Early pulmonary response in rats infected with Trichinella spiralis

Impact of resveratrol and zinc on biomarkers of oxidative stress induced by Trichinella spiralis infection

Trichinellosis is a re-emerging worldwide foodborne zoonosis. Oxidative stress is one of the most common detrimental effects caused by trichinellosis. In addition, Trichinella infection poses an infinite and major challenge to the host's immune system. Resistance and side effects limit the efficiency of the existing anti-trichinella medication. Given that concern, this work aimed to investigate the anti-helminthic, antioxidant, anti-inflammatory and immunomodulatory effects of resveratrol and zinc during both phases of Trichinella spiralis infection. Sixty-four Swiss albino mice were divided into four equal groups: non-infected control, infected control, infected and treated with resveratrol, and infected and treated with zinc. Animals were sacrificed on the 7th and 35th days post-infection for intestinal and muscular phase assessments. Drug efficacy was assessed by biochemical, parasitological, histopathological, immunological, and immunohistochemical assays. Resveratrol and zinc can be promising antiparasitic, antioxidant, anti-inflammatory, and immunomodulatory agents, as evidenced by the significant decrease in parasite burden, the significant improvement of liver and kidney function parameters, the increase in total antioxidant capacity (TAC), the reduction of malondialdehyde (MDA) level, the increase in nuclear factor (erythroid-derived 2)-like-2 factor expression, and the improvement in histopathological findings. Moreover, both drugs enhanced the immune system and restored the disturbed immune balance by increasing the interleukin 12 (IL-12) level. In conclusion, resveratrol and zinc provide protection for the host against oxidative harm and the detrimental effects produced by the host's defense response during Trichinella spiralis infection, making them promising natural alternatives for the treatment of trichinellosis.

The bronchus-associated-lymphoid tissue (BALT) an unique lymphoid organ in man and animals

The development structure and number of bronchus-associated lymphoid tissue (BALT) will be described in many different animals (like chicken, rabbit, mouse, rat, farm animals and particular the pig, monkey) and these data compared to healthy man and in human diseases. The term induced BALT should not be used because it is a tertiary lymphoid structure, which lacks the contact to a bronchus and does not consist of the important area (dome area) which is essential for antigen uptake of microbial stimuli, which are essential in the development of BALT. Mycoplasma seems to play a critical role as shown in pigs but there not been documented in other species like rabbits. More studies have to be performed in health and disease (e.g. in apes) to document the structural and functional basis to use BALT as an entry site for vaccination protocols.

Cellular and molecular changes and immune response in the intestinal mucosa during Trichinella spiralis early infection in rats

Background:

The main targets of the host’s immune system in Trichinella spiralis infection are the adult worms (AW), at the gut level, and the migrant or newborn larvae (NBL), at systemic and pulmonary levels. Most of the studies carried out in the gut mucosa have been performed on the Payer’s patches and/or the mesenteric lymph nodes but not on the lamina propria, therefore, knowledge on the gut immune response against T. spiralis remains incomplete.

Methods

This study aimed at characterizing the early mucosal immune response against T. spiralis, particularly, the events taking place between 1 and 13 dpi. For this purpose, Wistar rats were orally infected with muscle larvae of T. spiralis and the humoral and cellular parameters of the gut immunity were analysed, including the evaluation of the ADCC mechanism exerted by lamina propria cells.

Results

A marked inflammation and structural alteration of the mucosa was found. The changes involved an increase in goblet cells, eosinophils and mast cells, and B and T lymphocytes, initially displaying a Th1 profile, characterised by the secretion of IFN-γ and IL-12, followed by a polarization towards a Th2 profile, with a marked increase in IgE, IgG1, IL-4, IL-5 and IL-13 levels, which occurred once the infection was established. In addition, the helminthotoxic activity of lamina propria cells demonstrated the role of the intestine as a place of migrant larvae destruction, indicating that not all the NBLs released in the gut will be able to reach the muscles.

Conclusions

The characterization of the immune response triggered in the gut mucosa during T. spiralis infection showed that not only an effector mechanism is directed toward the AW but also towards the NBL as a cytotoxic activity was observed against NBL exerted by lamina propria cells.

Preliminary Trichinella spiralis Infection Ameliorates Subsequent RSV Infection-Induced Inflammatory Response

Respiratory syncytial virus (RSV) infection affects the lives of neonates throughout the globe, causing a high rate of mortality upon hospital admission. Yet, therapeutic options to deal with this pulmonary pathogen are currently limited. Helminth therapy has been well received for its immunomodulatory role in hosts, which are crucial for mitigating a multitude of diseases. Therefore, in this study, we used the helminth Trichinella spiralis and assessed its capabilities for modulating RSV infection as well as the inflammatory response induced by it in mice. Our results revealed that RSV-specific antibody responses were enhanced by pre-existing T. spiralis infection, which also limited pulmonary viral replication. Diminished lung inflammation, indicated by reduced pro-inflammatory cytokines and inflammatory cell influx was confirmed, as well as through histopathological assessment. We observed that inflammation-associated nuclear factor kappa-light-chain enhancement of activated B cells (NF-κB) and its phosphorylated forms were down-regulated, whereas antioxidant-associated nuclear factor erythroid 2-related factor 2 (Nrf2) protein expression was upregulated in mice co-infected with T. spiralis and RSV. Upregulated Nrf2 expression contributed to increased antioxidant enzyme expression, particularly NQO1 which relieved the host of oxidative stress-induced pulmonary inflammation caused by RSV infection. These findings indicate that T. spiralis can mitigate RSV-induced inflammation by upregulating the expression of antioxidant enzymes.

Role of iBALT in Respiratory Immunity

Pulmonary respiration inevitably exposes the mucosal surface of the lung to potentially noxious stimuli, including pathogens, allergens, and particulates, each of which can trigger pulmonary damage and inflammation. As inflammation resolves, B and T lymphocytes often aggregate around large bronchi to form inducible Bronchus-Associated Lymphoid Tissue (iBALT). iBALT formation can be initiated by a diverse array of molecular pathways that converge on the activation and differentiation of chemokine-expressing stromal cells that serve as the scaffolding for iBALT and facilitate the recruitment, retention, and organization of leukocytes. Like conventional lymphoid organs, iBALT recruits naïve lymphocytes from the blood, exposes them to local antigens, in this case from the airways, and supports their activation and differentiation into effector cells. The activity of iBALT is demonstrably beneficial for the clearance of respiratory pathogens; however, it is less clear whether it dampens or exacerbates inflammatory responses to non-infectious agents. Here, we review the evidence regarding the role of iBALT in pulmonary immunity and propose that the final outcome depends on the context of the disease.

Protein malnutrition impairs the immune control of Trichinella spiralis infection

OBJECTIVES

We aimed to analyze the effect of a protein-deficient diet on mucosal and systemic immunity during a Trichinella spiralis infection.

METHODS

Two groups of weaning Wistar rats received a protein-deficient diet (6.5% casein) and the other two groups received a control diet (20% casein). After 10 d, one group of each diet was infected (PD_I and C_I) with muscle larvae (infecting stage). Food intake and body weight were assessed over time. Blood eosinophils counts, antibodies in serum, and tissue extracts were assessed at different days postinfection. Histologic studies were done in the lungs and intestines, and adult worm (AW) fecundity index score and muscle parasite burden were determined.

RESULTS

Food and protein intake were lower in PD_I than in C_I. Body weight was lower in PD_I than in a non-infected protein-deficient diet. Eosinophils counts were lower in PD_I than in C_I. Total and specific antibodies were lower in PD_I than C_I. PD_I had a reduced number of mast and goblet cells in the lungs and intestines compared with C_I. The persistence of AW in the intestines and migrant larvae at the lungs was longer in PD_I than in C_I.. The AW fecundity index score was higher in PD_I than in C_I. Finally, PD_I evidenced a higher muscular parasite burden than C_I.

CONCLUSIONS

Protein deficiency affects the mucosal and systemic immune response to Trichinella spiralis and delays the expulsion and increases the fecundity index score of AW, which leads to a higher parasite burden in the muscles.

Chitin, a key factor in immune regulation: lesson from infection with fungi and chitin bearing parasites

The probability of infection with fungi, as well as parasitic nematodes or arthropods may increase in overcrowded population of animals and human. The widespread overuse of drugs and immunosuppressants for veterinary or medical treatment create an opportunity for many pathogenic species. The aim of the review is to present the common molecular characteristics of such pathogens as fungi and nematodes and other chitin bearing animals, which may both activate and downregulate the immune response of the host. Although these pathogens are evolutionary distinct and distant, they may provoke similar immune mechanisms. The role of chitin in these phenomena will be reviewed, highlighting the immune reactions that may be induced in mammals by this natural polymer.

Trichinella spiralis: killing of newborn larvae by lung cells

The migratory stage of Trichinella spiralis, the newborn larva (NBL), travels along the pulmonary microvascular system on its way to the skeletal muscle cells. The present work studies the capability of lung cells to kill NBL. For this purpose, in vitro cytotoxicity assays were performed using NBL, lung cell suspensions from Wistar rats, rat anti-NBL surface sera, and fresh serum as complement source. The cytotoxic activity of lung cells from rats infected on day 6 p.i. was compared with that from noninfected rats. Two and 20 h-old NBL (NBL2 and NBL20) were used as they had shown to exhibit different surface antigens altering their biological activity. Sera antibodies were analyzed by indirect immunofluorescence assay, and cell populations used in each assay were characterized by histological staining. The role of IgE in the cytotoxic attack against NBL was analyzed using heated serum. The FcεRI expression on cell suspensions was examined by flow cytometry. Results showed that lung cells were capable of killing NBL by antibody-dependent cell-mediated cytotoxicity (ADCC). Lung cells from infected animals yielded the highest mortality percentages of NBL, with NBL20 being the most susceptible to such attack. IgE yielded a critical role in the cytotoxic attack. Regarding the analysis of cell suspensions, cells from infected rats showed an increase in the percentage of eosinophils, neutrophils, and the number of cells expressing the FcεRI receptor. We conclude that lung cells are capable of killing NBL in the presence of specific antibodies, supporting the idea that the lung is one of the sites where the NBL death occurs due to ADCC.

Comparative ultrastructural studies of the alterations to mouse lung parenchyma during Trichinella spiralis or Toxocara canis infection

Trichinella spiralis and Toxocara canis larvae migrated through the lung and induced many alterations in the lung parenchyma. Using electron microscopy, we identified and described the histopathological changes. These changes resulted from mechanical damage or from local inflammatory reactions provoked by larvae. The pattern of changes was described between 6 and 12 days post-infection (DPI) with T. spiralis larvae, and between 21 and 28 DPI with T. canis. The ultrastructural studies demonstrated that T. spiralis larvae migrating through the lungs evoked mainly destruction of type I epithelial cells, destruction of lamellar bodies of epithelial cells or extracellular alveolar lining layer. The severity of these changes was dependent on the number of infective larvae (400 or 800 T. spiralis larvae) and possibly the result of mechanical damage in the lung parenchyma. In contrast, infection with T. canis larvae initiated mainly eosinophilic perivasculitis and vasculitis as well as macrophage accumulation in the lung, which were additionally impacted by numerous crystalloid inclusions in macrophages. Trichinella spiralis larvae and T. canis larvae induced different pathological changes in the lungs of infected mice.

Trichinella spiralis infection rapidly induces lung inflammatory response: the lung as the site of helminthocytotoxic activity

In the present work, we studied the kinetics of the appearance of different immunological parameters in the lungs during the intestinal phase of infection with Trichinella spiralis. We also evaluated the lung's role in the retention and death of this helminth in its migratory stage. To study these parameters, we used lung extracts, lung cell suspensions and rat lung tissue sections. During the intestinal phase of infection (days 0-13 post-infection, p.i.), an inflammatory response is elicited in the lungs, which reflects humoral, cellular and functional changes. These changes included an increased number of mast cells and eosinophils and the local production of IL-4, IL-5, IL-10, TNFα, IFNγ, IL-13, CCL11 and CCL28. We found hyperplasia of the bronchus-associated lymphoid tissue (BALT). Total and specific IgA, IgE, IgG1 and IgG2a were detected locally. The retention of the migratory larvae in the lung, together with the ex vivo cytotoxic capacity of the lung cells and antibodies present in the lung extracts, suggested that the lung was one of the immune defense organs against the pathogen's migration stage.

Immunoparasitological evaluation of Trichinella spiralis infection during human pregnancy: a small case series

The clinical background, vertical transmission of Trichinella spiralis and helminthotoxic activity of sera were evaluated in four pregnant women infected at different gestation times. Parasitological and immunological parameters were analyzed. Patients presented clinical symptoms and a seroconversion pattern typical of Trichinella infection, independently of the gestation trimester. All patients, including one patient treated with mebendazole, gave birth to healthy infants at full term. Studies performed in placentas and umbilical cords by artificial digestion and/or immunofluorescence did not reveal the presence of parasites or parasite antigens. Specific antibodies were found in placental extraction and maternal sera by immunofluorescence, ELISA and/or immunoelectrotransfer blot assay. Specific IgG, IgE and IgA were found in the umbilical cord sera. One umbilical cord demonstrated immune-complexed specific IgM and circulating parasite antigens were found in the corresponding infant up to 10 months after birth. Patients' sera were able to kill newborn larvae in cytotoxicity assays, even in the absence of specific antibodies; this effect was abrogated by mifepristone. The results suggest that in human trichinellosis during pregnancy there is an enhanced helminthotoxicity to newborn larvae, dependent in part on progesterone, leading to a mild or moderate course of the infection. The results also indicate that the transplacental passage of migrating larvae is possible.