Early response of guinea-pig lungs to Trichinella spiralis infection

A review on Trichinella infection in South America

Trichinella spp. causes human trichinellosis by means of the consumption of raw or inadequately treated meat from domestic or game animals. In the Americas, as well as in other continents, Trichinella infection is a health issue for humans and has a negative impact on the pork meat market, generated by people's fear of becoming infected with the parasite. The distribution of human cases and the sources of this disease in humans and animals were analysed in this report, which summarizes the information available regarding Trichinella infection in animals and humans in South America. Within South America, human infection with Trichinella was documented in Argentina and Chile during the period 2005-2019. Trichinellosis is endemic in these countries for, with human cases and foci in domestic and wild animals. In Argentina, human cases occur throughout the country, with foci found in pigs and wild animals. In Argentina, during the period 2012-2018, the number of suspected human cases reached 6,662. T. spiralis was identified in one South American sea lion (Otaria flavescens) from Patagonia, Argentina, for the first time in the region in 2018. In Chile, 258 human cases of trichinellosis were confirmed during the period 2005-2015; out of those 258 cases, most samples which tested positive for Trichinella spp. (29.5 %) were detected in the Metropolitan district (Santiago de Chile and outskirts), and 17.4 % in The Lake district. Regarding age brackets, people between 30-49 years of age showed the most cases (40.1 %). In Brazil, the infection is absent in domestic species but it has been found in wild boars (Sus scrofa) but limited to one or more region of the country. Within the animal species destined for food in South America, those that showed higher parasitical loads were pigs and wild boars, while armadillos (Chaetophractus villosus) and peccaries (Tayassu tajacu) showed very low Trichinella spp. larvae loads (0.04-0.1 larvae/g). Antibodies against Trichinella spp. have been detected in pigs from Ecuador and Bolivia. In Bolivia, antibodies were also found in humans. Peru, Colombia and Uruguay have no documented presence of Trichinella spp. in animals and humans. There is insufficient information regarding the presence of Trichinella spp. in domestic and wild animals, as well as in humans, since only a very limited number of surveys have been carried out. No papers with information on Trichinella spp. circulating in animals or humans have been published regarding the situation in Guyana, Surinam, French Guiana, Venezuela and Paraguay. Considering the growth of the guinea pig meat market in the Andean region, and the high prevalence of the disease reported in free range pigs and wild boars, as well as other game animal species, it is important to focus on the role of biosecurity and risk management, while improving meat market regulations, and detection of infection prior to consumption, in order to reduce the risk of transmission of this zoonotic disease to humans.

A review on Trichinella infection in South America

Trichinella spp. causes human trichinellosis by means of the consumption of raw or inadequately treated meat from domestic or game animals. In the Americas, as well as in other continents, Trichinella infection is a health issue for humans and has a negative impact on the pork meat market, generated by people's fear of becoming infected with the parasite. The distribution of human cases and the sources of this disease in humans and animals were analysed in this report, which summarizes the information available regarding Trichinella infection in animals and humans in South America. Within South America, human infection with Trichinella was documented in Argentina and Chile during the period 2005-2019. Trichinellosis is endemic in these countries for, with human cases and foci in domestic and wild animals. In Argentina, human cases occur throughout the country, with foci found in pigs and wild animals. In Argentina, during the period 2012-2018, the number of suspected human cases reached 6,662. T. spiralis was identified in one South American sea lion (Otaria flavescens) from Patagonia, Argentina, for the first time in the region in 2018. In Chile, 258 human cases of trichinellosis were confirmed during the period 2005-2015; out of those 258 cases, most samples which tested positive for Trichinella spp. (29.5%) were detected in the Metropolitan district (Santiago de Chile and outskirts), and 17.4% in The Lake district. Regarding age brackets, people between 30-49 years of age showed the most cases (40.1%). In Brazil, the infection is absent in domestic species but it has been found in wild boars (Sus scrofa) but limited to one or more region of the country. Within the animal species destined for food in South America, those that showed higher parasitical loads were pigs and wild boars, while armadillos (Chaetophractus villosus) and peccaries (Tayassu tajacu) showed very low Trichinella spp. larvae loads (0.04 - 0.1 larvae/g). Antibodies against Trichinella spp. have been detected in pigs from Ecuador and Bolivia. In Bolivia, antibodies were also found in humans. Peru, Colombia and Uruguay have no documented presence of Trichinella spp. in animals and humans. There is insufficient information regarding the presence of Trichinella spp. in domestic and wild animals, as well as in humans, since only a very limited number of surveys have been carried out. No papers with information on Trichinella spp. circulating in animals or humans have been published regarding the situation in Guyana, Surinam, French Guiana, Venezuela and Paraguay. Considering the growth of the guinea pig meat market in the Andean region, and the high prevalence of the disease reported in free range pigs and wild boars, as well as other game animal species, it is important to focus on the role of biosecurity and risk management, while improving meat market regulations, and detection of infection prior to consumption, in order to reduce the risk of transmission of this zoonotic disease to humans.

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.

Trichinella: Differing effects of antigens from encapsulated and non-encapsulated species on in vitro nitric oxide production

Trichinellosis is a cosmopolitan zoonotic disease affecting a wide variety of animals, including man. Non-encapsulated and encapsulated species diverge with respect to their developmental strategies. Little is known at the molecular level about parasite-derived mediators responsible for host muscle cell transformation occurring during trichinellosis. In this context, host-parasite relationships in Trichinella-infected animals could be related to different host-immune and cell mediators, e.g. nitric oxide (NO). Here, we investigate the stimulatory/inhibitory role of L1 antigens from four encapsulated (T. spiralis, T. britovi, T. nelsoni and T. nativa) and one non-encapsulated (T. pseudospiralis) Trichinella species on NO production from rat macrophages in vitro. Our results demonstrate that encapsulated and non-encapsulated Trichinella species differ in their capacity to stimulate the secretion of NO from host macrophages. Biological significance of these differences should be further assessed in the available experimental models.

Trichinella spiralis infection affects p47phox protein expression in guinea-pig alveolar macrophages

To establish whether NADPH oxidase activation, responsible for previously demonstrated Trichinella spiralis-induced respiratory burst, results from assembling of membrane and cytosolic NADPH oxidase components and/or increased expression of the oxidase complex proteins, the superoxide anion production and expression of the regulatory p47(phox) subunit were measured in cultured alveolar macrophages obtained during T. spiralis infection of guinea pigs. The results demonstrate for the first time helminth parasite-infection-induced stimulation of NADPH oxidase p47(phox) subunit protein expression, with the effect being decreased by in vivo treatment with cyclosporin A, previously shown to inhibit T. spiralis infection-induced respiratory burst in guinea-pig alveolar macrophages. However, although the expression of the p47(phox) subunit protein remained induced during secondary infection, it was accompanied by superoxide anion production that was significantly suppressed in comparison with that observed during primary infection, suggesting suppressive action of T. spiralis on host's alveolar macrophage immune response, presumably connected with NADPH oxidase complex activity attenuation.

Trichinella spiralis: Macrophage activity and antibody response in chronic murine infection

The role of macrophages, their products, and the specific antibody response were examined during chronic Trichinella spiralis infection in BALB/c mice. Adult T. spiralis in intestines were detected from 5 to 20 dpi. Muscle larvae numbers peaked at 45 dpi and thereafter a reduction was noted. The highest numbers of macrophages in the peritoneal cavity of infected mice were obtained up to 30 dpi. The production of NO by macrophages in infected mice was suppressed at 5 dpi, and then NO release increased until 45 dpi. The levels of NO in plasma and urine were lower in infected mice during the entire experiment in comparison to control. The production of O(2)(-) in peritoneal macrophages was inhibited during the first two weeks after infection and then increased until 90 dpi. Circulating T. spiralis antigens in plasma and urine were detected from 5 to 30 dpi. Specific IgM and IgA in serum increased until 20 dpi. IgG, IgG(1), and IgG(2) levels in serum increased until 60 dpi.

A non-classical type of alveolar macrophage response to Trichinella spiralis infection

Studies of arginase expression and activity in guinea pig alveolar macrophages during Trichinella spiralis infection, prompted by earlier observation of innate lung response to the parasite, showed the macrophages to express both activity and protein of arginase type I. In cultured macrophages part of the enzyme was found to be always released to the extracellular medium. Whereas BCG in vivo treatment, alone or preceded by T. spiralis infection, stimulated arginase activity, T. spiralis infection alone affected the enzyme distribution between intracellular and extracellular fractions, and properties (K(m) and V(max)), rather than total (intracellular + extracellular) activity, with TGF-beta apparently responsible for a part of the effect. Anti-TGF-beta antibody treatment of the animals influenced both arginase activation by Mn(2+) and dependence of the enzyme-catalysed reaction on pH. Whereas T. spiralis infection activated guinea pig alveolar macrophages by the type II macrophage activation, as indicated by constant arginase expression, associated with previously demonstrated lack of stimulation of nitric oxide production, BCG treatment invoked an alternative type of activation mechanism, reflected by stimulation of macrophage arginase, but not iNOS, activity.

Inhibition of neutrophil recruitment by ES of Nippostrongylus brasiliensis

It has been reported that excretory-secretory (ES) material from the parasitic nematode Nippostrongylus brasiliensis has potential modulatory effects on the host's immune system. We observed that intratracheal instillation of ES from the L3 stage of the parasite reduced neutrophil numbers in LPS-induced inflammation as assessed by bronchoalveolar lavage.