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Injection of the rat with guinea pig myelin basic protein (MBP) induces an inflammatory demyelination that leads to development of a condition mimicking human multiple sclerosis (MS), including severe depressions in mobility, coordination, and strength in the affected animal. This model was used to observe and compare the antiinflammatory effects of the intestinal and late migratory phases of infection with Trichinella pseudospiralis on development of MBP-induced, MS-like debilitation in rats. Animal performance was measured in an activity monitor and in a series of physical tests designed to assess animal coordination and strength. Uninfected animals injected with MBP showed declines in mobility, coordination, and strength typical for this model. These changes were similar in rats infected so that the intestinal phase of infection coincided with the peak of MBP-induced debilitation. Rats infected so that the late migratory phase of infection occurred during the period of peak MBP-induced debilitation showed significantly higher performance scores in mobility, coordination and strength compared to the latter 2 groups. These finding demonstrate the potency of the anti-inflammatory effects of elevations in host corticosteroids seen during the migratory phase of infection with T. pseudospiralis.

Immunological parameters were measured during the first 20 days of infection with Trichinella spiralis in the rat. Expulsion of adult worms was complete by day 15 postinfection. Eosinophil and neutrophil numbers rose in the blood of infected rats above preinfection levels on days 3 and 6, respectively, and remained high to day 20 postinfection. Release of cytokines by Trichinella-antigen-stimulated mesenteric lymph node cells was measured, and a significant elevation in interferon (IFN)-gamma release was detected during the early stage of infection. Although initiated later, interleukin (IL)-10 release showed a pattern similar to IFN-gamma. Biphasic release of IL-5 was seen with significant elevation above the preinfection level on day 3 and after day 6 postinfection to the end of the study. IL-4 and IL-2 showed biphasic secretion as well, with the level of IL-4 high in the early and middle part of infection, while the level of IL-2 was detectable only at days 2, 3 and 6 postinfection. Serum anti-parasite IgE rose above preinfection levels after day 6 postinfection. Anti-parasite Ig-positive mesenteric lymph node (MLN) cells were evident by day 3 postinfection for IgM, and day 9 postinfection for IgA and total IgG. The number of Ig-positive MLN cells for all antibody classes returned to preinfection levels by day 20 postinfection. Evaluation of the temporal interactions of the key anti-parasite immune components with which the host engages Trichinella shows a complex interplay between Th1 and Th2 helper subsets.

The deleterious effects of maternal ethanol consumption on neonatal immune development and early immune responses has been well documented. However, the effects of such neonatal exposure to maternally consumed ethanol on the neonates' immune responses in their adult life, especially in combination with additional ethanol exposure, has received little attention. For these experiments, female rats were fed on either 6% ethanol or pair-fed isocaloric control Lieber-DeCarli liquid diets for 30 days prior to, and during, pregnancy and lactation. One day after weaning their pups, the mothers were infected with 1000 Trichinella spiralis larvae, and maintained on diets for an additional 20 days. At this time, they were challenged with 2000 T. spiralis larvae, killed 3 days later, and their immune status determined. These animals served as the first generation alcohol animals. Their female offspring served as the experimental second generation animals. These animals received maternal ethanol during pregnancy and lactation and control diet during their juvenile period (from weaning to 90 days of age). They were then subjected to a schedule of ethanol or pairfeeding, identical to the first generation dams. Two groups of second generation animals were established: Group 1 was exposed to ethanol during their dam's pregnancy and lactation periods only, with no subsequent ethanol treatment; Group 2 received ethanol during their dam's pregnancy and lactation periods and then again throughout their adult experimental period. Our previous studies showed only minimal changes following a secondary challenge in T. spiralis-immunized rats; however, neonates born to alcohol-consuming mothers did show some depressed secondary immune responses when challenged soon after weaning. We chose to use a secondary immune challenge to assess further immune alterations in second generation adult animals. No differences between any of the ethanol and pair-fed groups were observed in intestinal worm burdens, which is similar to data previously reported for adult alcohol-consuming animals. However, second generation group 2 animals demonstrated significantly reduced proliferation responses to T. spiralis antigen and Concanavalin A (Con A) stimulation relative to the ethanol first generation and to the second generation Group 1 animals. This group also demonstrated significantly lower absorbencies in the ELISA assay for specific IgM and IgG anti-T. spiralis antibodies than the pair-fed, ethanol first and second generation Group 1 animals. The proportion of total T cells and cytotoxic T cells was significantly lower and the proportion of natural killer cells was elevated in both second generation ethanol Groups 1 and 2 relative to the ethanol first generation and pair-fed groups. In addition, Group 2 second generation animals showed significantly lower proportions of total leukocytes and T cells than Group 1 second generation animals. Although secondary immune responses to T. spiralis infection were not altered in rats exposed to ethanol only as adults, exposure to maternal ethanol does affect some specific immune responses in second generation adult life and maternal exposure may exert cumulative immune effects in concert with later consumption of ethanol by offspring born to alcoholic mothers.

Alcohol consumption has been shown to be associated with immune suppression and immune modulation. In this study, the effects of ethanol ingestion on the host immune responses to Trichinella spiralis infection and the subsequent secretion of T-helper cell-associated cytokines were investigated in rats. At the early phase of T. spiralis infection, ethanol-fed animals showed decreased numbers of blood neutrophils and eosinophils, and a decreased secretion of interferon-gamma (IFN-gamma) by mesenteric lymph node cells, compared with pair-fed controls. Suppression of this early inflammatory response to infection in the ethanol-treated groups resulted in a slower rate of expulsion of intestinal adult worms and a higher fecundity rate for female worms, compared with pair-fed controls. A dramatic decrease in blood neutrophils in the ethanol-treated groups was also manifested on day 9 postinfection. At that time, mesenteric lymph node cells from the ethanol-treated groups secreted higher amounts of mast cell proliferation-enhancing activity, which has been shown to contain T-helper type 2-associated cytokines. At the later phase of infection (day 12 to 20 day postinfection), ethanol-treated animals contained higher numbers of blood eosinophils and secreted an increased amount of interleukin-5 and mast cell proliferation-enhancing activity, compared with pair-fed controls. Although there was a slight rise with time after infection, the level of serum corticosterone was not significantly increased in the ethanol groups. Therefore, it is not likely that the observed immune modulations caused by ethanol consumption, especially in the early phase of infection, is the effect of elevated levels of corticosterone in the circulation. The present study found that ethanol consumption suppressed the initial amount of interferon-gamma secretion and inflammatory response, and may have directly or indirectly led to an enhancement of the secretion of T-helper type 2-type cytokines later in the primary immune response to T. spiralis infection.

Immunoperoxidase staining of muscle infected with Trichinella spiralis for murine collagen types I and IV provided both qualitative and quantitative evidence of extensive synthesis of both types of collagen by fibroblasts in infected muscle compared to that seen in uninfected muscle. Moreover, fibroblasts in muscle infected with T. pseudospiralis, a nonencapsulating species, showed significantly less staining for both types of collagen compared to muscle from mice infected with T. spiralis. Analysis of collagen composition of isolated nurse cells using an ELISA specific for either type I or type IV murine collagen suggested that of these 2 types of collagen, only type IV basement membrane collagen is found in Trichinella capsular collagen. Excretory/secretory products of T. spiralis and T. pseudospiralis induced extensive synthesis of exclusively type IV collagen by 3T3 murine fibroblasts in vitro.

Examination of the cuticle of Trichinella pseudospiralis by transmission electron microscopy revealed an epicuticle, exocuticle, and mesocuticle, each divided into several layers. The epicuticle consisted of an outermost thin plasmalemmalike infracuticular material covering an inner trilaminar membrane. The exocuticle was granular and could be divided into 2 regions on the basis of density. The mesocuticle was fibrillar and 3 regions could be distinguished based on the orientation of fibrils. The cuticle appears attached to the hypodermis by hemidesmosomes. The infracticular structure was altered following isolation of larvae by pepsin-HCl digestion of host muscle.

Infection of the mouse with Trichinella pseudospiralis is accompanied by pronounced suppression of host inflammatory response. This study examines the effects of infection with this parasite on several key elements in cell-mediated immunity. Early down-regulation of host granulomatous response to subcutaneously implanted cotton string and delayed-type hypersensitivity (DTH) response to trinitrochlorobenzene (TNCB) was followed later during infection by normalization of these parameters compared to that seen in uninfected mice. Cytotoxic T lymphocyte responses to tumor-specific antigens expressed on the syngeneic P91 mastocytoma were depressed early following infection with T. pseudospiralis relative to that seen in uninfected mice but were similar in these two groups during the later stages of infection. Down-regulation of the components of cell-mediated reaction examined herein accompanied the presence of migratory larvae in the host.

Infectivity of Trichinella pseudospiralis in Chinese hamsters was greater than that of Trichinella spiralis. Concurrent infection with these two species of parasite was accompanied by an increase in infectivity of T. spiralis. The infectivity of T. pseudospiralis, but not that of T. spiralis, was significantly influenced by host age. Regardless of host age, T. pseudospiralis was more infective for the Chinese hamster than was T. spiralis. Early during infection, enteritis (myeloperoxidase activity) in hamsters infected with T. pseudospiralis alone was significantly less than that seen in animals infected with T. spiralis alone or with both species concurrently. Myositis in hamsters infected with T. pseudospiralis alone was significantly less on days 14, 17 and 25 post-infection (p.i.) than that observed in concurrently infected or T. spiralis-infected animals. On days 11 and 14 p.i. inflammation in diaphragm muscle from concurrently infected hamsters was significantly less than that seen in animals infected with T. spiralis alone. Muscle histology supported these chemical data on myositis. Suppression of the host inflammatory response against early muscle-stage larvae of T. pseudospiralis underlies the greater infectivity of this parasite for the Chinese hamster.

During infection with Trichinella pseudospiralis a strong neutrophil response is evident in the peripheral circulation of the mouse. This study compared the chemotactic response of neutrophils from uninfected, T. pseudospiralis-infected and Trichinella spiralis-infected mice to extracts from adult worms, newborn larvae and muscle-stage larvae of both species of parasite. The chemotactic response of neutrophils from T. pseudospiralis-infected mice to Zymosan-activated mouse serum (ZAMS) was significantly greater than that seen with neutrophils from either uninfected or T. spiralis-infected mice. Unstimulated chemotactic response of neutrophils from these three groups of animals to medium alone was similar. The chemotactic response of neutrophils from the three groups of animals was unaffected by either the concentration or source of serum. The chemotactic response of neutrophils from T. pseudospiralis-infected mice was significantly greater than that observed with cells from uninfected or T. spiralis-infected mice. Among parasite extracts, those from newborn larvae displayed the strongest chemotactic potential for neutrophils. Extracts from muscle larvae of T. spiralis and T. pseudospiralis and extracts of T. spiralis adult worms showed the weakest attraction for neutrophils. Extracts from adult T. pseudospiralis and from newborn larvae of both species elevated the chemotactic response of uninfected mouse neutrophils to a significantly greater level than that seen with ZAMS alone, while a significant reduction in this response was evident only when ZAMS was presented to neutrophils with 500 micrograms of extract from muscle larvae of T. pseudospiralis or T. spiralis.(ABSTRACT TRUNCATED AT 250 WORDS)

We have shown that antigen-specific T lymphocytes can mediate maternal-to-neonatal immunity during lactation. Present studies address the dynamics of lymphocyte accumulation in the mammary gland during normal and disease stimulated conditions. Monoclonal antibodies specific for total T cells, suppressor/cytotoxic and helper subsets, and macrophages were used in conjunction with immunohistochemistry to identify and count the individual cell types. In unstimulated mammary tissue, following a rise in T cells to maximal numbers in late pregnancy, the total number of T cells/high power field (HPF) was significantly diminished in early lactation and continued to decline to the late lactation period. Both the numbers of T cells/HPF located in the mammary alveolar epithelium and surrounding connective tissue were significantly reduced in early lactation as compared to late pregnancy. This indicates the possible passage of cells into the milk during lactation. Prior infection of the mother with Trichinella spiralis and a secondary challenge 48 h. before sacrifice caused a significant reduction in the number of T cells in the mammary tissue in early lactation as compared with unstimulated controls, indicating the possibility of an even greater outflow of T cells into milk. In controls, the T-suppressor/cytotoxic subtype showed a reduction in early lactation versus late pregnancy but showed no shifts in total cells/HPF during infection. The T-helper subtype in controls remained unchanged from late pregnancy to early lactation with a considerable decline in late lactation. However, the T-helper cells were significantly decreased in T. spiralis-treated animals as compared with noninfected controls in early lactation.(ABSTRACT TRUNCATED AT 250 WORDS)

The reproductive capacity index for Trichinella pseudospiralis infective larvae was similar for worms isolated from mouse carcasses on the day upon which mice were killed (day 0: 104.4 +/- 18.6 [mean +/- SD]) and on day 5 following mouse death (106.1 +/- 23.6), but was reduced for worms recovered from carcasses on day 10 postkill (PK: 22.7 +/- 5.7). Larvae isolated from mouse carcasses held at 24 C after day 10 PK were not infective. The percentage of viable worms (tightly coiled or moving) isolated from carrion was similar on days 0 and 5 PK but had declined to 40.4% by day 10 PK and showed a further reduction to 11.8% for worms isolated from carrion on day 15 PK. Viable worms were not recovered from carcasses after day 15 PK.

The infectivity of Trichinella pseudospiralis infective larvae was reduced significantly following exposure to low pH or a combination of 1% pepsin at low pH compared to that for larvae isolated in phosphate-buffered saline (PBS) at pH 7.0. Reduction of host gastric pH by administration to mice of sodium bicarbonate solution in PBS was accompanied by an increase in the infectivity of larvae isolated in 1% pepsin/HCl (P/HCl) compared to that for worms inoculated into hosts given PBS alone. Fewer adult worms developing from larvae isolated in P/HCl became established in the host small bowel than was seen with larvae isolated in PBS; moreover, the fecundity in vitro of adult worms developing from P/HCl-isolated larvae was reduced below that for adults developing from larvae isolated from host muscle in PBS. More adult worms were recovered following infection of immune hosts with PBS-isolated larvae than were recovered from immune mice challenged with larvae isolated in P/HCl. Similar findings were observed in mice immunized by infection with Trichinella spiralis and challenged with T. pseudospiralis larvae isolated in either P/HCl or PBS. Immunization of mice with T. pseudospiralis larvae isolated by either method and challenged with larvae of T. spiralis resulted in recovery of similar percentages of the challenge inoculum.

The effects of host's sex and hormones on the number of adult Trichinella spiralis in the small intestine, the number of migratory larvae produced in vitro by adult female worms, and the number of muscle larvae per gram of body weight were examined in CD-1 Swiss white mice. Nongonadectomized (intact) male mice housed greater numbers of adult worms and a greater number of muscle larvae per gram of body weight than did intact female mice. Adult female worms isolated from intact male mice deposited greater numbers of migratory larvae in vitro than did those obtained from intact female mice. These differences between intact male and intact female mice were eliminated by gonadectomy of male and female mice. Injection of increasing amounts of heterologous sex hormone into intact male and female mice was accompanied by decreasing rates of in vitro larvaposition by adult worms from male mice; but adult worms isolated from female mice showed increasing rates of in vitro larvaposition. Injection of heterologous sex hormone into gonadectomized male and female mice caused a reversal of the findings for intact, uninjected male and female mice stated above. This study has demonstrated that host sex and host sex hormones affect the biology of T. spiralis in the CD-1 Swiss white mouse.

Absorption of glucose in vitro by enteric stages of Trichinella spiralis was examined in worms isolated at different times following infection. Glucose absorption by 6-h-old worms was similar to that seen during moulting (24 h post-infection (p.i.]. As embryogenesis began (48 h p.i.) glucose absorption in vitro by the parasite rose dramatically to a peak in 72-h-old worms. Absorption of glucose in vitro remained high in 96-h-old worms but as larviposition began (120 h p.i.) glucose uptake by T. spiralis dropped significantly. Glucose absorption by worms isolated from the host during the primary immune response was unaffected. Glucose absorption in vitro remained at similar levels in worms isolated between 120 and 312 h p.i. The percentage of absorbed label incorporated into parasite tissues was greatest in 48- and 312-h-old worms. Glucose uptake in vitro by pre-adult and adult worms changed with time and these changes accompanied specific events in the biology of the parasite.

The effects of cortisone on fecundity, distribution, and numbers of adult Trichinella spiralis and on enteritis in the host were compared in mice receiving different numbers of larvae. As the amount of cortisone given to mice was increased enteritis decreased, and fecundity of adult worms increased. Injection of mice with cortisone caused retention of a greater percentage of adult worms in the anterior regions of the host small bowel than in uninjected mice. By day 11 PI, when adult worms in cortisone-injected mice were more widely distributed along the host small intestine, fecundity of adult worms isolated from mice receiving more worms (500, 1,000, or 2,000 worms) attained levels previously seen only in worms from mice infected with 250 T. spiralis. The extended longevity of adult worms in cortisone-injected mice was accompanied by a severe reduction in fecundity after day 11 PI. Addition of cortisone to the culture medium at concentrations above 0.1 mg% was accompanied by a reduction in fecundity of adult worms.

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.

Natural killer (NK) cell function was evaluated in mice infected with either Trichinella pseudospiralis or T. spiralis larvae. T. pseudospiralis-infected mice consistently demonstrated augmented pulmonary NK cell-mediated clearance of YAC-1 tumor cells in vivo but failed to display enhanced splenic NK cell-mediated lysis of the same tumor cells in vitro. Attempts to alter NK cell function in vivo by the injection of anti-asialo-GM1 antibody resulted in anaphylaxis and death of the hosts infected with T. pseudospiralis but not of mice infected with T. spiralis. Immunofluorescence studies demonstrated that larvae of both species bound large quantities of anti-asialo-GM1 antibody but did not react with another NK-associated antibody, anti-NK-1.1. Even though anti-asialo-GM1 antibody reacted with larvae of both species, intravenous injection of antibody elicited anaphylaxis only in hosts that were infected with T. pseudospiralis.

Intravenous injection of anti-asialo GM 1 antibody into mice infected with Trichinella pseudospiralis resulted in rapid acute illness or death accompanied by a dramatic rise in hematocrit values in these animals. The described antibody-induced changes were reversible by intravenous infusion of Hanks' balanced salt solution (HBSS). These effects were not seen in uninfected mice or in Trichinella spiralis-infected mice injected with anti-asialo GM 1 antibody. Viability of T. spiralis or T. pseudospiralis infective L1 larvae, both isolated worms and those housed in muscle, was unaffected by exposure to anti-asialo GM 1 antibody and complement. Infectivity of larvae of T. pseudospiralis decreased significantly following exposure to anti-asialo GM 1 antibody. Release of protein by T. pseudospiralis infective L1 larvae during incubation in the presence of anti-asialo GM 1 antibody was significantly greater than that released by worms incubated in normal rabbit serum or HBSS. Protein released by infective L1 larvae of T. pseudospiralis was identified as Trichinella excretory/secretory antigens by immunoblot. Intravenous injection of T. pseudospiralis excretory/secretory products resulted in anaphylaxis in T. pseudospiralis-infected mice but not in uninfected or T. spiralis-infected mice. Excretory/secretory product-induced anaphylactoid response also was reversible by the intravenous injection of HBSS or by injection of an antihistamine. Significantly higher levels of total IgE were observed in sera from mice infected with T. pseudospiralis compared to uninfected or T. spiralis-infected mice. Binding of anti-asialo GM 1 antibody to the surface of T. pseudospiralis muscle larvae induced release of excretory/secretory antigen by the parasite.(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of myeloperoxidase activity in the muscles of mice infected with Trichinella pseudospiralis, T. spiralis or both helminths allowed quantitation of host inflammatory response to the parasite. Infection of the host with T. pseudospiralis alone was accompanied by less inflammation in host diaphragm muscle than was the case in hosts infected with T. spiralis alone. A dramatic reduction in inflammation around s.c. implanted cotton string was observed in mice infected with T. pseudospiralis alone below that seen in uninfected mice. Concurrent infection of the host with T. spiralis and T. pseudospiralis resulted in a lowering of myositis below that seen in the diaphragm muscles of mice infected with T. spiralis alone.

Suppression of host inflammatory response in mice infected with Trichinella pseudospiralis was associated with host plasma corticosterone levels significantly higher than those seen in uninfected mice or in mice infected with T. spiralis. Increases in the population of mitochondria and depletion of lipid droplets in cells of the zona fasciculata were seen in the adrenals of mice infected with T. pseudospiralis. Elevations in enteritis, myositis and myocarditis accompanied 100% mortality in adrenalectomized mice infected with T. pseudospiralis, while lower levels of inflammation and no mortality were observed in sham operated or intact animals infected with this parasite. The severe myositis normally accompanying infection with T. spiralis was suppressed by concurrent infection with 1000 or 2000 T. pseudospiralis to levels equivalent to those seen in animals receiving 0.15 and 0.41 mg cortisone acetate/25 g mouse/day, respectively.

The effects of host sex on enteric inflammatory response to primary infection with Trichinella spiralis were examined. Enteritis in female mice was greater than that in male mice on days 7, 9 and 11 postinfection (PI) and similar to that in male mice by day 13 PI. Male and female mice given daily injections of 33 or 66 mg/kilo of cortisone acetate exhibited significantly reduced enteritis on days 7, 9 and 11 PI below that seen in uninjected, male and female mice. On days 7, 9 and 11 PI larviposition in vitro by adult worms isolated from uninjected female mice was significantly less than that for adult worms isolated from male mice. Suppression of enteritis below detectable levels in male and female mice by administration of cortisone acetate resulted in similar rates of larviposition by adult worms isolated from male or female mice (day 7 PI, 33 mg/kilo cortisone acetate; days 7, 9 and 11 PI, 66 mg/kilo cortisone acetate). A significantly greater percent of adult worms was recovered from the anterior half of the small intestines of uninjected male than from uninjected female mice on days 7, 9 and 11 PI. The percent of adult worms recovered on these same days from the anterior half of the small intestine of male and female mice injected with cortisone was similar.

A mean of 2,862 muscle larvae was recovered on day 45 postinfection (PI) from the total body musculature of Chinese hamsters infected with 498 Trichinella pseudospiralis. Infection of the Chinese hamster with 494 Trichinella spiralis resulted in recovery of a mean of 225 muscle larvae on day 45 PI. The reproductive capacity index for T. pseudospiralis was 5.74, whereas that for T. spiralis was 0.46 in this host species.