Nippostrongylus brasiliensis: intestinal goblet-cell response in adoptively immunized rats.

Goblet-cell differentiation was studied in the intestinal epithelium of rats infected with the nematode Nippostrongylus brasiliensis. An increase in the proportion of goblet cells occurred at the time of worm expulsion in rats infected with 1000 or 4000 third stage larvae. Adoptive immunization of infected rats with immune-thoracic duct lymphocytes (TDL) induced extensive goblet-cell differentiation whereas the transfer of immune-TDL into normal rats had no effect. The extent of goblet-cell differentiation in adoptively immunized infected rats was proportional to the number of cells transferred. A goblet-cell response also occurred in adoptively immunized rats harboring implanted “normal” and “damaged” worms but recipients of normal worms which were not given cells were unable either to expel their worm burden or to induce a goblet-cell response. Experiments in which the parasites were expelled with an anthelmintic drug suggested that the goblet-cell increase was not simply a repair process associated with the expulsion of the parasites. In all situations where immune expulsion of the parasites occurred, there was a concomitant rise in the proportion of goblet cells. These experiments suggest that thoracic duct lymphocytes either directly or indirectly regulate the differentiation of intestinal goblet cells.     

The absence of resistance in congenitally athymic nude mice toward infection with the intestinal nematode, Trichuris muris: resistance restored by lymphoid cell transfer

Congenitally athymic (nude) mice maintained infections of Trichuris muris for at least 40 days post-infection, whereas phenotypically normal mice expelled the worms by 18 days post-infection. Complete worm expulsion occurred in nude mice which had been given spleen cells. On the other hand, a partial resistance to the infection was observed in nude mice which received thymus or mesenteric lymph node cells. No significant worm reduction was seen by injection of immune serum.     

Immunity to intestinal parasites: role of mast cells and goblet cells

Nippostrongylus brasiliensis infection of rats and mice is a model for studying immunity at mucosal surfaces. Adult worms are spontaneously expelled from the intestine at the end of the second week of infection. Expulsion from the jejunum requires the presence of immune T lymphocytes and IgG antibodies. Mucosal mast cells (MMCs) are a prominent part of the jejunal inflammatory response. They are derived from a hematopoietic stem cell, possibly the same precursor as basophils. Their differentiation is not absolutely T dependent but their accumulation at the site of infection is. The possible involvement of IgE antibodies and intestinal MMCs through a "leak lesion" is still uncertain. Increased mucus secretion from epithelial goblet cells is also a prominent feature of the inflammatory reaction at the site of infection. Goblet cell numbers increase two to four times at the onset of worm expulsion; this increase is regulated by T lymphocytes and possibly immune serum. The mechanism of mucus secretion in these infections is not clear; it may be a response to mast cell mediators. Together with antiworm antibodies, intestinal mucus may trap worms and prevent them from surviving in the intervillous spaces of the jejunum. Thus, expulsion of this intestinal parasite may occur through a nonspecific process that is induced by specific immune mechanisms.     

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.     

Nippostrongylus brasiliensis: radioresistant IgE antibody-forming cells in infected rats

In Nippostrongylus brasiliensis-infected rats, anti-N. brasiliensis IgE antibody production was observed at 20 weeks postinfection, long after the worms, as a source of antigen, had been expelled. The persistent IgE production was not abrogated after whole body irradiation (800 R) administered at 12 or 20 weeks, suggesting the participation of radioresistant IgE-forming cells. Help of T cells and recruitment of B memory cells in the irradiated rats seems to be ruled out by the findings that the irradiation completely inhibited the initiation of anti-N. brasiliensis IgE production in rats shortly after the infection with N. brasiliensis or after primary and secondary immunization with N. brasiliensis-antigen. Moreover, clearance of anti-N. brasiliensis IgE antibody from circulation did not seem to be crucially affected by the irradiation. The radioresistant cells forming anti-N. brasiliensis IgE were most productive in mesenteric lymph nodes as compared to other lymph nodes. The recognition of antigens fractionated by chromatography on Sephadex G-200 was the same for IgE-forming cells from rats 12 weeks after infection as for those from 3 weeks after infection. Based on these results, one of the mechanisms of persistent elevation of IgE antibody in the host infected with helminth parasites might be explained by the participation of radioresistant IgE-forming cells.     

Nematospiroides dubius: susceptibility to infection and the development of resistance in hypothymic (nude) BALB/c mice.

BALB/c-nu/nu mice and their intact nu/+ littermates are equally susceptible to infection with third-stage larvae of Nematospiroides dubius. Unlike their heterozygous littermates, however, the nu/nu mice are unable to form ganulomata in the intestinal wall and become only partially resistant to rechallenge. Following two or more infections, nu/nu mice maintain a high burden of adult intestinal worms, whereas worms are lost from immune nu/+ mice. Studies in T cell-injected nu/nu mice suggest that a full complement of T cells is needed to develop maximum resistance against the infective third-stage larvae and to expel adult worms. Measurement of serum immunoglobulin levels indicate that infected nu/+ mice have very high levels of IgG1 whereas the levels of IgG2a are reduced. In infected T cell-injected nu/nu mice, IgG1 levels increase with the number of T cells injected, whereas IgG2a levels are variable but always higher than in infected nu/+ mice.     

Trichinella spiralis: role of non-H-2 genes in resistance to primary infection in mice

Two strains of mice which share identical H-2 genes but differ in their genetic backgrounds were compared for their ability to resist infection with Trichinella spiralis. The two strains of mice, C3HeB/FeJ and AKR/J, share the H-2k haplotype which is associated with susceptibility to primary infection with T. spiralis in H-2 congenic strains of mice. AKR/J mice, infected with 150 infective muscle larvae, harbored significantly fewer muscle larvae 30 days postinfection than did mice of the strain C3HeB/FeJ. Approximately equal numbers of worms establish in the small intestine of AKR and C3H mice, but the AKR mice expelled adult worms from the gut more rapidly than did mice of the C3H strain. By Day 9 postinfection, 50% of the worms had been expelled by the AKR mice whereas expulsion of worms from C3H mice was delayed beyond Day 9 and occurred primarily between Days 10 and 12. Over this same experimental period (Days 6-12), fecundity of female worms from AKR mice, measured as the mean newborn larvae/female/hour, was approximately one-half that of worms taken from C3H mice. These results support the conclusion that genes outside of the mouse H-2 complex regulate expulsion of adult worms from the gut. These background genes also markedly influence the fecundity of female worms.     

Rapid and specific alterations of goblet cell mucin in rat airway and small intestine associated with resistance against Nippostrongylus brasiliensis reinfection

The intestinal parasitic nematode Nippostrongylus brasiliensis is expelled rapidly from the rat in reinfection challenge compared with that of the primary infection owing to the host defense mechanisms raised against the pre-intestinal- and intestinal-stage larvae. We examined the relationship between the mucin alterations in airway and jejunal mucosae and the worm expulsion after third-stage larva reinfection. When rats had been inoculated with fourth-stage larvae and immunized with only the intestinal-stage worms for more than 8 days, the challenge larvae were expelled during the intestinal stage along with a rapid increase of the specific sialomucin in jejunal mucosa, without any effect on the bronchial mucus. When rats had been infected with third-stage larvae and immunized with only the pre-intestinal stage larvae by killing with antihelminthic, the challenge larvae were rejected during the pre-intestinal stage along with marked goblet cell hyperplasia and Muc5AC mucin hyperproduction on the bronchial mucosa, but not as a result of jejunal mucin alteration. Taking these finding together, immunization with pre-intestinal- and intestinal-stage worms independently increases the airway and intestinal goblet cell mucins, respectively, and in both cases, the mucin alterations may contribute to rapid worm expulsion upon reinfection.     

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.     

Nippostrongylus brasiliensis: reversibility of reduced-energy status associated with the course of expulsion from the small intestine in rats

Gastrointestinal nematodes require energy for active establishment in the gut against intestinal flow and peristaltic motion. In this study we employed CellTiter-Glo Luminescent Cell Viability Assay to measure the ATP value of individual adult Nippostrongylus brasiliensis during the course of immune-mediated expulsion from the small intestine in rats. The ATP values of adult worms taken from the lumen of the distal small intestine were lower than worms collected from the lumen of the proximal small intestine. Moreover, values from worms in the lumen of the proximal small intestine were lower than those from worms in the mucosa, the preferred site of adult N. brasiliensis. The reduction of ATP values in worms from each region was observed not only at expulsion phase, but also at established phases of the infection suggesting that energy metabolism of the parasites is independent of host immune response. When adult worms with low ATP values on day 12 post-infection were implanted surgically into the small intestine of na?ve rats, the worms re-established in recipients and completely restored the ATP values. Short in vitro culture of adult worms under low oxygen tension resulted in low ATP value in the worms. These results suggested that adult worms were dislodged from their preferred site by intact energy metabolism activity.     

Strongyloides ratti: 1. parasitological observations on primary and secondary infections in the small intestine of rats

Adult Strongyloides ratti were expelled from the small intestine of rats starting 14-18 days after a primary infection. In a secondary infection very few adult worms developed and most of these were expelled before day 14. At the time of expulsion the worms migrated posteriorly in the intestine and their size decreased.     

Action of diethylcarbamazine citrate on protective immunity in rats infected with Nippostrongylus brasiliensis

Rats made immune to Nippostrongylus brasiliensis and treated with diethylcarbamazine citrate (DEC) orally (250 mg/kg X 6) exhibited significant suppression of functional immunity. Similarly, administration of compound 48/80 (100 micrograms/rat i.p.) made the immune rats susceptible to challenge infection. Treatment of rats, with 22-day infection with compound 48/80, histamine (20 mg/rat, per os), or L-histidine (20 mg/rat, orally s.c.) did not accelerate worm expulsion. A massive complement-dependent adherence of peritoneal cells (1 X 10(8], isolated from immune DEC-treated and untreated rats, to infective larvae (L3) was observed. Likewise, heavy congregation of normal peritoneal cells to larvae was noticed when the cells were incubated with sera obtained from immune, DEC-treated or untreated rats. The rats receiving mesenteric lymph node cells (125 X 10(6) i.v.) or sera (0.5 ml or 1 ml X 3 i.p.), obtained from immune DEC-treated rats and challenged with infective larvae developed 50% more worms than those which received cells or serum from untreated immune donors. DEC appears to cause suppression of functional immunity and worm expulsion is not histamine mediated.     

Immunity to adult Heligmosomoides polygyrus (Nematospiroides dubius): survival or rejection of adult worms following transplantation to mice refractory to larval challenge

Experiments were carried out to explore the survival of 14-day adult H. polygyrus following transplantation to mice of four strains, immunized by various protocols. Adult worm establishment and survival was unimpaired in CFLP mice which were totally refractory to larval challenge. Transplanted adult worms were also successful in NIH mice immunized by the 9-day abbreviated infection regime. However, NIH mice exposed to irradiated larvae or subjected to the divided primary infection, expelled transplanted adults. The 9-day abbreviated infection was further examined in SJL and (C57 Bl10 X NIH) F1 mice which expel adult worms during a primary infection and although this regime was unsuccessful in causing NIH mice to reject adult worms, expulsion of adult worms was accelerated in SJL and F1 mice. The survival of adult H. polygyrus was discussed in the context of stage-specific immunity and the delicate balance between the immunogenic stimuli from developing larvae, the immunomodulatory activities of adult stages and the host's genetically determined capacity to respond to these opposing signals.     

Eosinophil and IgE responses of IL-5 transgenic mice experimentally infected with Nippostrongylus brasiliensis.

Eosinophil and IgE responses of interleukin (IL)-5 transgenic and normal C3H/HeN mice were studied after experimental infection with Nippostrongylus brasiliensis (Nb). Intestinal worms were recovered at day 5 post-infection (PI), and numbers of total white blood cells (WBC) and eosinophils, and total serum IgE and anti-hapten (dinitrophenyl) (DNP) specific IgE titers, were measured at days 0, 14 and 21 PI. IL-5 mice appeared resistant to Nb infection showing a significantly lower worm recovery rate than normal mice (P < 0.05). Total WBC and eosinophil counts (/mm3) were significantly increased in Nb infected normal mice (P < 0.05), but unchanged (total WBC) or decreased (eosinophils) in IL-5 mice at day 21 PI. The total serum IgE level remarkably increased in normal mice, but only a little in IL-5 mice at days 14 and 21 PI. Priming with DNP brought about more remarkable increases of the total and anti-DNP specific IgE in normal mice than in IL-5 mice. The results show that IL-5 mice are resistant to Nb infection, and that eosinophil and IgE responses in these mice are not augmented by Nb infection.     

Immunity to tapeworms: acquired resistance to Hymenolepis citelli in the mouse

The dynamics of secondary infections with Hymenolepis citelli in mice are described. A primary infection of one and six cysticercoids for 21 days sensitized CFLP male mice against homologous challenge infections. Acquired resistance was manifested mainly as stunting/destrobilation of secondary worms. The severity of stunting depended on the intensity of the primary infection. Secondary worms were not expelled more rapidly than primary worms but the protective response retards growth early in challenge infections. Sensitization of mice for seven days with six or 24 cysticercoids did not confer a measurable protective response, whereas priming by the same regime for 21 days induced a significant protective response. Acquired resistance to challenge waned with time in the absence of the primary worms. The growth and survival of a six-cysticercoid primary infection was enhanced by the administration of the immunosuppressant drug cortisone acetate. Worms from cortisone-treated mice were heavier than those from untreated controls. Acquired resistance to homologous challenge was also partially ablated in cortisone-treated mice. It is suggested that rejection of primary infections and stunting/destrobilation of secondary worms may be immunologically mediated.     

The pattern of peripheral blood leucocyte changes in mice infected with Nematospiroides dubius

Experiments were carried out to define the haematological changes taking place during the first six weeks of a primary infection with Nematospiroides dubius. The general pattern of changes was observed to comprise a rapid increase in circulating leucocytes (4 to 5-fold increase) which consisted of a neutropl a, lymphocytosis, monocytosis and an eosinophilia. However, in strong responder NIH mice leucocyte counts returned to normal more rapidly than in other strains (by day 28). In contrast, in weak responder C57BL/10 mice the leucocyte counts whilst falling significantly relative to day 7 did not return to normal within the experimental period. Mice infected with irradiated larvae did not experience as high a leucocytosis as did mice given an identical number of normal larvae. The peak lymphocytosis, neutrophilia and monocytosis were all lower. The removal of adult worms from infected animals by treatment with pyrantel on days 9, 11, 13 and 16, also significantly altered the pattern of leucocytosis. The neutrophilia which was evident on day 7 returned rapidly to normal, whereas in mice which had retained their worms a peak neutrophilia was observed on day 14. These haematological changes were discussed and related to the failure of host-protective immunity to operate effectively during the early stages of a primary infection with N. dubius.     

Impaired basophil induction leads to an age-dependent innate defect in type 2 immunity during helminth infection in mice

Parasitic-infection studies on rhesus macaque monkeys have shown juvenile animals to be more susceptible to infection than adults, but the immunological mechanism for this is not known. In this study, we investigated the age-dependent genesis of helminth-induced type 2 immune responses using adult (6-8-wk-old) and juvenile (21-28-d-old) mice. Following infection with the parasitic nematode Nippostrongylus brasiliensis, juvenile mice had increased susceptibility to infection relative to adult mice. Juvenile mice developed a delayed type 2 immune response with decreased Th2 cytokine production, IgE Ab responses, mouse mast cell protease 1 levels, and intestinal goblet cell induction. This innate immune defect in juvenile mice was independent of TLR signaling, dendritic cells, or CD4(+) cell function. Using IL-4-eGFP mice, it was demonstrated that the numbers of IL-4-producing basophil and eosinophils were comparable in young and adult naive mice; however, following helminth infection, the early induction of these cells was impaired in juvenile mice relative to older animals. In nonhelminth models, there was an innate in vivo defect in activation of basophils, but not eosinophils, in juvenile mice compared with adult animals. The specific role for basophils in this innate defect in helminth-induced type 2 immunity was confirmed by the capacity of adoptively transferred adult-derived basophils, but not eosinophils, to restore the ability of juvenile mice to expel N. brasiliensis. The defect in juvenile mice with regard to helminth-induced innate basophil-mediated type 2 response is relevant to allergic conditions.     

Effects of spleen cells and serum on transfer of immunity to Strongyloides venezuelensis infection in hypothymic (nude) mice

The course of Strongyloides venezuelensis infection in congenitally hypothymic (nu/nu) mice and their heterozygous thymus-bearing littermates (nu/+) was followed. Unlike the infected nu/+ mice, the nu/nu mice were unable to expel the worms until the end of the observation period (98 days post-infection). In addition, about three times as many eggs were counted at the peak level of infection in faeces of the infected nu/nu mice in comparison with the nu/+ mice. No acquired resistance to rechallenge was observed among the nu/nu mice. Auto-reinfection within the infected nu/nu mice could not be supposed in the present study. The worm expulsion mechanism was generated by nu/nu mice which had been given syngeneic spleen cells from intact +/+ mice. The expulsion of adult worms, as well as the protection against migrating larvae, occurred anamnestically when spleen cells from immune +/+ mice were transferred. The serum transfer, however, only caused a retardation of larval migration. The results support the hypothesis that direct worm immunity and worm expulsion are a T cell-dependent phenomenon.     

Trichinella spiralis infections of inbred mice: genetics of the host response following infection with different Trichinella isolates

The immune response of inbred strains of mice was studied following infection with isolates of Trichinella from a pig (P1), an arctic fox (AF1), and T. spiralis var. pseudospiralis (TP). Strains of mice previously characterized as highly resistant to a separate pig isolate of T. spiralis responded to the P1 and AF1 isolates by expelling over 80% of the worms by day 10 postinfection (PI), and by suppressing the in vitro release of newborn larvae by female worms. However, the response induced by AF1 worms was expressed more quickly when compared to responses induced by the P1 and TP isolates. The host response to TP was less as recovery was always higher at day 10 PI and antifecundity effects were not induced in TP worms even in highly resistant strains of mice. Strains of mice previously characterized as susceptible to T. spiralis infection were slow to develop resistance when compared to the resistant mouse strains, but even among the susceptible strains, infection with AF1 induced a more rapid response. The mouse strains used in these experiments allowed us to assess the role of the major histocompatibility complex (MHC) and/or non-MHC genes in influencing the responses observed. As previously reported for a pig isolate of T. spiralis, both MHC and non-MHC genes influenced the rate at which worms were expelled from the gut and the host response that limits the fecundity of adult female worms.     

Effects of PGE1 or PGE2 and/or acetazolamide on expulsion of Nippostrongylus brasiliensis from rats

PGE1 and PGE2 have been reported to enhance natural expulsion of Nippostrongylus brasiliensis, a nematode parasite, from the intestine of the rat. Mucus production may also be a key element of worm rejection. Our study attempts to determine if 1) PGE1 or PGE2 alter the normal course of infection with N. brasiliensis in rats, 2) a known mucous enhancing drug, acetazolamide, can augment the rate of worm expulsion, and 3) combinations of prostaglandins and acetazolamide affect N. brasiliensis in the rat. Rats were inoculated with approximately 1,000 infective larvae of N. brasiliensis. Animals were administered, intraduodenally, one of the following: 0.2 ml 0.9% NaCl; 0.2 ml 100% ethanol; 250 micrograms PGE1/0.2 ml 100% ethanol; 250 micrograms PGE2/0.2 ml 100% ethanol; 250 micrograms acetazolamide/0.2 ml 100% ethanol; 250 micrograms PGE1 or PGE2 + 250 micrograms acetazolamide/0.2 ml 100% ethanol. These solutions were given in a single bolus on day 6 postinoculation (PI) or twice daily on days 6-9 PI. Following these treatments the number of parasite ova per gram feces per day for days 6-10 PI and numbers of worms present at necropsy on day 10 PI were determined. Treatment with prostaglandins or acetazolamide or both failed to adversely affect egg deposition by adult female worms or the number of worms in the small intestine. These results do not support the involvement of prostaglandins in the expulsion of N. brasiliensis from the host intestine.