of the IgG1-induced PCA in mice was also obtained. We believe that the relative unresponsiveness of infected mice is due to an increase in production of IgE which competitively blocks the mast cell sites for other IgE molecules.     

Thymus dependence and independence of intestinal pathology in a Trichinella spiralis infection: a study in congenitally athymic (nude) mice.

The hypothesis that non-specific histopathological gut changes are thymus-dependent was tested in a helminth infection--the nematode Trichinella spiralis. The study was performed in congenitally athymic (nu/nu) mice and their thymus-bearing heterozygous litter-mates (+/mu). The non-specific histopathological changes of the small intestine were judged on villus/crypt ratio and mitotic index; for the specific (= immunological) reaction the number of pyroninophilic cells in the small intestine was used as criterion. T. spiralis induced non-specific histopathological reactions both in nu/nu and +/nu mice, whereas the number of pyroninophilic cells was only increased in +/nu mice. It was concluded that the immunological reaction was dependent on the immune status of the host, whereas the non-specific histopathological changes were not, i.e. they were thymus-independent.     

Trichinella spiralis infection decreases the diversity of the intestinal flora in the infected mouse

BackgroundTrichinella spiralis is a kind of intestinal nematode that can strongly modulate the host immune system. However, the effects of T. spiralis infection on the intestinal flora are poorly understood. This study aimed to explore the effect of T. spiralis infection on the intestinal flora.MethodsThe intestinal contents of T. spiralis infected mice were examined through high-throughput sequencing (Illumina) of the V3–V4 hypervariable region in bacterial 16S rRNA gene. The sequences were analyzed using the QIIME software package and other bioinformatics methods.ResultsAltogether 2,899,062 sequences were generated from the samples collected from different intestinal regions at various infection time points; the 44,843 Operational Taxonomic Unit (OTUs) analysis showed that T. spiralis infection would decrease the diversity of intestinal flora in the infected mice relative to that in the uninfected ones, especially in the large intestine and feces. Further analysis indicated that, the genera Oscillospira from the phylum Firmicutes showed a higher abundance in the helminth-infected small and larger intestines; the genera Bacteroides from the phyla Bacteroides, the genera Lactobacillus from the phyla Firmicutes, the genera Escherichia from the phyla Proteobacteria, and the genera Akkermansia from the phyla Verrucomicrobia displayed increased abundances in the T. spiralis positive fecal samples compared with those in the negative samples.ConclusionsT. spiralis infection decreases the diversity of the intestinal flora in the infected mouse. However, it remains unclear about the association between the changes in intestinal flora caused by T. spiralis infection and the parasite pathogenesis, which should be further examined.     

Lymphokine production by T cells generated during infection with Trichinella spiralis

Lymphokine production by mesenteric lymph node cells (MLNC) taken from mice during infection with the intestinal nematode parasite Trichinella spiralis was investigated. Upon stimulation in vitro with a protective crude antigen preparation of the infective L1 larvae, MLNC proliferated in a specific manner, and were observed to release the T-cell lymphokines IL-2, IL-3 and interferon. IL-2 and IL-3 release by MLNC was greatest when taken during the early intestinal phases of infection. Interferon was also released by cells taken from infected mice, with highest levels observed shortly after expulsion of the parasite from the gut. MLNC taken during the early intestinal phases of infection were also able to respond and proliferate to an exogenous source of IL-2, suggesting clonal expansion of T cells within the node. Lymphokine release from T. spiralis specific T-cell lines was also examined.     

Development of cellular immune response of mice to infection with low doses of Trichinella spiralis, Trichinella britovi and Trichinella pseudospiralis larvae

The murine cellular immune response to the infection with ten larvae of encapsulating (Trichinella spiralis, Trichinella britovi) and non-encapsulating species (Trichinella pseudospiralis) was studied. Both T. spiralis and T. britovi stimulated the proliferation of splenic T and B lymphocytes during the intestinal phase of infection, but T. spiralis activated the proliferative response also at the muscle phase, particularly in B cells. Non-encapsulating T. pseudospiralis stimulated the proliferation of T and B cells only on day 10 post-infection (p.i.) and later at the muscle phase. The numbers of splenic CD4 and CD8 T cells of T. spiralis infected mice were significantly increased till day 10 p.i., i.e., at the intestinal phase, and then at the late muscle phase, on day 60 p.i. T. britovi infection increased the CD4 and CD8 T cell numbers only on day 30 p.i. Decreased numbers of CD4 and CD8 T cells after T. pseudospiralis infection suggest a suppression of cellular immunity. Both encapsulating Trichinella species induced the Th2 response (cytokines interleukin-5 (IL-5) and interleukin-10) at the intestinal phase and the Th2 dominant response at the advanced muscle phase. Interferon-γ (IFN-γ) production (Th1 type) started to increase with migrating newborn larvae from day 15 p.i. till the end of the experiment. IL-5 production was suppressed during the intestinal phase of T. pseudospiralis infection. The immune response to T. pseudospiralis was directed more to the Th1 response at the muscle phase, the high IFN-γ production was found on day 10 p.i. and it peaked on days 45 and 60 p.i.     

Genetic factors controlling the intestinal mast cell response in mice infected with Trichinella spiralis.

Inbred strains of mice showed marked variation in their mast cell (MC) response to infection with Trichinella spiralis. Variation was under genetic control, the ability to respond to infection being inherited as a dominant trait. MHC-linked genes may influence the absolute level of response, but overall response kinetics appear to be controlled by genes which are not linked to the MHC. An enhanced MC response was transferred adoptively with immune mesenteric lymph node cells (IMLNC), but reciprocal adoptive transfers between H-2 compatible rapid (NIH) and slow (B10.G) responder strains showed that the degree of enhancement was determined by the response phenotype of the recipient, not that of the donor. Similarly, in bone marrow (BM) chimaeras, produced by reconstituting lethally irradiated F1 (B10.G x NIH) mice with parental BM, the MC response to T. spiralis was determined by the response phenotype of the BM donor, whether or not rapid responder IMLNC were transferred. The data are discussed in terms of a T lymphocyte regulated, bone marrow stem cell origin of mucosal MC and interpreted as showing that genetic regulation of the MC response is expressed at the level of stem cell or precursor response to T cell derived mastopoietic factors.     

Identification and partial characterization of a T-cell-derived antigen-binding factor from mice infected with the intestinal helminth Trichinella spiralis

Immunochemical and biological characterization was performed of an antigen-binding factor derived from culture supernatants of T cells from mice infected 4 days previously with the intestinal helminth Trichinella spiralis. Affinity chromatography with T. spiralis antigen resulted in the purification of a protein, provisionally designated Trichinella factor (Tric-F), that shared antigenic and other properties with a known T-cell-derived antigen-binding factor of different antigenic specificity, picryl chloride factor, which mediates an early 2-hour component of contact sensitivity. Tric-F lacked determinants of immunoglobulins and possessed determinants shared by other antigen-specific T cell factors, as determined by ELISA and antibody affinity chromatography. Biological activity of Tric-F was assayed in vivo and in vitro. Mice injected intravenously with Tric-F developed an antigen-specific early 2-hour ear swelling response following local challenge with T. spiralis antigen. These results corresponded to delayed-type hypersensitivity responses in the ears of T. spiralis-infected mice that comprised early 2-hour and late classical 24-hour responses. In vitro, Tric-F induced serotonin release by mast cells in the presence of T. spiralis antigen. Mast cells sensitized with Tric-F formed rosettes with antigen-coated sheep erythrocytes. It is suggested that Tric-F, an antigen-binding molecule that is T-cell-derived, mediates the early 2-hour component of delayed-type hypersensitivity and is involved in the initiation and regulation of T-cell-mediated intestinal inflammation during a T. spiralis infection in mice.     

旋毛虫感染对小鼠结肠上皮通透性的影响

目的: 观察旋毛虫( T.spiralis )感染对小鼠结肠上皮通透性的影响及其作用机制。方法: T.spiralis 感染BALB/c小鼠。7 d后直肠灌注辣根过氧化物酶(HRP),在其后的0 min、60 min、120 min,分别检测小鼠血液中HRP的情况,尾静脉采血检测IgG₁和IgG_2a,随后处死小鼠,以ELISA法和流式细胞术检测肠系膜淋巴结中白细胞介素4(IL-4)的表达。另外,以 T.spiralis 感染 STAT6 敲除小鼠,同前法一样操作,观察相同指标。结果: T.spiralis 感染组结肠通透性明显增加,IL-4和IgG₁明显增高,IgG_2a明显降低(均P<0.05)。 STAT6 敲除小鼠实验, T.spiralis 感染并未导致结肠通透性的增加(P>0.05);与BALB/c感染组小鼠相比, STAT6 敲除感染组小鼠IL-4明显较低(P<0.05)。结论: T.spiralis 感染能够导致小鼠结肠上皮通透性的增加,其作用机制可能是通过诱导IL-4的分泌来实现的。     

Trichinella spiralis infection in congenitally athymic (nude) mice. Parasitological, serological and haematological studies with observations on intestinal pathology.

In six experiments the course of a Trichinella spiralis infection in congenitally athymic (nu/nu) mice and their heterozygous thymus-bearing littermates (+/nu) was followed. In the +/nu mice worms were expelled at day 10 post infection. In nu/nu mice worms remained in the intestine until the end of the observation period (83 days post infection). In testing the yield of muscle larvae in +/nu and nu/nu mice 4--5 times more muscle larvae were isolated from nu/nu mice than from infected +/nu mice. The following phenomena were observed in +/nu mice only: anti-T. spiralis antibodies detected by immunofluorescence, intestinal plasma-cell production and intestinal eosinophilia. In nu/nu mice no blood eosinophilia was observed in contrast to the induction of eosinophilia both in infected +/nu and infected nu/nu mice reconstituted with thymuses from heterozygous littermates. Intra-epithelial lymphocytes, more numerous in +/nu than in nu/nu mice, were not attracted by Trichinella antigen. The data supported the hypothesis that worm expulsion is a T cell-dependent phenomenon. Plasma cell and antibody production as well as tissue and blood eosinophilia were shown to be thymus-dependent in a T. spiralis infection.     

Persistence of Trichinella spiralis muscle larvae in natural decaying mice

The influence of natural weather conditions on the viability and reproductive capability of Trichinella spiralis muscle larvae in mouse corpses exposed to summer and winter conditions in the Buenos Aires Province, Argentina, was studied. For this purpose, a total of 49 mouse corpses harbouring muscle larvae of T. spiralis were exposed for a period of 1, 2, 4 and 6 weeks in each of the seasons. Control corpses maintained at 8°C were also included. In summer, T. spiralis muscle larvae were recovered from corpses exposed up to 1 week only. The viability of these larvae was 54.2%, and the reproductive capability index in mice (RCI) was 13.1 and significantly lower than the control (p<0.0005). Morphologic deterioration and reduction in the glycogen content of cysts and larvae were observed at the second week of exposition. By week 4, larval stages of Dermestes maculatus were observed inside corpses, and 22 live muscle larvae of T. spiralis were obtained by artificial digestion of their bodies. In winter, T. spiralis muscle larvae were always recovered, the viability being almost 100% except for a significant reduction by week 6 of exposition (p<0.0001). For this season, the RCI were 50.5, 46.9, 59.7 and 45.2 for the periods of 1, 2, 4 and 6 weeks of exposition, respectively. The morphology of cysts and larvae did not show alterations, and no variations were observed as well in glycogen reserves during the 6-week period of exposition. RCI of non-exposed muscle larvae were always significantly higher that any of those recorded from muscle larvae that belonged to exposed corpses (p=0.0005). The present results demonstrate that muscle larvae of T. spiralis are able to survive in nature and keep infective for a 1-week period in summer and at least for 6 weeks in winter, becoming an important source of infection for scavengers. In summer, larvae stages of D. maculatus, and probably other insects, may play an important role in the survival and transmission of T. spiralis in the sylvatic cycle.     

Helminthotoxic responses of intestinal eosinophils to Trichinella spiralis newborn larvae.

Because the gastrointestinal lamina propria is the first line of defense against invasion with Trichinella spiralis newborn larvae, we investigated the helminthotoxic characteristics of isolated lamina propria eosinophils. Eosinophils were isolated from the intestinal lamina propria of rats and purified to nearly 90% purity by a combination of velocity sedimentation through Percoll and unit gravity sedimentation through a continuous gradient of bovine serum albumin. Isolated eosinophils were of high viability and responded to surface receptor stimulation. Freshly isolated intestinal eosinophils lacked cytotoxic capacity when incubated with newborn larvae in the presence of specific antiserum. Peritoneal eosinophils from the same rats exhibited 100% helminthotoxicity after 24 h. Cytotoxicity could be stimulated in the intestinal eosinophils by the addition of recombinant murine interleukin-5.