Eosinophils mediate SIgA production triggered by TLR2 and TLR4 to control Ascaris suum infection in mice

Human ascariasis is the most prevalent but neglected tropical disease in the world, affecting approximately 450 million people. The initial phase of Ascaris infection is marked by larval migration from the host's organs, causing mechanical injuries followed by an intense local inflammatory response, which is characterized mainly by neutrophil and eosinophil infiltration, especially in the lungs. During the pulmonary phase, the lesions induced by larval migration and excessive immune responses contribute to tissue remodeling marked by fibrosis and lung dysfunction. In this study, we investigated the relationship between SIgA levels and eosinophils. We found that TLR2 and TLR4 signaling induces eosinophils and promotes SIgA production during Ascaris suum infection. Therefore, control of parasite burden during the pulmonary phase of ascariasis involves eosinophil influx and subsequent promotion of SIgA levels. In addition, we also demonstrate that eosinophils also participate in the process of tissue remodeling after lung injury caused by larval migration, contributing to pulmonary fibrosis and dysfunction in re-infected mice. In conclusion, we postulate that eosinophils play a central role in mediating host innate and humoral immune responses by controlling parasite burden, tissue inflammation, and remodeling during Ascaris suum infection. Furthermore, we suggest that the use of probiotics can induce eosinophilia and SIgA production and contribute to controlling parasite burden and morbidity of helminthic diseases with pulmonary cycles.

Lectin-Mediated Bacterial Modulation by the Intestinal Nematode Ascaris suum

Ascariasis is a global health problem for humans and animals. Adult Ascaris nematodes are long-lived in the host intestine where they interact with host cells as well as members of the microbiota resulting in chronic infections. Nematode interactions with host cells and the microbial environment are prominently mediated by parasite-secreted proteins and peptides possessing immunomodulatory and antimicrobial activities. Previously, we discovered the C-type lectin protein AsCTL-42 in the secreted products of adult Ascaris worms. Here we tested recombinant AsCTL-42 for its ability to interact with bacterial and host cells. We found that AsCTL-42 lacks bactericidal activity but neutralized bacterial cells without killing them. Treatment of bacterial cells with AsCTL-42 reduced invasion of intestinal epithelial cells by Salmonella. Furthermore, AsCTL-42 interacted with host myeloid C-type lectin receptors. Thus, AsCTL-42 is a parasite protein involved in the triad relationship between Ascaris, host cells, and the microbiota.

2-Methyl-pentanoyl-carnitine (2-MPC): a urine biomarker for patent Ascaris lumbricoides infection

Infections with intestinal worms, such as Ascaris lumbricoides, affect hundreds of millions of people in all tropical and subtropical regions of the world. Through large-scale deworming programs, World Health Organization aims to reduce moderate-to-heavy intensity infections below 1%. Current diagnosis and monitoring of these control programs are solely based on the detection of worm eggs in stool. Here we describe how metabolome analysis was used to identify the A. lumbricoides-specific urine biomarker 2-methyl pentanoyl carnitine (2-MPC). This biomarker was found to be 85.7% accurate in determining infection and 90.5% accurate in determining a moderate-to-heavy infection. Our results also demonstrate that there is a correlation between 2-MPC levels in urine and A. lumbricoides DNA detected in stool. Furthermore, the levels of 2-MPC in urine were shown to rapidly and strongly decrease upon administration of a standard treatment (single oral dose of 400 mg albendazole). In an Ascaris suum infection model in pigs, it was found that, although 2-MPC levels were much lower compared to humans, there was a significant association between urinary 2-MPC levels and both worm counts (p = 0.023) and the number of eggs per gram (epg) counts (p < 0.001). This report demonstrates that urinary 2-MPC can be considered an A. lumbricoides-specific biomarker that can be used to monitor infection intensity.

Localized multigene expression patterns support an evolving Th1/Th2-like paradigm in response to infections with Toxoplasma gondii and Ascaris suum

Human infectious diseases have been studied in pigs because the two species have common microbial, parasitic, and zoonotic organisms, but there has been no systematic evaluation of cytokine gene expression in response to infectious agents in porcine species. In this study, pigs were inoculated with two clinically and economically important parasites, Toxoplasma gondii and Ascaris suum, and gene expression in 11 different tissues for 20 different swine Th1/Th2-related cytokines, cytokine receptors, and markers of immune activation were evaluated by real-time PCR. A generalized Th1-like pattern of gene expression was evident in pigs infected with T. gondii, along with an increased anti-inflammatory gene expression pattern during the recovery phase of the infection. In contrast, an elevated Th2-like pattern was expressed during the period of expulsion of A. suum fourth-stage larvae from the small intestine of pigs, along with low-level Th1-like and anti-inflammatory cytokine gene expression. Prototypical immune and physiological markers of infection were observed in bronchial alveolar lavage cells, small intestinal smooth muscle, and epithelial cells. This study validated the use of a robust quantitative gene expression assay to detect immune and inflammatory markers at multiple host tissue sites, enhanced the definition of two important swine diseases, and supported the use of swine as an experimental model for the study of immunity to infectious agents relevant to humans.

Selective alterations in mast cell subsets and eosinophil infiltration in two complementary types of intestinal inflammation: ascariasis and Crohn's disease

OBJECTIVE

Numbers of mast cells (MCs) of different subpopulations and the extent of eosinophil infiltration were compared in Crohn's disease and ascariasis. These two types of intestinal inflammation are complementary with regard to T cell response (TH1 versus TH2), prevalence and environmental factors.

METHODS

Histochemical, immunohistochemical and ultrastructural tools were applied to biopsies of morphologically uninvolved colon, ileum and duodenum from Crohn's and ascariasis patients, as well as resection margins and tissues from an experimental porcine ascariasis model. MC subsets were defined by their dye-binding properties, and their chymase content was analysed using biochemical tools.

RESULTS

The TH2 (IgE-mediated) response in ascariasis was characterised by a dramatic increase in mucosal- type MCs (MMCs) and eosinophils in both the mucosa and the deeper layers of the intestinal wall and a simultaneous decrease of connective tissue-type MCs (CTMCs). Uninvolved intestine of Crohn's patients showed moderate proliferation of CTMCs in the deeper layers of the intestinal wall, but a significant decrease of the MMCs, associated with moderate eosinophilia in all layers of the gut. Similar changes were present in the uninvolved duodenum of Crohn's patients. Comparable amounts of chymase could be extracted from mucosal and submucosal duodenum, with similar proportions of its two principal isoforms in each.

CONCLUSIONS

Our results indicate that T cell responses (TH1 or TH2) are associated with different MC subsets in intestinal inflammation. Changes remote from the focus of inflammation point to the systemic nature of the different MC responses.

Serum malondialdehyde level in patients infected with Ascaris lumbricoides

AIM: The aim of the study was to investigate the changes of serum malondialdehyde level, i.e; the oxidative stress hypothesis in patients infected with Ascaris lumbricoides.

METHODS: Serum malondialdehyde activity was measured in 43 patients who were positive for intestinal parasite of Ascaris lumbricoides. Scores were obtained for the positives and their age-and sex-matched 60 Ascaris lumbricoides negative healthy controls.

RESULTS: The difference between malondialdehyde levels of patients infected with Ascaris lumbricoides and control group was statistically significant both for females (P < 0.05) and for males (P < 0.05). In the patient and control groups, no correlation was found between age and malondialdehyde levels (P > 0.05) both in females and in males. In addition, no significant correlation could be found between malondialdehyde levels of both females and males for patients and control groups (P > 0.05).

CONCLUSION: Malondialdehyde levels clearly increase in patients infected with Ascaris lumbricoides.

Increase in serum beta-carotene following dark green leafy vegetable supplementation in Mebendazole-treated school children in Bangladesh

OBJECTIVE

To study the effect of consumption of dark green leafy vegetables (DGLV) and sweet pumpkin on serum beta-carotene and retinol concentrations in children treated for Ascaris lumbricoides.

DESIGN

Experimental study with a randomised design.

SUBJECTS

A total of 110 primary school children aged 8-12 y in northwestern Bangladesh.

INTERVENTIONS

All children were de-wormed and 2 weeks later randomly assigned to one of three groups to receive for 6 days per week, for 6 weeks, one complete meal containing either: (1) 4.4 mg beta-carotene from DGLV (n=37, after 18 dropouts); (2) 1.5 mg beta-carotene from sweet pumpkin (n=36, 18 dropouts); or (3) vegetables containing virtually no beta-carotene (control) (n = 37, 18 dropouts).

RESULTS

Significant increases (P < 0.001) in mean serum beta-carotene concentrations were seen in all three study groups, with a statistically higher increase (micromol/l) in the DGLV group (0.44; 95% confidence interval (CI) 0.32, 0.55) compared to the control group (0.20; 95% CI 0.14, 0.26; P = 0.002). The increase in serum retinol (micromol/l) was statistically significant (P=0.04) only in the DGLV group (mean 0.066; 95% CI 0.002, 0.13), but this increase was not different from the increase in the control group.

CONCLUSION

In children successfully treated for Ascaris lumbricoides, a substantial increase in serum beta-carotene was seen after feeding with a moderately high cumulative dose of DGLV for 6 weeks.

Relationship of childhood protein-energy malnutrition and parasite infections in an urban African setting

A clear understanding of protein-energy malnutrition (PEM), parasite infection and their interactions is essential in formulating health and development policies. We studied the prevalence of PEM indicators and the prevalence and/or intensity of infection in 558 Zairian children aged 4 months to 10 years. Multivariate analyses were used to estimate relationships between PEM indicators and parasitic infection. Stunting was found in 40.3% of children, wasting in 4.9% and kwashiorkor in 5.1%. The risk of stunting was significantly higher in children with Ascaris lumbricoides. The risk of wasting was higher in children with A. lumbricoides or Trichuris trichiura, whereas the risk of kwashiorkor was high with T. trichiura but very reduced in those with A. lumbricoides. Plasmodium infection was not related to nutritional indicators. These relationships highlight important interactions, both synergistic and antagonistic, between nutrition and parasites in central Africa.

Effect of intestinal helminthiasis on intestinal permeability of early primary schoolchildren

Intestinal permeability of 246 early primary schoolchildren at 2 schools (106 of whom were infected with intestinal helminths) was assessed by using the lactulose/mannitol differential absorption test. The ratio of the urinary recoveries of lactulose and mannitol was determined after oral administration of a standard solution of the 2 sugars. Assessment of intestinal permeability was repeated on 100 infected children after treatment and on a cohort of 68 uninfected children. Infected and uninfected groups were compared with respect to baseline lactulose/mannitol ratio (L/M1) and change in lactulose/mannitol ratio between assessments (delta L/M). The correlations between baseline intensity of infection and L/M1, and between fall in intensity and delta L/M, were evaluated. Based on a crude index of socioeconomic status, each child was assigned to one of 3 socioeconomic groups; all but 3 children belonged to either groups 2 or 3. Trichuris trichiura and Ascaris lumbricoides were the 2 predominant infections; the hookworm infection rate was relatively low. The results suggested that helminthiasis exerted only a marginal effect on intestinal permeability, the impact of which in children from lower socioeconomic backgrounds was negligible in comparison with the cumulative effects of other factors.

Vitamin A absorption in children with ascariasis

The effect of Ascaris lumbricoides infection on retinol absorption was investigated in young children from a slum area of Dhaka City, Bangladesh. Twenty-four children aged 4-10 years were screened and in every case eggs of either Ascaris, Trichuris or hookworm were isolated from the stool. The average serum retinol was 0.91 (SD 0.35) mumol/l and sixteen children had levels below 1.05 mumol/l. This compared with a serum retinol concentration of 1.70 (SD 0.52) mumol/l in five reference children from a more privileged social background. An oral dose of retinol (41.8 mumol) was given to ten children in whom the concentration of Ascaris eggs in the stool varied. Less than 1% of the supplement could be recovered in the stools collected over the following 48 h. Ascaris worms were isolated from the stool and assayed for retinol content. In no case was retinol detected in the worms. These findings do not support the contention that infection with Ascaris predisposes to malabsorption of vitamin A.

Absorption of carbohydrate from rice in Ascaris lumbricoides infected Burmese village children

With the objective of determining the relationship between ascariasis and carbohydrate absorption from rice, breath hydrogen tests (BHT's) were performed in two study populations of Burmese village children. Using a rice test meal, breath hydrogen peaks greater than 10 ppm above baseline within 4 hours (indicating rice malabsorption) were seen in 24 out of 55 (44 per cent) Ascaris lumbricoides infected children and 3 out of 18 (17 per cent) non-infected children (age 18-59 months). In another ascaris endemic village 139 children (age 36-108 months) underwent a rice meal BHT. Seventy children had been regularly dewormed for 2 years (single dose levamisole 50 mg every 3 months) whilst 69 children had been dewormed once in 2 years, 6 weeks before breath testing. Regularly dewormed children showed a lower prevalence of rice malabsorption (33 per cent) compared to the control group (54 per cent) (P < 0.05). These findings suggest that malabsorption of carbohydrate from rice can occur during Ascaris lumbricoides infection in children.

Influence of intestinal parasitism on lactose absorption in well-nourished African children

Hydrogen breath tests were performed in Gabon (Central Africa) after a loading dose of lactose in 67 well-nourished African children (50 with intestinal parasites and 17 unparasitized) and in 18 unparasitized young adults. All had normal nutritional status, and none had diarrhea or digestive symptoms. Parasites that were found included Ascaris lumbricoides in 76% of the parasitized children, Trichuris trichiura in 58%, Giardia in 24%, Entamoeba histolytica in 20%, Schistosoma intercalatum in 16%, and Necator Americanus in 14%. A similar proportion of parasitized (64%) or unparasitized (62.8%) subjects were lactose malabsorbers. Giardia infection was associated with a higher, but not significantly different, proportion of lactose intolerance (10 of 12, 83.3%). The presence of infection with A. lumbricoides or T. trichiura did not increase the percentage of lactose malabsorption. These data indicate that a decrease of lactase activity in well-nourished African children is not related to the presence or the importance of Ascaris or other intestinal parasites if the nutritional status is normal.

[Experience with the use of nemocide (pyrantel pamoate) in nematodiases]

The clinical efficacy of and tolerance to the nemocide pyranthel pamoate produced by "IPCA" (India) and applied to nematodiasis treatment have been investigated. A high efficacy of the drug (94.4-100%) for ascariasis, enterobiasis and ancylostomiasis treatment has been established. The drug is well tolerated by adults and induces slight short-term alterations of hepatic functional activity in 5-10-year-old children.

Ascaris suum ova-induced bronchoconstriction, eosinophilia, and IgE antibody responses in experimentally infected primates did not lead to histamine hyperreactivity

The hypothesis that active immunization of primates to give airway allergic responses would also confer on them a hyperreactivity to a nonspecific stimulus such as histamine was tested in 29 normal rhesus primates. At 6 wk after immunization, specific primate IgE (Rast) to Ascaris antigen had increased from 0.35 +/- 0.17 to 0.98 +/- 0.35 units/ml x 10(2) (p less than 0.05). Histamine released from bronchial alveolar lavage cells in response to antigen increased from 5.4 +/- 0.67 to 24 +/- 1.8ng/10(6) cells (p less than 0.05). In a subgroup of seven animals, airway resistance RL and compliance before and after feeding embryonated Ascaris ova increased from RL 3.5 +/- 3.1 to 275 +/- 212 cm H2O/L/s (p = 0.02) and Cdyn fell from 81 +/- 10 to 11.3 +/- 12 ml/cm H2O (p less than 0.05). The bronchial lavage fluid contained a very high percentage of eosinophils after infection, 8 +/- 3.1 to 24 +/- 13% per 500 cells counted, and did not increase appreciably upon later antigen challenge, 24 +/- 13 to 31 +/- 11% of the cells at 9.5 h after antigen challenge (p = NS). When a group of seven of these 29 animals were compared for their histamine responsiveness before and after acquired Ascaris airway reactivity, there was no difference in 19 animals. Pulmonary response to histamine delivered from freon canisters at doses of 0.005, 0.01, 0.025, and 0.05% did not change (RL, 141 +/- 102 to 93 +/- 62; Cdyn, 49 +/- 7 to 46 +/- 11% change before and after, respectively) (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of ascariasis and its treatment on drug absorption

Ascariasis has been reported to impair the absorption of nutrients, vitamin A, and D-xylose, which is corrected on treatment. The effect of ascariasis and its treatment on the absorption of sulphadimidine and isoniazid has been investigated. There was no difference between drug absorption before and after the treatment or in comparison with a normal population.

Plasma albumin concentrations and intestinal permeability in Bangladeshi children infected with Ascaris lumbricoides

Plasma albumin concentration and intestinal permeability have been investigated in Bangladeshi children before and 9-14 d after successful treatment for ascariasis. Children infected with A. lumbricoides had lower plasma albumin concentrations than counterparts not harbouring this worm and values increased with successful treatment. Intestinal permeability tests indicated that the children had impaired gastrointestinal function and some loss of mucosal integrity; these factors had not improved 9-14 d after A. lumbricoides expulsion. The lowered nitrogen nutritional status implied by the reduced plasma albumin values in infected children, and the improvement following treatment, are in keeping with previous reports that A. lumbricoides impairs protein digestion or absorption. This may be the basis of the better growth rates of dewormed children in this area.

Influence of an experimental infection of Ascaris suum on performance of pigs

Thirty-two pigs (average 26.6 kg live weight) were individually housed and fed to study the effect of an infection of Ascaris suum (either 0, 600, 6,000 or 60,000 A. suum eggs/pig) on performance of growing-finishing pigs. Increasing the level of A. suum infection produced linear (P less than .07) and quadratic (P less than .09) effects on final weight, weight gain and average daily gain. Feed to gain ratio and number of A. suum worms recovered from the intestines of pigs at slaughter increased linearly (P less than .01) with increasing doses of A. suum eggs. Pigs receiving 60,000 A. suum eggs were 13% less (P less than .01) efficient than the noninfected controls. In each of two trials, eight crossbred barrows (15.7 kg in trial 1 and 16.1 kg body weight in trial 2) were examined for the effects of two levels of A. suum infection (0 and 20,000 eggs/pig) on digestibility coefficients for dry matter, crude protein and gross energy. The infection did not affect (P greater than .05) digestibility coefficients during the first two collection periods (d 6 through 10 and 19 through 23). However, digestion coefficients for dry matter, crude protein and gross energy obtained from the total collection period on d 33 through 37 postinfection were greater (P less than .01) for control pigs than for pigs given 20,000 A. suum eggs each. Also, N retention was greater (P less than .05) for control pigs than for infected pigs.

Some experimental approaches to the study of nutrition and parasitic infection

Two experimental models to examine the relationship between host nutrition and parasitic infection are considered. Moniliformis dubius, an acanthocephalan parasite of the laboratory rat, is dependent on the type and amount of host dietary carbohydrate for growth and reproduction. Starch, glucose, fructose, and mannose in host diets support parasite growth and development, but much lower dietary amounts of starch, fructose, and mannose are needed compared to free glucose. The pig-Ascaris suum relationship is considered as a model for human ascariasis. Experimental Ascaris infections in pigs resulted in reduced growth, reduced food intake, lowered biological value of dietary protein, and reduced intestinal lactase activity and lactose tolerance. These results are similar in some respects to reported effects of Ascaris infection in humans.

Ascariasis: nutritional implications

Ascaris lumbricoides, the roundworm, is one of the largest parasites of man and probably infects one in four persons in the world. Despite its prevalence, ascariasis is a largely neglected public health problem that has attracted relatively little scientific inquiry. Frequently, a number of biases contribute to the uncritical conclusion that infection with A. lumbricoides adversely affects the nutritional status of the host. This situation is exacerbated by number of studies that have confirmed these biases but have employed questionable methods, such as the use of small samples and indistinct categories, the neglect of the double-blind safeguard, the selection of inadequate controls, and the performance of experiments that are not reproducible in a variety of circumstances. It is interesting to note that studies claiming positive correlation between ascariasis and protein energy malnutrition have not found a significant difference in weight between infected and uninfected children before intervention. Furthermore, several recent studies have shown no significant improvement in nutritional status after intervention. Thus, the causal relationship between ascariasis and protein energy malnutrition is not clearly proved, and it is premature to advocate mass treatment of children in ascariasis-endemic areas as a method to enhance their growth and development.

Absorption of macronutrients from a rice-vegetable diet before and after treatment of ascariasis in children

The apparent absorption of nitrogen (N), fat, and total energy from a rice and vegetable diet was measured in 13 children of similar nutritional status but infected with varying loads of Ascaris lumbricoides. Apparent N absorption was modestly decreased initially in subjects with heavy infections as compared to those with light infections (57.2% of intake versus 64.1% of intake, 0.05 < P < 0.1). After antihelminthic therapy there ws a significant improvement in apparent N absorption (P < 0.02), apparent N retention (P < 0.05), and apparent fat absorption (P < 0.05) for the group as a whole, particularly for those with heavy infections. Total energy absorption improved slightly, but not significantly, after treatment, and there was no change in xylose excretion tests. Treatment of ascariasis may be nutritionally advantageous for children with heavy worm burdens and marginal protein availability.

Ascariasis and malnutrition. A study in urban Ethiopian children

Treatment of 13 urban Ethiopian children with mild ascariasis did not produce any evidence of improved intestinal morphology and absorption or nutritional status. Ascariasis treatment had no impact on anthropometric measures in an additional study group of 84 children. A review of the literature reveals that the nutritional consequences of ascariasis are uncertain.

Malabsorption of water miscible vitamin A in children with giardiasis and ascariasis

Vitamin A absorption was studied using a water-miscible oral preparation of vitamin A in 19 children ages 1 1/2 to 9 years old with giardiasis and/or ascariasis, both before and after their eradication with appropriate therapy, and in three children without parasites. Marked impairment of vitamin A absorption was noted when administered in a water miscible form in children with 1) combined infection with Giardia lamblia and Ascaris lumbricoides, 2) giardiasis alone, and 3) in a proportion of children with ascariasis alone. In children with both giardiasis and ascarasis eradication of the infections promptly lead to a significant improvement in vitamin A absorption and restored it to normal. Children with giardiasis alone also showed improved vitamin A absorption after therapy. In children with ascariasis alone successful therpay did not lead to a statistically significant improvement.

Vitamin A absorption in ascariasis

Vitamin A absorption was studied in a group of 28 adult patients with ascariasis and 12 healthy adult controls, using a simplified vitamin A absorption test. In over 70% of the patients with ascariasis malabsorption of vitamin A was demonstrated. Stool egg counts for ascaris were not related to the degree of vitamin A malabsorption. Of the 23 patients in whom a D-xylose absorption test was performed, seven showed excretion less than 20% in 5 hr. Immediately after expulsion of the worms, vitamin A absorption improved in 13 out of 14 patients tested (in nine to normal level). The results of this study suggest that ascariasis in populations on marginal intakes of vitamin A and its precursors is an important contributing factor in producing clinical vitamin A deficiency.

Absorption of vitamin A in children with ascariasis

Absorption of labelled vitamin A was studied in normal children and in children with round-worm infestation. Absorption of the vitamin was significantly low in children with ascariasis. In two subjects, in whom the studies were repeated, absorption of vitamin A was significantly increased after antihelminthic treatment. These results suggest that ascariasis may aggravate vitamin A deficiency by interfering with the absorption of the vitamin.