Trypanosoma musculi with Trichinella spiralis or Heligmosomoides polygyrus: concomitant infections in the mouse

Inbred mice infected with Trypanosoma musculi displayed wide variations in peak blood parasitemia. The most susceptible mice were C3H and A strain, while Balb/c, C57B1/6, and the related congenic B10 strains were the most resistant. The effect of an intestinal infection with either Trichinella spiralis or Heligmosomoides polygyrus on proliferation of T. musculi was investigated. T. spiralis infections given at the same time or up to 45 days before a T. musculi infection always caused an increase in blood parasitemia in C3H mice. Maximum increases were observed when T. spiralis infections preceded T. musculi by 5-10 days. In all mouse strains examined, dual infections increased maximum parasitemia by two- to four-fold, regardless of the degree of resistance of that mouse strain to either T. musculi or T. spiralis. This suggested that the immunological "cost" of a T. spiralis infection was the same for strains that were strong or weak responders to a primary infection with T. spiralis. In contrast, infection with H. polygyrus did not promote T. musculi parasitemia over the level of a single infection. The increase in blood parasitemia in T. spiralis-infected mice was largely due to the intestinal adult worm, but migratory larvae and mature muscle larvae also stimulated increased parasitemias. The increase in parasitemia was proportionate to the dose of T. spiralis, and the sex of the host did not affect the blood trypanosome level.     

Trypanosome-induced suppression of responses to Trichinella spiralis in vaccinated mice.

Mice vaccinated against the gastro-intestinal (GI) nematode Trichinella spiralis by injection of muscle larval homogenate antigen express a strong immunity to subsequent infection, reflected in earlier expulsion of adult worms from the intestine and reduced female worm fecundity. Infection with Trypanosoma brucei at the time of vaccination, or at the time of infection with T. spiralis, significantly reduced the level of immunity expressed, the effect being greatest when vaccination and T. brucei infection were given together. Trypanosome infection reduced T. spiralis-specific antibody responses in vaccinated mice, the effect being most apparent against IgM, IgG1 and IgG2b, and ablated the eosinophil response to T. spiralis. In vaccinated mice infected with both trypanosomes and T. spiralis, the proliferative responses of lymphocytes to the mitogen Con A or to T. spiralis antigen were much lower than in vaccinated mice infected only with the nematode. Whereas cells from mice infected only with T. spiralis produced the cytokine IL-4 and little or no IFNgamma when stimulated in vitro, cells from animals infected with T. spiralis and with trypanosomes released large amounts of IFNgamma but no IL-4. These observations are consistent with the known, IFNgamma-dependent, nitric-oxide-mediated suppressive effects of trypanosomes on lymphocyte function and the Th1 bias associated with these infections, both of which reduce the effectiveness of the Th2-mediated responses involved in immunity against GI nematode infections. The data are discussed in the context of the possible use of vaccines against GI nematodes in ruminants in countries where concurrent trypanosome-GI nematode infections are widespread.     

Contrasting effects of acute and chronic gastro-intestinal helminth infections on a heterologous immune response in a transgenic adoptive transfer model

We have previously found that co-immunisation with ovalbumin (OVA) and the body fluid of the helminth Ascaris suum inhibited an OVA-specific delayed type hypersensitivity (DTH) response by reducing OVA-specific CD4+ T lymphocyte proliferation via an IL-4 independent mechanism. In the present study, we determined whether parasite infections themselves could induce similar changes to peripheral immunisation by examining the modulation of OVA-specific immune responses during acute and chronic helminth infections. Surprisingly, an acute infection with Trichinella spiralis, but not a chronic infection with Heligmosomoides polygyrus, inhibited the OVA-specific DTH reaction. Correspondingly, the T helper 1 (Th1) OVA-specific response was decreased in mice infected with T. spiralis, but not with H. polygyrus. Inhibition of the Th1 response may be a result of a shift in the Th1/Th2 balance as although both H. polygyrus and T. spiralis infected mice induced a Th2 OVA-specific response, that exhibited by T. spiralis was more potent. Furthermore, although IL-10 secretion upon OVA restimulation was similarly increased by both infections, production of this immunoregulatory cytokine may play a role in the suppression of immune responses observed with T. spiralis infection depending on the context of its release. Interestingly, analysis of the OVA-specific T lymphocyte division by carboxyfluorescein diacetate succinimidyl ester (CFSE) staining revealed that gastro-intestinal infection with the acute helminth T. spiralis, but not with chronic H. polygyrus, inhibited the systemic immune response by significantly inhibiting the antigen-specific T cell proliferation during the primary response, a mechanism similar to that observed when A. suum parasite extracts were directly mixed with the OVA during immunisation in our previous studies.     

Effects of Trichinella spiralis infections upon bone marrow stem cells in BALB/c mice

Trichinella spiralis infections provoke a variety of responses in the host, some of which involve stem cell proliferation and myeloid cell maturation, increases in the mast cell precursor cell populations, and maturation and eosinopoiesis. Very little is known about the influence of T. spiralis upon bone marrow stem cells and splenic colony formation. In the present communication we report that T. spiralis infection in mice stimulates the generation of colony-forming units in the spleen (CFU-S). Passive transfer of bone marrow cells from uninfected BALB/c mice to X-irradiated (650 R) T. spiralis-infected recipients resulted in a significant increase of CFU-S at 14 and 24 days postinfection. Passive transfer of bone marrow cells from T. spiralis-infected mice to X-irradiated uninfected mice also resulted in increased numbers of CFU-S in the donor mice at 24 days postinfection. These findings strongly suggest that T. spiralis infection conditions the microenvironment in the spleen which stimulates CFU-S.     

Susceptibility of adult Heligmosomoides polygyrus to intestinal inflammatory responses induced by heterologous infection.

Adult H. polygyrus are capable of surviving for many months after primary exposure of mice to infective larvae, raising the possibility that worms of this species have inherent resistance to intestinal immune responses. Accordingly experiments were carried out to determine whether H. polygyrus are resistant to the inflammatory changes elicited during the acute phase of the intestinal response to Trichinella spiralis. Adult worms were expelled from mice when their presence coincided with the most intense phase of inflammation elicited by T. spiralis. The effect was dose-dependent with more intense T. spiralis challenge resulting in a correspondingly greater loss of H. polygyrus. Even the less pathogenic species T. pseudospiralis elicited a response of sufficient intensity in NIH mice to cause the expulsion of H. polygyrus from concurrently infected animals. Tissue larval stages of H. polygyrus were protected from expulsion by their location deep in the intestinal walls and the maximum detrimental effect against H. polygyrus was observed during the adult phase or during the establishment of L3 larvae. Acceleration of the response to T. spiralis in immune challenged mice resulted in earlier loss of H. polygyrus. When the expulsion of T. spiralis was delayed (e.g. from slow responder C57BL/10 mice) the loss of H. polygyrus took place correspondingly later. These experiments demonstrate unequivocally that mouse strains which normally tolerate chronic infections with H. polygyrus have the capacity to mount intestinal inflammatory responses of sufficient vigour to remove the worms but that this potential is not normally realized. However, the observation that some H. polygyrus always survived even when the response induced by T. spiralis was of the rapid secondary type suggests that the parasites are resilient in the face of the inflammatory response capable of removing most of the worms. It is suggested that in addition to the immunomodulatory strategy employed by adult worms to prevent the intestinal response being elicited, the worms have a second line of defence which is reflected in their resilience to responses which they have been unable to prevent.     

Comparison of rapid expulsion of Trichinella spiralis in mice and rats

Alizadeh H. and Wakelin D. 1982. Comparison of rapid expulsion of Trichinella spiralis in mice and rats. International Journal for Parasitology12: 65–73. Primary infections of Tricliinella spiralis in both NIH mice and Wistar rats resulted in increased levels of mucosal mast cells and goblet cells. In mice the numbers of both cell types rose sharply before worm expulsion (days 8–10), remained at an increased level for a short time and declined quickly, reaching control levels on day 14 for goblet cells and between days 28 and 35 for mast cells. In contrast, in rats, the numbers of goblet cells and mast cells increased during worm expulsion and remained above control levels for a prolonged period. Challenge infections given shortly after expulsion of a primary infection (day 14) were expelled rapidly, worm loss being virtually complete with 24 h. In mice this response to challenge was short-lived and persisted only until day 16 after primary infection. After this time, challenge worms were expelled more slowly after infection. In rats the rapid expulsion response was expressed for at least 7 weeks after primary infection. Mice and rats showed differences in the conditions of infection necessary to prime for rapid expulsion, mice requiring larger and longer duration primary infections, but the expression of the response appeared to be similar in both species. In mice it was shown that rapid expulsion of T. spiralis was a response evoked specifically by prior infection with this species; infections with other intestinal nematodes had no effect. Similarly, the effect upon challenge infection was also specific to T. spiralis. The rapidity with which challenge infections are expelled suggests that either the specific inflammatory changes generated during primary infection result in an environment that is unsuitable for establishment of subsequent infections or that challenge infections provide a stimulus that can provoke an almost instantaneous response in the primed intestine. The relationship of the observed cellular changes to such mechanisms is discussed.     

Evaluation of a possible functional relationship between chemical structure of intestinal brush border and immunity to Trichinella spiralis in the rat

Primary exposure to Trichinella spiralis in the rat, while immunizing against reinfection, induces changes in the carbohydrate structure of intestinal brush border membranes. Immunity is expressed in heightened resistance to mucosal invasion by L1 larvae, and the change in structure is evident in reduced membrane binding of the lectin, wheat germ agglutinin. The possibility that altered membrane composition is a requisite for expression of immunity was hypothesized and this was evaluated by correlating the maximum, specific binding of wheat germ agglutinin by isolated brush border membranes with (1) the expression of immunity acquired passively through serum transfer, and (2) the loss of immunity acquired from serial infections terminated in the intestinal phase. The hypothesis was further evaluated by determining whether the change in membrane structure represents a stimulus-specific response. We observed that (1) passively acquired immunity was not associated with a reduction in lectin binding and (2) short-term exposure to the intestinal stages of T. spiralis led to a reduction in lectin binding that was detectable at a time when rats were incapable of resisting reinfection. The change in lectin binding associated with trichinosis also accompanied infection with Nippostrongylus brasiliensis. Results uniformly support the conclusion that immunity to T. spiralis is independent of brush border membrane changes reflected in reduced binding of wheat germ agglutinin.     

Effects of Trichinella spiralis on survival,total mass,and organ mass of oldfield mice (Peromyscus polionotus)

Trichinella spiralis is a parasitic nematode that infects many mammals, including humans. Hosts may experience significant physiological changes or may die because of acute inflammatory immune responses toward the parasite. In this study, oldfield mice (Peromyscus polionotus) were used as a new experimental host for T. spiralis. Males of P. polionotus were infected with increasing doses of T. spiralis to determine the effect infection had on survival, mass change, total mass, and relative organ masses. Total juvenile worm burden increased in an asymptotic fashion with infective dose. Large doses (> or = 600 juveniles) significantly reduced survival. There were significant negative correlations between infection intensity (log10[juveniles]/g) and both mass gain and final total mass. Infection had no effect on liver or spleen size. But there were significant negative correlations between T. spiralis intensity and both testis and seminal vesicle masses. These effects on male size and reproductive organs may help explain behavioral changes, such as the elimination of male dominance, seen in previous studies on mice infected with T. spiralis.     

Immunity to primary and challenge infections of Trichinella spiralis in mice: a re-examination of conventional parameters.

In young (6- to 8-week-old) NIH strain inbred mice expulsion of a primary infection of Trichinella spiralis began on day 8 and was virtually complete by day 11-5. In older mice expulsion occurred 1 or 2 days earlier. Experience of a primary infection elicited strong immunity to challenge, whether the challenge was given immediately after worm expulsion (day 14) or delayed (day 42). Challenge infections were expelled rapidly the majority of worms being lost during the first day. Immunity to challenge was elicited by low-level primary infections and was effective against large ventionally accepted parameters of immunity to T. spiralis in mice which, it is considered, are applicable only to mice with a genetically determined low-level of responsiveness to the parasite.     

Proteomic analysis of mouse jejunal epithelium and its response to infection with the intestinal nematode, Trichinella spiralis

Infection with the intestinal nematode Trichinella spiralis induces profound, but stereotypic pathological changes to the epithelium, which are common to many nematode infections. This study describes changes in jejunal epithelial protein expression that reflect these stereotypic responses. Adult male BALB/c mice were infected with T. spiralis, and groups (n = 4) examined on day 14/15 (time of worm rejection) were compared with uninfected controls (n = 4). Jejunal epithelium was harvested and extracted for two-dimensional gel electrophoresis. Tryptic peptide mass fingerprinting was used to create a reference map consisting of a total of 52 landmark spots. Of these, 16 were observed to change in intensity during infection. The changes observed at day 14/15 were of relevance to such mechanisms as lipid utilization and transport (increase in triacylglycerol lipase, and reduction in intestinal fatty acid binding protein) and innate immunity (appearance of intelectin-2). As a result, candidate molecules have been identified for further focused studies on their role in the host response to intestinal nematode infection.     

Protease-activated receptor 2 is involved in Th2 responses against Trichinella spiralis infection

In order to get a better understanding of the role of protease-activated receptor 2 (PAR2) in type 2 helper T (Th2) cell responses against Trichinella spiralis infection, we analyzed Th2 responses in T. spiralis-infected PAR2 knockout (KO) mice. The levels of the Th2 cell-secreted cytokines, IL-4, IL-5, and IL-13 were markedly reduced in the PAR2 KO mice as compared to the wild type mice following infection with T. spiralis. The serum levels of parasite-specific IgE increased significantly in the wild type mice as the result of T. spiralis infection, but this level was not significantly increased in PAR2 KO mice. The expression level of thymic stromal lymphopoietin, IL-25, and eotaxin gene (the genes were recently known as Th2 response initiators) of mouse intestinal epithelial cells were increased as the result of treatment with T. spiralis excretory-secretory proteins. However, the expression of these chemokine genes was inhibited by protease inhibitor treatments. In conclusion, PAR2 might involve in Th2 responses against T. spiralis infection.     

Immune responses to Trichinella pseudospiralis and Trichinella spiralis in mice

Primary infections with Trichinella pseudospiralis and Trichinella spiralis were followed in rapid- (NIH) and slow- (B10G) responder strains of mice. Expulsion of T. pseudospiralis was slower in both strains, but markedly so only in slower responder B10G mice. Blast cell activity in the mesenteric lymph nodes of the mice correlated with the expulsion patterns. In NIH mice, both parasites stimulated a strong response by day 8 of infection and activity had returned to control levels by day 11. In B10G mice, T. spiralis elicited an earlier peak response (day 12) than T. pseudospiralis (day 18), but in both, activity returned to control levels by day 21. Immunity to T. pseudospiralis and T. spiralis could be stimulated in NIH mice by prior infection with either parasite, by injection of T. spiralis larval antigen and by adoptive transfer of immune mesenteric lymph node cells taken from mice infected with either parasite. This extensive cross reactivity, and the differences seen during primary infections, are discussed in relation to the biology and specific identity of the two worms.     

The effect of the expulsion phase of Trichinella spiralis on Hymenolepis diminuta infection in rats.

The effect of the intestinal changes brought about by the expulsion of Trichinella spiralis in rats was studied in relation to the growth and survival of a concurrent infection with Hymenolepis diminuta, a cestode not normally rejected by the rat in low-level infections. Growth of H. diminuta was stunted in rats given T. spiralis just before, or after, infection with H. diminuta, the stunting being more pronounced when the cestode was given closer to the period of inflammation. There was no loss of the cestode from dual-infected rats and no evidence for destrobilation was found. Lower T. spiralis burdens had a correspondingly weaker effect on growth of H. diminuta, and stunting was abolished by administration of the anti-inflammatory drug cortisone acetate. It is concluded that the stunting of H. diminuta is probably due to the non-specific inflammatory component of the rat's response to T. spiralis infection.     

The intestinal mast cell response to Trichinella spiralis infection in mast cell-deficient w/wv mice

The intestinal mast cell response and lymphoblast activity, as measured by the incorporation of 3H-thymidine into mesenteric lymph node cells (MLN) of WBB6F1-w/wv(w/wv) mice, their normal congenic littermates (+/+) and C57BL/6J mice, were compared after infection with Trichinella spiralis. Marked and similar blast cell activity and an increase in number of cells were observed in the MLN of infected w/wv and C57BL/6J mice 7 and 15 days P.I. In contrast to C57BL/6J mice, primary T. spiralis intestinal infections were prolonged in w/wv mice and more muscle larvae were recovered from w/wv mice 29 days post-infection. In C57BL/6J mice mucosal mast cell (MMC) numbers increased on day 7 P.I. whereas in w/wv mice these cells did not increase significantly until day 15 post-infection, reaching a peak on day 22. In w/wv mice, the response to secondary infection as determined by an accelerated expulsion of adult worms did not occur until day 11 postchallenge whereas in +/+ and C57BL/6J mice worm expulsion was nearly complete at that time. In both primary and secondary infections, the MMC numbers in w/wv mice were significantly lower than in C57BL/6J or +/+ mice. The results suggest that prolongation of T. spiralis infection in w/wv mice is associated with delayed appearance of mast cells in the intestinal mucosa which may reflect slow generation of the intestinal inflammatory response.     

Trichinella spiralis in an agricultural ecosystem. III. Epidemiological investigations of Trichinella spiralis in resident wild and feral animals

As part of a larger epidemiological study examining the transmission of Trichinella spiralis in an agricultural ecosystem, resident wild and feral animals were trapped to determine the extent of their involvement in the natural, on-farm cycling of the parasite among swine. During a 21-mo-study, seven of 15 skunks (Mephitis mephitis), one of three opossums (Didelphis virginiana), two of two feral domestic cats and a raccoon (Procyon lotor) were found to be infected, while five shrews (Blarina brevicauda) and 18 deer mice (Peromyscus spp.) were uninfected. Most of the former hosts probably became infected by scavenging dead infected swine or rats (Rattus norvegicus). However, infections obtained through predation of living rats, particularly with regard to the cats, cannot be excluded. Our observations do not suggest that there was transmission of T. spiralis from the wild animals to swine. Therefore, transmission of T. spiralis appeared to occur only from the farm's swine and rats to the associated wild and feral animals.     

建立适用于旋毛虫抗肿瘤相关基因筛选的动物模型

目的为利用抑制消减杂交（SSH）法筛选旋毛虫抗肿瘤相关基因,建立理想的动物模型获取可靠的实验样本。方法Balb／c小鼠随机分为检测组（Tester）和驱动组（Driver）,Tester为经口服感染旋毛虫250条、400条和550条组,Driver为不接种组,在感染后11d,两组同时在皮下分别接种SP^2/0细胞2×10^6个,只,检测组和驱动组小鼠荷瘤后,于20d后处死,采集两组肿瘤组织和脾脏组织,用天平称量肿瘤块的重量,游标卡尺测量肿瘤块3个互相垂直直径进行体积比较;为了检测两组小鼠免疫情况,又采用流式细胞术检测体内T淋巴细胞的动态变化,以便评估所需样本的可靠性。结果将肿瘤组织与正常组织分离后,经统计分析比较两组肿瘤块重量和体积大小的差异均极为显著（P〈0．01）通过检测T淋巴细胞亚类,FACS共检测1×10^5个细胞,分别得到脾细胞中CD3^＋、CD4^＋和CD8^＋T淋巴细胞的数量,感染组小鼠机体的CD3^＋、CD4^＋、CD8^＋和CD4^＋／CD8^＋显著增高,在接种不同剂量的旋毛虫后荷瘤,小鼠脾脏特异的T淋巴细胞亚类：CD3^＋差异显著（P〈0．05）;CD4^＋差异显著（P〈0．05）;CD8^＋差异显著（P〈0．05）;CD4^＋／CD8^＋差异显著（P〈0．05）。通过以上指标的测定,我们认为所建立的动物模符合SSH的实验要求。结论建立的旋毛虫抗实体瘤动物模型,可用于旋毛虫抗肿瘤差异基因筛选的实验起始材料,为进一步研究旋毛虫抗肿瘤分子机制创造条件。     

Mouse mast cell tryptase mMCP-6 is a critical link between adaptive and innate immunity in the chronic phase of Trichinella spiralis infection

Although the innate immune function of mast cells in the acute phase of parasitic and bacterial infections is well established, their participation in chronic immune responses to indolent infection remains incompletely understood. In parasitic infection with Trichinella spiralis, the immune response incorporates both lymphocyte and mast cell-dependent effector functions for pathogen eradication. Among the mechanistic insights still unresolved in the reaction to T. spiralis are the means by which mast cells respond to parasites and the mast cell effector functions that contribute to the immunologic response to this pathogen. We hypothesized that mast cell elaboration of tryptase may comprise an important effector component in this response. Indeed, we find that mice deficient in the tryptase mouse mast cell protease-6 (mMCP-6) display a significant difference in their response to T. spiralis larvae in chronically infected skeletal muscle tissue. Mechanistically, this is associated with a profound inability to recruit eosinophils to larvae in mMCP-6-deficient mice. Analysis of IgE-deficient mice demonstrates an identical defect in eosinophil recruitment. These findings establish that mast cell secretion of the tryptase mMCP-6, a function directed by the activity of the adaptive immune system, contributes to eosinophil recruitment to the site of larval infection, thereby comprising an integral link in the chronic immune response to parasitic infection.     

Nitric oxide mediates intestinal pathology but not immune expulsion during Trichinella spiralis infection in mice

The relationship between intestinal pathology and immune expulsion of gastrointestinal (GI) nematodes remains controversial. Although immune expulsion of GI helminth parasites is usually associated with Th2 responses, the effector mechanisms directly responsible for parasite loss have not been identified. We have previously shown that while the intestinal pathology accompanying the expulsion of the GI parasite Trichinella spiralis may be dependent on IL-4 and mediated by TNF, parasite loss is independent of TNF. In contrast, intestinal pathology in other disease models has been attributed to Th1 cytokines, although it closely resembles that seen in helminth infections. Whereas production of inducible NO synthase (iNOS) in the gut is important for both homeostasis of the epithelial layer and in protection against pathogenic microorganisms, overproduction of NO has been implicated in the pathogenesis of a number of inflammatory conditions. We therefore investigated the role of NO in T. spiralis infection using iNOS-deficient mice. iNOS-/- and iNOS-/+ mice were infected with T. spiralis, and parasite expulsion and intestinal pathology were followed. Parasite expulsion proceeded similarly in both groups of animals, but significant intestinal pathology was only observed in the heterozygous mice. Thus it appears that, although the protective effects of Th2 responses in GI helminth infection do not require NO, this mediator contributes substantially to the associated enteropathy. NO may therefore be an important mediator of enteropathy in both Th1- and Th2-inducing conditions.