Dynamics of collagen accumulation and polymorphism in murine Schistosoma japonicum

Role of the IL-33/ST2 Activation Pathway in the Development of the Hepatic Fibrosis Induced by Schistosoma mansoni Granulomas in Mice

Schistosoma mansoni eggs retained in host tissues induce innate cytokine release, contributing to the induction of Type-2 immune responses and granuloma formation, important to restrain cytotoxic antigens, but leading to fibrosis. Interleukin(IL)-33 participates in experimental models of inflammation and chemically induced fibrosis, but its role in S. mansoni-induced fibrosis is still unknown. To explore the role of the IL-33/suppressor of the tumorigenicity 2 (ST2) pathway, serum and liver cytokine levels, liver histopathology, and collagen deposition were comparatively evaluated in S. mansoni-infected wild-type (WT) and IL-33-receptor knockout (ST2-/-) BALB/c mice. Our data show similar egg counts and hydroxyproline in the livers of infected WT and ST2-/- mice; however, the extracellular matrix in ST2-/- granulomas was loose and disorganised. Pro-fibrotic cytokines, such as IL-13 and IL-17, and the tissue-repairing IL-22 were significantly lower in ST2-/- mice, especially in chronic schistosomiasis. ST2-/- mice also showed decreased α-smooth muscle actin (α-SMA) expression in granuloma cells, in addition to reduced Col III and Col VI mRNA levels and reticular fibres. Therefore, IL-33/ST2 signalling is essential for tissue repairing and myofibroblast activation during S. mansoni infection. Its disruption results in inappropriate granuloma organisation, partly due to the reduced type III and VI collagen and reticular fibre formation.

Proteomics Investigations of Potential Protein Biomarkers in Sera of Rabbits Infected With Schistosoma japonicum

Schistosomiasis is a chronic parasitic disease that continues to be a pressing public health problem in many developing countries. The primary pathological damage from the disease is granuloma and fibrosis caused by egg aggregation, and early treatment can effectively prevent the occurrence of liver fibrosis. Therefore, it is very important to identify biomarkers that can be used for early diagnosis of Schistosoma japonicum infection. In this study, a label-free proteomics method was performed to observe the alteration of proteins before infection, 1 and 6 weeks after infection, and 5 and 7 weeks after treatment. A total of 10 proteins derived from S. japonicum and 242 host-derived proteins were identified and quantified as significantly changed. Temporal analysis was carried out to further analyze potential biomarkers with coherent changes during infection and treatment. The results revealed biological process changes in serum proteins compared to infection and treatment groups, which implicated receptor-mediated endocytosis, inflammatory response, and acute-phase response such as mannan-binding lectin serine peptidase 1, immunoglobulin, and collagen. These findings offer guidance for the in-depth analysis of potential biomarkers of schistosomiasis, host protein, and early diagnosis of S. japonicum and its pathogenesis. Data are available via ProteomeXchange with identifier PXD029635.

Role of stellate cells in hepatic echinococcosis in cattle

Hydatid cysts formed by the metacestodes of Echinococcus granulosus. Cattle suffering from hydatid cyst shows fluid-filled structures, especially in liver. These parasite-induced cysts localized by forming fibrous capsules in the liver. Fibrogenesis is the host immune response in the liver against these parasites. Hepatic stellate cells (HSCs) are localized perisinusoidal space also known as vitamin A-storing cells, characterize the important fibrogenic cell type. In this study, livers from 15 animals with hydatid cyst and 8 healthy animals were used. Hematoxylin and Eosin, masson trichrome staining were performed on the prepared liver sections. Microscopically, cysts were bordered eosinophilic necrotic debris blended with degenerate neutrophils, macrophages, eosinophils, lymphocytes, plasma cells and multinucleated giant cells, which extend into the adjacent fibrous connective tissue. In Masson trichrome staining, the fibrous connective tissue was observed surrounding of hydatid cyst. Glial fibrillary acidic protein (GFAP), collagen I, GFAP/collagen I, positive cells were investigated using either indirect single- or double-labeling immunohistochemical staining. The results indicated that anti-GFAP-positive staining was seen in areas including fibrous tissue just under the foreign body giant cells surrounding the cyst wall. In double immunohistochemical staining, it was observed that HSCs labeled with anti-GFAP antibody in the fibrous connective tissue also labeled anti-collagen I antibody. This study shows that HSCs may responsible for synthesis the collagen I in the development of parasitic fibrosis in cystic echinococcosis in the liver of cattle.

Understanding the mechanism of hepatic fibrosis and potential therapeutic approaches

Hepatic fibrosis (HF) is a progressive condition with serious clinical complications arising from abnormal proliferation and amassing of tough fibrous scar tissue. This defiance of collagen fibers becomes fatal due to ultimate failure of liver functions. Participation of various cell types, interlinked cellular events, and large number of mediator molecules make the fibrotic process enormously complex and dynamic. However, with better appreciation of underlying cellular and molecular mechanisms of fibrosis, the assumption that HF cannot be cured is gradually changing. Recent findings have underlined the therapeutic potential of a number of synthetic compounds as well as plant derivatives for cessation or even the reversal of the processes that transforms the liver into fibrotic tissue. It is expected that future inputs will provide a conceptual framework to develop more specific strategies that would facilitate the assessment of risk factors, shortlist early diagnosis biomarkers, and eventually guide development of effective therapeutic alternatives.

Understanding the mechanism of hepatic fibrosis and potential therapeutic approaches

Hepatic fibrosis (HF) is a progressive condition with serious clinical complications arising from abnormal proliferation and amassing of tough fibrous scar tissue. This defiance of collagen fibers becomes fatal due to ultimate failure of liver functions. Participation of various cell types, interlinked cellular events, and large number of mediator molecules make the fibrotic process enormously complex and dynamic. However, with better appreciation of underlying cellular and molecular mechanisms of fibrosis, the assumption that HF cannot be cured is gradually changing. Recent findings have underlined the therapeutic potential of a number of synthetic compounds as well as plant derivatives for cessation or even the reversal of the processes that transforms the liver into fibrotic tissue. It is expected that future inputs will provide a conceptual framework to develop more specific strategies that would facilitate the assessment of risk factors, shortlist early diagnosis biomarkers, and eventually guide development of effective therapeutic alternatives.

Hepatic stellate cells and parasite-induced liver fibrosis

Fibrogenesis is a common feature of many diseases where there is severe insult to the liver. The hepatic stellate cell trans-differentiation into a myofibroblast has been identified as an important event in liver fibrogenesis and has been well investigated over the last few years in a number of liver diseases. The trans-differentiation process can be monitored in vitro by evaluation of biomarkers that are characteristic of normal quiescent hepatic stellate cells or activated myofibroblasts. Two major parasitic diseases associated with liver injury and fibrosis are schistosomiasis and echinococcosis. Recent studies have highlighted a role for activated hepatic stellate cells in both murine and human schistosomiasis as well as demonstrating that schistosome antigens are able to regulate this trans-differentiation process. Study of the hepatic stellate cell and its interaction with parasite-derived antigens may be pivotal in our understanding of the pathology associated with schistosomiasis and other parasitic diseases, including echinococcosis, as well as revealing new information on the trans-differentiation process in this cell type.

Dynamics of hepatic stellate cells, collagen types I and III synthesis and gene expression of selected cytokines during hepatic fibrogenesis following Mesocestoides vogae (Cestoda) infection in mice

In the present study, the relationship between progression of Mesocestoides vogae infection in the liver of mice, the accumulation rate of collagen types I and III, gene expression of fibrogenic factors and cytokines was examined within 6weeks p.i. Due to asexual multiplication, the total number of larvae in the liver increased considerably and 63.4% were found in collagen capsules on day 42 p.i. Intense staining for both collagens was recorded in the activated hepatic stellate cells (HSCs) throughout the period of this study in the inflammatory lesions. With progressing infection, cellular expression of both collagens was confined to the flat cells, myofibroblasts, which were scattered among collagen fibres in parenchymal lesions and capsules. Collagen-positive areas mirrored immunostaining of alpha-smooth muscle actin (alpha-SMA) in HSCs and myofibroblasts. Gene expression of both collagens increased rapidly within 14days p.i. and their expression pattern resembled that for pro-fibrotic cytokine transforming growth factor (TGF)-beta1 and alpha-SMA protein. IL-10 cytokine expression was up-regulated following day 14 p.i. and that of IL-13 was up-regulated early p.i., then transcription elevated gradually mirroring the activity of other pro-fibrotic markers. In contrast, transcription activity of TNF-alpha and IFN-gamma was elevated shortly after infection, followed by the partial down-regulation of gene expression, indicating the lack of larval killing, enhanced granulomatous inflammation and the perpetuation of hepatic fibrosis. Histomorphometric analysis of the parenchymal fibrous lesions, surface areas of larvae surrounded with the inflammatory infiltrates and surface areas of developing or mature larva-containing granulomas, correlated with the proportion of free and encapsulated larvae, immunostaining and gene expression patterns of collagens and pro-fibrotic markers. At a later stage of infection (day 28 p.i. onwards) collagen I-positive areas occupied a greater surface area and formed mature larval capsules and scars in the liver. In contrast, collagen III was less abundant and was localised mainly in the fibrous lesions in damaged parenchyma, suggesting their specific up-regulation as the part of host-protecting and tissue-healing responses.

The wound repair response controls outcome to cutaneous leishmaniasis

Chronic microbial infections are associated with fibrotic and inflammatory reactions known as granulomas showing similarities to wound-healing and tissue repair processes. We have previously mapped three leishmaniasis susceptibility loci, designated lmr1, -2, and -3, which exert their effect independently of T cell immune responses. Here, we show that the wound repair response is critically important for the rapid cure in murine cutaneous leishmaniasis caused by Leishmania major. Mice congenic for leishmaniasis resistance loci, which cured their lesions more rapidly than their susceptible parents, also expressed differentially genes involved in tissue repair, laid down more ordered collagen fibers, and healed punch biopsy wounds more rapidly. Fibroblast monolayers from these mice repaired in vitro wounds faster, and this process was accelerated by supernatants from infected macrophages. Because these effects are independent of T cell-mediated immunity, we conclude that the rate of wound healing is likely to be an important component of innate immunity involved in resistance to cutaneous leishmaniasis.

Immunopathology of granuloma formation and fibrosis in schistosomiasis

In schistosomiasis the deposition of parasite ova within host tissues is the initial event in a complex pathophysiological cascade which is characterized by granuloma formation, and may terminate in fibrosis and related sequelae (Fig. 1). In spite of intensive study, the complex relationship between infection and morbidity remains poorly understood. In this article, Michael Phillips and Patrick Lammie review current concepts of the mechanisms of granuloma formation and its regulation in schistosome infections.

Anti-interleukin-4 treatment diminishes secretion of Th2 cytokines and inhibits hepatic fibrosis in murine schistosomiasis japonica

Anti-interleukin-4 (IL-4) treatment of Schistosoma japonicum-infected mice markedly inhibited in vitro secretion of the Th2 cytokines IL-4 and IL-5 from antigen-stimulated spleen cells, but enhanced the secretion of the Th1 cytokine IFN-gamma. IL-2 secretion was unaffected. Hepatic fibrosis was markedly diminished in anti-IL-4-treated-mice at ten weeks of infection while granulomas around S. japonicum eggs in the livers were slightly-to-moderately increased in size. The number of eggs per worm pair in the tissues and feces did not differ significantly in treated and untreated mice. These findings suggest that Th2 cytokine responses are important in the genesis of schistosomal hepatic fibrosis.

Hepatic fibrosis and gene expression changes induced by praziquantel treatment during immune modulation of Schistosoma japonicum infection

In the present study fibrogenic gene expression was determined in murine Schistosoma japonicum infection during the progression of immune modulation of infection and following chemotherapy during the course of immune modulation. Histomorphometric analysis of granuloma size and collagen deposition revealed peak granuloma size in acute infection (5 weeks) and peak hepatic collagen content at 16 weeks of infection. Peak Type I collagen gene expression was concomitant with TGF-beta 1 gene expression at 8-11 weeks. Chemotherapy during either acute (9 weeks) or chronic (24, 28 weeks) infection resulted in increased collagen deposition and increased gene expression of Type I collagen and TGF-beta 1. However, chemotherapy at 14-16 weeks resulted in decreased levels of TGF-beta 1 gene expression and essentially minimal change in Type I collagen deposition and gene expression. These data indicate that chemotherapy of schistosomiasis japonica does not reverse hepatic fibrogenesis when administered in acute infection-when granuloma size is maximal-or in chronic infection. However, a beneficial effect on hepatic fibrogenesis is seen when chemotherapy is administered at 14-16 weeks post-infection, a time of decreasing granuloma size and maximal hepatic collagen content. Thus the ability to reverse schistosomal-induced hepatic fibrogenesis by chemotherapy may depend on disease stage.

Schistosoma japonicum-infected mice show reduced hepatic fibrosis and eosinophilia and selective inhibition of interleukin-5 secretion by CD4+ cells after treatment with anti-interleukin-2 antibodies

Schistosoma japonicum-infected mice were injected with antibodies to interleukin-2 (IL-2) and/or IL-2 receptor to clarify the role of IL-2 on the granulomatous reaction around schistosome eggs in the liver. Granulomas were of normal or slightly increased size in animals subjected to IL-2 blockade, but hepatic fibrosis was markedly decreased in treated animals 10 weeks after infection. Anti-IL-2 treatment significantly decreased the in vitro secretion of IL-5 by antigen-stimulated spleen cells, and peripheral eosinophilia and tissue eosinophilia were diminished. Secretion of IL-2, IL-4, and gamma interferon was unaffected. Our results indicate that IL-2 is not an essential determinant of granuloma size in S. japonicum-infected mice but that, as in Schistosoma mansoni infection, the development of hepatic fibrosis is critically dependent on IL-2 levels and granuloma size and hepatic fibrosis are differentially regulated.

Experimental schistosomiasis mansoni: modulation of granulomas by inhibition of collagen cross-link formation. Preliminary report

beta-Aminopropionitrile (BAPN) is an inhibitor of the lysyl oxidase required for cross-link formation in collagen maturation. The efficacy of BAPN, alone or in association with the anti-schistosomal drug, praziquantel (PZQ), was primarily assessed by measuring the reduction in liver and intestinal egg loads in murine schistosomiasis mansoni. Depending on the treatment group (PZQ, BAPN, BAPN + PZQ), organ-specific effects were observed using microscope image analysis. Most notable was the relatively small size of granulomas in the livers of BAPN-treated mice, which contrasted with the relatively large size and irregular shape of the granulomas in the intestinal tissues of these mice. Mice treated with the combination of BAPN and PZQ had decreased liver and spleen weights, and a significant reduction in the number of eggs trapped in both the liver (86%) and the intestine (99.1%), compared with untreated mice and those given PZQ alone. The lowest number of living eggs/g of tissue in both the liver and intestine was recorded in the combined BAPN + PZQ-treated group. These results suggest that the concurren treatment of infected mice with PZQ and BAPN enhances the release of eggs trapped in the intestine and also results in a significant reduction of liver egg load. The mechanism by which BAPN reduces the number of liver granulomas in PZQ-treated mice is currently being investigated.

Analysis of egg granuloma formation in Schistosoma japonicum-infected mice treated with antibodies to interleukin-5 and gamma interferon

Schistosoma japonicum-infected mice were treated with antibodies to interleukin-5 (IL-5) or gamma interferon (IFN-gamma) from week 3 or 4 to week 10 of infection. Neither antibody affected egg production by the parasite, and neither had a consistent effect on the secretion of IFN-gamma or IL-5 cell-related cytokines by spleen cells from infected mice. Mice treated with antibody to murine IL-5 had only rare eosinophils in hepatic circumoval granulomas. Granulomas around single eggs were reduced in volume by a third, but hepatic fibrosis was unaffected. Treatment with antibody to murine IFN-gamma also reduced the size of granulomas and also did not affect hepatic fibrosis, which was measured as hydroxyproline. Our results, taken together with the studies of others, indicate that a complex interaction of cytokines affects granuloma size and that the size and fibrosis of granulomas are to some extent regulated independently.

In vivo regulation of S. japonica granuloma formation by an IL-2 antagonist

The present study shows an in vivo role for interleukin-2 in the formation of hepatic granulomatous inflammation in murine Schistosoma japonicum infection. Mice which had been administered an inhibitor to interleukin-2 function during acute infection were noted to have reduced cell-mediated immune responses to ConA and S. japonicum soluble egg antigen (SEA). Lymphoid tissue from these treated mice also have reduced numbers of cells which could be activated by ConA to produce interleukin-2 mRNA as shown by in situ hybridization studies. Mice with less activated lymphocytes had, on the average, a 70% reduction in the granulomatous inflammation surrounding eggs deposited in hepatic tissues of acutely infected mice. The data demonstrate that IL-2 is a key factor in the generation of granulomatous inflammation in S. japonicum infection and suggest that a potential anti-pathology vaccine could be generated based on limiting the presence of IL-2 generated during acute infection.

Desmin expression in fibroblasts of murine periovular granuloma during liver Schistosoma mansoni infection

We have studied the expression of the desmin gene, a muscle-specific intermediate filament protein in the granuloma cells of mouse liver infected with Schistosoma mansoni. In situ hybridization using a desmin DNA probe showed that fibroblastic cells in the granuloma strongly expressed desmin mRNAs, while in normal liver these cells did not express this mRNA to a detectable degree. The quantitative analysis of total RNAs demonstrated that the proportion of specific desmin mRNA increased from 14 to 18 weeks after infection and decreased at 20 weeks. The analysis of collagen gene expression indicated that the amount of type III collagen mRNAs was still increasing after 18 weeks from infection; in contrast, the amount of type I collagen mRNAs remained unchanged at that stage. A good correlation was observed between the detection of the specific mRNAs and the detection of both desmin and collagen molecules. Therefore, these data point to a coordinate induction of desmin and collagen gene expression during Schistosomal granuloma formation. They also suggest that the expression of the myofibroblast phenotype involves the induction of both genes.

Patterns of sulfated glycosaminoglycan synthesis and accumulation in hepatic granulomas induced by schistosomal infection

We have characterized sulfated glycosaminoglycans of periovular granulomas induced in mouse liver by experimental infection with Schistosoma mansoni and determined parameters of their synthesis and accumulation by metabolic incorporation of 35S. The major component of glycosaminoglycans isolated from granulomas was dermatan sulfate and the minor component was heparan sulfate. A similar proportion was observed among newly synthesized 35S-labeled glycosaminoglycans, with a slight increase in the relative amount of heparan sulfate. Neither qualitative nor quantitative differences were observed between glycosaminoglycans isolated from granulomas of the acute and the chronic phase of the disease. In contrast, collagen content of granulomas increased eightfold during evolution of the disease from the acute to the chronic phase. It may be concluded that different mechanisms control glycosaminoglycan and collagen synthesis in schistosomal granulomas, as well as the ratio between these components in the extracellular matrix. This is consistent with the loose organization of the extracellular matrix in acute inflammatory reactions and its dense organization in the chronic reactions.

Dynamics of hepatic connective tissue matrix constituents during murine Schistosoma mansoni infection

Hepatic fibrosis is the major clinical sequela of infection with the helminth Schistosoma mansoni. However, little is known regarding its dynamics and regulation in schistosomiasis. The present study presents the dynamics of deposition and resorption of two major extracellular matrix components of fibrosis, glycosaminoglycans and collagens, during the course of experimental S. mansoni infection. Early in infection (6 weeks), glycosaminoglycan biosynthesis was markedly elevated, as was collagen biosynthesis. This led to significant accumulations of these two molecules at a glycosaminoglycan/collagen ratio similar to that observed in livers of uninfected mice (uronic acid/hydroxyproline ratio of 1.10 at 6 weeks compared to normal value of 1.25). During maximal hepatic fibrosis (12 to 18 weeks), both collagen and glycosaminoglycan biosynthesis continued to increase but the extracellular matrix shifted to a lower glycosaminoglycan/collagen ratio of 0.42, suggesting enhanced glycosaminoglycan breakdown. In addition, during this acute stage of infection, Type I collagen was the predominant isotype synthesized, whereas total collagenolytic activity degrading Type I collagen was maximal. During chronic infection, a decrease in the content of both hepatic glycosaminoglycans and collagens were noted, with a glycosaminoglycan/collagen ratio of 0.63. Decreased glycosaminoglycan content paralleled diminished biosynthetic rates. On the other hand, an over 50% reduction in collagen content (from 18 to 24 weeks) appeared not to result from diminished biosynthesis but from a switch in the predominant collagen isotype synthesized (from Type I to Type III), matched by an enhanced constitutive collagenolytic activity directed toward this type of collagen.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of chemotherapy on hepatic collagen and glycosaminoglycan metabolism in Schistosoma mansoni-infected mice

The dynamics of biosynthesis and accumulation of collagenous proteins and glycosaminoglycans (GAGs) in liver granulomas induced by eggs of Schistosoma mansoni were studied in mice following eradication of adult worms by chemotherapy. The relatively synchronous granulomas around parasite eggs were isolated from the livers at ensuing 2-week intervals; the number of recoverable granulomas per liver gradually decreased and was 7% of initial values at 20 weeks. Hepatic or granuloma-associated extracellular matrix components increased for 4 weeks after treatment despite cessation of ova deposition. At 12 weeks after chemotherapy the rate of GAG biosynthesis per total liver granuloma fraction, measured by 3H-glucosamine incorporation, decreased dramatically; this was followed by a decrease in the amount of GAGs present. The rate of collagen biosynthesis per total liver granuloma fraction, measured by 3H-proline incorporation, began to decline at 14 weeks and a decrease in the amount of collagen present was noted at 16 weeks. Our results demonstrated that liver granulomas induced by S. mansoni eggs synthesize collagens and GAGs for about 4-6 weeks following parasitological cure. The subsequent resolution of granulomas proceeds first by a reduction in GAG biosynthesis followed 4-8 weeks later by decreased collagen biosynthesis, followed by accelerated resolution of both collagen and GAGs.

Collagen isotypes, laminin, and fibronectin in granulomas of the liver and intestines of Schistosoma mansoni-infected mice

Patterns of fibrosis within hepatic and intestinal granulomas of Schistosoma mansoni-infected mice were analyzed by indirect immunofluorescence. Deposition of collagen isotypes, laminin, and fibronectin was evaluated semiquantitatively between 8 and 20 weeks of the infection. Liver granulomas were the largest at 8 weeks and contained low amounts of type I and higher amounts of type III collagen and fibronectin. Collagen deposition became pronounced as infection progressed. The relative amounts of type I collagen deposits rose and equalled that of type III. In the smaller immunomodulated granulomas at 20 weeks both types I and III were high, and type IV collagen deposition was observed. Fibronectin and laminin deposits were also detected. The small ileal granulomas did not change their size during the course of the infection. At 8 weeks, connective tissue matrix deposition was barely detectable within these lesions. Gradually, small deposits of types I and III appeared in equal amounts and attained highest levels by 20 weeks of the infection. Fibronectin deposits at that time were very prominent but laminin and type IV collagen were absent. Colon granulomas at 8 weeks of the infection were only somewhat smaller than those of the liver, yet contained very sparse deposits of types I and III collagen. During the ensuing weeks collagen deposits rose only slightly. By 20 weeks the granulomas diminished in size and within those lesions type III collagen was predominant. Whereas the presence of fibronectin was pronounced, type IV collagen and laminin were detectable only in trace amounts. These observations indicate the existence of important organ-related differences in the intragranulomatous deposition of connective tissue matrix.

Dynamics of hepatic glycosaminoglycan accumulation in murine Schistosoma japonicum infection

Hepatic fibrosis is the major pathologic sequela of schistosomiasis and is comprised of extracellular collagen and proteoglycan macromolecules. Glycosaminoglycans (GAGs), the major constituents of proteoglycan molecules, were studied in mice infected with Schistosoma japonicum. Total GAG content was measured by extraction of uronic acid from murine liver sections and isolated hepatic granulomas during the progression from acute (0-15 wk) to chronic (20-30 wk) infection. Infected livers contained elevated levels of uronic acid throughout infection when compared to noninfected livers. Glycosaminoglycan content was found to peak at a value of 2.5 +/- 0.1 pmol/mg tissue (five times normal value) in acute infection (6-15 wk), a time of increasing hepatic fibrosis. Peak uronic acid content in isolated granulomas was also observed during acute infection with a maximal value of 7.1 +/- 0.9 pmol/mg tissue (9-11 wk). During chronic infection (30 wk), hepatic uronic acid content was reduced by 68% in unfractionated liver tissue and by 49% in isolated granulomas (both p less than 0.05). This modulation in GAG accumulation appeared to result from decreased biosynthesis, inasmuch as during chronic infection GAG biosynthetic rates fell by 42% in liver tissue and 53% in isolated granulomas (both p less than 0.05). In addition to these quantitative changes in GAG metabolism, GAG disaccharides were examined qualitatively by high-pressure liquid chromatography, which resolved nonsulfated, 6-sulfated, and 4-sulfated disaccharides. Few qualitative changes were seen in the GAG profile between normal liver and acutely or chronically infected liver. Both the rapid modulation of GAG accumulation despite ongoing infection and its qualitative makeup differentiate hepatic fibrosis seen in schistosomiasis japonica from that observed in many other forms of fibrotic liver disease.

Network interactions in Schistosoma japonicum infection. Identification and characterization of a serologically distinct immunoregulatory auto-antiidiotypic antibody population

This study examined the role of naturally occurring anti-idiotypic antibody (anti-id), specific for epitopes on antibodies to schistosome egg antigens (SEA), in serosuppression during Schistosoma japonicum infection. Three anti-id preparations were obtained from pools of infected serum at 12, 16, and 30 wk of infection. Anti-id (12 wk) bound 36% of labeled anti-SEA antibodies, had an idiotype binding capacity (IBC) of 5 micrograms/ml, and did not suppress SEA-induced proliferation. Anti-id (16 wk) bound 17% of labeled anti-SEA antibodies, had 29 micrograms IBC/ml, and reduced 3H incorporation from 21.4 +/- 0.5 (10 micrograms/ml normal Ig) to 9.1 +/- 1.5 X 10(4) cpm (P less than 0.01). Anti-id (30 wk) bound 66% of labeled anti-SEA antibody, had 84 micrograms IBC/ml, and suppressed 3H incorporation by 88% (4.8 +/- 0.3 X 10(4) cpm, P less than 0.001). Analysis of the serologic reactivity of these three populations of anti-idiotypic antibodies revealed that anti-id (12 wk) described an idiotypic population of anti-SEA molecules containing a minor cross-reactive idiotype (SJ-CRIm). In contrast, anti-id (30 wk) described a serologically distinct, idiotypic population containing a major cross-reactive idiotype of anti-SEA molecules (SJ-CRIM). A monoclonal anti-id, which reacted with greater than 50% of the anti-SEA molecules describing SJ-CRIM, was profoundly suppressive in vitro and reduced granulomatous inflammation around parasite eggs in vivo from 113 X 10(3) micron2 to 23 X 10(3) micron2 (80% suppression, P less than 0.001). These observations suggest that immune network interactions modulate inflammation in chronic murine S. japonicum infection.