Iron transport across the human placenta is regulated by hepcidin.

BACKGROUND: Transport of iron across the placenta is critical for appropriate development of the fetus. Iron deficiency during pregnancy remains a major public health concern, particularly in low- and middle-income countries, often exacerbated by infectious diseases leading to altered iron trafficking via inflammatory responses. Herein, we investigate the role of hepcidin, a master regulator of iron homeostasis, on regulation of iron transport across trophoblast cells. METHODS: We utilized the Jeg-3 choriocarcinoma cell line for analysis of the expression of transferrin receptor, ferritin, and ferroportin as well as the export of 59Fe in the presence of hepcidin. Placental tissue from human term pregnancies was utilized for immunohistochemistry. RESULTS: Hepcidin treatment of Jeg-3 cells decreased the expression of ferroportin and transferrin receptor (TfR) and reduced the cellular export of iron. Lower expression of TfR on the syncytiotrophoblast was associated with the highest levels of hepcidin in maternal circulation, and ferroportin expression was positively associated with placental TfR. Placentas from small-for-gestational-age newborns had significantly lower levels of ferroportin and ferritin gene expression at delivery. CONCLUSIONS: Our data suggest that hepcidin plays an important role in the regulation of iron transport across the placenta, making it a critical link in movement of iron into fetal circulation. IMPACT: Hepcidin has a direct impact on iron transport across the human placenta. This study provides the first evidence of direct regulation of iron efflux from human trophoblast cells by hepcidin. These data extend our understanding of iron transport across the maternal-fetal interface, a process critical for fetal health and development.

Prevalence of Schistosoma japonicum infection among animals in fifty villages of Samar province, the Philippines.

In the Philippines, there is a need to understand the contribution of different domestic and wild animals in transmitting Schistosoma japonicum infection to humans better. The current study describes variation in animal S. japonicum prevalence across 50 endemic villages of Samar Province, the Philippines. A total of 50 villages were selected, 25 with predominantly rain-fed farms and 25 with some irrigation system. At least 35 cats, dogs, pigs, and water buffaloes each were randomly selected and 30 rat traps were set in each village. Fecal samples were collected for up to three consecutive days for each species. The Danish Bilharziasis Laboratory method (DBL method) was used to determine S. japonicum infection status. A hierarchical logistic regression model with clustering by village and with adjustment for measurement error of the DBL method was used to estimate the prevalence of infection per village and species. Stool samples were collected from 23.4% (1189), 28.6% (1274), 36.3% (1899), and 49.4% (873) of the censused dogs, cats, pigs, and water buffaloes, respectively, and from 663 rats. The adjusted prevalence of S. japonicum infection varied greatly across villages ranging from 1.6% (95% Bayesian Credible Interval: 0.1%-10.2%) to 86.3% (65.9%-97.8%) for dogs, from 0.1% (0%-2.1%) to 21.7% (4.7%-51.2%) for cats, from 0.01% (0.0%%-1.0%) to 18.4% (7.1%-34.7%) for pigs, from less than 0.1% (0.0%-1.2%) to 72.5% (46.0%-97.4%) for water buffaloes, and from 0.7% (0.0%-9.0%) to 95.4% (77.2%-99.9%) for rats. This is the most comprehensive study of animal S. japonicum infection conducted to date. Our results show that, unlike what has been reported in China, very few water buffaloes were infected whereas rats and dogs show high prevalence proportions of infection. This, combined with significant village-to-village variation in prevalence of S. japonicum infection, suggest possible different transmission dynamics of the infection in the Province of Samar in the Philippines and China.

Th2 cytokines are associated with persistent hepatic fibrosis in human Schistosoma japonicum infection.

We conducted a prospective cohort study in Leyte, the Philippines, among 611 Schistosoma japonicum-infected participants 7-30 years old, all of whom were treated with praziquantel at baseline. To detect hepatic fibrosis, abdominal ultrasound was performed at baseline and 12 months after treatment. Stool for assessment of S. japonicum infection was collected at baseline and at 3, 6, 9, and 12 months after treatment. Cytokines (interleukin [IL]-4, IL-5, IL-10, IL-13, tumor necrosis factor- alpha , and interferon- gamma ) produced by peripheral-blood mononuclear cells in response to soluble worm antigen preparation (SWAP), soluble egg antigen (SEA), and control medium were measured once 4 weeks after treatment. IL-4 to SWAP and IL-10 to both SWAP and SEA were associated with the presence of baseline fibrosis after adjustment for potential confounding variables (P<.03, for all). In participants with fibrosis at baseline, IL-4 to SWAP and IL-5 and IL-13 to both SWAP and SEA were associated with persistent fibrosis at 12 months after treatment (P<.05, for all). Males showed consistently stronger T helper 2 (Th2) cytokine responses to both SWAP and SEA than did females (P<.02, for all). These results suggest an independent role for Th2-biased cytokine responses to S. japonicum antigens in persistent hepatic fibrosis and indicate that Th2 cytokines may contribute to the male-biased prevalence of fibrosis.

Hepatosplenic morbidity in schistosomiasis japonica: evaluation with Doppler sonography.

In Southeast Asia, schistosomiasis japonica is an important cause of hepatic fibrosis and gastrointestinal hemorrhage. Reliable methods to investigate portal hypertension (PHT) clinically and epidemiologically on community level are lacking. Doppler sonography is an established tool for investigating PHT in hospital settings. In Leyte, The Philippines, 137 individuals underwent color Doppler sonography, stool examination, and serology for hepatitis B and C, liver cell injury and cholestasis. A total of 85% of the study population had been infected with Schistosoma japonicum. Sonographically, periportal liver fibrosis was seen in 25% and reticular echogenicities (network pattern) in 44%. Portal blood flow was decreased or portosystemic collaterals were present in 10% (adults throughout) and correlated with periportal fibrosis, but not with network lesions. Chronic viral hepatitis was rare. Thus, hepatic lesions are frequent in adults but not in children in areas endemic for S. japonicum. Periportal liver fibrosis indicates a risk of PHT, and network pattern fibrosis apparently does not. Doppler sonography is suitable for research under tropical field conditions.

Identification of the Schistosoma japonicum 22.6-kDa antigen as a major target of the human IgE response: similarity of IgE-binding epitopes to allergen peptides.

Human resistance to reinfection with Schistosoma mansoni and Schistosoma haematobium correlates with elevated IgE titers against worm antigens (soluble worm antigen preparation, SWAP). In S. mansoni infection, low levels of reinfection following chemotherapy are associated with the recognition of a cloned tegumental protein Sm22.6. Because of potential species-specific differences in resistance to schistosomes, we attempted to identify Schistosoma japonicum antigens recognized by human IgE. Following a survey of 176 infected individuals in Leyte, Philippines, we show that IgE antibodies from the majority of older, high-IgE/SWAP responders recognize antigens in the 22 (Sj22)-, 45-, 78- and 97-kDa range in SWAP. Limited IgE cross-reactivity between Sj22 and Sm22 was observed following a comparison of Filipino IgE responses to these antigens. The antigen was cloned from an adult S. japonicum lambda-ZAP cDNA library (Mindoro strain) by immunoscreening with pooled high-titer IgE antisera and a rabbit anti-Sj22 polyclonal antibody. The deduced amino acid sequence of the identified cDNA clone, MJ-1, showed significant homology to Sm22.6 (74%) and Sj22.6 (99%). Although the molecular sequence of Sj22.6 has already been reported, this is the first demonstration of its recognition by human IgE, thereby strengthening its potential as a vaccine candidate. Using an overlapping peptide approach, four IgE-binding epitopes were identified in Sj22.6, two of which exhibited similarities to known IgE-binding epitopes from codfish (Gad c 1) and beta-lactoglobulin-related allergens. These findings suggest that allergy and protective immunity to helminth infection may be linked by the structural similarities of epitopes recognized by human IgE.

The influence of sex and age on antibody isotype responses to Schistosoma mansoni and Schistosoma japonicum in human populations in Kenya and the Philippines.

We have investigated the effects of host age and sex on human antibody isotype responses to Schistosoma mansoni and Schistosoma japonicum adult worm (AW) and soluble egg (SEA) antigens, using sera from subjects in Kenya and the Philippines. Similar trends with age were observed between the two populations despite host, parasite and environmental differences between the two geographical locations. IgE to AW increased with age, whereas most isotype responses to SEA decreased with age. IgG1, IgG3 and IgG4 subclass responses to adult worm, however, did not show a broadly rising or falling pattern with age. Males were found to have higher IgG1, IgG4 and IgE to AW in both populations. This sex difference remained significant in the Kenyan population even after controlling statistically for confounding factors such as age and differences in intensity of infection. Analysis of S. mansoni and S. japonicum adult worm antigens reactive with IgE revealed a predominant 22 kDa band in both parasites. Only those individuals with relatively high IgE titres specifically reactive with S. mansoni or S. japonicum AW had detectable IgE against Sj22 or Sm22.

Schistosomiasis japonica in the Philippines: the long-term impact of population-based chemotherapy on infection, transmission, and morbidity.

The long-term impact of annual case-finding and chemotherapy with praziquantel on schistosomiasis japonica was examined in an 8-year longitudinal study in the Philippines. The prevalence, incidence, and intensity of infection and schistosome-induced hepatomegaly significantly decreased within 3-4 years of treatment and then stabilized despite continual population-based chemotherapy. Hepatomegaly rapidly developed in acutely infected persons, with 82% of subjects developing hepatic enlargement within 2 years of reinfection. These data suggest that abrupt discontinuation of current control measures in the Philippines may result in a rapid rebound in morbidity. Age-dependent acquired resistance to reinfection also developed in subjects chronically exposed to schistosomiasis japonica, suggesting that a vaccine may represent an alternative approach for control of this parasitic infection.

Impact of annual screening and chemotherapy with praziquantel on schistosomiasis japonica on Jishan Island, People's Republic of China.

The impact of annual screening and treatment with praziquantel on schistosomiasis japonica was examined on Jishan Island in Po Yang Lake, Jiangxi Province. China. Prevalence of infection in the community decreased from 39% in year 1 to 33% in year 3 with a corresponding decrease in the geometric mean egg count from 51 eggs per gram of stool (epg) to 31 epg. The most dramatic changes in infection status and intensity of infection were observed in younger individuals (0-19 years of age). The prevalence of hepatosplenomegaly also significantly decreased, again primarily in younger individuals. No change in the community prevalence of schistosome-induced hepatic fibrosis was observed as determined by ultrasonography. Longitudinal cohort analysis, however, demonstrated significant improvement in treated individuals with advanced hepatic fibrosis. These data indicate that annual screening and treatment had a significant impact on infection status and morbidity and suggest that community therapy may be an effective approach to control schistosomiasis japonica in lake regions and marshlands in China. Further studies are necessary to determine the optimal and most cost-effective approach for drug delivery.

Schistosomiasis japonica on Jishan Island, Jiangxi Province, People's Republic of China: persistence of hepatic fibrosis after reduction of the prevalence of infection with age.

Hepatic fibrosis due to schistosomiasis japonica was examined by ultrasonography in a cross-sectional community study of 825 individuals on Jishan Island, Jiangxi Province, China. The prevalence of active infection was 39.4% with peak infection in the 10-19.9 years age group followed by a significant decline. A similar pattern was observed for intensity of infection. The prevalence of hepatomegaly in the midsternal line > or = 6 cm peaked at 60% in the fourth decade and remained elevated. A progressive increase in the severity of hepatic periportal fibrosis was observed with age, with advanced fibrosis peaking in the fifth decade. The proportion of individuals with advanced fibrosis was significantly greater in males than in females despite equivalent prevalence and intensity of schistosome infection. In addition, a positive association (P < 0.01) was found between periportal fibrosis and both hepatomegaly > or = 6 cm and splenomegaly. This study suggests that the natural history of schistosomiasis japonica in this hyperendemic community in China is marked by persistence of hepatomegaly and schistosome-induced periportal fibrosis in adults despite a decrease in the prevalence of infection.

HBV exposure and HBsAg positivity rates in schistosomiasis japonica: study in a Philippine community endemic for both infections.

HBV exposure and HBsAg positivity rate were examined in 561 residents of an area endemic for S. japonicum and 22 additional cases with severe HSS japonica were also included. The differences in HBV exposure and HBsAg positivity rates among the groups without the parasitism, with schistosomiasis japonica and with HSS (53 cases) were not statistically significant. Comparison of the same parameters between those with and without S. japonicum infection according to sex and age groupings did not also show significant differences. Increasing intensity of S. japonicum infection was not associated with either increasing or decreasing HBV exposure and HBsAg positivity. It is postulated that HBV infection does not contribute to the production of HSS japonica mainly because HBV infection occurs at a much earlier age than S. japonicum infection.

Relationship of prevalence and intensity of infection to morbidity in schistosomiasis japonica: a study of three communities in Leyte, Philippines.

To determine whether prevalence and intensity of infection are factors in morbidity in schistosomiasis japonica, a cross-sectional study was undertaken in three villages in Leyte, Philippines, namely, Santol (A), Santa Rosa (B), and Macanip (C). Kato thick-smear fecal examination and egg counts were made on 289 of 341 residents in Village A (85%), 824 of 1,008 in Village B (82%), and 1,113 of 1,241 in Village C (90%). Prevalences of 26%, 39%, and 44%, respectively, were found in the three villages, the majority of their populations (56-74%) remaining uninfected. Most of the infected persons (17-30% of the total population) had light infections (10-100 eggs/g feces). Moderately infected persons (101-400 eggs/g) comprised a smaller segment (7-14%), while a very small proportion (2-7%) had heavy infections (greater than or equal to 401 eggs/g). Age prevalence and egg excretion peaked earlier in the areas with higher prevalence (B and C) than in the area with the lowest prevalence (A). There was no relationship between area prevalence and mean egg count. Symptoms of inability to work, weakness, abdominal pain, and diarrhea correlated with the presence of infection in the area with the highest prevalence (C), but not in the area with the lowest prevalence (A). Except for diarrhea, there was no relationship between symptoms and intensity of infection. Very few persons presented with hepatomegaly and/or splenomegaly (1-5%). The frequency of liver enlargement on the midsternal (measuring 3-6 cm and 6 cm or more) and midclavicular line (2-4 cm), as well as spleen enlargement (Hackett 2 or greater), correlated with the presence but not with the intensity of infection. Hepatomegaly was sex- and age-related, being most common among males and among adolescents aged 10-14 years.

Quantification, dynamics, and mechanisms of pulmonary inflammatory response around schistosomula of Schistosoma mansoni.

The inflammatory response around schistosomula injected into the lungs of uninfected mice and mice infected with Schistosoma mansoni was quantified. In uninfected mice, the inflammatory response started at 1 hour and peaked at 6 days, whereas in the infected mice, the inflammatory response was accelerated and peaked at 24 hours. This latter inflammatory reaction was 1.5 times greater than the 6-day reaction found in uninfected controls. Neutrophils and mononuclear cells were seen around schistosomula impacted into the pulmonary microvasculature by 1 hour; later, however, eosinophils constituted the predominant cell. This augmented inflammatory response was detected in mice infected with S mansoni first at 4 weeks after injection and peaked at 12 weeks. The augmented response correlated with acquired resistance as assayed by the recovery of the organisms from the lungs 4 days after challenge. Augmented inflammatory reaction and increased protection was induced by subcutaneous sensitization with dead schistosomula or eggs but not by cercariae or adult worms. Adoptive transfer of serum but not lymphoid cells from 12-15 week-infected mice resulted in augmented inflammation and enhanced resistance in recipient normal animals. The serum activity was absorbed by both schistosomula and eggs and was shown to reside in the fraction containing IgG1.