Proteomic changes at 8 weeks after infection are associated with chronic liver pathology in experimental schistosomiasis

Chronic Schistosoma mansoni infection can present as a moderate or severe disease, termed intestinal or hepatosplenic schistosomiasis, respectively. Similarly, either moderate splenomegaly or hypersplenomegaly syndrome develops in CBA/J mice by 20 weeks of infection and is similar to intestinal or hepatosplenic schistosomiasis respectively. Using this mouse model and two-dimensional differential in gel electrophoresis, the liver proteomic signatures of uninfected mice and mice infected for 6, 8, 12, or 20 weeks were compared, and significant protein spots identified using mass spectrometry. We found the greatest number of changes at 12 weeks suggesting that this period represents the peak time of change. Pathway analysis identified specific proteins and pathways that correlated to the pathological changes indicative of severe disease, and these pathways were involved as early as 8 weeks after infection. These findings provide insight into the development of severe liver pathology in schistosomiasis and may aid in developing biomarkers for hepatosplenic schistosomiasis.     

Morbidity of Schistosomiasis mansoni in the state of Minas Gerais, Brazil

From 2002 to 2005, a program of active search for patients with hepatosplenic schistosomiasis and schistosomal myeloradiculopathy has been implemented in the state of Minas Gerais by the local Health Department. The state was divided in 28 regional health centers and the local representatives have been trained to identify and direct patients with hepatosplenic schistosomiasis and neuroschistosomiasis to a reference center in Belo Horizonte, the capital of the state of Minas Gerais. Seventy five patients with hepatosplenic schistosomiasis and 54 with schistosomal myeloradiculopathy have been referred and examined in the reference center in a period of time of 3 years. Schistosomal myeloradiculopathy should be emphasized because the number of cases reported is increasing rapidly and when timely diagnosed and treated, they respond promptly to treatment. Left untreated, they die or become invalid for life. In our view, the time has come for more active investigation of the different aspects of morbidity caused by schistosomiasis mansoni in Brazil.     

Haemostatic abnormalities in hepatosplenic schistosomiasis mansoni

Hepatosplenic schistosomiasis is a complex immuno-regulatory disease and is major health problem in endemic countries. Acute bleeding is one of its most serious complications and often life-threatening. Clinical studies have demonstrated that the patients with hepatosplenic schistosomiasis are prone to develop complex haemostatic abnormalities that may be linked to the potential risk of bleeding from ruptured esophageal varices in these patients. The deficit in haemostatic parameters is more pronounced with the advancement of the disease and is maximal in the patients with experience of haematomesis. Evidences of enhanced generation of thrombin and plasmin indicate the presence of low-grade DIC in advanced hepatosplenic schistosomiasis, which is considered as a principal cause of haemostatic abnormalities in this endemic disease. Demonstration of procoagulant expression in peripheral blood monocytes of the patients and in the livers, spleens and intestines of S. mansoni-infected mice suggest their possible implication in the causation of DIC in S. mansoni infections. Moreover, because in vitro analysis indicates a participation of immune mechanisms in the localized procoagulant expression, it seems likely that the immune responses to schstosomes play a major role in the pathogenic mechanisms of haemostatic abnormalities in hepatosplenic schistosomiasis.     

Clinical aspects of hepatosplenic schistosomiasis: a contrast with cirrhosis.

The clinical picture of liver disease in endemic areas of Schistosomiasis mansoni differs in many ways from that observed in alcoholic and other types of cirrhosis. In hepatosplenic schistosomiasis there is predominance of the clinical manifestations of portal hypertension, e.g., bleeding esophageal varices, while ascites, jaundice, and hepatic precoma or coma are much less common. Ammonia tolerance is usually normal and helps explain the low mortality rate during bleeding. Of special interest is the observation of a high incidence of persistent hepatitis B surface antigenemia among patients with hepatosplenic schistosomiasis, suggesting increased susceptibility of such patients to the development of virus-induced chronic active hepatitis.     

Splenectomy Improves Hemostatic and Liver Functions in Hepatosplenic Schistosomiasis Mansoni

Background

Schistosomiasis mansoni is a chronic liver disease, in which some patients (5–10%) progress to the most severe form, hepatosplenic schistosomiasis. This form is associated with portal hypertension and splenomegaly, and often episodes of gastrointestinal bleeding, even with liver function preserved. Splenectomy is a validated procedure to reduce portal hypertension following digestive bleeding. Here, we evaluate beneficial effects of splenectomy on blood coagulation factors and liver function tests in hepatosplenic schistosomiasis mansoni compared to non-operated patients.

Methodology/Principal Findings

Forty-five patients who had undergone splenectomy surgery were assessed by laboratory analyses and ultrasound examination and compared to a non-operated group (n = 55). Blood samples were obtained for liver function tests, platelet count and prothrombin time. Coagulation factors (II, VII, VIII, IX and X), protein C and antithrombin IIa, plasminogen activator inhibitor-1 were measured by routine photometric, chromogenic or enzyme-linked immunosorbent assays, while hyperfibrinolysis was defined by plasminogen activator inhibitor-1 levels. Both groups had similar age, gender and pattern of periportal fibrosis. Splenectomized patients showed significant reductions in portal vein diameter, alkaline phosphatase and bilirubin levels compared to non-operated patients, while for coagulation factors there were significant improvement in prothrombin, partial thromboplastin times and higher levels of factor VII, VIII, IX, X, protein C and plasminogen activator inhibitor-1.

Conclusion/Significance

This study shows that the decrease of flow pressure in portal circulation after splenectomy restores the capacity of hepatocyte synthesis, especially on the factor VII and protein C levels, and these findings suggest that portal hypertension in patients with hepatosplenic schistosomiasis influences liver functioning and the blood coagulation status.     

Clinical versus ultrasound examination in the evaluation of hepatosplenic schistosomiasis mansoni in endemic areas

The best way to appraise the size of abdominal organs remains undefined. Herein we compare the size of liver and spleen in hepatosplenic schistosomiasis using clinical and ultrasound (US) examination, and the size of the organs measured by US with their visualization below the costal margin ("palpable by US"). For this study, 411 individuals from an endemic area for schistosomiasis mansoni in Brazil have been selected. We found that palpable spleens and left liver lobes are larger than non palpable ones. Also, 23% of normal spleens measured by US were palpable on clinical examination, and 22% of spleens increased in size on US were non palpable. A total of 21% of normal spleens were "palpable by US". We also found 54% of normal sized right liver lobes palpable on clinical examination, whilst 54% of the increased livers, measured by US, were non palpable. About 76% of normal right liver lobes were "palpable by US". We conclude that the association of clinical, ultrasound and magnetic resonance imaging (MRI) examinations, in the near future, should give the investigators the necessary tools to perform a more accurate clinical diagnosis of hepatosplenic schistosomiasis mansoni.     

Myofibroblasts in schistosomal portal fibrosis of man

Myofibroblasts, cells with intermediate features between smooth muscle cells and fibroblasts, have been described as an important cellular component of schistosomal portal fibrosis. The origin, distribution and fate of myofibroblasts were investigated by means of light, fluorescent, immunoenzymatic and ultrastructural techniques in wedge liver biopsies from 68 patients with the hepatosplenic form of schistosomiasis. Results demonstrated that the presence of myofibroblasts varied considerably from case to case and was always related to smooth muscle cell dispersion, which occurred around medium-sized damaged portal vein branches. By sequential observation of several cases, it was evident that myofibroblasts derived by differentiation of vascular smooth muscle and gradually tended to disappear, some of them further differentiating into fibroblasts. Thus, in schistosomal pipestem fibrosis myofibroblasts appear as transient cells, focally accumulated around damaged portal vein branches, and do not seem to have by themselves any important participation in the pathogenesis of hepatosplenic schistosomiasis.     

Clinical features of cerebral schistosomiasis, especially in cerebral and hepatosplenomegalic type

Clinical features of cerebral schistosomiasis type (CST) and hepatosplenic schistosomiasis type (HST), and typical cases of each type were presented. Results of comparative study of clinical symptoms of both type among three countries in Japan, China and Philippines were discussed. CST in Japan and HST in the Philippines showed unique profiles when they were compared with those in other two countries. Although the reason for the difference is not clear, it might be determined by infection burden, pathogenicity of schistosome and/or immune response to the parasite antigen in human hosts.     

Hemostatic Dysfunction Is Increased in Patients with Hepatosplenic Schistosomiasis Mansoni and Advanced Periportal Fibrosis

Background

Schistosomiasis mansoni is an endemic parasitic disease and a public health problem in Northeast Brazil. In some patients, hepatic abnormalities lead to periportal fibrosis and result in the most severe clinical form, hepatosplenic schistosomiasis. This study aimed to evaluate whether abnormal blood coagulation and liver function tests in patients with hepatosplenic schistosomiasis (n = 55) correlate with the severity of their periportal fibrosis.

Methodology/Principal Findings

Blood samples were used for liver function tests, hemogram and prothrombin time (International Normalized Ratio, INR). The blood coagulation factors (II, VII, VIII, IX and X), protein C and antithrombin IIa (ATIIa), plasminogen activator inhibitor 1 (PAI-1) and D-dimer were measured by photometry or enzyme linked immunosorbent assay. Hyperfibrinolysis was defined on the basis of PAI-1 levels and a D-dimer concentration greater than a standard cut-off of 483 ng/mL. Standard liver function tests were all abnormal in the patient group compared to healthy controls (n = 29), including raised serum transaminases (p<0.001) and lower levels of albumin (p = 0.0156). Platelet counts were 50% lower in patients, while for coagulation factors there was a 40% increase in the INR (p<0.001) and reduced levels of Factor VII and protein C in patients compared to the controls (both p<0.001). Additionally, patients with more advanced fibrosis (n = 38) had lower levels of protein C compared to those with only central fibrosis (p = 0.0124). The concentration of plasma PAI-1 in patients was one-third that of the control group (p<0.001), and D-dimer levels 2.2 times higher (p<0.001) with 13 of the 55 patients having levels above the cut-off.

Conclusion/Significance

This study confirms that hemostatic abnormalities are associated with reduced liver function and increased liver fibrosis. Of note was the finding that a quarter of patients with hepatosplenic schistosomiasis and advanced periportal fibrosis have hyperfibrinolysis, as judged by excessive levels of D-dimer, which may predispose them to gastrointestinal bleeding.     

Schistosomal glomerular disease (a review)

In this review paper schistosomal glomerulopathy is defined as an immune-complex disease. The disease appears in 12-15 per cent of the individuals with hepatosplenic schistosomiasis. Portal hypertension with collateral circulation helps the by pass of the hepatic clearance process and the parasite antigens can bind to antibodies in the circulation and be trapped in the renal glomerulus. Chronic membranous-proliferative glomerulonephritis is the most common lesion present and the nephrotic syndrome is the usual form of clinical presentation. The disease can be experimentally produced, and schistosomal antigens and antibodies, as well as complement, can be demonstrated in the glomerular lesions. Specific treatment of schistosomiasis does not seem to alter the clinical course of schistosomal nephropathy.     

Interference with the Host Haemostatic System by Schistosomes

Schistosomes, parasitic flatworms that cause the tropical disease schistosomiasis, are still a threat. They are responsible for 200 million infections worldwide and an estimated 280,000 deaths annually in sub-Saharan Africa alone. The adult parasites reside as pairs in the mesenteric or perivesicular veins of their human host, where they can survive for up to 30 years. The parasite is a potential activator of blood coagulation according to Virchow''s triad, because it is expected to alter blood flow and endothelial function, leading to hypercoagulability. In contrast, hepatosplenic schistosomiasis patients are in a hypocoagulable and hyperfibrinolytic state, indicating that schistosomes interfere with the haemostatic system of their host. In this review, the interactions of schistosomes with primary haemostasis, secondary haemostasis, fibrinolysis, and the vascular tone will be discussed to provide insight into the reduction in coagulation observed in schistosomiasis patients.Interference with the haemostatic system by pathogens is a common mechanism and has been described for other parasitic worms, bacteria, and fungi as a mechanism to support survival and spread or enhance virulence. Insight into the mechanisms used by schistosomes to interfere with the haemostatic system will provide important insight into the maintenance of the parasitic life cycle within the host. This knowledge may reveal new potential anti-schistosome drug and vaccine targets. In addition, some of the survival mechanisms employed by schistosomes might be used by other pathogens, and therefore, these mechanisms that interfere with host haemostasis might be a broad target for drug development against blood-dwelling pathogens. Also, schistosome antithrombotic or thrombolytic molecules could form potential new drugs in the treatment of haemostatic disorders.     

Schistosoma mansoni: a comparative study of plasma and erythrocyte lipid alterations in the experimentally infected mouse and in selected human patients

Alterations of plasma and erythrocyte lipids associated with hepatosplenic schistosomiasis mansoni were studied in the mouse and in human patients. Qualitative and quantitative differences were observed between the two species which indicated that the experimentally infected mouse should not be used as a model for altered lipid metabolism associated with Schistosoma mansoni infections in man. Also blood lipid values should not be used as prophylactic indicators for experimental therapeutical studies in the infected mouse, although lipid determinations could have clinical value in studies of human patients. In infected mice plasma cholesterol and phospholipid were significantly reduced (40 and 25%, respectively), but proportions of individual plasma phospholipids were unchanged. In contrast, only plasma cholesterol was reduced in human patients with compensated or decompensated hepatosplenic schistosomiasis (16 and 29%, respectively); of the individual phospholipids, lecithin was significantly increased and lysolecithin was decreased. The percentage of plasma total cholesterol was reduced in infected mice and patients suggesting that hypocholesterolemia is due mainly to decreased cholesteryl ester. Lipid changes also occurred in erythrocytes. Those of infected mice had significantly elevated membrane phospholipid content and no changes in cholesterol or in the proportions of the individual phospholipid fractions. In marked contrast, the erythrocytes of two groups of human patients had significantly higher levels of cholesterol without a raised total phospholipid concentration. Moreover, decreased proportions of lysolecithin and increased proportions of lecithin were apparent although only the increased membrane lecithin associated with compensated patients was statistically significant.     

Pathology of Schistosomiasis mansoni in rabbits

The pathology of schistosomiasis mansoni in rabbits was studied with special consideration to worm burden and duration of infection. Heavy and prolonged infections resulted in severe changes involving the intrahepatic portal vein branches, such as: polypoid endophlebitis, granulomatous endophlebitis and, later on, vascular occlusion and recanalization, vascular ectasia, fibrosis and hyalinization of the endothelial polyps. Living and dead adult worms, rather than the mature eggs, were the main pathogenetic factors. For some time the lesions tend to be limited to the portal vein branches, not extending to the periportal tissues, but, after 8 to 10 months, variable degree of portal, septal and intra-parenchymal fibrosis can be formed. However, both vascular and fibrotic changes in the liver had a focal distribution and therefore did not appear to cause portal hypertension and had no resemblance to the human pathology seen in cases of hepatosplenic schistosomiasis. Pathology of schistosomiasis in rabbits has peculiar aspects, which are worthwhile studying, since the model can be of interest for investigations, especially concerning the immunology and immunopathology of schistosomiasis mansoni.     

Histocompatibilty-linked susceptibility for hepatospleenomegaly in human schistosomiasis mansoni.

In schistosomiasis mansoni, the pathogenesis of hepatosplenic disease has been shown to be due primarily to immune mechanisms. The present study was designed to examine the relationship between the development of schistosomal hepatosplenomegaly in Egyptian school children and the HLA antigens. Two groups of schistosome-infected children with similar fecal egg counts were examined: one group (23 children) had no clinically demonstrable hepatosplenomegaly whereas all the children (28) in the second group suffered from liver enlargement. Furthermore, 13 of the 28 individuals in the latter group had splenomegaly as well. Our results show that hepatosplenomegaly was related to the presence of two HLA antigens: HLA AI and B5. The average relative risk of developing hepatomegaly is 29 for HLA AI and 18.9 for 55.6. Furthermore, the severity of hepatomegaly was correlated with the presence of these two HLA antigens. These findings represent a step toward elucidating the factors controlling the pathogenic mechanisms in human schistosomiasis mansoni.     

A Comparative Study of the Spatial Distribution of Schistosomiasis in Mali in 1984–1989 and 2004–2006

Background

We investigated changes in the spatial distribution of schistosomiasis in Mali following a decade of donor-funded control and a further 12 years without control.

Methodology/Principal Findings

National pre-intervention cross-sectional schistosomiasis surveys were conducted in Mali in 1984–1989 (in communities) and again in 2004–2006 (in schools). Bayesian geostatistical models were built separately for each time period and on the datasets combined across time periods. In the former, data from one period were used to predict prevalence of schistosome infections for the other period, and in the latter, the models were used to determine whether spatial autocorrelation and covariate effects were consistent across periods. Schistosoma haematobium prevalence was 25.7% in 1984–1989 and 38.3% in 2004–2006; S. mansoni prevalence was 7.4% in 1984–1989 and 6.7% in 2004–2006 (note the models showed no significant difference in mean prevalence of either infection between time periods). Prevalence of both infections showed a focal spatial pattern and negative associations with distance from perennial waterbodies, which was consistent across time periods. Spatial models developed using 1984–1989 data were able to predict the distributions of both schistosome species in 2004–2006 (area under the receiver operating characteristic curve was typically >0.7) and vice versa.

Conclusions/Significance

A decade after the apparently successful conclusion of a donor-funded schistosomiasis control programme from 1982–1992, national prevalence of schistosomiasis had rebounded to pre-intervention levels. Clusters of schistosome infections occurred in generally the same areas accross time periods, although the precise locations varied. To achieve long-term control, it is essential to plan for sustainability of ongoing interventions, including stengthening endemic country health systems.     

Pathogenesis of pipe-stem fibrosis of the liver (experimental observation on murine schistosomiasis)

Mice infected with 30 cercariae of Schistosoma mansoni developed portal and septal fibrosis due to the massive and concentrated deposition of eggs in the periportal areas which occurred following the 16th week after infection. The lesion resembled pipe-stem fibrosis seen in human hepatosplenic schistosomiasis in the following characters: portal fibrosis interconnecting portal spaces as well as portal spaces and central canals; portal inflammation; periovular granulomas; vascular obstruction and telangiectasia. The liver parenchyma maintained its normal architecture. Vascular injection techniques with Indian ink and vinylite revealed that the portal system developed numerous dilated collateral venules coming from the large and medium-sized portal branches, about 10 weeks after schistosome infection. The lodging of schistosome eggs into these collaterals resulted in granulomatous inflammation and fibrosis along all the portal tracts, thus forming the pipe-stem lesion. Although not readily demonstrable grossly, the pipe-stem fibrosis of murine schistosomiasis has many similarities with the human lesion and can be considered to have the same basic pathogenesis.     

Immune responses during human schistosomiasis mansoni. XVI. Idiotypic differences in antibody preparations from patients with different clinical forms of infection

Antibodies were purified from pooled sera from patients with different clinical forms of schistosomiasis mansoni on immunoaffinity columns of schistosome soluble egg Ag (SEA). As previously reported, T lymphocytes in PBMC preparations from schistosomiasis patients (but not control subjects who have never been infected) proliferate when cultured in the presence of certain of these anti-SEA purified antibodies. We now show that PBMC from most patients with chronic schistosomiasis, regardless of the clinical form of their infection, respond to anti-SEA antibodies from sera of asymptomatic (intestinal) or hepatointestinal patients. In stark contrast, none responds to anti-SEA antibodies purified from sera of acute or hepatosplenic patients. All of these multiclonal anti-SEA antibody preparations were active in anti-SEA ELISA assays and gave comparable patterns of reactivity with SEA upon immunoblotting analysis. Immunization of rabbits with some of these anti-SEA antibody preparations, followed by absorption of the rabbit antisera on absorbents of normal Ig, produced specific anti-Id reagents. Use of these reagents in competitive ELISA systems demonstrated that the Id in stimulatory and nonstimulatory anti-SEA antibody preparations differ with regard to the proportion of the serologically defined Id expressed by each. It appears possible to screen patients' plasmas for the presence of shared Id by use of suitable Id/anti-Id competitive ELISA assays. Taken together these data indicate that only certain Id-positive preparations are stimulatory to patients' PBMC, and the expression of these T cell stimulatory, immunoregulatory Id on anti-SEA antibodies correlates with the clinical form of a patient's infection.     

TIPS and splenorenal shunt for complications of portal hypertension in chronic hepatosplenic schistosomiasis–A case series and review of the literature

BackgroundTransjugular intrahepatic portosystemic shunt (TIPS) and shunt surgery are established treatment options for portal hypertension, but have not been systematically evaluated in patients with portal hypertension due to hepatosplenic schistosomiasis (HSS), one of the neglected tropical diseases with major impact on morbidity and mortality in endemic areas.MethodsIn this retrospective case study, patients with chronic portal hypertension due to schistosomiasis treated with those therapeutic approaches in four tertiary referral hospitals in Germany and Italy between 2012 and 2020 were included. We have summarized pre-interventional clinical data, indication, technical aspects of the interventions and clinical outcome.FindingsOverall, 13 patients with confirmed HSS were included. 11 patients received TIPS for primary or secondary prophylaxis of variceal bleeding due to advanced portal hypertension and failure of conservative management. In two patients with contraindications for TIPS or technically unsuccessful TIPS procedure, proximal splenorenal shunt surgery in combination with splenectomy was conducted. During follow-up (mean follow-up 23 months, cumulative follow-up time 31 patient years) no bleeding events were documented. In five patients, moderate and transient episodes of overt hepatic encephalopathy were observed. In one patient each, liver failure, portal vein thrombosis and catheter associated sepsis occurred after TIPS insertion. All complications were well manageable and had favorable outcomes.ConclusionsTIPS implantation and shunt surgery are safe and effective treatment options for patients with advanced HSS and sequelae of portal hypertension in experienced centers, but require careful patient selection.     

Prevalence of schistosome infections within molluscan populations: observed patterns and theoretical predictions

The paper draws together a large and scattered body of empirical evidence concerning the prevalence of snail infection with schistosome parasites in field situations, the duration of the latent period of infection in snails (and its dependence on temperature), and the mortality rates of infected and uninfected snails in field and laboratory conditions. A review and synthesis of quantitative data on the population biology of schistosome infections within the molluscan host is attempted and observed patterns of infection are compared with predictions of a schistosomiasis model developed by May (1977) which incorporates differential snail mortality (between infected and uninfected snails) and latent periods of infection. It is suggested that the low levels of prevalence within snail populations in endemic areas of schistosomiasis are closely associated with high rates of infected snail mortality and the duration of the latent period of infection within the mollusc. In certain instances, the expected life-span of an infected snail may be less than the duration of the latent period of infection. Such patterns generate very low levels of parasite prevalence. A new age prevalence model for schistosome infections within snail populations is developed and its predictions compared with observed patterns. The implications of this study of observed and predicted patterns of snail infection within molluscan populations are discussed in relation to the overall transmission dynamics of schistosomiasis.     

Evaluation of a 25-year-program for the control of schistosomiasis mansoni in an endemic area in Brazil

Background

Various studies showed that chemotherapy can control schistosomiasis morbidity, but association of measures (water supply, sewage disposal and increase of socioeconomic conditions) is necessary for transmission control.

Methodology/Principal Findings

A survey dealing with socioeconomic conditions, snail survey, contact with natural waters, and clinical and stool examinations was undertaken at an endemic area in the State of Minas Gerais, Brazil. The methodology used was the same for both evaluations (1981 and 2005). Four hundred and seventy-five out of 1,474 individuals studied in 1981 could be contacted. From these, 358 were submitted to stool examination, and 231 of them were clinically examined. Patients eliminating S. mansoni eggs in their stools were treated. The results showed that the prevalence rate in Comercinho, a municipality of the State of Minas Gerais, Brazil, was substantially reduced to 70.4% and 1.7% in 1981 and 2005, respectively, as well as the frequency of the hepatosplenic form (7% to 1.3%) after five treatments effectuated between 1981 and 1992. No other new case of this form was detected from 1981 onwards. Another important aspect to be considered was the improvement of people''s living standard that occurred in the region after more than two decades'' efforts (better housing, professional skill and adequate basic sanitation).

Conclusion/Significance

The control of morbidity and very significant decrease of schistosomiasis transmission in an area until then considered as hyperendemic was possible by means of association of successive specific treatments of the local population, together with the construction of privies, water supply in the houses and improvement of socioeconomic conditions.