Suppression of peripheral eosinophilia by the coccidium Eimeria nieschulzi (Apicomplexa: Eimeriidae) in experimentally infected rats

Four groups of 60 rats each were used to examine interspecific interactions between Eimeria nieschulzi and Nippostrongylus brasiliensis. Rats in group 1 served as uninoculated controls. Group 2 rats were each injected subcutaneously with 2.0 X 10(3) L3 larvae of N. brasiliensis. Group 3 rats were each inoculated per os with 2.5 X 10(5) sporulated oocysts of E. nieschulzi. Rats in group 4 were first infected with 2.0 X 10(3) larvae of N. brasiliensis and, at 8 days postinoculation, with 2.5 X 10(5) oocysts of E. nieschulzi. Ten animals from groups 1-3 were sacrificed at 4-day intervals postinoculation and group 4 rats were sacrificed at 4-day intervals beginning after the secondary infection. Blood smears were prepared from each animal to determine differential blood cell counts, bone marrow was examined at the times of peak infection for absolute and relative numbers of eosinophils, portions of the duodenum and jejunum were examined histologically for mast cells, and feces obtained from the cecum and large intestine were examined for ova/gram of feces. Results revealed that relative numbers of peripheral neutrophils and monocytes became elevated during the course of infection for all infected animals, and rats infected with the helminth only also had elevated eosinophil levels. However, rats infected singly with E. nieschulzi, or concurrently with the coccidium and helminth, had peripheral eosinophil levels that were not significantly different from controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

Suppression of Nippostrongylus brasiliensis (Nematoda)-induced lysophospholipase activity and peripheral eosinophilia by Eimeria nieschulzi (Apicomplexa)

Interspecific interactions between Nippostrongylus brasiliensis and Eimeria nieschulzi were studied by measuring fecal lysophospholipase (LYPH) activity and relative numbers of peripheral eosinophils in rats singly or concurrently infected with one or both parasite species. Three groups of 10 rats each were inoculated with 2 X 10(3) N. brasiliensis L3 larvae and/or 5 X 10(5) E. nieschulzi sporulated oocysts. Groups 1 and 2 were infected with E. nieschulzi or N. brasiliensis, respectively. Group 3 rats were infected first with N. brasiliensis, followed on day 8 postinoculation (PI) with E. nieschulzi. Each rat served as its own control. Results revealed LYPH levels rose steadily in Group 2 rats, reaching significant peaks on days 10 and 12 PI before decreasing to control levels. Lysophospholipase activity in Groups 1 and 3, however, did not differ from control values. Group 2 rats also demonstrated peripheral eosinophilia, with peak values occurring on days 10, 12, 14, and 16 PI, while rats in Groups 1 and 3 exhibited no eosinophilia. These results demonstrate that E. nieschulzi suppressed intestinal LYPH activity and relative peripheral eosinophilia and demonstrate that a host's immune response to a single parasite may be significantly altered when a second parasite species is present.     

Transfer of Eimeria nieschulzi using extraintestinal tissue

The issue of extraintestinal infection by Eimeria nieschulzi in the rat was addressed by transferring various tissues from infected to uninfected rats by mouth. All 6 rats receiving liver, spleen, or small intestine from rats killed at 3 or 8 hr postinoculation (PI), and all 5 rats receiving spleen and small intestine from rats killed 8 days PI, showed infections. Rats receiving tissues from rats killed at 8 days PI showed infections 24 hr later, indicating that fourth-generation merozoites were transferred. This is the first demonstration of an extraintestinal rodent eimerian.     

Arrested development in Eimeria nieschulzi (Apicomplexa: Eimeriina): results of single infections

Arrested development of Eimeria nieschulzi in the rat was investigated by feeding tissues of infected rats to coccidia-free rats. Intestinal tissue of 33 infected rats was fed on days 9, 10, 11, 14, 17, 21, and 28 PI to 43 uninfected recipients. Eight recipients, which represent 24.2% of the donors, later showed infection. Infections were retained for as long as 21 days after the initial infection. A prepatent period of 6 to 7 days in the recipients allowed the inference that the retained stage was the sporozoite. No infections were observed in 14 recipients fed spleen, lymph nodes, liver, or lung of infected animals.     

Nippostrongylus brasiliensis-induced depression of heterologous immune responses: effects of the histamine H2 receptor antagonist, cimetidine

Both mucosal and systemic immune responses are depressed in mice infected with the nematode Nippostrongylus brasiliensis and this is correlated with a striking increase in the numbers of histamine-containing, mucosal-associated mast cells. As suppressor T cells bear histamine H2 receptors, we have used the H2 antagonist, cimetidine, to test whether histamine mediates N. brasiliensis-induced immunodepression. In uninfected mice, mitogenic responses to PHA and Con A were increased by treatment with cimetidine; in some experiments this treatment also increased antibody responses to a T-dependent antigen (TNP-BGG). By contrast, these T- and B-cell responses were markedly depressed in mice infected with N. brasiliensis, and cimetidine treatment did not alter this parasite-induced immunodepression. These results imply that although histamine can modulate immune responses in uninfected animals, it is not a major component of the immunoregulatory pathway induced by infection with N. brasiliensis.     

Intestinal absorption studies with glycyl-proline, glycine and ethanol in rats infected with Eimeria nieschulzi

The absorption of glycyl-proline, glycine, and ethanol through the intestinal wall was studied in vitro by an everted sac technique in rats infected with the coccidial parasite Eimeria nieschulzi which causes damage and atrophy to the intestinal villi. The absorption of the dipeptide and of the amino-acid was reduced through tissue from infected animals but the transport of ethanol was similar in both infected and uninfected rats. The replacement of sodium by potassium in the mucosal bathing fluid as well as the separate addition of the metabolic inhibitors, potassium cyanide and dinitrophenol, reduced the amount of amino-acids transferred in both the infected and uninfected tissue in a similar proportion. The results support the conclusion that infection by the parasite affects several different elements of transport across the ileal wall but does not selectively reduce any single one.     

Physiological responses of rats to primary infection with Nippostrongylus brasiliensis

The physiological responses of well-nourished rats to primary infection with the intestinal nematode Nippostrongylus brasiliensis were examined. Infected rats fed ad libitum were compared with uninfected control rats fed ad lib. and with uninfected rats which were pair-fed to the infected rats. Following infection with N. brasiliensis rat food intake was reduced from day 2 post infection (pi) and there were two periods of minimal food intake (days 2 to 3 and 8 to 9 pi). The water intake of infected rats was only reduced on days 2, 3 and 9 pi and not to the same extent as food intake. Muscle catabolism in infected rats was more severe than could be explained on the basis of their food intake reduction. The rectal temperature and rate of oxygen consumption per g body-weight of rats was not significantly altered by the infection. Host responses to N. brasiliensis are compared with those seen in microbial infections and some of them are found to be considerably different.     

Nippostrongylus brasiliensis: infection induces upregulation of acetylcholinesterase activity on rat intestinal epithelial cells

Expression of cholines terases and muscarinic acetylcholine receptors in the jejunal mucosa has been investigated during infection of rats with the nematode parasite Nippostrongylus brasiliensis. Selective expression of m3 receptors was observed on epithelial cells from uninfected rats and animals 7 days postinfection, and saturation binding with [(3)H]quinuclidinyl benzilate indicated that receptor expression on cell membranes was unaltered by infection. Butyrylcholinesterase was highly expressed in mucosal epithelia, but acetylcholinesterase was present at low levels in uninfected animals. In contrast, discrete foci of intense acetylcholinesterase activity were observed on the basement membrane of intestinal epithelial cells in animals infected with N. brasiliensis. This was demonstrated to be due to upregulation of expression of endogenous enzyme, which peaked at Day 10 postinfection and subsequently declined to preinfection levels. It is suggested that this occurs in response to hyper-activation of the enteric nervous system as a result of infection, and may benefit the host by limiting excessive fluid secretion due to cholinergic stimulation.     

Phylogenetic relationships among rodent Eimeria species determined by plastid ORF470 and nuclear 18S rDNA sequences

Phylogenetic analyses for 10 rodent Eimeria species from different host genera based on plastid ORF470 and nuclear 18S rDNA sequences were done to infer the evolutionary relationships of these rodent Eimeria species and their correlation to morphology and host specificity. The phylogenies based on both data sets clearly grouped the 10 rodent Eimeria species into two major lineages, which reflect more their morphological differences than host specificity. Species in lineage A have spheroidal to subspheroidal sporulated oocysts, are similar in size (18-29 x 17-23; xbar = 22 x 20 microm), have an oocyst residuum and one-two polar granules; these include Eimeria albigulae (Neotoma), Eimeria arizonensis (Peromyscus, Reithrodontomys), Eimeria onychomysis (Onychomys) and Eimeria reedi (Perognathus). Species in lineage B, including Eimeria falciformis (Mus), Eimeria langebarteli (Reithrodontomys), Eimeria nieschulzi (Rattus), Eimeria papillata (Mus), Eimeria separata (Rattus) and Eimeria sevilletensis (Onychomys) have different shapes (ovoid, ellipsoid, elongated ellipsoid, etc.), differ greatly in size (10-27 x 9-24; xbar = 19 x 16 microm) and all lack an oocyst residuum. Thus, The oocyst residuum was the most determinant feature that differentiated the two lineages. The accession numbers of ORF470 of E. albigulae, E. arizonensis, E. falciformis, E. nieschulzi, E. onychomysis, E. papillata, E. reedi, E. separata, E. sevilletensis, E. langebarteli are AF311630-AF311639 and 18S rDNA of E. langebarteli, E. papillata, E. reedi, E. separata, E. sevilletensis are AF311640-AF311644.     

Local and systemic effects on inflammation during Eimeria nieschulzi infection

Rats infected with Eimeria nieschulzi, a coccidium that inhabits intestinal epithelium, have a lower basal inflammatory state in their intestinal mucosa eight days postinoculation as reflected by a drop in mucosal peroxidase activity and a decrease in the number of granulocytes in the lamina propria. The reduction of systemic inflammation in infected rats was assessed from a reduction in the formation of granulation tissue around a sterile cotton string implanted under the abdominal skin of the hosts. This reduced inflammatory response, both locally and systemically, occurs during the development of gamonts by the parasite and the release of oocysts from the host. These results plus the presence of normal or slightly elevated numbers of granulocytes in peripheral blood lead to the conclusion that the parasite does not affect hematopoiesis but interferes with some phase in the directed migration of leukocytes to specific sites.     

MECHANISM OF EOSINOPHILIA

Eosinophil leucocyte production was studied in the bone marrow of normal rats and rats given single injections of Trichinella spiralis larvae which stimulated eosinopoiesis. the development sequence of eosinophils in the bone marrow was based on morphological criteria combined with studies of the extent of eosinophil labelling after injections of tritiated thymidine. the proliferative compartment contained at least three recognizable steps in eosinophil development which were defined.
There was a delay of 23 hr after injection of larvae before the proportion of eosinophils in the bone marrow increased and it had doubled by 49 hr. the mitotic index increased by a factor of 3 after stimulation. Estimates of the cell cycle parameters were made for marrow eosinophils 1-3 days after stimulation, using the technique of analysing labelled mitoses. the results were compared with a similar group of normal rats, and were processed by using a computer program. Marrow eosinophil cell cycle time was 30 hr in normal rats and 9 hr in stimulated rats, and this acceleration was associated with a reduced spread of cell cycle times. the number of eosinophil cell divisions and the transit times for each compartment in normal and stimulated rats were estimated. This showed that the stimulus may have resulted in five or six additional divisions among the youngest eosinophils in the dividing compartment. From these figures an outline of eosinopoiesis in the marrow of normal and stimulated rats is proposed.     

Phylogenetic position of Eimeria antrozoi, a bat coccidium (Apicomplexa: Eimeriidae) and its relationship to morphologically similar Eimeria spp. from bats and rodents based on nuclear 18S and plastid 23S rDNA sequences.

Partial plastid 23S and nuclear 18S rDNA genes were amplified and sequenced from 2 morphologically similar Eimeria species. E. antrozoi from a bat (Antrozous pallidus) and E. arizonensis from deer mice (Peromyscus spp.), as well as some other Eimeria species from bats and rodents. The phylogenetic trees clearly separated E. antrozoi from E. arizonensis. The phylogenies based on plastid 23S rDNA data and combined data of both plastid and nuclear genes grouped 2 bat Eimeria and 3 morphologically similar Eimeria species from rodents into 2 separate clades with high bootstrap support (100%, 3 rodent Eimeria species; 72-97%, 2 bat Eimeria species), which supports E. antrozoi as a valid species. The rodent Eimeria species did not form a monophyletic group. The 2 bat Eimeria species formed a clade with the 3 morphologically similar rodent Eimeria species (E. arizonensis, E. albigulae, E. onychomysis, all from cricetid rodents) with 100% bootstrap support, whereas 2 other rodent Eimeria species (E. nieschulzi, E. falciformis, from murid rodents) formed a separate clade with 100% bootstrap support. This suggests that the 2 Eimeria species from bats might be derived from rodent Eimeria species and may have arisen as a result of lateral host transfer between rodent and bat hosts.     

Nippostrongylus brasiliensis: physiological and metabolic responses of rats to primary infection

Primary infection of rats with Nippostrongylus brasiliensis was associated with alterations in host protein, carbohydrate and lipid metabolism. Infected rats fed ad libitum were compared with uninfected, weight matched, pair fed rats. Metabolic changes detected were related to the level of infection (larvae/g body weight) and also the time course of development of the parasite. The intestinal stage of the infection was associated with marked catabolism of skeletal muscle which did not appear to be mediated by increased secretion of corticosteroids. Plasma concentrations of protein in infected rats were altered even at the lowest dose (27 l/g), and in a biphasic manner corresponding to larval and adult stages of the parasite. Plasma globulin concentrations were increased on Day 2 after infection while from Days 5-10 after infection, plasma concentrations of both globulin and albumin were much reduced. Hypoglycemia developed on Days 8-9 after infection in rats given a dose of greater than or equal to 39 l/g. Infected rats had increased plasma concentrations of non-esterified fatty acids and in marked contrast with their pair fed partners, plasma triglyceride concentration increased dramatically with both the dose of parasites given and the duration of infection. The responses of the rat to infection with N. brasiliensis are compared with host responses to other helminths and microorganisms, and suggestions are made as to their possible functions and significance.     

Pyridoxal 5'-phosphate dependent enzymes in the nematode Nippostrongylus brasiliensis.

Eight classes of pyridoxal 5'-phosphate dependent enzymes have been investigated in Nippostrongylus brasiliensis in parallel with rat tissues. The range of decarboxylases detected in N. brasiliensis was limited in comparison with rat tissues. N. brasiliensis possessed a highly active L-serine hydroxymethyltransferase, but in contrast with rat liver, 5-aminolevulinic acid synthetase was absent. Similar levels of L-serine and L-threonine dehydratase activities were detected in N. brasiliensis and rat liver, and both organisms lacked L-alanine racemase, L-tryptophan synthetase and L-methionine gamma-lyase. The demonstration of cystathionine beta-synthase and gamma-cystathionase in N. brasiliensis suggests the presence of a functional trans-sulphuration sequence. The substrate specificities of the nematode cystathionine beta-synthase and gamma-cystathionase varied significantly from those of the corresponding mammalian enzymes. Particularly striking was the ability of N. brasiliensis cystathionine beta-synthase to catalyse the non-mammalian 'activated L-serine sulphydrase' reaction (L-cysteine + R-SH----cysteine thioether + H2S). N. brasiliensis and rat liver exhibited comparable abilities to transaminate amino acids via the 2-oxoglutarate: glutamate system.     

Jejunal malabsorption in the rat infected by the nematode Nippostrongylus brasiliensis

Symons L. E. A., Gibbins J. R. and Jones W. O., 1970. Jejunal malabsorption in the rat infected by the nematode Nippostrongylus brasiliensis. International Journal for Parasitology, 1: 179–187. The rate of jejunal absorption of a range of substances absorbed actively or by diffusion was depressed in the rat infected by the nematode Nippostrongylus brasiliensis. The degree of malabsorption of actively absorbed substances was directly related to the severity of the infection.     

Nippostrongylus brasiliensis: malabsorption in experimentally infected rats

Glucose absorption and net small intestinal water movement were examined in rats infected with Nippostrongylus brasiliensis at Days 4, 6, 9, 13, and 19 after inoculation. Rats were infected with 4 X 10(3) N. brasiliensis third stage larvae. The entire small intestine was divided into three segments and each segment perfused simultaneously in vivo with Krebs-Ringer phosphate buffer containing 80 mM glucose, 6 X 10(5) dpm/ml [3H]glucose, and 6.2 X 10(3) dpm/ml [14C]polyethylene glycol. Rats perfused on Days 6, 9, 13, and 19 after inoculation showed a significant (P less than 0.05) decrease in glucose absorption rates from all three segments of the small intestine when compared to uninfected controls. In the three segments of uninfected rat small intestine and those perfused on Days 4, 13, and 19 after inoculation, net absorption of water occurred. However, in the proximal and distal segments perfused on Day 6 and the proximal segment perfused on Day 9, net water movement into the lumen occurred. This is the first report of depressed glucose absorption along the entire length of the small intestine during nippostrongylosis and contradicts previous reports of unaltered net glucose absorption in response to this parasite.     

Estimation of effective eosinopoiesis and bone marrow eosinophil reserve capacity in normal man.

The eosinophil reserve capacity of the post-mitotic granulocyte compartment in the bone marrow and the effective eosinopoiesis in three haematologically normal men have been quantified by means of kinetic parameters of [3H]thymidine flash-labelled peripheral blood eosinophils. From (a) the time of the appearance in the blood of labelled eosinophils after the tracer injection, (b) the inflow characteristics of the labelled eosinophils in the blood and (c) the magnitude of the eosinophil granulocyte pool in the venous blood, the effective eosinopoiesis (i.e. the eosinophil turnover) was calculated to range between 0.014 and 0.031 x 10(9) cells/kg body weight per day (mean 0.22 x 10(9) cell/kg per day). The post-mitotic eosinophil reserve capacity of the bone marrow ranged from 0.09 to 0.20 x 10(9) cells/kg body weight (mean 0.14 x 10(9) cells/kg). The large reserve pool and the high turnover rate may contribute to sudden rises of the peripheral blood oesinophil counts in some cases of eosinophilia.     

Variations of broncho-alveolar lavage techniques affect cell recoveries

Broncho-alveolar lavage (BAL) has become a routine method of sampling airway and alveolar milieu. Variations of BAL techniques, such as application of chest massage, may have an effect on cell yields. We compared numbers and composition of cells obtained by BAL with and without chest massage from naive rats and from rats infected 7 days earlier with 3,000 larvae of Nippostrongylus brasiliensis. Both techniques revealed significant increases in numbers of agranulocytes and granulocytes after N. brasiliensis infection, but the total yield of cells was 4-5 times greater when massage was used. The use of massage consistently increased the yield of macrophages, but did not result in consistently greater yields of lymphocytes or granulocytes.     

Results of Blood Transfusions from Donor Rabbits Infected with Eimeria stiedai to Recipient Coccidia-free Rabbits*

Blood, withdrawn by heart puncture, from donor rabbits infected with Eimeria stiedai, was transfused by heart puncture, to uninfected recipient rabbits. Fifty-nine of 76 young coccidia-free recipients, given heparinized whole blood, erythrocytes or leucocytes from donors orally inoculated up to 27 days earlier, developed E. stiedai infections.     

Cross-transmission studies with Eimeria arizonensis-like oocysts (Apicomplexa) in New World rodents of the Genera baiomys, Neotoma, Onychomys, Peromyscus, and Reithrodontomys (Muridae).

Cross-transmission experiments were performed using oocysts of an Eimeria arizonensis-like coccidian from Peromyscus leucopus and Peromyscus truei, an E. arizonensis-like coccidian from Reithrodontomys fulvescens, Eimeria baiomysis and Eimeria taylori from Baiomys taylori, Eimeria albigulae from Neotoma albigula, and Eimeria onychomysis from Onychomys spp., between representatives of the above host genera. The E. arizonensis-like coccidian from R. fulvescens infected Reithrodontomys megalotis, Reithrodontomys montanus, and Peromyscus leucopus. Oocysts of E. arizonensis from P. leucopus could be transmitted to both P. leucopus and R. megalotus. Oocysts of E. baiomysis and E. taylori infected only B. taylori. Oocysts of E. arizonensis from P. truei infected P. truei but not Neotoma mexicana or Onychomys leucogaster. Oocysts of E. albigulae from N. albigula were infective for N. mexicana but not for P. truei or O. leucogaster. Oocysts of E. onychomysis from Onychomys spp. infected O. leucogaster but not N. mexicana or P. truei. These results demonstrate that Peromyscus and Reithrodontomys, genera known to be related very closely evolutionarily, are capable of sharing E. arizonensis, whereas morphologically similar coccidians (E. albigulae, E. baiomysis, and E. onychomysis) from more distantly related hosts, are probably distinct and more stenoxenous. This also is the first report of coccidians infecting species of Reithrodontomys.