Role for nitric oxide in hookworm-associated immune suppression

Comparison of percutaneous vs oral infection of hamsters with the hookworm Ancylostoma ceylanicum: Parasite development, pathology and primary immune response

BACKGROUND

Hundreds of millions of people in poor countries continue to suffer from disease caused by bloodfeeding hookworms. While mice and rats are not reliably permissive hosts for any human hookworm species, adult Golden Syrian hamsters are fully permissive for the human and animal pathogen Ancylostoma ceylanicum. Similar to humans, hamsters may be infected with A. ceylanicum third-stage larvae orally or percutaneously. Oral infection typically leads to consistent worm yields in hamsters but may not accurately reflect the clinical and immunological manifestations of human infection resulting from skin penetration.

METHODOLOGY/PRINCIPAL FINDINGS

In this study we compared host responses following percutaneous infection to those utilizing an established oral infection protocol. Infected hamsters exhibited a dose-dependent pathology, with 1000 percutaneous larvae (L3) causing anemia and adult worm recovery comparable to that of 50 orally administered L3. A delayed arrival and maturity of worms in the intestine was observed, as was variation in measured cellular immune responses. A long-term study found that the decline in blood hemoglobin was more gradual and did not reach levels as low, with the nadir of disease coming later in percutaneously infected hamsters. Both groups exhibited moderate growth delay, an effect that was more persistent in the percutaneously infected group. Fecal egg output also peaked later and at lower levels in the percutaneously infected animals. In contrast to orally infected hamsters, antibody titers to larval antigens continued to increase throughout the course of the experiment in the percutaneous group.

CONCLUSIONS/SIGNIFICANCE

These results demonstrate that the route of infection with A. ceylanicum impacts disease pathogenesis, as well as humoral and cellular immune responses in an experimental setting. These data further validate the utility of the Golden Syrian hamster as a model of both oral and percutaneous infection with human hookworms.

Genetically-engineered hamster models: applications and perspective in dyslipidemia and atherosclerosis-related cardiovascular disease

Cardiovascular disease is the leading cause of morbidity and mortality in both developed and developing countries, in which atherosclerosis triggered by dyslipidemia is the major pathological basis. Over the past 40 years, small rodent animals, such as mice, have been widely used for understanding of human atherosclerosis-related cardiovascular disease (ASCVD) with the advantages of low cost and ease of maintenance and manipulation. However, based on the concept of precision medicine and high demand of translational research, the applications of mouse models for human ASCVD study would be limited due to the natural differences in metabolic features between mice and humans even though they are still the most powerful tools in this research field, indicating that other species with biological similarity to humans need to be considered for studying ASCVD in future. With the development and breakthrough of novel gene editing technology, Syrian golden hamster, a small rodent animal replicating the metabolic characteristics of humans, has been genetically modified, suggesting that gene-targeted hamster models will provide new insights into the precision medicine and translational research of ASCVD. The purpose of this review was to summarize the genetically-modified hamster models with dyslipidemia to date, and their potential applications and perspective for ASCVD.

Syrian Hamster as an Animal Model for the Study on Infectious Diseases

Infectious diseases still remain one of the biggest challenges for human health. In order to gain a better understanding of the pathogenesis of infectious diseases and develop effective diagnostic tools, therapeutic agents, and preventive vaccines, a suitable animal model which can represent the characteristics of infectious is required. The Syrian hamster immune responses to infectious pathogens are similar to humans and as such, this model is advantageous for studying pathogenesis of infection including post-bacterial, viral and parasitic pathogens, along with assessing the efficacy and interactions of medications and vaccines for those pathogens. This review summarizes the current status of Syrian hamster models and their use for understanding the underlying mechanisms of pathogen infection, in addition to their use as a drug discovery platform and provides a strong rationale for the selection of Syrian hamster as animal models in biomedical research. The challenges of using Syrian hamster as an alternative animal model for the research of infectious diseases are also addressed.

Recombinant Haemonchus contortus 24 kDa excretory/secretory protein (rHcES-24) modulate the immune functions of goat PBMCs in vitro

A 24 kDa protein is one of the important components in Haemonchus contortus (barber pole worm) excretory/secretory products (HcESPs), which was shown to have important antigenic function. However, little is known about the immunomodulatory effects of this proteinon host cell. In the present study gene encoding 24kDa excretory/secretory protein (HcES-24) was cloned. The recombinant protein of HcES-24 (rHcES-24) was expressed in a histidine-tagged fusion protein soluble form in Escherichia coli. Binding activity of rHcES-24 to goat PBMCs was confirmed by immunofluorescence assay (IFA) and its immunomudulatory effect on cytokine secretion, cell proliferation, cell migration and nitric oxide production were observed by co-incubation of rHcES-24. IFA results revealed that rHcES-24 could bind to the PBMCs. The interaction of rHcES-24 increased the production of IL4, IL10, IL17 and cell migration in dose dependent manner. However, rHcES-24 treatment significantly suppressed the production of IFNγ, proliferation of the PBMC and Nitric oxide (NO) production. Our findings showed that the rHcES-24 played important regulatory effects on the goat PBMCs.

Hookworm excretory/secretory products modulate immune responses to heterologous and species-specific antigens

Approximately one billion people are currently infected with hookworm. Despite its high prevalence and the concomitant immune suppression seen in infected individuals, little research has been performed on the mechanism of immunosuppression by hookworm. Our study focused on characterizing mechanisms utilized by hookworm to suppress the host immune response. Splenocytes and draining lymph node cells from mice injected with hookworm excretory/secretory (ES) proteins showed decreased proliferation in response to both heterologous and species-specific antigens while also having increased nitric oxide secretion. Analysis by fluorescence-activated cell sorting revealed that mice injected with ES had reduced percentages of CD4⁺ T cells indicating potential effects of ES proteins on lymphocyte homeostasis. Antibody and cytokine response analyses demonstrated that immunization with ES proteins decreased IgG and IgG1 levels, also decreased interleukin (IL-)-4 and increased IL-12 and interferon-gamma (IFN-γ) cytokine production suggesting impairment of B-cell activation and a shift towards a nonhealing IL-12 directed T helper-1 immune response. Together, these data demonstrate for the first time that host immunosuppression by hookworms is orchestrated by ES proteins and provide mechanisms underlying the shift towards a nonhealing Th-1 profile as seen in humans suffering from hookworm infection.

Animal models of smoke inhalation injury and related acute and chronic lung diseases

Smoke inhalation injury leads to various acute and chronic lung diseases and thus is the dominant cause of fire-related fatalities. In a search for an effective treatment and validation of therapies different classes of animal models have been developed, which include both small and large animals. These models have advanced our understanding of the mechanism of smoke inhalation injury, enabling a better understanding of pathogenesis and pathophysiology and development of new therapies. However, none of the animal models fully mirrors human lungs and their pathologies. All animal models have their limitations in replicating complex clinical conditions associated with smoke inhalation injury in humans. Therefore, for a correct interpretation of the results and to avoid bias, a precise understanding of similarities and differences of lungs between different animal species and humans is critical. We have reviewed and presented comprehensive comparison of different animal models and their clinical relevance. We presented an overview of methods utilized to induce smoke inhalation injuries, airway micro-/macrostructure, advantages and disadvantages of the most commonly used small and large animal models.

Syrian Hamsters as a Small Animal Model for Emerging Infectious Diseases: Advances in Immunologic Methods

The use of small animal models for the study of infectious disease is critical for understanding disease progression and for developing prophylactic and therapeutic treatment options. For many diseases, Syrian golden hamsters have emerged as an ideal animal model due to their low cost, small size, ease of handling, and ability to accurately reflect disease progression in humans. Despite the increasing use and popularity of hamsters, there remains a lack of available reagents for studying hamster immune responses. Without suitable reagents for assessing immune responses, researchers are left to examine clinical signs and disease pathology. This becomes an issue for the development of vaccine and treatment options where characterizing the type of immune response generated is critical for understanding protection from disease. Despite the relative lack of reagents for use in hamsters, significant advances have been made recently with several hamster specific immunologic methods being developed. Here we discuss the progress of this development, with focus on classical methods used as well as more recent molecular methods. We outline what methods are currently available for use in hamsters and what is readily used as well as what limitations still exist and future perspectives of reagent and assay development for hamsters. This will provide valuable information to researchers who are deciding whether to use hamsters as an animal model.

Phenolic Metabolites of Dalea ornata Affect Both Survival and Motility of the Human Pathogenic Hookworm Ancylostoma ceylanicum

Hookworms are ubiquitous human parasites, infecting nearly one billion people worldwide, and are the leading cause of anemia and malnutrition in resource-limited countries. Current drug treatments rely on the benzimidazole derivatives albendazole and mebendazole, but there is emerging resistance to these drugs. As part of a larger screening effort, using a hamster-based ex vivo assay, anthelmintic activity toward Ancylostoma ceylanicum was observed in the crude extract of aerial parts of Dalea ornata. These studies have led to the isolation and characterization of phenolic metabolites 1-10. The structures were determined by 1D and 2D NMR spectroscopy, and the absolute configuration of 1 was assigned using electronic circular dichroism data. The new compound, (2S)-8-(3-methylbut-2-en-1-yl)-6,7,4'-trihydroxyflavanone (1), was weakly active at 7.3 μM, with 17% reduction in survival of the hookworms after 5 days. The rotenoids deguelin (9) and tephrosin (10), predictably perhaps, were the most active, with complete worm mortality observed by day 4 (or earlier) at 6.3 and 6.0 μM, respectively. The effects of 1-10 on hookworm motility and on toxicity to hamster splenocytes were also explored as important measures of treatment potential.

The crowding effect in Ancylostoma ceylanicum: density-dependent effects on an experimental model of infection

This study compared the course of Ancylostoma ceylanicum infection in hamsters infected with different inocula and the consequences for the host and helminth populations. The average of adult worms recovered, according to the number of third stage larva used, were 28.0, 24.8, 24.6, and 24.8% to inocula size of 25 L3, 75 L3, 125 L3, and 250 L3, respectively. The size of the inoculum did not affect the establishment, survival, or fecundity of adult helminths. Reductions in the red blood cell and hemoglobin levels in the infected group were inversely proportional to the number of white blood cells. Moreover, differential cell counting revealed a positive correlation between the worm load and leucocyte numbers. The humoral response against excretion-secretion antigens was more robust and sensitive compared with the response against crude extract, with no direct linear correlation with the number of worms. The effect of the population density was more evident in females.

Protein malnutrition impairs the immune response and influences the severity of infection in a hamster model of chronic visceral leishmaniasis

Leishmaniasis remains one of the world's most devastating neglected tropical diseases. It mainly affects developing countries, where it often co-exists with chronic malnutrition, one of the main risk factors for developing the disease. Few studies have been published, however, on the relationship between leishmaniasis progression and malnutrition. The present paper reports the influence of protein malnutrition on the immune response and visceral disease development in adult hamsters infected with Leishmania infantum fed either standard or low protein diets. The low protein diet induced severe malnutrition in these animals, and upon infection with L. infantum 33% had severe visceral leishmaniasis compared to only 8% of animals fed the standard diet. The infected, malnourished animals showed notable leukocyte depletion, mild specific antibody responses, impairment of lymphoproliferation, presence of parasites in blood (16.67% of the hamsters) and significant increase of the splenic parasite burden. Animals fed standard diet suffered agranulocytosis and monocytopenia, but showed stronger specific immune responses and had lower parasite loads than their malnourished counterparts. The present results show that protein malnutrition promotes visceral leishmaniasis and provide clues regarding the mechanisms underlying the impairment of the immune system.

Statistics in Infection and immunity revisited

In 2003, a review of the use of statistics in Infection and Immunity (IAI) found that more than half of articles had errors of statistical analysis or reporting of statistical results. This updated review of recent articles identifies and discusses the most common statistical methods reported in IAI and provides examples of both good reporting and common mistakes. Furthermore, it expands on the criteria for statistical analysis and reporting presented in the IAI "Instructions to Authors," with the goal of helping both readers and authors better understand and apply the criteria.

Use of the Syrian hamster as a new model of ebola virus disease and other viral hemorrhagic fevers

Historically, mice and guinea pigs have been the rodent models of choice for therapeutic and prophylactic countermeasure testing against Ebola virus disease (EVD). Recently, hamsters have emerged as a novel animal model for the in vivo study of EVD. In this review, we discuss the history of the hamster as a research laboratory animal, as well as current benefits and challenges of this model. Availability of immunological reagents is addressed. Salient features of EVD in hamsters, including relevant pathology and coagulation parameters, are compared directly with the mouse, guinea pig and nonhuman primate models.

Frequency and intensity of exposure mediate resistance to experimental infection with the hookworm, Ancylostoma ceylanicum

Hookworms are bloodfeeding intestinal nematodes that are a major cause of anemia in resource-limited countries. Despite repeated exposure beginning in early childhood, humans retain lifelong susceptibility to infection without evidence of sterilizing immunity. In contrast, experimental infection of laboratory animals is typically characterized by varying degrees of resistance following primary infection, although the mechanisms underlying this phenomenon remain unknown. In this study, hamsters subjected to a single drug-terminated infection with 100 third stage hookworm larvae were confirmed to be resistant to pathological effects following a subsequent challenge. In a second experiment, hamsters infected twice-weekly with 10 third stage larvae (low inoculum) exhibited clinical and parasitological evidence of continued susceptibility, while those given 100 L3 (high inoculum) developed apparent resistance within 3 days following the initial exposure. The kinetics of parasite-specific IgA, IgM, and IgG antibody production varied by group, which suggests that the humoral immune response to hookworm infection is stimulated by the nature (frequency and intensity) of larval exposure. These results suggest that intermittent low-inoculum larval exposure, which is characterized by prolonged susceptibility to infection, may serve as a more representative model of human hookworm disease for studies of pathogenesis, as well as drug and vaccine development.

Induction of CD4(+)CD25(+)FOXP3(+) regulatory T cells during human hookworm infection modulates antigen-mediated lymphocyte proliferation

Hookworm infection is considered one of the most important poverty-promoting neglected tropical diseases, infecting 576 to 740 million people worldwide, especially in the tropics and subtropics. These blood-feeding nematodes have a remarkable ability to downmodulate the host immune response, protecting themselves from elimination and minimizing severe host pathology. While several mechanisms may be involved in the immunomodulation by parasitic infection, experimental evidences have pointed toward the possible involvement of regulatory T cells (Tregs) in downregulating effector T-cell responses upon chronic infection. However, the role of Tregs cells in human hookworm infection is still poorly understood and has not been addressed yet. In the current study we observed an augmentation of circulating CD4(+)CD25(+)FOXP3(+) regulatory T cells in hookworm-infected individuals compared with healthy non-infected donors. We have also demonstrated that infected individuals present higher levels of circulating Treg cells expressing CTLA-4, GITR, IL-10, TGF-β and IL-17. Moreover, we showed that hookworm crude antigen stimulation reduces the number of CD4(+)CD25(+)FOXP3(+) T regulatory cells co-expressing IL-17 in infected individuals. Finally, PBMCs from infected individuals pulsed with excreted/secreted products or hookworm crude antigens presented an impaired cellular proliferation, which was partially augmented by the depletion of Treg cells. Our results suggest that Treg cells may play an important role in hookworm-induced immunosuppression, contributing to the longevity of hookworm survival in infected people.

T cells are not required for pathogenesis in the Syrian hamster model of hantavirus pulmonary syndrome

Andes virus (ANDV) is associated with a lethal vascular leak syndrome in humans termed hantavirus pulmonary syndrome (HPS). In hamsters, ANDV causes a respiratory distress syndrome closely resembling human HPS. The mechanism for the massive vascular leakage associated with HPS is poorly understood; however, T cell immunopathology has been implicated on the basis of circumstantial and corollary evidence. Here, we show that following ANDV challenge, hamster T cell activation corresponds with the onset of disease. However, treatment with cyclophosphamide or specific T cell depletion does not impact the course of disease or alter the number of surviving animals, despite significant reductions in T cell number. These data demonstrate, for the first time, that T cells are not required for hantavirus pathogenesis in the hamster model of human HPS. Depletion of T cells from Syrian hamsters did not significantly influence early events in disease progression. Moreover, these data argue for a mechanism of hantavirus-induced vascular permeability that does not involve T cell immunopathology.

Twenty-first century progress toward the global control of human hookworm infection

Hookworms are bloodsucking nematodes that afflict up to 740 million persons in tropical and subtropical regions, with Asia and sub-Saharan Africa exhibiting particularly high infection rates. Prevalence, intensity, and pathology often vary considerably at both the regional and local level, and may be influenced by coinfection with other parasitic infections such as malaria. Immunoepidemiological studies suggest that hookworms manipulate the host immune response and may provide some protection from allergy and asthma. There has been substantial progress in elucidating the molecular pathogenesis of hookworm disease, with anticoagulants, protease inhibitors, digestive proteases, and novel excretory/secretory proteins being of particular interest. Mass chemotherapy remains a mainstay of hookworm control strategies, although continued use of drugs may lead to reduced efficacy and treatment failures have been observed. Consequently, a need exists for innovative approaches, such as vaccination; recent studies have identified and/or evaluated candidate vaccine antigens in human and animal models.

Immunopathogenesis of Ascaridia galli infection in layer chicken

Gastro-intestinal nematode infections in mammals are associated with local T lymphocyte infiltrations, Th2 cytokine induction, and alterations in epithelial cell secretion and absorption. This study demonstrates that Ascaridia (A.) galli infection in chicken also elicits local gut-associated immune reactions and changes in the intestinal electrogenic nutrient transport. In A. galli-infected birds we observed infiltrations of different T cell populations in the intestinal lamina propria and accumulation of CD4+ lymphocytes in the epithelium. The Th2 cytokines IL-4 and IL-13 dominated the intestinal immune reactions following A. galli infection. A. galli-specific systemic IgY antibodies were detected after two weeks post infection, and did only poorly correlate with detected worm numbers. Electrogenic transport of alanin and glucose was impaired in A. galli-infected chicken. Our data provide circumstantial evidence that local immune responses and electro-physiological intestinal functions may be connected and contribute to the elimination of worm infection.

CD4 T cells mediate mucosal and systemic immune responses to experimental hookworm infection

Hookworm infection is associated with anaemia and malnutrition in many resource-limited countries. Ancylostoma hookworms have previously been shown to modulate host cellular immune responses through multiple mechanisms, including reduced mitogen-mediated lymphocyte proliferation, impaired antigen presentation/processing, and relative reductions in CD4(+) T cells in the spleen and mesenteric lymph nodes. Syrian hamsters were depleted of CD4(+) for up to 9 days following intraperitoneal injection (200 microg) of a murine anti-mouse CD4 monoclonal IgG (clone GK1.5). CD4(+) T-cell-depleted hamsters infected with the hookworm Ancylostoma ceylanicum exhibited a threefold higher mean intestinal worm burden and more severe anaemia than animals that received isotype control IgG. In addition, depletion of CD4(+) T cells was associated with impaired cellular and humoral (serum and mucosal) immune responses to hookworm antigens. These data demonstrate an effector role for CD4(+) T cells in hookworm immunity and disease pathogenesis. Ultimately, these studies may yield important insights into the relationship between intestinal nematode infections and diseases that are associated with CD4(+) T-cell depletion, including HIV.

Duplex real-time reverse transcriptase PCR to determine cytokine mRNA expression in a hamster model of New World cutaneous leishmaniasis

Background

The Syrian hamster, Mesocricetus auratus, has distinct immunological features and is uniquely susceptible to intracellular pathogens. Studies in hamsters are limited by the relative unavailability of tools to conduct immunological studies. To address this limitation we developed duplex real-time reverse transcriptase (RT) PCR assays for the relative quantification of the mRNAs of hamster cytokines, chemokines, and related immune response molecules.

Results

Real-time RT-PCR primers and probes were synthesized for analysis of interleukin (IL)-4, IFN-γ, TNF-α, IL-10, IL-12p40, TGF-β, IL-13, IL-21, chemokine ligand (CCL) 22, CCL17, Chemokine (C-C motif) receptor 4 and FoxP3 expression. Standard curves and validation experiments were performed for each real-time RT-PCR assay, allowing us to use the comparative Ct (2^-ΔΔCt) method to calculate changes in gene expression. Application of the real-time RT PCR assays to a biological model was demonstrated by comparing mRNA expression in skin and lymph node tissues between uninfected and Leishmania panamensis infected hamsters.

Conclusions

The duplex real-time RT PCR assays provide a powerful approach for the quantification of cytokine transcription in hamsters, and their application to a model of cutaneous leishmaniasis suggests that a balanced type 1 and type 2 cytokine response contributes to the chronic, nonprogressive course of disease. These new molecular tools will further facilitate investigation into the mechanisms of disease in the hamster, not only for models of leishmaniasis, but also for other viral, bacterial, fungal, and parasitic infections.

Electrochemistry and nitric oxide mass transport in cancer: why ingestion of sodium nitrite could be effective in treating vascularized tumors

Nitric oxide concentrations in tumors do not reach apoptosis inducing levels when their excess NO is rapidly depleted. The out-flux of NO from a tumor to air or blood scales with the contacting area and with the concentration gradient; the gradient scales with the tumor-air or tumor-blood concentration difference and scales inversely with the thickness of the boundary layer, i.e. the fluid's flow rate. Air-contacting skin and lung cancers account for approximately 60% of all cancers in part because out-diffusion of NO from nascent tumors to air increases the likelihood of their survival. Out-diffusion of NO also explains their initially 2-D spreading at the air interface. Blood is an NO sink because its proteins are rapidly S-nitrosated; depletion of NO by the blood explains the dormancy of tumors until their vascularization and their virulence after vascularization. Erythrocytes store NO(2)- and their carbonic anhydrase converts it to NO and NO(3)(-). Thus, NaNO(2), a common additive in cured meats, may reduce NO out-diffusion by raising the blood NO concentration.

Antibacterial nitric oxide-releasing polyester for the coating of blood-contacting artificial materials

The emergence of multidrug-resistant bacteria associated with blood-contacting artificial materials is a growing health problem, which demands new approaches in the field of biomaterials research. In this study, a poly(sulfhydrylated polyester) (PSPE) was synthesized by the polyesterification reaction of mercaptosuccinic acid with 3-mercapto-1,2-propanediol and blended with poly(methyl methacrylate) (PMMA) from solution, leading to solid PSPE/PMMA films, with three different PSPE : PMMMA mass ratios. These films were subsequently S-nitrosated through the immersion in acidified nitrite solution, yielding poly(nitrosated)polyester/PMMA (PNPE/PMMA) films. A polyurethane intravascular catheter coated with PNPE/PMMA was shown to release nitric oxide (NO) in phosphate buffered saline solution (pH 7.4) at 37 degrees C at rates of 4.6 nmol/cm(2)/h in the first 6 h and 0.8 nmol/cm(2)/h in the next 12 h. When used to coat the bottom of culture plates, NO released from these films exerted a potent dose- and time-dependent antimicrobial activity against Staphylococcus aureus and a multidrug-resistant Pseudomonas aeruginosa strains. This antibacterial effect of PSPE/PMMA films opens a new perspective for the coating of blood-contacting artificial materials, for avoiding their colonization with highly resistant bacteria.

The mucosal response of hamsters to a low-intensity superimposed secondary infection with the hookworm Ancylostoma ceylanicum

An experiment was conducted to assess the mucosal response to low-dose superimposed challenge with Ancylostoma ceylanicum. Hamsters were assigned to five treatment groups (1–5 respectively): naïve controls; primary immunizing infection controls; challenge controls; immunized, anthelmintic–treated, challenged group; immunized, superimposed challenge group. Group 4 hamsters were resistant to challenge, whereas most of the challenge inoculum larvae established in Group 5. Villus height and crypt depth measurements were initially markedly divergent between these two groups but over time post-challenge (pc) values for both parameters drew nearer and by day 31 pc they were indistinguishable. The greatest change was experienced by Group 4 which showed increasing inflammation and gut pathology during the challenge infection. Mitotic activity in crypts and mast cell counts in the mucosa were highest in Group 5 on day 10 pc, but there was little to distinguish between Groups 4 and 5 by day 31 pc. Goblet cell, eosinophil and Paneth cell counts were very similar throughout in both groups but, in the case of Paneth cells, they were consistent with a possible role in protective immunity to challenge. Some adult worms survived throughout the period of intense inflammation, emphasizing their tremendous resilience and resistance to mucosal host protective responses.

Nematode challenge induces differential expression of oxidant, antioxidant and mucous genes down the longitudinal axis of the sheep gut

To characterize the role of a range of oxidant, antioxidant and mucous-related genes in the primary response to gastrointestinal nematodes, groups of genetically resistant sheep were challenged with either Haemonchus contortus or Trichostrongylus colubriformis and necropsied for retrieval of tissue at days 0, 3, 7, 14 and 21. To determine if the response was localized to the site of parasite infection, four different gut tissues were sampled: the abomasum, proximal and distal jejunum and ileum. Basal expression patterns of all candidate genes were determined using the day 0 (pre-challenge) samples. A conserved innate response involving elevated expression of dual oxidase, glutathione peroxidase and trefoil factor was initiated within 3 days of challenge and extended out to 21 days. An increase in host gene expression levels at the preferred site of infection (the abomasum for H. contortus and the proximal jejunum for T. colubriformis) was also common to both nematodes. However, these increases were concomitant with reduced expression in other areas of the gut suggesting a compartmentalized response. Other aspects of the response were parasite-specific, with T. colubriformis challenge inducing expression peaks at times corresponding to nematode life-stage transitions.

The mucosal response to secondary infection with Ancylostoma ceylanicum in hamsters immunized by abbreviated primary infection

We assessed the mucosal response of previously infected hamsters to low-dose challenge with the hookworm, Ancylostoma ceylanicum. Hamsters were assigned to five treatment groups (Groups 1-5, respectively): naïve, controls; uninterrupted primary infection from day 0; infected, but treated with anthelmintic on day 35 p.i.; challenge control group given only the second infection on day 63; infected initially, cleared of worms and then challenged. Animals were culled on days 73 and 94 (10 and 31 days after challenge), but additional animals were culled from Group 5 on days 80 and 87. The results showed that villus height declined markedly and progressively over time after challenge in Group 5, whilst depth of the Crypts of Lieberkühn and number of mitotic figures in the crypts increased. Mucosal mast cell numbers were only marginally higher than those in naïve controls and not as high as those in mice with uninterrupted infections. Goblet cell counts showed a major increase, as did eosinophils in relation to naïve controls. Paneth cells were also elevated, but did not change over the course of the experiment. The results also drew attention to the tremendous resilience of hookworms, some adult worms surviving throughout, despite highly inflamed intestines.