Schistosome Egg Granuloma Research Articles

Characterization of mononuclear phagocytes in schistosomal egg granulomas of athymic mice.

Macrophages from schistosomal egg granulomas of athymic mice (nu/nu GM) and their euthymic littermates (nu/+ GM) were analyzed phenotypically for the expression of antigens encoded by the I-A subregion of the major histocompatibility complex and for their ability to perform as antigen-presenting cells. Only 11 to 15% of nu/nu GM expressed I-A antigens as compared to 61.5 to 75% of nu/+ GM. Although both populations of cells appeared to be equally effective as antigen-presenting cells appropriately sensitized lymphocytes in the presence of specific antigens--soluble schistosomal egg antigen (SEA) and human gamma-globulin (HGG)--only nu/nu GM, but not nu/+ GM, were found to stimulate I-A-restricted proliferation of schistosome-sensitized T cell populations in the absence of SEA added in vitro. Furthermore, nu/nu GM but not nu/+ GM were shown to exhibit significant proliferative capacity in vitro, but this phenomenon could not account for the observed difference in SEA-independent T cell stimulation. Finally, culture supernatants from nu/nu GM displayed significant thymocyte-stimulating activity, consistent with interleukin 1, which was not observed in nu/+ GM. These findings point to significant differences between nu/nu GM and nu/+ GM, which may be part of an adaptive mechanism of granulomatous reactivity in the absence of a competent T cell system.

Immunopathology of experimental schistosome (S. Mansoni) egg granulomas in mice--possible defence mechanisms mediated by local immune complexes.

A ten month experimental S. Mansoni infection was followed in mice by studying schistosome egg granulomatous inflammation, antigen and immunoglobulins deposits in the granulomata and the circulating antibodies. During the experimental infection it was demonstrated that while the granulomatous reaction matures there is a progressive restriction of the antigens to the miracidia. Furthermore, immunoglobulins, particularly IgG and C3 deposits were demonstrated in the granulomata. Our data support the concept that schistosome egg granuloma is a hypersensitivity high turnover granuloma that is particularly efficient in walling off the antigen. Whereas the granuloma is built up largely by a cell mediated immune reaction, antibody deposits are also found, probably functioning as a local humoral antibody barrier which allows a slow and progressive neutralisation of the antigens. Viewed as a whole, experimental schistosome egg granuloma might be considered as a mixed, chiefly cell but also humoral antibody mediated immune reaction.

Fibroblast stimulation in schistosomiasis. IV. Isolated egg granulomas elaborate a fibroblast chemoattractant in vitro.

Hepatic fibrosis complicates the chronic granulomatous inflammatory reaction to Schistosoma mansoni eggs, and is the major cause of morbidity and mortality in human schistosomiasis. We previously presented evidence that schistosomal egg granulomas secreted factors that can stimulate fibroblast proliferation and collagen synthesis in vitro. We now report that serum-free supernatants from cultures of hepatic egg granulomas isolated from S. mansoni-infected mice contained activity that stimulated the directional migration of human and guinea pig dermal fibroblasts in modified Boyden chambers. This fibroblast chemotactic activity was also detected in culture supernatants of granuloma adherent cells highly enriched for macrophages (95% latex-ingesting) but not in culture supernatants from resident peritoneal macrophages of uninfected or infected mice. This suggests that granuloma macrophages are a source of the chemotactic activity. The chemoattractant had the properties of large molecular weight (greater than 200,000 daltons; Sephadex G-200 gel filtration), pl approximately 4.5 (preparative flatbed isoelectrofocusing in granular matrix), heat stability (56 degrees C; 45 min), and trypsin sensitivity. Since preincubation of the partially purified granuloma and adherent-cell derived chemoattractants with rabbit anti-human fibronectin antibody abolished their chemotactic activity, it appears that the factor is antigenically similar to fibronectin. We propose that egg granuloma macrophages are activated in vivo to secrete a fibronectin-like molecule with activity that stimulates the directional migration of fibroblasts. This factor may therefore play a role in the local recruitment of fibroblasts and, in concert with other granuloma-derived factors, may play an important role in the pathogenesis of hepatic fibrosis in schistosomiasis.

Regulation of fibroblast functions by products of schistosomal egg granulomas: potential role in the pathogenesis of hepatic fibrosis.

Recent observations suggest a molecular link between granuloma formation and hepatic fibrosis in schistosomiasis. Egg granulomas isolated from Schistosoma mansoni-infected mice, when cultured in serum-free medium, produce a variety of biologically active molecules that affect fibroblast function. One group of molecules--proteins with an estimated relative molecular mass (Mr) of 30 000--stimulate fibroblast proliferation in vitro. These molecules have interleukin (IL)-1-like activity when assayed in thymocyte cultures but are biochemically distinct from previously characterized murine IL-1. Fibroblast mitogenic activity is also produced by macrophages isolated from granulomas and by extracts of S. mansoni eggs. The egg-derived activity is distinct from the granuloma cell-derived material on the basis of Mr and isoelectric point determinations. Egg extracts also contain concanavalin A-binding substances which are not directly mitogenic for fibroblasts but can stimulate spleen cells from infected mice to produce fibroblast mitogenic activity in vitro. A large chemoattractant molecule (greater than 200 000 Mr) for fibroblasts has also been identified in supernatants from granuloma cultures and in supernatants from macrophages isolated from granulomas. This activity is abolished by treatment with anti-fibronectin antibody, suggesting that it is fibronectin or a cleavage product thereof. Molecules similar to or identical with the fibroblast mitogenic factors from the granulomas have been identified, and they inhibit the contraction of fibroblast-populated collagen lattices. These activities may be important in the pathogenesis of hepatic fibrosis in schistosomiasis, and pharmacological modification of their production or of their effects on target fibroblasts might theoretically prevent hepatic fibrosis in this disease.

Autotransplantation of Hepatic Granulomas into the Skin of Mice with Schistosoma mansoni Infection

Hepatic egg granulomas of mice infected with Schistosoma mansoni were transplanted into the skin of the same animal and changes occurring to macrophages, eosinophils, and mast cells over time were studied by light and electron microscopy and by autoradiographic techniques. Disappearance of cellular components about the egg granulomas occurred within 1 week; the entire implant became encapsulated by inflammatory cells and stroma. By 3 weeks mononuclear cells and macrophages reorganized the granulomas around the eggs and neutrophils disappeared. Activated macrophages contained both secretory rough endoplasmic reticulum and lysosomal-dense bodies. Granuloma size increased up to 5 weeks after implantation and mast cells and eosinophils tended to migrate into the granulomas. The mast cell index always remained lower than in the original hepatic granulomas, while eosinophils were seen in large numbers. During 3 to 8 weeks after implantation mononuclear cells undergoing DNA synthesis in the granulomas ranged from 2.9-4.8%. Some 3-week-old autotransplants were injected with 3H-thymidine and biopsied from 1 to 21 days later. Labeled mononuclear cells peaked in the granulomas by 10 days (24%) and the numbers fell off sharply after that. These findings indicate that autologously implanted schistosome egg granulomas can be maintained successfully in the skin for prolonged periods with marked ingress of macrophages and eosinophils. The autoradiographic data suggest the lesions are high turnover granulomas.

Acquired immunity in B cell-deficient mice to challenge exposure following primary infection with Schistosoma mansoni.

Mice were made B cell-deficient by injections of globulin prepared from goat antimouse mu-chain serum. Anti-mu globulin was administered throughout the experiments (18 or 23 weeks). B cell deficiency was determined at the time of assay of worm burden levels (7 weeks after challenge with Schistosoma mansoni) by quantitation of serum IgM and IgG, by assaying the specific antibody response to cercarial and adult worm antigens in enzyme-linked immunosorbent assay and by histologic examination of the spleen and mesenteric (regional) lymph nodes. Four-week-old mice were exposed to S. mansoni and 8 weeks later were challenged with a second exposure. The B cell-deficient mice developed a degree of resistance (79%) similar to that of the intact controls (81%). The IgM and IgG levels of the B cell-deficient mice were markedly suppressed. Follicular development was not detected in their lymph nodes; but in the spleen of some animals clusters of cells morphologically similar to B cells were observed peripheral to a central T cell-like area. B cell-deficient mice developed schistosome egg granulomas comparable to those of the intact controls. Control animals developed an antibody response with titers of 1:64 to 1:1,024 against cercarial and adult worm antigens; B cell-deficient animals were nonreactive in these assays. The data suggest that specific antibody does not play a major role in resistance acquired within 8 weeks as a result of a primary infection in murine schistosomiasis.

Granulomatous inflammation in normal and athymic mice infected with schistosoma mansoni: an ultrastructural study.

Inflammatory cell types and their interrelationships were studied in hepatic schistosome egg granulomas by correlated light and electron microscopy in thymus-intact and athymic mice. Intact animals developed large granulomas composed of phagocytes, stimulated macrophages, epithelioid cells, eosinophils and mast cells. The lesions peaked in size between 10--14 weeks after infection and tended to heal after 16 weeks. In athymic mice only phagocytes, stimulated macrophages and possible epithelioid cells appeared in the granulomas which were much smaller and less well organised than in intact mice. Virtually no eosinophils or mast cells entered the granulomas. These findings support the idea that development of granulomatous inflammation per se is not determined by CMI, but T cell co-operation seems to be required for its full expression in schistosomiasis. Since CMI closely regulates ingress of eosinophils and mast cells into the granuloma, the nature of T cell co-operation probably occurs at several levels in this complex infectious granuloma.

Schistosoma Mansoni Infection in Intact and B cell Deficient Mice: The Effect of Pretreatment with BCG in These Experimental Models

The course of infection with Schistosoma mansoni was determined in B cell deficient mice by means of a schistosomule lung recovery assay 6 days after infection or by determination of the adult worm burden 7 weeks after infection. The intensity of infection was not significantly different from that in age- and sex-matched intact controls. B cell deficiency was demonstrated by absence of surface immunoglobulin-bearing cells in the spleen and by absence of B cell areas in the lymphoid follicles of the spleen and mesenteric lymph nodes. In addition, B cell deficient mice infected for 7 weeks with S. Mansoni were unable to form anti-schistosome antibodies detectable by the Cercarienhüllenreaktion. A normal granulomatous response, however, was observed around schistosome eggs. Pretreatment with BCG suppressed infection with S. mansoni comparably in intact and B cell deficient mice. A marked depletion of eosinophils occurred in the schistosome egg granuloma of all BCG treated mice.

The ultrastructural development of the schistosome egg granuloma in mice.

Hepatic granulomas from mice infected with Schistosoma mansoni for periods of 8 weeks to 1 year studied by electron microscopy. The different cell types present in the granulomas suggested that whilst a delayed hypersensitivity response predominated during early stages of infection an Arthus-type reaction associated with delayed hypersensitivity occurred at later stages of infection.

Induced and spontaneous diabetes mellitus and suppression of cell-mediated immunologic responses. Granuloma formation, delayed dermal reactivity and allograft rejection.

These investigations delineate the recently described suppression of a form of cellular hypersensitivity in mice with streptozotocin-induced diabetes mellitus using a variety of cell-mediated immunologic responses in animals with several different forms of diabetes. Streptozotocin- and alloxan-induced diabetic mice and db/db genetically determined diabetic mice showed reductions in the areas of inflammation around Schistosoma mansoni eggs injected into the pulmonary vasculature of 68, 70, 77%, respectively. In contrast, streptozotocin-induced diabetes had no effect on the nonimmunologic foreign body granuloma around divinyl benzene copolymer beads injected into the pulmonary arterioles. Animals protected from diabetes by treatment with nicotinamide before streptozotocin administration did not develop hyperglycemia and had normal areas of immunologic granuloma formation around schistosome eggs. Treatment with insulin reversed the suppression of schistosome egg granuloma formation in both streptozotocin- and alloxan-diabetic animals. Two additional in vivo parameters of cellular immunologic reactivity were examined in streptozotocin-induced diabetes: delayed footpad swelling was essentially eliminated; skin graft survival across the H-2 area was significantly prolonged from 10.2 days in the controls to 14.4 days in moderately diabetic A/J mice. These observations suggest that diabetes mellitus is associated with suppression of cell-mediated reactions in vivo and that the defect is reversible with insulin treatment.

The secretion of migration inhibitory factor by intact schistosome egg granulomas maintained in vitro.

TUBERCLE formation and delayed type dermal reactivity are the hallmarks of tuberculosis, yet the relationship between the two has only recently begun to be elucidated. Most experts still believe that the tuberculous granuloma is a tissue response to the irritative effect of mycobacterial lipids1,2. While the strength of this concept made it difficult to establish granulomatous inflammation as a host immunologic response3,5 Warren et al.6 showed that the schistosome egg granuloma is a manifestation of delayed hypersensitivity, as demonstrated by anamnestic reactivity, specificity, and transferability with immune lymphoid cells but not with antiserum. It was subsequently correlated with other parameters of the cell-mediated immune reaction, including delayed dermal reaction, lymphocyte transformation and macrophage-migration inhibition7. Similar results have been provided for the experimental tuberculous granuloma8–13. Here we report the secretion of a lymphokine by intact granulomas maintained in vitro, further confirming the hypersensitivity character of the schistosome egg granuloma.

Specific Granulomatous Hypersensitivity elicited by Bentonite Particles coated with Soluble Antigens from Schistosome Eggs and Tubercle Bacilli

THE infectious granuloma is a form of focal inflammation which occurs around various infectious agents1. The schistosome egg granuloma has been investigated as a model of granulomatous inflammation2, and it has been shown that mice previously exposed to eggs of Schistosoma mansoni develop larger granulomas than unsensitized mice and that peak size is attained earlier3. The anamnestic response is specific, it can be transferred passively with lymphoid cells, but not by serum, and is inhibited by immunosuppressive drugs4, neonatal thymectomy5 and anti-lymphocyte serum6. It has been concluded therefore that the formation of granuloma around S. mansoni eggs is a manifestation of delayed hypersensitivity.

Schistosoma mansoni: Stage specificity of granuloma formation around eggs after exposure to irradiated cercariae, unisexual infections, or dead worms

Schistosoma mansoni: Stage specificity of granuloma formation around eggs after exposure to irradiated cercariae, unisexual infections, or dead worms. Experimental Parasitoloty 27 , 60–66. Humoral antibody-mediated immediate hypersensitivity responses are relatively nonspecific in comparison with cell-mediated delayed hypersensitivity reactions as has been demonstrated in both in vivo and in vitro systems. Studies of both antibody formation and immediate intradermal reactions in schistosomiasis have shown marked cross-reactivity between schistosomes and other helminths, among the three major human schistosome species, and among the different stages of development of individual schistosome species. The recent demonstration that the schistosome egg granuloma is a form of cell-mediated delayed hypersensitivity has resulted in a series of investigations of the specificity of this reaction. It was initially shown that there was no cross-reactivity between Schistosoma mansoni and Ascaris suis eggs. Then it was found that there was relatively little cross-reactivity among the eggs of the three human schistosome species, and finally, mice with early schistosomiasis, prior to the onset of egg laying by the worms, were not sensitized to granuloma formation around homologous eggs. In the present study mice were each exposed to 1000 irradiated S. mansoni cercariae (10,000 r), were unisexually infected with large numbers of male or female S. mansoni worms, or were injected intraperitoneally with killed 4-week-old worms of the same species. S. mansoni eggs isolated from the livers of mice with schistosomiasis mansoni of 8 weeks' duration were injected intravenously into the lungs of experimental mice. In comparison with control unsensitized mice and mice sensitized with homologous eggs in which markedly accelerated and augumented granuloma formation occurred, the mice exposed to irradiated cercariae, those with unisexual infections, and those injected with killed 4-week-old worms all acted as unsensitized animals. The cell-mediated delayed hypersensitivity granulomatous reaction which develops around S. mansoni eggs appears to be a stage-specific reaction.

The role of chemical mediators in the inflammatory response induced by foreign bodies: comparison with the schistosome egg granuloma.

Both divinyl benzene copolymer (plastic) beads and schistosome eggs produce inflammatory reactions after intravenous deposition into the lung of a mouse. As reported previously, the schistosome egg granuloma is an immunologic reaction of the delayed hypersensitivity type; this inflammatory process is prevented by immunosuppressive measures, and characteristically demonstrates an anamnestic response. In contradistinction, the plastic bead granuloma appears to be characteristic of a foreign body reaction; it is unaffected by immunosuppressive measures and does not demonstrate an anamnestic response with repeated exposure. The data in this report suggest that the granuloma formation around plastic beads is a nonimmunologic reaction induced by chemical mediators of inflammation. This proposal is supported by the following findings: the plastic beads activate Hageman factor in normal human and mouse plasma; the plastic beads induce vascular permeability-enhancing activity as measured in guinea pig skin and kinin-like activity in normal human and mouse plasma that is dependent on Hageman factor; ellagic acid, an agent that activates Hageman factor in vivo and is reported to diminish kininogen by consumptive depletion, markedly depresses the plastic bead granuloma. These data are consistent with the idea that the plastic bead granuloma and perhaps other foreign body inflammatory reactions are in major part dependent on kinin formation. Ellagic acid also suppressed the schistosome egg granuloma, but not to the same degree as the plastic bead granuloma. The implications of this observation are discussed in the text. Silicosis and "blue velvet disease", pathologic processes associated with the deposition of silica and magnesium trisilicate, respectively, in the lung, and the induction of a foreign body reaction may also be dependent on the activation of chemical mediators of inflammation by the silica and magnesium trisilicate particles with immunologic mechanisms participating in only a minor way, if at all. The marked suppression of experimental silicosis and blue velvet disease in mice by ellagic acid supports this idea.