Cells containing IgE in the intestinal mucosa of mice infected with the nematode parasite Trichinella spiralis are predominantly of a mast cell lineage

To determine whether IgE+ cells in the intestinal mucosa of nematode-infected mice were of a mast cell or a lymphocyte lineage, the intestinal mucosae of mast cell-deficient w/wv mice were examined for IgE+ cells after inoculation with Trichinella spiralis muscle-stage larvae. Immunofluorescence staining techniques were used to detect IgE associated with cells in the intestinal mucosa. Comparisons were made among four strains of mice, w/wv (mast cell-deficient), +/+ (normal congenic littermates of w/wv), BALB/c, and SJL, that were either uninfected controls or inoculated with T. spiralis. Tissue sections from the small intestine of T. spiralis-infected BALB/c, SJL, and +/+ mice were fixed in ethanol and were stained with an affinity-purified F(ab')2 rabbit anti-mouse IgE followed by FITC goat anti-rabbit IgG. Large numbers of cells in the intestinal mucosa exhibited bright fluorescence. When other sections of intestines from these mice were processed in Carnoy's fixative and were stained with alcian blue at low pH (a metachromatic stain for mast cells) or alcian blue followed by immunofluorescence staining for IgE, large numbers of mast cells were observed in the intestinal mucosa, and 70 to 90% stained positively for IgE. There was a considerable number of cells in the intestinal mucosa which were IgE+ but which did not stain with alcian blue. Few alcian blue-positive cells and no IgE+ staining cells were present in the intestinal mucosa of control, uninfected +/+, BALB/c, and SJL mice. To determine whether these IgE+ alcian blue-negative cells were of a lymphocyte or a mast cell lineage, the mast cell-deficient w/wv mouse strain was examined after infection with T. spiralis. In contrast to BALB/c, SJL, or +/+ mice, few cells in the intestinal mucosa of T. spiralis-infected w/wv mice stained with alcian blue or were positive for IgE. However, when the IgE response in the MLN of the w/wv mice was compared to the IgE response of BALB/c, SJL, and +/+ mice, numerous IgE+ cells, but no alcian blue-positive cells, were observed in the parenchyma of the MLN from all four strains of T. spiralis-infected mice. In addition, flow microfluorometric analysis of MLN cells stained for surface IgE in suspension showed a comparable proportion of IgE-bearing cells, which were mostly B lymphocytes, among all four strains of T. spiralis-infected mice.(ABSTRACT TRUNCATED AT 400 WORDS)     

Oxygen uptake in mice infected with Trichinella spiralis

Oxygen consumption, rectal temperature, and the level of activity in mice infected with Trichinella spiralis were significantly reduced below that seen in uninfected controls for periods of time during the first 30 days following infection. The differences in oxygen consumption between controls and infected animals were evident throughout the 24-hr period comprising day 7 postinfection. Both oxygen consumption and rectal temperature increased with decreasing level of infection. These changes in oxygen consumption, rectal temperature, and activity are discussed in terms of pathophysiologic and immunopathologic changes known to occur during the course of 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 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.     

Impaired protection against Trichinella spiralis in mice with high levels of IgE

Helminth infection induces production of a large amount of immunoglobulin E (IgE) to nonhelminth antigens. Although such “irrelevant” IgE is a major proportion of total IgE in the host, its biological significance remains unclear. Therefore, I examined protective activity against Trichinella spiralis in mice with high levels of IgE by repeated injections of anti-dansyl IgE monoclonal antibody or Nippostrongylus brasiliensis infection. Injected anti-dansyl IgE occupied IgE receptors on mast cells in naive mice. Protective activity against T. spiralis, determined with number of muscle larvae 5 weeks after infection, was impaired in mice treated with anti-dansyl IgE. The impaired protection was found in mice treated with anti-dansy IgE 7 and 14 days after infection, but not 21 and 28 days after infection, indicating that IgE-dependent protection operates at an early stage after infection. In the next experiments, mice were infected with N. brasiliensis 4 weeks before T. spiralis infection to obtain high levels of IgE. The protective activity against T. spiralis was decreased by N. brasiliensis infection. On the other hand, protection against T. spiralis was comparable in IgE-deficient SJA/9 mice and in anti-IgE-treated BALB/c mice with or without N. brasiliensis infection, suggesting that impairment of protection is dependent on IgE. These results indicate that the high levels of irrelevant IgE are beneficial for helminths and, alternatively, that anti-helminth IgE antibodies are protective for hosts. In addition, the impaired protection was found in IgE high-responder mice but not in low-responder mice, suggesting that protection against T. spiralis is controlled by IgE responsiveness in the host.     

Biphasic hypothermia in mice infected with a parasitic nematode, Trichinella spiralis.

In BALB/c mice infected with Trichinella spiralis, changes in body temperature (Tb) were observed over 35 days after the infection. T. spiralis infection induced hypothermia two times at 7 and 28 days after infection. The initial decrease persisted for about one week with a peak (37.1 +/- 0.62 degrees C) around 10 days after the infection, while the later phase persisted for at least one week. Both 10 and 35 days after the infection, there were remarkable decreases in Tb. The serum glucose level of infected mice at 10 days was significantly (p < 0.01) decreased compared with that of control mice at the same number of days, while the level in infected mice at 35 days was not decreased. Moreover, the later phase of hypothermia was prevented by the cyclooxygenase inhibitor indomethacin (10 mg/kg i.p.), while the initial phase was not. We conclude that hypothermia was caused by two different mechanisms, involving the effects of hypoglycemia and prostaglandins.     

Trichinella spiralis: skeletal muscle membrane potentials in infected and uninfected mice

Male albino mice were infected orally with 400 ± 10 excysted Trichinella spiralis larvae. Skeletal muscle resting membrane potentials were recorded from the tibialis anterior muscles of infected and uninfected mice on the following days postinfection (PI): 1–15, 18, 20, 24, 28, 30–60 (at 5-day intervals), 90, 120, 150, and 180. The membrane potentials were significantly (P < 0.05) lower in infected muscle (82 vs 85 mV) on Day 30 PI. On Days 60, 90, 120, 150, and 180 PI the mean membrane potential in infected muscle (62 mV) was about 23 mV lower than the mean for uninfected muscle (85 mV) and this difference was highly significant (P < 0.001). These findings are discussed in relationship to other physiological alterations known to occur in skeletal muscles infected with T. spiralis larvae.     

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.     

The effect of Trichinella spiralis on muscular activity of experimentally infected mice

Nematodes of genus Trichinella are wide-spread zoonotic parasites, able to infect a large variety of vertebrates. Animal hosts are usually regarded as asymptomatic carriers. However, there is little data regarding the functional consequences that T. spiralis infection renders on muscle cells. The aim of the present study was to assess the effect of T. spiralis on the effort capacity of experimentally infected mice. Overall, 60 mice, divided into three groups were used: M (uninfected), L200 and L1000, infected with 200 or 1000 larvae/mouse respectively. The mice were periodically weighed and their effort capacity was evaluated (days 0, 7, 15, 35 and 60). From each group, two randomly selected mice were euthanized after evaluation carcasses were artificially digested in order to establish the number of larvae per gram (LPG). On day 0, there were no significant differences among groups. Starting with day 7, the effort capacity of infected groups decreased, with significant differences between group M and the infected groups. From day 15, the differences between the infected groups also became significant. The LPG gradually increased and the differences between groups were always significant. A strong correlation between the LPG and decreased effort capacity was noted. The present study demonstrates the reduction of muscular capacity in mice experimentally infected with Trichinella spiralis, in correlation with the infective dose, providing new insights in this parasite's transmission strategy.     

Enteral and parenteral responses in mice after primary infection with Trichinella spiralis (Nematoda)

Enteral and enteral-parenteral infections were produced with T. spiralis in albino, Swiss Webster, outbred mice. Primary enteral infections abbreviated with thiabendazole stimulated inflammatory changes in Peyer's patches and the lamina propria of the small intestine of mice. These changes were accompanied by increased IgA in the intestinal luminal wash. Primary enteral-parenteral infections similarly stimulated the gut, and, in addition, the spleen. Splenic stimulation resulted in production of IgG1, and IgG2 antibodies specific for T. spiralis L3.     

Antigen-specific lymphocyte proliferative responses in inbred mice after Trichinella spiralis infection.

The in vitro antigen-specific lymphoproliferative response of spleen, mesenteric lymph node (MLN), and coeliac lymph node (CLN) cells taken from various strains of inbred mice infected with Trichinella spiralis was assessed. In most experiments cell populations were stimulated with excretory/secretory antigens (ESA) derived from adult and larval worms. Lymphoid cells collected 5-7 days postinfection were usually the most responsive to ESA as measured by [3H]thymidine uptake. Spleen cells were more responsive than either MLN or CLN cells. There was a correlation between in vitro ESA stimulation and worm rejection in strong- and weak-responder strains of mice. Spleen and MLN cells of NFS mice showed higher antigen-specific responsiveness, whereas the same cells from B10.BR (H-2k) and B10.Q (H-2q) strains of mice were less responsive. Among intermediate responder strains 2 patterns were observed. Spleen and MLN cells of BuB and DBA/1 mice responded more strongly than those of C3H mice. Dose-response experiments demonstrated that increasing the infective dose of larvae to the host usually increased subsequent in vitro antigen-specific lymphoproliferation. Furthermore, non-MHC-linked genes appear to be the primary determinant of antigen-specific T-cell-proliferative responses in inbred mice infected with T. spiralis.     

Osteolysis in Trichinella spiralis infected vs noninfected rats

1. Based upon the present inability to describe the mechanism by which calcification takes place, and the unexplored metabolism of calcium during trichinosis, studies of rat bone involvement were undertaken. 2. Significant (P less than 0.05) differences were found in experimental (Trichinella spiralis infected) rat femurs vs those of noninfected rats. 3. Analysis by atomic absorption spectroscopy, dry femur weight, and tensile stress resistance indicated an overall reduction in calcium content. 4. This calcium reduction is due to active cyst calcification. 5. Results confirming this finding revealed significant (P less than 0.05) differences at days 60-80 postinfection (the beginning of cyst calcification.     

Trichinella spiralis infections of inbred mice: immunologically specific responses induced by different Trichinella isolates

The immune response of inbred mice was studied following infection with Trichinella spiralis var. pseudospiralis (TP) or with isolates of T. spiralis derived from a pig or from an arctic fox. Animals given a primary infection with 1 isolate of Trichinella and challenged 21 days later with the same or different isolates responded more quickly by expelling worms from the homologous challenge. In addition, although mesenteric lymph node cells from mice infected with each isolate of Trichinella would proliferate in vitro when cultured with antigen derived from each of the others, the strongest proliferation response always occurred when cells were cultured in the presence of antigen prepared from the specific isolate used to infect the mouse from which the cells were derived. In addition, it was possible to prepare monoclonal antibodies that recognized an antigen expressed by TP which was not shared by T. spiralis isolates and vice versa. Collectively, these data support the conclusion that the differences observed in the kinetics of immune responsiveness to different Trichinella isolates are referable, at least in part, to differences among the isolates in the expression of functionally relevant antigens.     

Slow cycling intestinal stem cell and Paneth cell responses to Trichinella spiralis infection

There is limited information regarding responses by slow cycling stem cells during T. spiralis-induced T-cell mediated intestinal inflammation and how such responses may relate to those of Paneth cells. Transgenic mice, in which doxycycline induces expression of histone 2B (H2B)-green fluorescent protein (GFP), were used. Following discontinuation of doxycycline (“chase” period), retention of H2B-GFP enabled the identification of slow cycling stem cells and long-lived Paneth cells. Inflammation in the small intestine (SI) was induced by oral administration of T. spiralis muscle larvae. Epithelial retention of H2B-GFP per crypt cell position (cp) was studied following immunohistochemistry and using the Score and Wincrypts program. Compared to non-infected controls, there was significant reduction in the number of H2B-GFP-retaining stem cells in T. spiralis-infected small intestines. H2B-GFP-retaining stem cells peaked at around cp 4 in control sections, but smaller peaks at higher cell positions (>10) were seen in sections of inflamed small intestines. In the latter, there was a significant increase in the total number of Paneth cells, with significant reduction in H2B-GFP-retaining Paneth cells, but a marked increase in unlabelled (H2B-GFP-negative) Paneth cells. In conclusion, following T. spiralis-infection, putative slow cycling stem cell numbers were reduced. A marked increase in newly generated Paneth cells at the crypt base led to higher cell positions of the remaining slow cycling stem cells.     

A freeze-fracture study of muscle fibres infected with Trichinella spiralis

The muscle fibres of mice containing the infective-stage larvae of the nematode Trichinella spiralis have been studied by means of the freeze-fracturing technique. The larva lies in what appears to be a fluid-filled cavity within the cytoplasm of an altered muscle fibre. There is no membrane separating the cytoplasm of the nurse cell from the cavity surrounding the larva which is therefore truly intracellular, unlike many parasites that reside within a membrane-lined parasitophorous vacuole within the host cell. This altered muscle fibre, known as a nurse cell, lacks myofilaments but does contain extensive cisternae of endoplasmic reticulum; membrane-bound vesicles are budded off from the endoplasmic reticulum and traverse the cytoplasm towards the cavity containing the nematode where they apparently pass into the cavity. It is suggested that the contents of these vesicles are used to sustain the nematode. Attention is drawn to the similarity to giant cells that have been induced by the plant-parasitic nematode Meloidogyne in the roots of host plants and which sustain the nematode. The conversion of the muscle fibre into a nurse cell is probably brought about by the presence of a metabolic sink, the larval nematode, within the cell. This take-over of the control of a metazoan cell by another metazoan organism is most unusual and warrants further study.