Profiles of Th1 and Th2 cytokines after primary and secondary infection by Schistosoma mansoni in the semipermissive rat host

Immune response, oxidative stress, and histological changes of Wistar rats after being administered with Parascaris equorum antigen

Worldwide, particularly in developing nations, helminth infections are the leading causes of livestock illness and mortality. Parascaris (P.) equorum, a parasitic worm from the Ascarididae family, significantly impacts the production, health, and working performance of equines. This study aimed to investigate the impact of intraperitoneal sensitization of P. equorum on the immune system, oxidative stress, and histology in Wistar rats. After acclimatization for 7 days, we divided the rats into five groups, each consisting of six rats. Group I, serving as the control, was administered distilled water, followed by groups II (day 7), III (day 14), IV (day 21), and V (day 33). The rats were euthanized every day mentioned (Days 7-33). On day 0, a dosage of 1ml/100 gm rat (containing 500 μg/ml protein content) emulsified crude antigen extract with an incomplete Freund's adjuvant (1:1 volume), followed by a second dose of the same antigen concentration on day 7. To assess the allergenicity of this nematode, we measured a whole blood profile, serum levels of IFN-γ, IL-5, IL-10, IL-13, and IL-33, total immunoglobulins IgE and IgG, and oxidative stress markers. Also, we examined histological changes in the liver, kidney, and spleen. The results showed that values of total leukocyte count, granulocytes, monocytes, and lymphocytes were significantly (P < 0.05) increased on day 14 post-infection relative to other days of investigation. It was found that the levels of total immunoglobulins (IgE and IgG) and cytokines (INF-γ, IL-5, IL-13, and IL-33) on days 14 and 21 were significantly higher than in the control group. At all periods of the experiment, the injected group exhibited significantly higher concentrations of MDA and NO compared to the control group (P < 0.05). Conversely, GSH and CAT levels (P < 0.05) dropped significantly on days 7, 14, and 21. Different rat tissues showed alterations. Ultimately, this study described the detrimental effects of P. equorum crude antigen administration on the immune system, oxidative states, and histological changes of Wistar rats at various intervals.

An intranasal influenza virus vector vaccine protects against Helicobacter pylori in mice

Helicobacter pylori is a human pathogen that infects almost half of the population. Antibiotic resistance in H. pylori threatens health and increases the demand for prophylactic and therapeutic vaccines. Traditional oral vaccine research faces considerable challenges because of the epithelial barrier, potential enterotoxicity of adjuvants, and the challenging conditions of the gastric environment. We developed an intranasal influenza A virus (IAV) vector vaccine based on two live attenuated influenza viruses with modified acidic polymerase protein (PA) genes encoding the A subunit of H. pylori neutrophil-activating protein (NapA), named IAV-NapA, including influenza virus A/WSN/33 (WSN)-NapA and A/Puerto Rico/8/34 (PR8)-NapA. These recombinant influenza viruses were highly attenuated and exhibited strong immunogenicity in mice. Vaccination with IAV-NapA induced antigen-specific humoral and mucosal immune responses while stimulating robust Th1 and Th17 cell immune responses in mice. Our findings suggest that prophylactic and therapeutic vaccination with influenza virus vector vaccines significantly reduces colonization of H. pylori and inflammation in the stomach of mice.IMPORTANCEHelicobacter pylori is the most common cause of chronic gastritis and leads to severe gastroduodenal pathology in some patients. Many studies have shown that Th1 and Th17 cellular and gastric mucosal immune responses are critical in reducing H. pylori load. IAV vector vaccines can stimulate these immune responses while overcoming potential adjuvant toxicity and antigen dosing issues. To date, no studies have demonstrated the role of live attenuated IAV vector vaccines in preventing and treating H. pylori infection. Our work indicates that vaccination with IAV-NapA induces antigen-specific humoral, cellular, and mucosal immunity, producing a protective and therapeutic effect against H. pylori infection in BALB/c mice. This undescribed H. pylori vaccination approach may provide valuable information for developing vaccines against H. pylori infection.

Potential anthelmintic effect of chitosan on Syphacia muris infecting Wistar rats: biochemical, immunological, and histopathological studies

Natural products extracted from animal sources have many biological activities, such as chitosan, which is being researched for its medicinal or therapeutic potential. Syphacia muris is the most well-known intestinal nematode, infecting laboratory rats and influencing their immune systems. In this study, we looked at the anthelminthic activity of chitosan particles against S. muris infection using biochemical, immunological, and histopathological methods. Chitosan particles were characterized using Fourier-transform infrared spectroscopy (FTIR). Rats were separated into four groups, each consisting of seven individuals (n = 7). The first group was the control (non-infected), the second group was infected, and both groups received 0.5 ml of 1% glacial acetic acid orally. The third group was the infected group (treated), and the fourth group (normal) received 0.5 ml of 30 mg/kg/day chitosan dissolved in 1% glacial acetic acid for 14 days using gavage. Liver and kidney parameters, oxidative stress markers, serum levels of cytokines (IFN-γ, IL-5, IL-13, IL-33, and IL-10), as well as immunoglobulins (total IgE and IgG), were assessed. Histological examinations of host tissues (intestine, liver, kidney, and spleen) were also performed. Following chitosan treatment, a significant decrease in worm count (P < 0.05) was indicated; this was associated with an enhancement of biochemical and oxidative stress biomarkers, which were altered due to infection. Moreover, immunological analysis revealed a significant drop in INF-γ, IL-5, IL-13, and IL-33 levels and total immunoglobulins (IgE and IgG) as well as an improvement in rat tissues. Conclusively, this study showed the anthelminthic effect of chitosan against S. muris infection.

Evaluation of immunogenicity-induced DNA vaccines against different SARS-CoV-2 variants

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in 2019 and caused the coronavirus disease 2019 (COVID-19) pandemic worldwide. As of September 2023, the number of confirmed coronavirus cases has reached over 770 million and caused nearly 7 million deaths. The World Health Organization assigned and informed the characterization of variants of concern (VOCs) to help control the COVID-19 pandemic through global monitoring of circulating viruses. Although many vaccines have been proposed, developing an effective vaccine against variants is still essential to reach the endemic stage of COVID-19. We designed five DNA vaccine candidates composed of the first isolated genotype and major SARS-CoV-2 strains from isolated Korean patients classified as VOCs, such as Alpha, Beta, Gamma, and Delta. To evaluate the immunogenicity of each genotype via homologous and heterologous vaccination, mice were immunized twice within a 3-week interval, and the blood and spleen were collected 1 week after the final vaccination to analyze the immune responses. The group vaccinated with DNA vaccine candidates based on the S genotype and the Alpha and Beta variants elicited both humoral and cellular immune responses, with higher total IgG levels and neutralizing antibody responses than the other groups. In particular, the vaccine candidate based on the Alpha variant induced a highly diverse cytokine response. Additionally, we found that the group subjected to homologous vaccination with the S genotype and heterologous vaccination with S/Alpha induced high total IgG levels and a neutralization antibody response. Homologous vaccination with the S genotype and heterologous vaccination with S/Alpha and S/Beta significantly induced IFN-γ immune responses. The immunogenicity after homologous vaccination with S and Alpha and heterologous vaccination with the S/Alpha candidate was better than that of the other groups, indicating the potential for developing novel DNA vaccines against different SARS-CoV-2 variants.

Salmonella typhimurium exacerbates injuries but resolves fibrosis in liver and spleen during Schistosoma mansoni infection

BACKGROUND

In most developing or undeveloped countries, patients are often co-infected with multiple pathogens rather than a single pathogen. While different pathogens have their impact on morbidity and mortality, co-infection of more than one pathogen usually made the disease outcome different. Many studies reported the co-infection of Schistosoma with Salmonella in pandemic areas. However, the link or the underlying mechanism in the pathogenesis caused by Schistosoma-Salmonella co-infection is still unknown.

METHODS

In this study, Salmonella typhimurium (S. typhimurium) was challenged to Schistosoma mansoni (S. mansoni)-infected mice. Further experiments such as bacterial culture, histopathological examination, western blotting, and flow cytometry were performed to evaluate the outcomes of the infection. Cytokine responses of the mice were also determined by ELISA and real-time quantitative PCR.

RESULTS

Our results demonstrated that co-infected mice resulted in higher bacterial excretion in the acute phase but higher bacterial colonization in the chronic phase. Lesser egg burden was also observed during chronic schistosomiasis. Infection with S. typhimurium during schistosomiasis induces activation of the inflammasome and apoptosis, thereby leading to more drastic tissue damage. Interestingly, co-infected mice showed a lower fibrotic response in the liver and spleen. Further, co-infection alters the immunological functioning of the mice, possibly the reason for the observed pathological outcomes.

CONCLUSION

Collectively, our findings here demonstrated that S. mansoni-infected mice challenged with S. typhimurium altered their immunological responses, thereby leading to different pathological outcomes.

iNOS is essential to maintain a protective Th1/Th2 response and the production of cytokines/chemokines against Schistosoma japonicum infection in rats

Humans and a wide range of mammals are generally susceptible to Schistosoma infection, while some rodents such as Rattus rats and Microtus spp are not. We previously demonstrated that inherent high expression levels of nitric oxide (NO), produced by inducible nitric oxide synthase (iNOS), plays an important role in blocking the growth and development of Schistosoma japonicum in wild-type rats. However, the potential regulatory effects of NO on the immune system and immune response to S. japonicum infection in rats are still unknown. In this study, we used iNOS-knockout (KO) rats to determine the role of iNOS-derived NO in the immune system and immunopathological responses to S. japonicum infection in rats. Our data showed that iNOS deficiency led to weakened immune activity against S. japonicum infection. This was characterized by the impaired T cell responses and a significant decrease in S. japonicum-elicited Th2/Th1 responses and cytokine and chemokine-producing capability in the infected iNOS-KO rats. Unlike iNOS-KO mice, Th1-associated cytokines were also decreased in the absence of iNOS in rats. In addition, a profile of pro-inflammatory and pro-fibrogenic cytokines was detected in serum associated with iNOS deficiency. The alterations in immune responses and cytokine patterns were correlated with a slower clearance of parasites, exacerbated granuloma formation, and fibrosis following S. japonicum infection in iNOS-KO rats. Furthermore, we have provided direct evidence that high levels of NO in rats can promote the development of pulmonary fibrosis induced by egg antigens of S. japonicum, but not inflammation, which was negatively correlated with the expression of TGF-β3. These studies are the first description of the immunological and pathological profiles in iNOS-KO rats infected with S. japonicum and demonstrate key differences between the responses found in mice. Our results significantly enhance our understanding of the immunoregulatory effects of NO on defensive and immunopathological responses in rats and the broader nature of resistance to pathogens such as S. japonicum.

Schistosomiasis is a zoonosis that affects more than 200 million people worldwide. A wide range of mammals, including mice, are permissive hosts of Schistosoma and develop chronic disease characterized by egg-granuloma formation and fibrosis after infection. Rats, on the other hand, are non-permissive hosts and develop efficient immune responses to eliminate the worms. Interestingly, schistosome eggs elicit a dominant Th2 immune response within mouse hosts, whereas rats with schistosomiasis develop a significant Th2 response in the absence of available egg production. The Th2 response in rats seems to play an essential role in the protection of the host against Schistosoma. So far, the factors that lead to the different immune responses to Schistosoma infection in both hosts have not been demonstrated. In this study, our results show that an iNOS-dependent mechanism maintains the function of the immune system in rats by modulating CD4⁺ T cell-mediated Th1/Th2-associated cytokine responses and chemokine production. Additionally, the absence of iNOS led to slow clearance of parasites, increases in the development of worms, and an exacerbation of granuloma formation and fibrosis in rats. Furthermore, high levels of NO in rats can promote the development of fibrosis induced by inflammation (rapid inflammatory repair). Therefore, this study demonstrates that the difference in iNOS levels between mice and rats is responsible for the different immune responses and outcomes induced by schistosome infection in both hosts.

Development of a skin- and neuro-attenuated live vaccine for varicella

Varicella caused by the primary infection of varicella-zoster virus (VZV) exerts a considerable disease burden globally. Current varicella vaccines consisting of the live-attenuated vOka strain of VZV are generally safe and effective. However, vOka retains full neurovirulence and can establish latency and reactivate to cause herpes zoster in vaccine recipients, raising safety concerns. Here, we rationally design a live-attenuated varicella vaccine candidate, v7D. This virus replicates like wild-type virus in MRC-5 fibroblasts and human PBMCs, the carrier for VZV dissemination, but is severely impaired for infection of human skin and neuronal cells. Meanwhile, v7D shows immunogenicity comparable to vOka both in vitro and in multiple small animal species. Finally, v7D is proven well-tolerated and immunogenic in nonhuman primates. Our preclinical data suggest that v7D is a promising candidate as a safer live varicella vaccine with reduced risk of vaccine-related complications, and could inform the design of other herpes virus vaccines.

Current varicella vaccines retain neurovirulence and can establish latency and reactivate. Here, the authors present preclinical results of a rationally-designed, skin- and neuro-attenuated varicella vaccine candidate, v7D, showing its attenuation in human skin and neuronal cells and its immunogenicity in small animal models and nonhuman primates

Effect of multi-epitope derived from HIV-1 on REM sleep deprivation-induced spatial memory impairment with respect to the level of immune factors in mice

Objectives

Sleep deprivation (SD) has a negative impact on cognitive functions including learning and memory. Many studies have shown that rapid-eye-movement (REM) SD also disrupts memory performance. In this study, we aimed to investigate the effect of multi-epitope Gag-Pol-Env-Tat derived from Human immunodeficiency virus 1 (HIV-1) on REM SD-induced spatial memory impairment with respect to the levels of interleukin-4 (IL-4), interleukin-17 (IL-17), interferon-gamma (IFN-γ), immunoglobulin G1 (IgG1), immunoglobulin G2a (IgG2a), and lymphocyte proliferation in NMRI mice. We used multi-epitope Gag-Pol-Env-Tat derived from HIV-1 because Gag-Pol-Env-Tat immunogen sequence is one of the most sensitive immunogen sequences of HIV-1 that can significantly augment cellular and humoral immune systems, leading to the improvement of cognitive functions.

Materials and Methods

Morris water maze apparatus was used to assess spatial memory, and multi-platform apparatus was used to induce RSD for 24 hr. Multi-epitope derived from HIV-1 was subcutaneously injected at the dose of 20 µgr/ml, once and fourteen days before RSD.

Results

RSD impaired spatial memory and injection of multi-epitope derived from HIV-1 reversed this effect. RSD decreased IL-4, IgG1, and IgG2a levels, while multi-epitope derived from HIV-1 reversed these effects. Multi-epitope derived from HIV-1 also increased lymphocyte proliferation and decreased IL-17 levels in both control and RSD mice.

Conclusion

Multi-epitope derived from HIV-1 may improve memory performance via induction of anti-inflammatory immune response.

Alum and metoclopramide synergistically enhance cellular and humoral immunity after immunization with heat-killed Salmonella typhimurium vaccine

Typically, the killed form of microorganisms in combination with alum does not produce strong cellular immune responses. A recent investigation has indicated the role of dopamine D2 receptor antagonists like metoclopramide in reducing the polarization of immune responses toward Th2 immunity. This study was performed to evaluate the effects of a combination of alum and metoclopramide on the induction of cellular and humoral immunity in response to a heat-killed preparation ofSalmonella typhimurium(HKST). Wistar rats were immunized with the HKST vaccine alone or in combination with alum, metoclopramide, or the alum-metoclopramide mixture twice with a two-week interval. Fourteen days after the last vaccination, immune responses against S. typhimurium and the protective potential of the vaccines were assessed. The combination of alum and metoclopramide as an adjuvant augmented the potential of the HKST vaccine to enhance lymphocyte proliferation, delayed-type hypersensitivity reaction, and antibody titer. These results were concurrent with the polarization of immune response towards the Th1 response and improving protective immunity against S. typhimurium. Overall, the combination of alum and metoclopramide as an adjuvant synergistically enhanced cellular and humoral immunity after immunization with the HKST vaccine.

Intranasal Administration of RBD Nanoparticles Confers Induction of Mucosal and Systemic Immunity against SARS-CoV-2

Mucosal immunity plays a significant role in host defense against viruses in the respiratory tract. Because the upper respiratory airway is a primary site of SARS-CoV-2 entry, immunization at the mucosa via the intranasal route could potentially lead to induction of local sterilizing immunity that protects against SARS-CoV-2 infection. In this study, we evaluated the immunogenicity of a receptor-binding domain (RBD) of SARS-CoV-2 spike glycoprotein loaded into N,N,N-trimethyl chitosan nanoparticles (RBD-TMC NPs). We showed that intranasal delivery of RBD-TMC NPs into mice induced robust local mucosal immunity, as evidenced by the presence of IgG and IgA responses in BALs and the lungs of immunized mice. Furthermore, mice intranasally administered with this platform of immunogens developed robust systemic antibody responses including serum IgG, IgG1, IgG2a, IgA and neutralizing antibodies. In addition, these immunized mice had significantly higher levels of activated splenic CD4⁺ and CD8⁺ cells compared with those that were administered with soluble RBD immunogen. Collectively, these findings shed light on an alternative route of vaccination that mimics the natural route of SARS-CoV-2 infection. This route of administration stimulated not only local mucosal responses but also the systemic compartment of the immune system.

High-throughput rat immunoglobulin G N-glycosylation profiling revealed subclass-specific changes associated with chronic stress

Immunoglobulin G (IgG) glycosylation corresponds well with immune system changes, so it can potentially be used as a biomarker for the consequences of chronic stress such as low-grade inflammation and enhanced immunosenescence in older animals. Here we present a high-throughput glycoproteomic workflow, including IgG enrichment, HILIC glycopeptide purification, and nano-LC-MS analysis of tryptic glycopeptides applied for the analysis of rat IgG. A cohort of 80 animals was exposed to seven stressors in a customized chronic stress protocol with blood and tissue sampling in three timepoints. Young female rats experienced an increase in agalactosylated glycoforms on IgG2a and IgG2c accompanied by a decrease in monogalactosylation. Among old females, increased galactosylation was observed in the IgG2b subclass, pointing to an anti-inflammatory activity of IgG. Additionally, IgG Fc N-glycosylation patterns in Sprague Dawley rats were analyzed, quantified, and reported for the first time. Our findings emphasize age-, sex- and subclass-dependent differences in IgG glycosylation related to chronic stress exposure, confirming the relevance of newly developed methods for further research in glycobiology of rodent immune response. SIGNIFICANCE: In this study, we showed that a high-throughput streamlined methodology based on protein L 96-well monolithic plates for efficient rat IgG immunoaffinity enrichment from blood plasma, paired with appropriate tryptic glycopeptide preparation, HILIC-SPE enrichment, and nano-LC-MS methods was suitable for quick processing of large sample sets. We report a subclass-specific profiling and changes in rat IgG Fc galactosylation and adrenal gland immunohistochemistry of male and female animals exposed to a customized chronic stress protocol.

Loss of natural resistance to schistosome in T cell deficient rat

Schistosomiasis is among the major neglected tropical diseases and effective prevention by boosting the immune system is still not available. T cells are key cellular components governing adaptive immune response to various infections. While common laboratory mice, such as C57BL/6, are highly susceptible to schistosomiasis, the SD rats are extremely resistant. However, whether adaptive immunity is necessary for such natural resistance to schistosomiasis in rats remains to be determined. Therefore, it is necessary to establish genetic model deficient in T cells and adaptive immunity on the resistant SD background, and to characterize liver pathology during schistosomiasis. In this study we compared experimental schistosomiasis in highly susceptible C57BL/6 (B6) mice and in resistant SD rats, using cercariae of Schistosoma japonicum. We observed a marked T cell expansion in the spleen of infected B6 mice, but not resistant SD rats. Interestingly, CD3e^−/− B6 mice in which T cells are completely absent, the infectious burden of adult worms was significantly higher than that in WT mice, suggesting an anti-parasitic role for T cells in B6 mice during schistosome infection. In further experiments, we established Lck deficient SD rats by using CRISPR/Cas9 in which T cell development was completely abolished. Strikingly, we found that such Lck deficiency in SD rats severely impaired their natural resistance to schistosome infection, and fostered parasite growth. Together with an additional genetic model deficient in T cells, the CD3e^−/− SD rats, we confirmed the absence of T cell resulted in loss of natural resistance to schistosome infection, but also mitigated liver immunopathology. Our further experiments showed that regulatory T cell differentiation in infected SD rats was significantly decreased during schistosomiasis, in contrast to significant increase of regulatory T cells in infected B6 mice. These data suggest that T cell mediated immune tolerance facilitates persistent infection in mice but not in SD rats. The demonstration of an important role for T cells in natural resistance of SD rats to schistosomiasis provides experimental evidences supporting the rationale to boost T cell responses in humans to prevent and treat schistosomiasis.

Schistosomiasis is among the major neglected tropical diseases and affects mainly the developing countries. Although the role of the immune system in driving immunopathology in schistosomiasis has been extensively studied, how adaptive immunity contributes to disease resistance during schistosome infection is still not completely understood. Most livestock species as well as humans are susceptible to schistosomiasis, while some mammals are extremely resistant. The common laboratory C57BL/6 mice are highly susceptible to schistosomiasis; however, the SD rats are extremely resistant. In this study, we first used T cell deficient CD3e^−/− C57BL/6 mice and experimental Schistosoma japonicum infection and further established novel T cell deficient models in SD rats to assess anti-parasite roles of T cells. Strikingly, we found that the natural resistance of SD rat to schistosomiasis was abolished in the absence of T cells, despite the fact that the liver pathology was mitigated following infection. Therefore, our study presented experimental support for the rationale to boost T cell function for clearance of schistosome parasites.

Mechanisms of Resistance to Schistosoma japonicum Infection in Microtus fortis, the Natural Non-permissive Host

Human schistosomiasis, which is caused by schistosomes, is a zoonosis that is difficult to control because of the many reservoir hosts. However, Microtus fortis is the only mammal that is naturally resistant to Schistosoma japonicum infection known in China, in which S. japonicum growth and development were arrested on day 12, and the worms eliminated on day 20 post-infection. In this review, we present an overview of the established and purported mechanisms of resistance to S. japonicum infection in M. fortis in comparison to Rattus norvegicus, a semi-permissive host. Clarifying the mechanism of this efficient resistance can help us to better understand host-parasite interaction and to provide better methods to control schistosomiasis.

Nanodelivery system enhances the immunogenicity of dengue-2 nonstructural protein 1, DENV-2 NS1

Nonstructural protein 1 (NS1) of dengue virus (DENV) is currently recognized as a dengue vaccine candidate. Unfortunately, most of non-replicating immunogens typically stimulate unsatisfactory immune responses, thus, the additional adjuvant is required. In this study, C-terminal truncated DENV-2 NS1 loaded in N,N,N, trimethyl chitosan nanoparticles (NS1_1-279TMC NPs) was prepared through the ionic gelation method. The immunogenicity of NS1_1-279TMC NPs was investigated using human ex vivo as well as the murine model. Through a human ex vivo model, it was demonstrated in this study that not only can TMC particles effectively deliver NS1_1-279 protein into monocyte-derived dendritic cells (MoDCs), but also potently stimulate those cells, resulting in increased expression of maturation marker (CD83), costimulating molecules (CD80, CD86 and HLA-DR) and markedly secreted various types of innate immune cytokines/chemokines. Moreover, mice administered with NS1_1-279TMC NPs strongly elicited both antibody and T cell responses, produced higher levels of IgG, IgG1, IgG2a and potently activated CD8⁺ T cells, as compared to mice administered with soluble NS1_1-279. Importantly, we further demonstrated that anti-NS1_1-279 antibody induced by this platform of NS1_1-279 effectively eliminated DENV-2 infected cells through antibody dependent complement-mediated cytotoxicity. Significantly, anti-DENV2 NS1_1-279 antibody exerted cross-antiviral activity against DENV-1 and -4 but not against DENV-3 infected cells. These findings demonstrate that TMC exerts a desirable adjuvant for enhancing delivery and antigenicity of NS1 based dengue vaccine.

Resistance against Trichinella spiralis infection in pups delivered by T. spiralis-infected dam

Maternal antibody transmission via placenta and breastmilk are known to confer protection in infants. In this study, we investigated the maternal immunity transmission in pups delivered by rats infected with Trichinella spiralis and assessed the resulting resistance against subsequent parasitic infection. Our results revealed that parasite-specific IgG, IgG1 and IgG2a antibodies were present in pups prior to breastmilk ingestion (pre-milk), in which IgG and IgG1 antibodies persisted until week 8 after birth while parasite-specific IgG2a antibodies only lasted until week 4. After weaning on week 3, pups delivered by T. spiralis-infected dam and subsequently challenge-infected (immune-challenge) were found to possess higher mucosal IgG antibodies than control groups, whereas mucosal IgA levels were not significantly different across all groups. T. spiralis excretory-secretory antigen was discovered to react with pup sera until week 8, correlating with the resistance against parasitic infection which is represented by lessened worm burden. Upon T. spiralis infection at weeks 3 and 8, lower levels of eosinophil responses were detected in immune-challenge pups compared to naïve-challenge pups, indicating correlates of resistances in which ADCC may be involved. Findings from the present study demonstrate that resistances against T. spiralis infection in pups can be acquired by maternally-derived IgG, IgG1 and IgG2a antibody transmission through the placenta and breastmilk from T. spiralis-infected dam, which lasts until week 8.

Comparison of immunogenicity and vaccine efficacy between heat-shock proteins, HSP70 and GrpE, in the DnaK operon of Mycobacterium tuberculosis

Antigens (Ags) in Mycobacterium tuberculosis (Mtb) that are constitutively expressed, overexpressed during growth, essential for survival, and highly conserved may be good vaccine targets if they induce the appropriate anti-Mtb Th1 immune response. In this context, stress response-related antigens of Mtb might serve as attractive targets for vaccine development as they are rapidly expressed and are up-regulated during Mtb infection in vivo. Our group recently demonstrated that GrpE, encoded by rv0351 as a cofactor of heat-shock protein 70 (HSP70) in the DnaK operon, is a novel immune activator that interacts with DCs to generate Th1-biased memory T cells in an antigen-specific manner. In this study, GrpE was evaluated as a subunit vaccine in comparison with the well-known HSP70 against the hyper-virulent Mtb Beijing K-strain. Both HSP70- and GrpE-specific effector/memory T cells expanded to a similar extent as those stimulated with ESAT-6 in the lung and spleen of Mtb-infected mice, but GrpE only produced a similar level of IFN-γ to that produced by ESAT-6 stimulation during the late phase and the early phase of Mtb K infection, indicating that GrpE is highly-well recognised by the host immune system as a T cell antigen. Mice immunised with the GrpE subunit vaccine displayed enhanced antigen-specific IFN-γ and serum IgG2c responses along with antigen-specific effector/memory T cell expansion in the lungs. In addition, GrpE-immunisation markedly induced multifunctional Th1-type CD4⁺ T cells co-expressing IFN-γ, TNF-α, and IL-2 in the lungs of Mtb K-infected mice, whereas HSP70-immunisation induced mixed Th1/Th2 immune responses. GrpE-immunisation conferred a more significant protective effect than that of HSP70-immunisation in terms of bacterial reduction and improved inflammation, accompanied by the remarkable persistence of GrpE-specific multifunctional CD4⁺ T cells. These results suggest that GrpE is an excellent vaccine antigen component for the development of a multi-antigenic Mtb subunit vaccine by generating Th1-biased memory T cells with multifunctional capacity, and confers durable protection against the highly virulent Mtb K.

The novel immunogenic chimeric peptide vaccine to elicit potent cellular and mucosal immune responses against HTLV-1

This study reports on the immunogenicity assessment of a novel chimeric peptide vaccine including Tax, gp21, gp46, and gag immunodominant epitopes of human T-cell lymphotropic virus type 1 (HTLV-1) to induce immunity against HTLV-1 after subcutaneous (SC) or intranasal administration in a mice model. Additionally, to elevate the efficacy of the HTLV-1 vaccine, the chimera was physically mixed with monophosphoryl lipid A (MPLA) or ISCOMATRIX (IMX) adjuvants. For this purpose, the ISCOMATRIX with a size range of 40-60 nm were prepared using lipid film hydration method. Our investigation revealed that the mixture of IMX and chimera could significantly increase antibody titers containing IgG2a, and mucosal IgA, as well as IFN-γ and IL-10 cytokines and decrease the level of TGF-β1, compared to other vaccine formulations. The intranasal delivery of chimera vaccine in the absence or presence adjuvants stimulated potent mucosal sIgA titer relative to subcutaneous immunization. Furthermore, the SC or nasal delivery of various vaccine formulations could shift the immunity toward cell-mediated responses, as evident by higher IgG2a and IFN-γ, as well as suppressed TGF-β1 level. Our findings suggest that proper design, construction, and immunization of multi-epitope vaccine are essential for developing an effective HTLV-1 vaccine.

Is arachidonic acid an endoschistosomicide?

Schistosoma mansoni and Schistosoma haematobium are intravascular, parasitic flatworms that infect >250 million people in 70 developing countries, yet not all people of the same community and household are afflicted. Regarding laboratory rodents, mice but not rats are susceptible to infection with S. mansoni and hamsters but not mice are entirely permissive to infection with S. haematobium. A recent Brazilian publication has demonstrated that resistance of the water-rat, Nectomys squamipes to S. mansoni infection might be ascribed to stores of arachidonic acid (ARA)-rich lipids in liver. Several reports have previously shown that ARA is a safe and effective schistosomicide in vitro, and in vivo in mice, hamsters and in children. Schistosoma haematobium appeared more sensitive than S. mansoni to ARA in in vitro and in vivo experiments. Accordingly, it was proposed that ARA increased levels might be predominantly responsible for natural attrition of S. mansoni and S. haematobium in resistant experimental rodents. Therefore, the levels of ARA in serum, lung, and liver of rats (resistant) and mice (susceptible) at 1, 2, 3, 4 and 6 weeks after infection with S. mansoni cercariae and between mice (semi-permissive) and hamster (susceptible) at 1, 2, 3, 4, and 12 weeks after infection with S. haematobium cercariae were compared and contrasted. Neutral triglycerides and ARA levels were assessed in serum using commercially available assays and in liver and lung sections by transmission electron microscopy, Oil Red O staining, and specific anti-ARA antibody-based immunohistochemistry assays. Significant (P < .05), consistent, and reproducible correlation was recorded between ARA content in serum, lung, and liver and rodent resistance to schistosome infection, thereby implicating ARA as an endoschistosomicide.

Virus-like particles vaccine containing Clonorchis sinensis tegumental protein induces partial protection against Clonorchis sinensis infection

Background

Human clonorchiasis, caused by the infection of Clonorchis sinensis, is one of the major health problems in Southeast Asia. However, vaccine efficacy against C. sinensis infection remains largely unknown.

Methods

In this study, for the first time, we generated virus-like particles (VLPs) vaccine containing the C. sinensis tegumental protein 22.3 kDa (CsTP 22.3) and the influenza matrix protein (M1) as a core protein, and investigated the vaccine efficacy in Sprague-Dawley rats.

Results

Intranasal immunization of VLPs vaccine induced C. sinensis-specific IgG, IgG2a and IgG2c in the sera and IgA responses in the feces and intestines. Notably, upon challenge infection with C. sinensis metacercariae, significantly lower adult worm loads (70.2%) were measured in the liver of rats immunized with VLPs, compared to those of naïve rats. Furthermore, VLPs immunization induced antibody secreting cells (ASC) responses and CD4+/CD8+ T cell responses in the spleen.

Conclusions

Our results indicated that VLPs vaccine containing C. sinensis CsTP 22.3 kDa provided partial protection against C. sisnensis infection. Thus, VLPs could be a potential vaccine candidate against C. sinensis.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2526-5) contains supplementary material, which is available to authorized users.

Nitric oxide blocks the development of the human parasite Schistosoma japonicum

Human schistosomiasis, caused by Schistosoma species, is a major public health problem affecting more than 700 million people in 78 countries, with over 40 mammalian host reservoir species complicating the transmission ecosystem. The primary cause of morbidity is considered to be granulomas induced by fertilized eggs of schistosomes in the liver and intestines. Some host species, like rats (Rattus norvegicus), are naturally intolerant to Schistosoma japonicum infection, and do not produce granulomas or pose a threat to transmission, while others, like mice and hamsters, are highly susceptible. The reasons behind these differences are still a mystery. Using inducible nitric oxide synthase knockout (iNOS^-/-) Sprague-Dawley rats, we found that inherent high expression levels of iNOS in wild-type (WT) rats play an important role in blocking growth, reproductive organ formation, and egg development in S. japonicum, resulting in production of nonfertilized eggs. Granuloma formation, induced by fertilized eggs in the liver, was considerably exacerbated in the iNOS^-/- rats compared with the WT rats. This inhibition by nitric oxide acts by affecting mitochondrial respiration and energy production in the parasite. Our work not only elucidates the innate mechanism that blocks the development and production of fertilized eggs in S. japonicum but also offers insights into a better understanding of host-parasite interactions and drug development strategies against schistosomiasis.

Young Sprague Dawley rats infected by Plasmodium berghei: A relevant experimental model to study cerebral malaria

Cerebral malaria (CM) is the most severe manifestation of human malaria yet is still poorly understood. Mouse models have been developed to address the subject. However, their relevance to mimic human pathogenesis is largely debated. Here we study an alternative cerebral malaria model with an experimental Plasmodium berghei Keyberg 173 (K173) infection in Sprague Dawley rats. As in Human, not all infected subjects showed cerebral malaria, with 45% of the rats exhibiting Experimental Cerebral Malaria (ECM) symptoms while the majority (55%) of the remaining rats developed severe anemia and hyperparasitemia (NoECM). These results allow, within the same population, a comparison of the noxious effects of the infection between ECM and severe malaria without ECM. Among the ECM rats, 77.8% died between day 5 and day 12 post-infection, while the remaining rats were spontaneously cured of neurological signs within 24-48 hours. The clinical ECM signs observed were paresis quickly evolving to limb paralysis, global paralysis associated with respiratory distress, and coma. The red blood cell (RBC) count remained normal but a drastic decrease of platelet count and an increase of white blood cell numbers were noted. ECM rats also showed a decrease of glucose and total CO2 levels and an increase of creatinine levels compared to control rats or rats with no ECM. Assessment of the blood-brain barrier revealed loss of integrity, and interestingly histopathological analysis highlighted cyto-adherence and sequestration of infected RBCs in brain vessels from ECM rats only. Overall, this ECM rat model showed numerous clinical and histopathological features similar to Human CM and appears to be a promising model to achieve further understanding the CM pathophysiology in Humans and to evaluate the activity of specific antimalarial drugs in avoiding/limiting cerebral damages from malaria.

Anti-Arthritic Activity of Schistosoma mansoni and Trichinella spiralis Derived-Antigens in Adjuvant Arthritis in Rats: Role of FOXP3+ Treg Cells

A growing body of evidence supports the concept of helminths therapy in a variety of autoimmune diseases. Here, we aimed to investigate the protective effects of autoclaved Schistosoma mansoni antigen (ASMA) and Trichinella spiralis antigen (ATSA) on the clinical and immunopathological features of rheumatoid arthritis (RA). Adjuvant arthritis was induced by subcutaneous and intradermal injections of complete Freund's adjuvant into the plantar surface of the right hind paw and the root of the tail, respectively. Rats were randomly assigned to serve as normal control, untreated arthritis, ASMA or ATSA-treated arthritis groups. Antigens were given by intradermal injection in two doses, two weeks apart. The development, progression of arthritic features, and the impact on animals' gait and body weight were followed up for 4 weeks. The associated changes in serum cytokines (IL-17, IFN-γ and IL-10), joints' histopathology and immunohistochemistry of Foxp3+ T regulatory cells (Tregs) were evaluated at the end of the study. Treatment with either ASMA or ATSA attenuated the progression of clinical features of polyarthritis, improved gait and body weight gain, reduced the elevated serum IL-17 and further increased both IFN-γ and IL-10. Histopathologically, this was associated with a remarkable regression of paws' inflammation that was limited only to the subcutaneous tissue, and a significant increase in the number of Foxp 3+ cells versus the untreated arthritis group. In conclusion, both Schistosoma mansoni and Trichinella spiralis derived antigens exerted protective effect against adjuvant arthritis with better effect achieved by ASMA treatment. This anti-arthritic activity is attributed to upregulation of the Foxp3+ Tregs, with subsequent favorable modulation of both pro- and anti-inflammatory cytokines. The use of autoclaved parasitic antigens excludes the deleterious effects of imposing helminthic infection by using live parasites, which may pave the way to a new therapeutic modality in treating RA.

An immunomics approach to schistosome antigen discovery: antibody signatures of naturally resistant and chronically infected individuals from endemic areas

Schistosomiasis is a neglected tropical disease that is responsible for almost 300,000 deaths annually. Mass drug administration (MDA) is used worldwide for the control of schistosomiasis, but chemotherapy fails to prevent reinfection with schistosomes, so MDA alone is not sufficient to eliminate the disease, and a prophylactic vaccine is required. Herein, we take advantage of recent advances in systems biology and longitudinal studies in schistosomiasis endemic areas in Brazil to pilot an immunomics approach to the discovery of schistosomiasis vaccine antigens. We selected mostly surface-derived proteins, produced them using an in vitro rapid translation system and then printed them to generate the first protein microarray for a multi-cellular pathogen. Using well-established Brazilian cohorts of putatively resistant (PR) and chronically infected (CI) individuals stratified by the intensity of their S. mansoni infection, we probed arrays for IgG subclass and IgE responses to these antigens to detect antibody signatures that were reflective of protective vs. non-protective immune responses. Moreover, probing for IgE responses allowed us to identify antigens that might induce potentially deleterious hypersensitivity responses if used as subunit vaccines in endemic populations. Using multi-dimensional cluster analysis we showed that PR individuals mounted a distinct and robust IgG1 response to a small set of newly discovered and well-characterized surface (tegument) antigens in contrast to CI individuals who mounted strong IgE and IgG4 responses to many antigens. Herein, we show the utility of a vaccinomics approach that profiles antibody responses of resistant individuals in a high-throughput multiplex approach for the identification of several potentially protective and safe schistosomiasis vaccine antigens.

Schistosomiasis is a neglected tropical disease that kills as many as 300,000 people each year. Mass drug administration is widely used to control schistosomiasis, but fails to prevent rapid reinfection in endemic areas. There is a desperate need for a prophylactic vaccine; however, very few candidates have been developed. Herein, we take advantage of recent advances in systems biology and longitudinal studies in schistosomiasis endemic areas to pilot an immunomics approach to the discovery of vaccine antigens. The emerging field of immunomics enables the determination of an “antibody signature” to a pathogen proteome for both resistant and susceptible individuals. We constructed the first protein microarray for a multi-cellular pathogen and probed it with sera from naturally resistant vs. susceptible individuals from a high transmission area in Northeastern Brazil. Using multi-dimensional cluster analysis, we showed that resistant individuals mounted a distinct and robust IgG1 antibody signature to a small set of newly discovered and well-characterized surface antigens in contrast to infected individuals. This antigen discovery strategy can lead to identification of several potentially protective and safe schistosomiasis vaccine antigens.

[Immunological disorders of diabetes mellitus in experimental rat models]

A comprehensive understanding of the pathogenic mechanism is the prerequisite for proper disease management. However, the mechanisms of diabetes mellitus and diabetic complication remain extremely complicated and unresolved. While immune reactions are involved in the pathogenesis of diabetes and diabetic complication, the diabetic condition itself can influence immune responses. Furthermore, both diabetes and immune reactions are regulated by genetic and environmental factors. As a result, animal models have evolved to be powerful research tools to elucidate the complicated mechanisms for the pathogenesis of diabetes. Recently, various animal models of diabetes have been developed in rats, which provide advantages over mouse models in the scale of tissue samples and variation in type 2 diabetes models. In this review, we introduced rat models of diabetes and summarized the immune reactions in diabetic rats to propose the relationship between immune reactions and diabetes. Type 1 diabetes is induced by self-reactive cellular immune reactions. On the other hand, type 2 diabetes in rat models is associated with augmentation of innate immune reactions and increased humoral immunity. For example, helper T (Th) 1/Th17 cells are prevalent in non-obese type 1 diabetes rats (diabetes-prone BioBreeding rats), while non-obese type 2 diabetes rats (Goto-Kakizaki rat) show higher levels of natural IgM and T cell ratios with elevated Th2 cells compared with Wister rats. The investigation of immunological disorders in various diabetic rat models is useful to elucidate complicated mechanisms for the pathophysiology of diabetes. In future studies, immunological experimentations altering Th1/Th17 or Th2 cell levels and natural immune reactions may lend support to understanding the causes of diabetes and predicting the pathological conditions in diabetes.

The developing schistosome worms elicit distinct immune responses in different tissue regions

Schistosome parasites follow a complex migration path through various tissues, changing their antigenic profile as they develop. A thorough understanding of the antibody response in each tissue region could help unravel the complex immunology of these developing parasites and aid vaccine design. Here we used a novel strategy for analysing the local antibody responses induced by Schistosoma japonicum infection at each site of infection. Cells from rat lymph nodes draining the sites of larval migration (the skin and lungs), the liver-lymph nodes where adults reside and the spleens were cultured to allow the in vivo-induced antibody-secreting cells to release antibody into the media. The amount and isotype of antibodies secreted in the supernatants differed significantly in the different lymph nodes and spleen, corresponding with the migration path of the schistosome worms. In addition, there were significant differences in binding specificity, as determined by surface labelling, western blots and by screening a glycan array. Through capturing the local antibody response, this study has revealed dramatic differences in the quality and specificity of the immune response at different tissue sites, and highlighted the existence of stage-specific protein and carbohydrate antigens. This will provide a valuable tool for the isolation of novel vaccine targets against the larval stages of schistosomes.

Migrating Schistosoma japonicum schistosomula induce an innate immune response and wound healing in the murine lung

The migrating schistosomulum is an important stage of the schistosome lifecycle and represents a key target for elimination of infection by natural and vaccine-induced host immune responses. To gain a better understanding of how schistosomes initiate a primary host immune response we have characterised the host lung response to migrating Schistosoma japonicum schistosomula using a combination of histopathology, microarray analysis and real-time PCR. Our findings indicate that the early pulmonary response to these migrating larvae is characteristic of innate inflammation and wound healing. This response is associated with significant up-regulation of several genes with immunoregulatory function including Ch25h, Hmox1 and Retnla which may act to control the nature or magnitude of the inflammatory response to the migrating schistosomula, promoting both parasite and host survival. These findings contribute to our understanding of host-parasite interactions associated with schistosome and, especially, S. japonicum infection, and may aid the future design of novel vaccines that target the lung stage schistosomulum.

Recent advances in the characterization of genetic factors involved in human susceptibility to infection by schistosomiasis

Human resistance to infection by schistosomes is associated to a strong Th2 immune. However a persistent Th2 response can cause severe kidney and liver disease in human. In this review, we mainly focused on the control of infection levels caused by schistosomes. Several experimental models allowed us to better understand the immunological mechanisms of the host against schistosome infection. High IgE and eosinophil levels are associated with resistance to infection by schistosomes and this effect is counterbalanced by IgG4. IgE and eosinophils are highly dependent on IL-4, IL-13, and Il-5, which are three main Th2 cytokines. We also examined the genetic factors involved in human susceptibility to infection by schistosomiasis. Infection levels are mainly regulated by a major locus SM1, in 5q31-q33 region, which contains the genes encoding for the IL-4, IL-13, and Il-5 cytokines. An association between an IL13 polymorphism, rs1800925, and infection levels has been shown. This polymorphism synergistically acts with another polymorphism (rs324013) in the STAT6 gene, encoding for the signal transducer of the IL13 pathway. This pathway has also been involved in atopic disorders. As helminthiasis, atopy is the result of aberrant Th2 cytokine response to allergens, with an increased production of IL-4, IL-13, Il-9 and Il-5, with high amounts of allergen-specific and total IgE and eosinophilia. However, the Th2 immune response is protective in helminthiasis but aggravating in atopic disorders. Several studies reported interplay between helminthic infections and allergic reactions. The different results are discussed here.

Schistosoma mansoni host-exposed surface antigens characterized by sera and recombinant antibodies from schistosomiasis-resistant rats

Antibodies from Schistosoma mansoni-infected rats, unlike mice, show a higher titer for schistosome apical tegumental antigens compared with non-apical membrane antigens. These antibodies bind to the surface of living lung-stage worms and to formaldehyde-fixed adult worms. We produced a single-chain antibody Fv domain (scFv) phage library displaying the antibody repertoire of rats highly immune to schistosome infection and we selected for scFvs that recognize the host-exposed surface of worms. Five unique rat scFvs (Teg1, Teg4, Teg5, Teg20 and Teg37) were obtained which recognize schistosome surface epitopes. Each of the scFvs recognizes the surface of living schistosomula and lung-stage schistosomules and/or the surface of formaldehyde-fixed adult worms. None of these scFvs reproducibly stained living adult worms. This suggests that a change occurs during the transition from lung schistosomules to 4-week adults such that at least some surface antigens, although remaining on the surface in living adult worms, can no longer be immunologically stained. Teg1 and Teg4 scFvs both recognize specific bands on Western blots. No bands were observed for the other three scFvs, suggesting that these scFvs may recognize non-protein or conformationally-dependent epitopes. Teg1 was unambiguously identified as recognizing the S. mansoni tetraspanin antigen, SmTSP-2, within the large extracellular domain. Teg4 recognizes a 35kDa band tentatively identified as Sm29 by proteomic analysis. These scFvs can now be used to characterize schistosome epitopes at the host-parasite interface, to target worms in vivo, and to study the mechanisms by which these worms naturally evade immune damage to the tegument within permissive hosts.

Immunomodulatory effects of dietary protein during Nippostrongylus brasiliensis re-infection in lactating rats

Periparturient relaxation of immunity (PPRI) to secondary infection with nematodes is believed to have a nutritional basis due to differential partitioning of scarce nutrient resources, particularly protein, to reproductive rather than immune functions. At times of protein scarcity, an increase in protein supply has been reported to assuage this phenomenon. The Nippostrongylus brasiliensis reinfected lactating rat model is now being utilized to investigate the immune reactions underlying the modifying role of dietary protein on PPRI. Herein, we demonstrate that lactating rats reinfected with N. brasiliensis under high protein (HP) dietary conditions exhibit decreased worm burdens and reduced colon egg counts compared to their low protein (LP) counterparts. These reductions correlated with increased mastocytosis and greater goblet cell hyperplasia. Additionally, the local antibody profile revealed that HP reinfected lactating rats developed a stronger antigen specific IgG2b response earlier in infection in comparison with their LP counterparts. Our study provides evidence that increased dietary protein content reduces the PPRI to N. brasiliensis re-infection in the lactating rat through improved mucosal immune responses.

Deviation of xenogeneic immune response and bystander suppression in rats fed porcine blood mononuclear cells

Reducing or deviating xenogeneic immune response prior to xenotransplantation may enhance the efficacy of conventional immunosuppressive therapies in prolonging xenograft survival. The potential to suppress or steer immune responses by oral administration of xenoantigens was evaluated. Based on knowledge of oral tolerance, hypotheses tested were that feeding xenoantigens would inhibit cell-mediated immune response (CMIR) and production of antibodies associated with graft rejection and induce bystander suppression. DA and LEW rats, high and low responders to xenoantigens, respectively, were fed dead porcine blood mononuclear cells (PBMC) and subsequently received live PBMC and hen egg-white lysozyme (HEWL, a third-party antigen) by subcutaneous injection. Delayed-type hypersensitivity (DTH) to PBMC was an indicator of CMIR. Quantification of T(H)1 (IgG(2b)) and T(H)2 (IgG(1))-associated antibodies and their ratio measured magnitude and bias of the antibody-mediated response to PBMC and HEWL. Feeding PBMC reduced IgG(2b) antibody production by 90% (DA) and 71% (LEW) and increased IgG(1) antibodies by 116% in DA but not LEW rats (p<or=0.05). DTH was unaffected (DA) or increased (LEW) in antigen-fed rats. Bystander suppression was demonstrated by inhibition of antibodies to HEWL in DA rats. LEW rats did not respond to HEWL. Evaluation of tertiary immune response to PBMC revealed DTH and antibodies to xenoantigens was inhibited. These data demonstrated orally-induced immune deviation and bystander suppression in rats given PBMC that may favor discordant xenograft survival and suggests a method to suppress xenogeneic immunity in high responders by repeated immunization with xenoantigens.

Prenatal stress has pro-inflammatory consequences on the immune system in adult rats

The in utero environment is critical for initiating the ontogeny of several physiological systems, including the immune surveillance. Yet, little is known about adverse early experiences on the offspring's immunity and vulnerability to disease. The present work aimed at investigating the impact of restraint prenatal stress (PS) on the development and responsiveness of in vitro and in vivo cellular and humoral immunity of male progeny aged 7 weeks and 6 months. In adult 6-month-old rats, we detected increased circulating CD8(+)-expressing and NK cells in PS rats as compared to controls, associated with higher mRNA expression of IFN-gamma. In addition, in vitro stimulation with phytohemagglutinin-A induced an increase in both the proliferation of T lymphocytes and the secretion of IFN-gamma in PS rats. Interestingly, these alterations were undetectable in younger PS rats (7-week old), except for a slight increase in the mRNA expression of several pro-inflammatory cytokines in peripheral blood mononuclear cells. Moreover, in vivo neutralization of IFN-gamma in young rats had no effects in PS group. In conclusion, we report for the first time long-lasting pro-inflammatory consequences of PS in rats.

Immune reactions and allergy in experimental anisakiasis

The third-stage larvae (L3) of the parasitic nematode, Anisakis simplex, have been implicated in the induction of hyperimmune allergic reactions in orally infected humans. In this work, we have conducted a review of an investigation into immune reactions occurring in animals experimentally infected with A. simplex L3. The patterns of serum antibody productions in the experimental animals against excretory-secretory products (ESP) of A. simplex L3 contributed to our current knowledge regarding specific humoral immune reactions in humans. In our review, we were able to determine that L3 infection of experimental animals may constitute a good model system for further exploration of immune mechanisms and allergy in anisakiasis of humans.

Susceptibility of experimental animals to reinfection with Clonorchis sinensis

The present study observed the resistance to reinfection with Clonorchis sinensis in various experimental animals including mice, guinea pigs, rabbits, and dogs, as well as rats and hamsters. The resistance rates to reinfection in rats, mice, hamsters, guinea pigs, rabbits, and dogs were 79.7%, 58.0%, -12.6%, 54.8%, 62.6%, and 6.0%, respectively. Worms recovered from reinfected rats and mice were immature, and significantly smaller than those from the primarily infected (P < 0.01), whereas those from other animals were fully matured to adults. These findings indicate that the protective response against reinfection with C. sinensis is prominent in rats and mice, and that they may be a good animal model to investigate the mechanism of resistance to reinfection with C. sinensis.

Caffeic acid phenethyl ester modifies the Th1/Th2 balance in ileal mucosa after γ-irradiation in the rat by modulating the cytokine pattern

AIM: To pharmacologically modulate Th polarization in the ileum exposed to ionizing radiation by using the immuno-modulatory/apoptotic properties of Caffeic Acid Phenethyl Ester (CAPE).

METHODS: Rats received CAPE (30 mg/kg) treatment ip 15 min prior to intestinal 10 Gy γ-irradiation and once a day for a 6 d period after irradiation. Expression of genes implicated in Th differentiation in ileal mucosa (IL-23/IL-12Rβ2), Th cytokine responses (IFN-γ, IL-2, IL-4, IL-13), Th migratory behaviour (CXCR3, CCR5, CCR4), Th signalling suppressors (SOCS1, SOCS3), transcription factor (T-Bet, GATA-3) and apoptosis (FasL/Fas, TNF/TNFR, XIAP, Bax, caspase-3) was analyzed by RT-PCR 6 h and 7 d post-irradiation. CD4⁺ and TUNEL positive cells were visualized by immunostaining.

RESULTS: The expression of Th1-related cytokine/chemokine receptors (IFN-γ, IL-2, CXCR3, CCR5) was repressed at 7 d post-irradiation while Th2 cell cytokine/chemokines (IL-4, IL-13, CCR4) were not repressed or even upregulated. The irradiation-induced Th2 profile was confirmed by the upregulation of both Th2-specific transcription factor GATA-3 and SOCS3. Although an apoptosis event occurred 6 h after 10 Gy of intestinal γ-irradiation, apoptotic mediator analysis showed a tendency to apoptotic resistance 7 d post-irradiation. CAPE amplified apoptotic events at 6h and normalized Bax/ FasL expressions at 7 d.

CONCLUSION: CAPE prevented the ileal Th2 immune response by modulating the irradiation-influenced cytokine environment and apoptosis.

Rat genotype influences quantitative and qualitative aspects of xenogeneic immune response to pig blood mononuclear cells

BACKGROUND

Xenotransplantation seeks to have cells with discordant genotypes co-exist. The hypothesis that host genotype modulates xenogeneic immune response (IR) was tested.

METHODS

Two inbred rat strains [Dark Agouti (DA) and Lewis (LEW)] representing diverse IR phenotypes were immunized with porcine blood mononuclear cells (BMC). Delayed-type hypersensitivity (DTH), immunoglobulin (Ig), antibody (Ab) and isotype bias of Ab response were evaluated.

RESULTS

DTH to pig BMC was greater in DA than in LEW rats. Natural Ab was qualitatively different between strains (IgM and IgA predominated in DA, IgM and IgG(2a) predominated in LEW). Twice as much IgG was elicited from DA than LEW rats and DA utilized all isotypes whereas LEW did not use IgG(2a) or IgG(2c). IR bias was diametrically opposed; type 1 in DA but type 2 in LEW. Strains even differed in Ig profiles and dermal responses to saline injections and mitogen. The DA rats were the higher responders to pig BMC.

CONCLUSIONS

Recipient genotype had significant and broad effects on IR to porcine BMC and may influence xenograft rejection and xenotolerance induction. Moreover, this study suggests that caution should prevail when interpreting data derived from a single inbred strain, particularly given that humans, the target species, are genetically diverse.

The time course of biological and immunochemical allergy states induced by anisakis simplex larvae in rats

Oral infection by Anisakis simplex third stage larvae (L3) frequently gives rise to an allergic response. To comprehend the allergic and immune responses induced by L3, we investigated the kinetics of specific antibody isotype expression and the time course of biological and immunochemical allergy states using sera prepared from rats orally infected with L3 twice, with an interval of 9 weeks between infections. Biological and immunochemical allergy states were analysed by RBL-2H3 exocytosis and by indirect ELISA for IgE, respectively. The peak IgM at reinfection (RI) was comparable or similar to that at primary infection (PI) both in levels analysed by indirect ELISA and in antigen recognition analysed by Western blot. IgG1 and IgG2a levels were higher and showed accelerated kinetics after RI vs. after PI. However, the level of IgG2b was substantially lower than that of IgG2a. Peak immunochemical and biological allergy states for RI were higher and were reached faster than those for PI. The peak biological allergy state was observed at 1 week postreinfection and this occurred sooner than that for the peak immunochemical allergy state found at 2 weeks postreinfection. Our analysis of the relationship between specific IgE avidity and biological allergy state did not show any meaningful correlation. These results suggest that the allergic response induced by L3 oral infection is predominantly caused by reinfection and that this is accompanied by an elevated IgM level, which further suggests that the biological allergy state might not be related to specific IgE avidity.

Resistance to reinfection in rats induced by irradiated metacercariae of Clonorchis sinensis

A study was made to observe the association between the resistance to reinfection induced by irradiated metacercariae (MC) of Clonorchis sinensis and antigen specific Th1- and Th2-type cytokine productions in rats. Rats were infected with 20 MC of C. sinensis, previously exposed to a single dose of gamma irradiation, which varied from 0 to 100 Gy. All of them, single dose of 12 Gy showed higher IgG antibody titer with lowest worm recovery. Thus, 50 MC were used to challenge infection in rats previously infected with 20 MC irradiated at 12 Gy and the highest resistance to challenge infection was observed. The results of lymphocyte proliferation with specific antigen, ES Ag were shown no difference of proliferative responses as compared with primary and challenge infection at 12 Gy irradiation dose. In the case of cytokines production were observed that interferon (IFN-gamma) and interlukin (IL-2) were significantly enhanced, while IL-4 and IL-10 was almost unchanged to make comparison between primary and secondary infection at 12 Gy irradiation dose. In conclusion, the single dose of 12 Gy could be adopted for induction of the highest resistance to challenge infection. Up-regulation of Th1 type cytokines, IFN-gamma and IL-2 may be affected to develop vaccine by irradiated MC.

Phage displaying peptides mimic schistosoma antigenic epitopes selected by rat natural antibodies and protective immunity induced by their immunization in mice

AIM: To obtain the short peptides mimic antigenic epitopes selected by rat natural antibodies to schistosomes, and to explore their immunoprotection against schistosomiasis in mice.

METHODS: Adults worm antigens (AWA) were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and enzyme-linked transferred immunoblotting methods with normal SD rat sera (NRS). The killing effects on schistosomula with fresh and heat-inactivated sera from SD rats were observed. Then the purified IgG from sera of SD rats was used to biopan a phage random peptide library and 20 randomly selected positive clones were detected by ELISA and 2 of them were sequenced. Sixty female mice were immunized thrice with positive phage clones (0, 2^nd, 4^th wk). Each mouse was challenged with 40 cercariae, and all mice were killed 42 d after challenge. The worms and the liver eggs were counted.

RESULTS: NRS could specifically react to the molecules of 75000, 47000, 34500 and 23000 of AWA. Sera from SD rats showed that the mortality rate of schistosomula was 76.2%, and when the sera were heat-inactivated in vitro, the mortality rate was decreased to 41.0% after being cultured for 48 h. The specific phages bound to IgG were enriched about 300-folds after three rounds of biopanning. Twenty clones were detected by ELISA, 19 of them bound to the specific IgG of rat sera. Immunization with these epitopes was carried out in mice. Compared with the control groups, the mixture of two mimic peptides could induce 34.9% (P = 0.000) worm reduction and 67.6% (P = 0.000) total liver egg reduction in mice. Two different mimic peptides could respectively induce 31.0% (P = 0.001), 14.5% (P = 0.074) worm reduction and 61.2% (P = 0.000), 35.7% (P = 0.000) total liver egg reduction. The specific antibody could be induced by immunization of the mimic peptides, and the antibody titer in immunized mice reached more than 1:6400 as detected by ELISA.

CONCLUSION: Specific peptides mimic antigenic molecules can be obtained by biopanning the phage random peptide library and a partially protective immunity against schistosome infection can be stimulated by these phage epitopes in mice.

Intraspecies variability in the dose-response relationship for Salmonella Enteritidis associated with genetic differences in cellular immune response

To evaluate the effects of differences in host cellular immunity, we studied the dose-response relationship for infection with Salmonella enterica serovar Enteritidis (SE) in two different rat strains, skewed towards T helper 1 (Th1, Lewis rats) or T helper 2 (Th2, Brown Norway rats) immunoregulation. Rats were exposed orally to different doses of SE after overnight starvation and neutralization of gastric acid. Animals were observed for clinical signs of disease, fecal excretion and SE load in spleen and cecum, histopathology of the cecum, hematology, and cellular and humoral immune responses. Exponential dose-response models were used for binary or continuous outcomes to analyze the experimental data. Cytokine patterns, antibody isotypes, and contact hypersensitivity tests confirmed that Lewis rats are Th1 prone, whereas Brown Norway rats are Th2 prone. The probability of infection per single SE cell was approximately 100 times higher in Brown Norway rats than in Lewis rats. Cellular immune responses were more pronounced in Lewis rats but antibody responses were higher in Brown Norway rats. When infected, colonization levels and inflammation are highest in the intestinal tract of Th2 skewed rats, but systemic infection is more intense in Th1 skewed rats. Successful colonization by only one or two SE clones resulted in a marked increase of neutrophil counts by a factor of two to three in both rat strains.

Development of resistance to reinfection by Clonorchis sinensis in rats

We investigated the induction of resistance to Clonorchis sinensis infection by prior infection in rat and hamster models. Animals were challenged with C. sinensis metacercariae, then treated with praziquantel and reinfected. Worm recovery rate in reinfected animals was used to estimate resistance to reinfection. The determined resistance rates to reinfection in rats and hamsters were 97.7% and 10.3%, respectively. In rats, cure from the primary infection of C. sinensis increased resistant to reinfection, and the greater the worm burden and the longer the duration of primary infection, the higher was the resistance rate. For primary infection doses of 10, 40 and 100 metacercariae per rat, the resistance rates were 87.4%, 93.8% and 98.4%, respectively. The resistance rates in rats after 2 or 8-week primary infection were 78.7% and 95.3%, respectively. All worms recovered from reinfected rats were immature. When cured rats were administered with methylprednisolone, resistance to reinfection became impaired. These findings indicate that rats develop a high degree of resistance to reinfection by C. sinensis after cure. The growths and maturations of reinfected worms were also impaired.

Concurrent infection with Schistosoma mansoni attenuates inflammation induced changes in colonic morphology, cytokine levels, and smooth muscle contractility of trinitrobenzene sulphonic acid induced colitis in rats

BACKGROUND AND AIMS

Crohn's disease, characterised by chronic T helper 1 (Th1) inflammation and dysmotility of the gut, is most prevalent in developed countries. Parasitic infections are most prevalent in developing countries and induce a T helper 2 (Th2) immune response. We hypothesised that this Th2 immune response protects against Th1 gut inflammation.

METHODS

The parasite Schistosoma mansoni induces a transient Th2 immune response in the semipermissive rat host. 2,4,6-Trinitrobenzene sulphonic acid (TNBS) induced colitis is an experimental model of Th1-like gut inflammation. The effect of concurrent infection with S mansoni on the course of TNBS induced colitis was assessed using macroscopic and microscopic damage scores, histology, myeloperoxidase (MPO) activity assay, cytokine production assay, and by studying in vitro contractility of longitudinal and circular colonic muscle strips.

RESULTS

TNBS induced colitis that spontaneously healed after four weeks. Concurrent infection with S mansoni significantly reduced the duration of TNBS induced colitis to two weeks, as shown by macroscopic and microscopic damage scores and by a faster decrease in colonic MPO activity. TNBS increased colonic interleukin 2 (IL-2) production whereas S mansoni increased splenic IL-4 and IL-2 levels. Contractility of longitudinal and circular muscle strips was maximally inhibited one week after TNBS and normalised after three weeks. After four weeks, longitudinal muscle strip contractility was significantly increased. Concurrent infection with S mansoni normalised longitudinal muscle contractility after one week whereas circular muscle contractility remained inhibited.

CONCLUSIONS

Concurrent infection with S mansoni significantly attenuates TNBS induced colitis in the rat. Inflammation induced disturbances in contractility of longitudinal and circular colonic muscle strips may outlast the inflammatory reaction.

The age-related resistance of rats to Plasmodium berghei infection is associated with differential cellular and humoral immune responses

In this study, we investigated how the age of rats would affect the course of infection of and the immune response to Plasmodium berghei. Both young (4-week-old) and adult rats (8-week-old) can be infected with P. berghei ANKA strain, with significantly higher levels of infected red blood cells in young rats. While 100% of young rats succumbed to infection, adult rats were able to clear blood parasites and no mortality was observed. Analysis of cellular distribution and circulating cytokines demonstrated the persistence of CD4+/CD25+ T cells and high expression of circulating interleukin-10 (IL-10) during the progression of infection in young-susceptible rats, whereas high levels of CD8+ T cells and natural killer T cells are detected in adult-resistant rats. Analysis of antibody isotypes showed that adult rats produced significantly higher levels of interferon-gamma (IFN-gamma)-dependent IgG2c antibodies than young rats during infection. Further evaluation of the role of IL-10, IFN-gamma and of immune cells showed that only the adoptive transfer of spleen cells from adult-resistant rats was able to convert susceptibility of young-susceptible rats to a resistant phenotype. These observations suggest that cell-mediated mechanisms are crucial for the control of a primary infection with P. berghei in young rats.

Induction of immunoglobulin G1, interleukin-6 and interleukin-10 by Taenia crassiceps metacestode carbohydrates

T helper type 2 (Th2) -polarized immune responses are characteristically dominant in helminth infections. Two murine models that show a Th1 to Th2 polarization with infection progression are those of Schistosoma mansoni and Taenia crassiceps. In both, an early Th1 response is replaced by a late Th2 response. We report that the nucleic acid-, protein- and lipid-free carbohydrate fraction of T. crassiceps metacestodes (denoted T-CHO) possesses Th2-like immunomodulatory activity. Immunization of two strains of rats (Dark Agouti and Albino Oxford) and BALB/c mice with chicken albumin in the presence of T-CHO resulted in selective enhancement of immunoglobulin G1 (IgG1) antibodies, considered to be associated with Th2 responses in both rats and mice. Interleukin-6 (IL-6) followed by IL-10 were the dominant cytokines detected in in vitro cultures of mouse spleen cells stimulated with T-CHO. IL-4 and IL-5 were not detected in these culture supernates. Furthermore, Taenia carbohydrates were mitogenic to spleen cells, activated serine phosphorylation of proteins and up-regulated the expression of the anti-apoptotic protein, Bcl-2. When mouse spleen cells were cultured in the presence of Taenia carbohydrates, a concentration-dependent down-regulation of IL-2 and an overlapping up-regulation of IL-6 secretion were seen.

Immune correlate study on human Schistosoma japonicum in a well-defined population in Leyte, Philippines: II. Cellular immune responses to S. japonicum recombinant and native antigens

Cellular immune responses to specific Schistosoma japonicum recombinant and native antigens were investigated in a defined study population of 155 individuals in the Philippines, where data collected from a 3-year observation of exposure, infection and reinfection pattern were used to categorically classify putative 'resistant' and 'susceptible' individuals. Using peripheral blood mononuclear cells (PBMC) of individuals enrolled in the study, in vitro lymphocyte proliferation and cytokine (IFN-gamma, IL-5 and IL-10) production in response to defined recombinant antigens (97 kDa paramyosin, 22 kDa tegumental antigen, 37 kDa glyceraldehyde-3-phosphate dehydrogenase, 14 kDa fatty acid binding protein and 28 kDa gluthathione-S-tranferase) and native antigen soluble worm antigen preparation (SWAP) were measured. Cellular responses to the recombinant and SWAP antigens suggest that Th1 type of response appear to be important in predicting resistance in this population. Of the five recombinant antigens tested, rPMY induced significant levels of IFN-gamma. The production of IL-10, a Th2-type cytokine was strongly implicated in immune regulation. Of importance was the evidence found for SWAP and rPMY induced IFN-gamma responses in predicting 'resistance'. It was noted that these associations were significant even after the effect of age and sex were accounted for in a multivariate analysis.