Dynamics of gut mucosal and systemic Th1/Th2 cytokine responses in interferon-gamma and interleukin-12p40 knock out mice during primary and challenge Cryptosporidium parvum infection

Pyroptosis Tuning in Intestinal Cryptosporidiosis via the Natural Histone Deacetylase Inhibitor Romidepsin

Cryptosporidium is an opportunistic protozoan, with many species of cross-human infectivity. It causes life-threatening diarrhoea in children and CD4-defective patients. Despite its limited efficacy, nitazoxanide remains the primary anti-cryptosporidial drug. Cryptosporidium infects the intestinal brush border (intracellular-extracytoplasmic) and down-regulates pyroptosis to prevent expulsion. Romidepsin is a natural histone deacetylase inhibitor that triggers pyroptosis. Romidepsin's effect on cryptosporidiosis was assessed in immunocompromised mice via gasdermin-D (GSDM-D) immunohistochemical expression, IFN-γ, IL-1β and IL-18 blood levels by ELISA, and via parasite scanning by modified Ziehl-Neelsen staining and scanning electron microscopy (SEM). Oocyst deformity and local cytokines were also assessed in ex vivo ileal explants. Following intraperitoneal injection of romidepsin, oocyst shedding significantly reduced at the 9th, 12th and 15th d.p.i. compared with infected-control and drug-control (nitazoxanide-treated) mice. H&E staining of intestinal sections from romidepsin-treated mice showed significantly low intestinal scoring with marked reduction in epithelial hyperplasia, villous blunting and cellular infiltrate. SEM revealed marked oocyst blebbing and paucity (in vivo and ex vivo) after romidepsin compared with nitazoxanide. Regarding pyroptosis, romidepsin triggered significantly higher intestinal GSDM-D expression in vivo, and higher serum/culture IFN-γ, IL-1β and IL-18 levels in romidepsin-treated mice than in the control groups. Collectively, in cryptosporidiosis, romidepsin succeeded in enhancing pyroptosis in the oocysts and infected epithelium, reducing infection and shifting the brush border towards normalisation.

Cryptosporidium and irritable bowel syndrome

Cryptosporidium is an apicomplexan parasite that causes gastrointestinal disease in a wide variety of hosts and is associated with waterborne outbreaks. Nonetheless, the parasite is underdiagnosed. Cryptosporidium has been proposed as an etiological cause of irritable bowel syndrome (IBS) in several studies. However, the exact mechanism of pathogenesis is unknown, and no direct link has been discovered. This review will discuss several parasite-induced modifications, such as immunological, microbiome, and metabolite modifications, as well as their interactions. To summarize, Cryptosporidium causes low inflammation, dysbiosis, and unbalanced metabolism, which leads to a lack of homeostasis in the intestine in a comparable pattern to postinfectious IBS.

Evaluation of the therapeutic efficacy of some essential oils in experimentally immunosuppressed mice infected with Cryptosporidium parvum

Cryptosporidiosis is a serious intestinal disease affecting mal-nourished children and immunocompromised individuals with severe fatal diarrhea. Our present work was done to evaluate the possible curative effects of different essential oils (Mint, Thyme, Chamomile and Basil) on Cryptosporidium parvum (C. parvum) in vivo compared with nitazoxanide (NTZ). Seventy immunosuppressed white Albino male mice were allocated in 7 groups as follows: group I infected and not treated (Positive control), group II (GII) treated with NTZ, group III (GIII) treated with Mint essential oil, group IV (GIV) treated with Thyme essential oil, group V (GV) treated with Chamomile essential oil, group VI (GVI) treated with Basil essential oil and group VII (GVII) naïve not infected mice (Negative control). Evaluation was done using parasitological, histopatholgical, serological as well as biochemical methods. All study groups revealed significant reduction (P value < 0.01) in the mean number of C. parvum oocysts in stool. Results of GII were the best with 87.7% reduction in the oocysts count followed by GIII (77.9%), GIV (74.7%), GVI (68.2%) and lastly GV (67.2%). Improvement of the histopathological damage in the small intestine was shown in treated groups. All treated mice showed significant upregulation in the interferon gamma (IFN-γ) levels, significant reduction in the malondialdehyde (MDA) levels and increase in superoxide dismutase (SOD) levels (P value < 0.0001). It is concluded that Mint, Thyme, Chamomile and Basil oils showed promising anti-cryptosporidial, anti-inflammatory and antioxidant functions.

Dendritic Cells and Cryptosporidium: From Recognition to Restriction

Host immune responses are required for the efficient control of cryptosporidiosis. Immunity against Cryptosporidium infection has been best studied in mice, where it is mediated by both innate and adaptive immune responses. Dendritic cells are the key link between innate and adaptive immunity and participate in the defense against Cryptosporidium infection. While the effector mechanism varies, both humans and mice rely on dendritic cells for sensing parasites and restricting infection. Recently, the use of mouse-adapted strains C. parvum and mouse-specific strain C. tyzzeri have provided tractable systems to study the role of dendritic cells in mice against this parasite. In this review, we provide an overview of recent advances in innate immunity acting during infection with Cryptosporidium with a major focus on the role of dendritic cells in the intestinal mucosa. Further work is required to understand the role of dendritic cells in the activation of T cells and to explore associated molecular mechanisms. The identification of Cryptosporidium antigen involved in the activation of Toll-like receptor signaling in dendritic cells during infection is also a matter of future study. The in-depth knowledge of immune responses in cryptosporidiosis will help develop targeted prophylactic and therapeutic interventions.

Structural Analyses of a Dominant Cryptosporidium parvum Epitope Presented by H-2Kb Offer New Options To Combat Cryptosporidiosis

Cryptosporidium parvum has gained much attention as a major cause of diarrhea in the world, particularly in those with compromised immune systems. The data currently available on how the immune system recognizes C. parvum are growing rapidly, but we lack data on the interactions among host major histocompatibility complex (MHC) diversity and parasitic T-cell epitopes. To identify antigenic epitopes in a murine model, we performed systematic profiling of H-2K^b-restricted peptides by screening the dominant Cryptosporidium antigens. The results revealed that the glycoprotein-derived epitope Gp40/15-SVF9 induced an immunodominant response in C. parvum-recovered C57BL/6 mice, and injection of the cytotoxic-T-lymphocyte (CTL) peptide with the adjuvant activated peptide-specific CD8⁺ T cells. Notably, the SVF9 epitope was highly conserved across Cryptosporidium hominis, C. parvum, and many other Cryptosporidium species. SVF9 also formed stable peptide-MHC class I (MHC I) complexes with HLA-A*0201, suggesting cross-reactivity between H-2K^b and human MHC I specificities. Crystal structure analyses revealed that the interactions of peptide-MHC surface residues of H-2K^b and HLA-A*0201 are highly conserved. The hydrogen bonds of H-2K^b-SVF9 are similar to those of a dominant epitope presented by HLA-A*0201, which can be recognized by a public human T-cell receptor (TCR). Notably, we found double conformations in position 4 (P4), 5 (P5) of the SVF9 peptide, which showed high flexibility, and multiple peptide conformations generated more molecular surfaces that can potentially be recognized by TCRs. Our findings demonstrate that an immunodominant C. parvum epitope and its homologs from different Cryptosporidium species and subtypes can benefit vaccine development to combat cryptosporidiosis. IMPORTANCE Adaptive immune responses and T lymphocytes have been implicated as important mechanisms of parasite-induced protection. However, the role of CD8⁺ T lymphocytes in the resolution of C. parvum infection is largely unresolved. Our results revealed that the glycoprotein-derived epitope Gp40/15-SVF9 induced an immunodominant CD8⁺ T-cell response in C57BL/6 mice. Crystal structure analyses revealed that the interactions of the H-2K^b-SVF9 peptide are similar to those of a dominant epitope presented by HLA-A*0201, which can be recognized by human TCRs. In addition, we found double conformations of the SVF9 peptide, which showed high flexibility and multiple peptide conformations that can potentially be recognized by TCRs.

Intestinal immune responses to commensal and pathogenic protozoa

The physical barrier of the intestine and associated mucosal immunity maintains a delicate homeostatic balance between the host and the external environment by regulating immune responses to commensals, as well as functioning as the first line of defense against pathogenic microorganisms. Understanding the orchestration and characteristics of the intestinal mucosal immune response during commensal or pathological conditions may provide novel insights into the mechanisms underlying microbe-induced immunological tolerance, protection, and/or pathogenesis. Over the last decade, our knowledge about the interface between the host intestinal mucosa and the gut microbiome has been dominated by studies focused on bacterial communities, helminth parasites, and intestinal viruses. In contrast, specifically how commensal and pathogenic protozoa regulate intestinal immunity is less well studied. In this review, we provide an overview of mucosal immune responses induced by intestinal protozoa, with a major focus on the role of different cell types and immune mediators triggered by commensal (Blastocystis spp. and Tritrichomonas spp.) and pathogenic (Toxoplasma gondii, Giardia intestinalis, Cryptosporidium parvum) protozoa. We will discuss how these various protozoa modulate innate and adaptive immune responses induced in experimental models of infection that benefit or harm the host.

Investigating the Potential Effects of COVID-19 Pandemic on Intestinal Coccidian Infections

New infectious agents pose a global threat to the healthcare system, and studies are conducted to estimate their health and epidemiological outcomes in the long run. The SARS-CoV-2 virus, which has caused the COVID-19 disease, was formerly assumed to be a respiratory virus; however, it can have serious systemic effects, affecting organs such as the gastrointestinal tract (GIT). Viral RNA was reported in the stool in a subset of patients, indicating another mode of transmission and diagnosis. In COVID-19, prolonged GIT symptoms, especially diarrhea, were associated with reduced diversity and richness of gut microbiota, immunological dysregulation, and delayed viral clearance. Intestinal coccidian parasites are intracellular protozoa that are most typically transmitted to humans by oocysts found in fecally contaminated food and water. Their epidemiological relevance is coupled to opportunistic infections, which cause high morbidity and mortality among immunocompromised individuals. Among immunocompetent people, intestinal coccidia is also involved in acute diarrhea, which is usually self-limiting. Evaluating the available evidence provided an opportunity to carefully consider that; the COVID-19 virus and coccidian protozoan parasites: namely, Cryptosporidium spp., Cyclospora cayetanensis, and Isospora belli, could mutually influence each other from the microbiological, clinical, diagnostic, and elimination aspects. We further systemically highlighted the possible shared pathogenesis mechanisms, transmission routes, clinical manifestations, parasite-driven immune regulation, and intestinal microbiota alteration. Finally, we showed how this might impact developing and developed countries prevention and vaccination strategies. To the best of our knowledge, there is no review that has discussed the reciprocal effect between coccidian parasites and COVID-19 coinfection.

Isolation and identification of sporozoite membrane protein of Cryptosporidium parvum and evaluation of calmodulin-like protein immune protection

Until now, no completely effective parasite-specific drugs or vaccines have been approved for the treatment of cryptosporidiosis. Through the separation and identification of the sporozoite membrane protein of Cryptosporidium parvum (C. parvum), 20 related proteins were obtained. Among them, a calmodulin-like protein (CML) has a similar functional domain-exchange factor hand (EF-hand) motif as calmodulin proteins (CaMs), so it may play a similarly important role in the invasion process. A 663 bp full gene encoding the C. parvum calmodulin-like protein (CpCML) was inserted in pET28a vector and expressed in Escherichia coli. An immunofluorescence assay showed that CpCML was mainly located on the surface of the sporozoites. Three-week-old female BALB/c mice were used for modeling the immunoreactions and immunoprotection of recombinant CpCML (rCpCML) against artificial Cryptosporidium tyzzeri (C. tyzzeri) infections. The results indicated a significantly increased in anti-CpCML antibody response, which was induced by the immunized recombinant protein. Compared to rP23(recombinant P23), GST6P-1(expressed by pGEX-6P-1 transfected E. coli) , GST4T-1(expressed by pGEX-4T-1 transfected E. coli) , glutathione (GSH), adjuvant, and blank control groups, rCpCML-immunized mice produced specific spleen cell proliferation in addition to different production levels of IL-2, IFN-γ, TNF-α, IL-4 and IL-5. Additionally, immunization with rCpCML led to 34.08% reduction of oocyst shedding in C. tyzzeri infected mice faeces which was similart to rP23. These results suggest that CpCML may be developed as a potential vaccine candidate antigen against cryptosporidiosis.

Curcumin mitigates Cryptosporidium parvum infection through modulation of gut microbiota and innate immune-related genes in immunosuppressed neonatal mice

Cryptosporidium parvum is a major cause of diarrheal disease in immature or weakened immune systems, mainly in infants and young children in resource-poor settings. Despite its high prevalence, fully effective and safe drugs for the treatment of C. parvum infections remain scarce, and there is no vaccine. Meanwhile, curcumin has shown protective effects against C. parvum infections. However, the mechanisms of action and relationship to the gut microbiota and innate immune responses are unclear. Immunosuppressed neonatal mice were infected with oocysts of C. parvum and either untreated or treated with a normal diet, curcumin or paromomycin. We found that curcumin stopped C. parvum oocysts shedding in the feces of infected immunosuppressed neonatal mice, prevented epithelial damage, and villi degeneration, as well as prevented recurrence of infection. Curcumin supplementation increased the relative abundance of Bacteroidetes and decreased the relative abundance of Firmicutes and Proteobacteria in mice infected with C. parvum as shown by 16S rRNA gene sequencing analysis. The relative abundance of Lactobacillus, Bacteroides, Akkermansia, Desulfovibrio, Prevotella, and Helicobacter was significantly associated with C. parvum infection inhibited by curcumin. Curcumin significantly (P < 0.01) suppressed IFN-γ and IL -18 gene expression levels in immunosuppressed neonatal C. parvum-infected mice. We demonstrate that the therapeutic effects curcumin are associated with alterations in the gut microbiota and innate immune-related genes, which may be linked to the anti-Cryptosporidium mechanisms of curcumin.

Commensal Cryptosporidium colonization elicits a cDC1-dependent Th1 response that promotes intestinal homeostasis and limits other infections

Cryptosporidium can cause severe diarrhea and morbidity, but many infections are asymptomatic. Here, we studied the immune response to a commensal strain of Cryptosporidium tyzzeri (Ct-STL) serendipitously discovered when conventional type 1 dendritic cell (cDC1)-deficient mice developed cryptosporidiosis. Ct-STL was vertically transmitted without negative health effects in wild-type mice. Yet, Ct-STL provoked profound changes in the intestinal immune system, including induction of an IFN-γ-producing Th1 response. TCR sequencing coupled with in vitro and in vivo analysis of common Th1 TCRs revealed that Ct-STL elicited a dominant antigen-specific Th1 response. In contrast, deficiency in cDC1s skewed the Ct-STL CD4 T cell response toward Th17 and regulatory T cells. Although Ct-STL predominantly colonized the small intestine, colon Th1 responses were enhanced and associated with protection against Citrobacter rodentium infection and exacerbation of dextran sodium sulfate and anti-IL10R-triggered colitis. Thus, Ct-STL represents a commensal pathobiont that elicits Th1-mediated intestinal homeostasis that may reflect asymptomatic human Cryptosporidium infection.

Role of interferon gamma in SARS-CoV-2-positive patients with parasitic infections

Background

By 27 June 2020, almost half a million people had died due to COVID-19 infections. The susceptibility and severity of infection vary significantly across nations. The contribution of chronic viral and parasitic infections to immune homeostasis remains a concern. By investigating the role of interferon (IFN)-γ, we conducted this study to understand the connection between the decrease in numbers and severity of COVID-19 cases within parasitic endemic regions. Our research included 375 patients referred to hospitals for diagnosis of COVID-19 infection. Patients were subjected to full investigations, in particular severe acute respiratory syndrome coronavirus-2 nucleic acid and Toxoplasma IgM and IgG antibody detection, stool examination, and quantitative IFN-γ measurement.

Results

The majority of the studied cases had chest manifestation either alone (54.7%) or in association with gastrointestinal (GIT) manifestations (19.7%), whereas 25.6% had GIT symptoms. We reported parasitic infections in 72.8% of mild COVID-19 cases and 20.7% of severe cases. Toxoplasma gondii, Cryptosporidium, Blastocyst, and Giardia were the most common parasitic infections among the COVID-19 cases studied.

Conclusion

The remarkable adaptation of human immune response to COVID-19 infection by parasitic infections with high levels of IFN-γ was observed in moderate cases compared with low levels in extreme cases. The potential therapeutic efforts aimed at the role of parasitic infection in immune system modulation are needed if this hypothesis is confirmed.

A systematic review of anti-Entamoeba histolytica activity of medicinal plants published in the last 20 years

Amoebiasis has emerged as a major health problem worldwide. It is endemic in the present scenario is different and sub-tropical regions especially in Asia, Latin America and also in Africa. Causative of amoebiasis is a protozoan known as Entamoeba histolytica. We screened all the databases such as PubMed, Science Direct, Medline and Google Scholar by using the keywords ‘anti-Entamoeba histolytica activity of medicinal plants, anti-Entamoeba histolytica activity of herbal drugs, the anti-amoebic activity of natural drugs’. In the present study, we found 7861 articles, where all articles were screened for bias analysis and included 32 full-matching articles in total reporting the use of medicinal plants as a remedy for amoebiasis. Through these articles, we found 42 herbs having anti-amoebic activity. In bias analysis, we also found four articles under high bias risk. In our study, seven medicinal plants were concluded to possess the most potent anti-amoebic activity based on their IC50 value, which was less than 1 μg mL−1. On bias analysis, we found four articles with high bias risk, hence these studies can be repeated for better results.

The immunomodulatory activity of secnidazole-nitazoxanide in a murine cryptosporidiosis model

Introduction. Cryptosporidium parvum causes intestinal parasitic infections affecting both immunosuppressed and immunocompetent individuals.Gap statement. Given the absence of effective treatments for cryptosporidiosis, especially in immunodeficient patients, the present study was designed to assess the therapeutic efficacy of secnidazole (SEC) and its combination with nitazoxanide (NTZ) in comparison to single NTZ treatment in relation to the immune status of a murine model of C. parvum infection.Methodology. The infected groups were administered NTZ, SEC or NTZ-SEC for three or five successive doses. At days 10 and 12 post-infection (p.i.), the mice were sacrificed, and the efficacy of the applied drugs was evaluated by comparing the histopathological alterations in ileum and measuring the T helper Th1 (interferon gamma; IFN-γ), Th2 [interleukin (IL)-4 and IL-10] and Th17 (IL-17) cytokine profiles in serum.Results. The NTZ-SEC combination recorded the maximal reduction of C. parvum oocyst shedding, endogenous stages count and intestinal histopathology, regardless of the immune status of the infected mice. The efficacy of NTZ-SEC was dependent on the period of administration, as the 5 day-based treatment protocol was also more effective than the 3 day-based one in terms of immunocompetence and immunosuppression. The present treatment schedule induced an immunomodulatory effect from SEC that developed a protective immune response against C. parvum infection with reduced production of serum IL-17, IFN-γ, IL-4 and IL-10.Conclusions. Application of NTZ-SEC combined therapy may be useful in treatment of C. parvum, especially in cases involving immunosuppression.

Copro-microscopical and immunological diagnosis of cryptosporidiosis in Egyptian buffalo-calves with special reference to their cytokine profiles

Cryptosporidiosis is considered to be one of the most devasting gastrointestinal diseases in calves. The aim of this study was to investigate Cryptosporidium parvum infection (C. parvum) in buffalo-calves with both copro-microscopic examination and enzyme linked immunosorbent assay (ELISA) using two C. parvum prepared antigens with regards to their cytokines profile; interferon- γ (IFN-γ), interleukin (IL)-12 and IL-14 to achieve a proper diagnosis. All collected buffalo- calves' fecal samples were examined by modified Ziehl-Neelsen staining technique. ELISA was performed to evaluate the diagnostic accuracy of the two C. parvum prepared antigens; crude whole oocyst (CWO) and crude sonicated oocyst (CSO) in detection of anti-C. parvum IgG in buffalo-calves' sera. As well, concentrations of INF-γ, IL-12 and IL-14 in the buffalo-calves' serum samples were estimated. The results revealed that the overall parasitological incidence of cryptosporidiosis was 40%. However, the serological diagnosis by ELISA assay showed 53.75% and 27.5% when using CWO and CSO antigen, respectively. Also, the diagnostic efficacy parameters of both antigens; CWO and CSO showed a significant high specificity (83.3%) achieved by CSO antigen and a high sensitivity (71.8%) by CWO antigen. The levels of INF-γ, IL-12 and IL-14 were significantly increased in positive Cryptosporidium infected group by both coprological and serological assays followed by the group which was positive for cryptosporidiosis by copro-microscopic examination only. The present study concluded that a combination of coprological and serological examination with reference to the cytokines profile is needed for proper diagnosis of cryptosporidiosis in buffalo-calves.

Mouse Models for Use in Cryptosporidium Infection Studies and Quantification of Parasite Burden Using Flow Cytometry, qPCR, and Histopathology

Cryptosporidiosis threatens life of young children in developing countries and newborn calves around the world. No vaccine or therapy can prevent or cure this diarrhea-inducing enteric disease caused by Cryptosporidium spp. protozoan parasites. There is an essential need to discover new therapeutic drugs efficient in reducing parasite burden in infected individuals. Research therefore relies on reliable small animal models of cryptosporidiosis. Here, we present excellent mouse models which can efficiently mimic pathogenesis of human and bovine cryptosporidiosis. We also describe methods to purify C. parvum oocysts from stool and intestine of infected mice to facilitate oocyst quantification. Moreover, we present protocols using flow cytometry, quantitative polymerase chain reaction, and histopathology to accurately quantify parasite burden in stool or intestine samples.

A protocol to count Cryptosporidium oocysts by flow cytometry without antibody staining

Cryptosporidiosis caused by the protozoan parasites Cryptosporidium hominis and C. parvum, threatens the lives of young children in developing countries. In veterinary medicine, C. parvum causes life-threatening diarrhea and dehydration in newborn dairy calves. Protocols to detect Cryptosporidium spp. oocysts using flow cytometry have been reported; however, these protocols use antibodies against the parasite and typically focus on detection of oocysts, not quantification. These techniques are not well-suited for studies that generate large variations in oocyst burdens because the amount of antibody required is proportional to the number of oocysts expected in samples. Also, oocysts are lost in washes in the staining protocol, reducing accuracy of oocyst counts. Moreover, these protocols require costly fluorochrome-conjugated monoclonal antibodies and are not optimal for studies involving large numbers of samples. Here we present an optimized protocol for purifying oocysts from mouse stool and intestine samples combined with a reliable method to quantify oocysts in a relatively pure population without the need for antibody staining. We used morphology (SSC-A vs FSC-A) and the innate characteristics of C. parvum oocysts compared to fecal and intestinal contaminants to develop a two-step gating strategy that can differentiate oocysts from debris. This method is a fast, reliable, and high-throughput technique to promote research projects on C. parvum infections in mice and potentially other animal hosts.

Diarrheal diseases are the second leading cause of death in children < 5 years old. Cryptosporidiosis caused by the unicellular parasite Cryptosporidium spp. is one of these diarrheal diseases. C. hominis and C. parvum cause moderate-to-severe diarrhea and dehydration that threaten the lives of young children in developing countries. Flow cytometry is a state-of-the-art technique to detect Cryptosporidium spp. oocysts, the infectious form of the parasite. Reported protocols typically focus on detection of oocysts using antibody staining. However, these techniques present several complications: oocysts are lost in washes used in the staining protocol and the amount of antibody required is proportional to the number of oocysts expected in samples; thus, parasite burden needs first to be estimated by optical microscopy. In addition, these protocols require costly antibodies. We developed a reliable method to quantify Cryptosporidium spp. oocysts in a relatively pure population without the need for antibody staining. We used known characteristics of the structure of oocysts to develop a strategy that can differentiate oocysts from debris. This method is fast, affordable and reliable and will facilitate pre-clinical projects on interventions to treat or prevent Cryptosporidium spp. infection.

Cellular immune response and scanning electron microscopy in the evaluation of Moringa leaves aqueous extract effect on Cryptosporidium parvum in buffalo intestinal tissue explants

Cryptosporidium is an apicomplexan parasite of human and animals and is considered as an important co-factor in neonatal diarrhea. In this study, an explant culture was used as an in vitro model of buffalo intestine to evaluate the effect of Moringa leaves extract on Cryptosporidium parvum (C. parvum) oocysts using light and scanning electron microscopy and measuring IFN-γ, IL-12 and IL-14 in the culture supernatants. C. parvum oocysts were collected from naturally-infected calf feces, isolated, excysted and then co-inoculated with ileal tissue explants culture medium. The prepared Moringa leaves extract was then introduced to the infected tissues in the concentrations of 100 mg/ml and 300 mg/ml. After 24 h, tissues were collected and processed for light and scanning electron microscopy. Also, culture supernatants were collected for cytokines measurement. C. parvum parasitophorous vacuoles were found attached to the surface of tissue in Cryptosporidium-infected ileal tissue explants. High magnification imaging of ileal tissue explants using scanning electron microscopy showed that Moringa leaves extracts had a great effect on Cryptosporidium-infected ileal tissue explants. There was a high significant (P < 0.001) increase in IFN-γ, IL-12 and IL-14 (375, 275 and 90 pg/ml, respectively) in the supernatants of infected non-treated ileal tissue explant culture plate wells compared to the control non-infected ones (74.66, 75 and 50 pg/ml, respectively). A concentration of 100 mg/ml Moringa extract exhibited the highest anticryptosporidial effect causing a significant decrease in IFN-γ, IL-12 and IL-14 levels (225, 150 and 65 pg/ml, respectively) compared with supernatants of infected non-treated ileal explant culture plate wells. In this study, explant culturing of buffalo ileal tissues allowed investigating the pathogenesis of cryptosporidiosis using light and scanning electron microscopy and studying changes in cytokine levels in tissues with and without Moringa leaves extract treatment. This model could help to understand the regulation of intestinal secretory and inflammatory responses, and could be useful for the screening of potential anticryptosporidial candidate compounds.

Human Intestinal Microbiota: Interaction Between Parasites and the Host Immune Response

The human gut is a highly complex ecosystem with an extensive microbial community, and the influence of the intestinal microbiota reaches the entire host organism. For example, the microbiome regulates fat storage, stimulates or renews epithelial cells, and influences the development and maturation of the brain and the immune system. Intestinal microbes can protect against infection by pathogenic bacteria, viruses, fungi and parasites. Hence, the maintenance of homeostasis between the gut microbiota and the rest of the body is crucial for health, with dysbiosis affecting disease. This review focuses on intestinal protozoa, especially those still representing a public health problem in Mexico, and their interactions with the microbiome and the host. The decrease in prevalence of intestinal helminthes in humans left a vacant ecological niche that was quickly occupied by protozoa. Although the mechanisms governing the interaction between intestinal microbiota and protozoa are poorly understood, it is known that the composition of the intestinal bacterial populations modulates the progression of protozoan infection and the outcome of parasitic disease. Most reports on the complex interactions between intestinal bacteria, protozoa and the immune system emphasize the protective role of the microbiota against protozoan infection. Insights into such protection may facilitate the manipulation of microbiota components to prevent and treat intestinal protozoan infections. Here we discuss recent findings about the immunoregulatory effect of intestinal microbiota with regards to intestinal colonization by protozoa, focusing on infections by Entamoeba histolytica, Blastocystis spp, Giardia duodenalis, Toxoplasma gondii and Cryptosporidium parvum. The possible consequences of the microbiota on parasitic, allergic and autoimmune disorders are also considered.

Lessons Learned from Protective Immune Responses to Optimize Vaccines against Cryptosporidiosis

In developing countries, cryptosporidiosis causes moderate-to-severe diarrhea and kills thousands of infants and toddlers annually. Drinking and recreational water contaminated with Cryptosporidium spp. oocysts has led to waterborne outbreaks in developed countries. A competent immune system is necessary to clear this parasitic infection. A better understanding of the immune responses required to prevent or limit infection by this protozoan parasite is the cornerstone of development of an effective vaccine. In this light, lessons learned from previously developed vaccines against Cryptosporidium spp. are at the foundation for development of better next-generation vaccines. In this review, we summarize the immune responses elicited by naturally and experimentally-induced Cryptosporidium spp. infection and by several experimental vaccines in various animal models. Our aim is to increase awareness about the immune responses that underlie protection against cryptosporidiosis and to encourage promotion of these immune responses as a key strategy for vaccine development. Innate and mucosal immunity will be addressed as well as adaptive immunity, with an emphasis on the balance between T_H1/T_H2 immune responses. Development of more effective vaccines against cryptosporidiosis is needed to prevent Cryptosporidium spp.-related deaths in infants and toddlers in developing countries.

Protective efficacy of recombinant Cryptosporidium parvum CpPRP1 sushi domain against C. tyzzeri infection in mice

Until now, there are no completely effective parasite-specific pharmaceuticals or immunotherapies for treatment against the zoonotic cryptosporidiosis. Sushi domain (CpSushi) is an important functional domain in Cryptosporidium parvum putative rhoptry protein-1 (CpPRP1), which is the only reported C. parvum rhoptry protein and may play key role in the course of invasion. Here, a 708-bp fragment encoding the CpSushi domain was amplified and expressed in E. coli. Immunofluorescence detection showed that CpSushi was located on the surface of C. parvum oocysts and the apical pole to the sporozoites that belonged to the position of rhoptry. Three-week-old female ICR mice were used for detecting the immunoreactions and immunoprotection of recombinant CpSushi (rCpSushi) to artificial C. tyzzeri infection. The results indicated that a significant increase of anti-CpSushi antibody response was induced by the recombinant protein. Compared to blank, Tris-EDTA (TE) buffer and adjuvant controls mice, rCpSushi-immunized mice produced specific spleen cell proliferation as well as enhanced IL4, IL5, IL12p70 and TNF-α production in vitro. The reduction rate of parasites shedding in stool in mice immunized with rCpSushi was 68.91% after challenging with C. tyzzeri. These results suggest that CpSushi could be a new promising cryptosporidiosis vaccine candidate antigen composition.

Modulation of the immune response by infection with Cryptosporidium spp. in children with allergic diseases

It has been demonstrated that the allergic response can be ameliorated by the administration of pathogen derivatives that activate Toll-like receptors and induce a Th1-type immune response (IR). Cryptosporidium is a parasite that promotes an IR via Toll-like receptors and elicits the production of Th1-type cytokines, which limit cryptosporidiosis. The aim of this study was to investigate allergy-related immune markers in children naturally infected with Cryptosporidium. In a cross-sectional study, 49 children with or without clinical diagnosis of allergies, oocysts of Cryptosporidium spp. in the faeces were screened microscopically. We microscopically screened for leucocytes, examined T and B cells for allergy-related activation markers using flow cytometry and evaluated serum for total IgE using chemiluminescence. Children with allergies and Cryptosporidium in the faeces had significantly lower levels of total IgE, B cells, CD19(+) CD23(+) and CD19(+) CD124(+) cells as well as a greater percentage of interferon-gamma (IFN-γ(+) ) and IL-4(+) CD4(+) cells than children with allergies without Cryptosporidium. This is the first description of the modulation of the IR in children with allergic diseases in the setting of natural Cryptosporidium infection. Our findings suggest the involvement of CD4(+) cells producing IL-4 and IFN-γ in the IR to Cryptosporidium in naturally infected children.

Infection Strategies of Intestinal Parasite Pathogens and Host Cell Responses

Giardia lamblia, Cryptosporidium sp., and Entamoeba histolytica are important pathogenic intestinal parasites and are amongst the leading causes worldwide of diarrheal illness in humans. Diseases caused by these organisms, giardiasis, cryptosporidiosis, and amoebiasis, respectively, are characterized by self-limited diarrhea but can evolve to long-term complications. The cellular and molecular mechanisms underlying the pathogenesis of diarrhea associated with these three pathogens are being unraveled, with knowledge of both the strategies explored by the parasites to establish infection and the methods evolved by hosts to avoid it. Special attention is being given to molecules participating in parasite–host interaction and in the mechanisms implicated in the diseases’ pathophysiologic processes. This review focuses on cell mechanisms that are modulated during infection, including gene transcription, cytoskeleton rearrangements, signal transduction pathways, and cell death.

Dynamics of Th17 associating cytokines in Cryptosporidium parvum-infected mice

Cryptosporidium parvum commonly inhabits the intestinal tract of animals and humans and can cause acute watery diarrhea and weight loss. However, host immune responses to Cryptosporidium infections are not fully understood. IL-17 (also called IL-17A) is a pro-inflammatory cytokine of Th17 cells that plays a role in the host response to Cryptosporidium baileyi infection. The present study examined levels of IL-17-specific messenger RNA (mRNA) and Th17 associating cytokines in C. parvum-infected immune-suppressed BALB/c mice using real-time quantitative PCR (qPCR). Levels of IL-17 protein were determined by ELISA. The results showed that levels of IL-17 mRNA and Th17 cell-related cytokines, namely TGF-β, IL-6, STAT-3, RORγt, IL-22, TNF-α, and IL-23, were significantly increased (P < 0.05) in gut-associated lymphoid tissue (GALT) and spleen. IL-17 protein levels in GALT were also significantly increased (P < 0.05) after infection. The present study suggested that Th17 cells play a role in host-C. parvum interaction. These results could inform future studies of the immune response against C. parvum infection in transient immunosuppressed populations.

Apicomplexan infections in the gut

Toxoplasma gondii and Cryptosporidium parvum are intracellular protozoan parasites that establish infection through the small intestinal bowel after the ingestion of contaminated food products. These Apicomplexan parasites have emerged as an important cause of chronic and fatal disease in immunodeficient individuals, in addition to being investigated as possible triggers of inflammatory bowel disease. T. gondii disseminates to the brain and other tissues after infection, whereas C. parvum remains localized to the intestine. In the following review, we will discuss the pathogenesis of these parasitic diseases in the small intestine, the site of initial invasion. Themes include the sequence of invasion, the structure of Th1 immunity provoked by these parasites and the contribution of intestinal microbiota to the development of the mucosal immune response.

The expression dynamics of IL-17 and Th17 response relative cytokines in the trachea and spleen of chickens after infection with Cryptosporidium baileyi

BACKGROUND

Cryptosporidium baileyi is the dominant Cryptosporidium species in birds causing emerging health problems in the poultry industry, and is also a model to study the biology of Cryptosporidium spp.. IL-17 (also called IL-17A) is a hallmark pro-inflammatory cytokine of Th17 cells that plays an important role in several human autoimmune diseases and microbial infection disease of many animals, and it may play a role in Cryptosporidium infection.

METHODS

The present study examined the mRNA level of IL-17 and Th17 response relative cytokines in the trachea and spleen of C. baileyi-infected chickens at different time points using real-time quantitative PCR (qPCR).

RESULTS

All examined cytokines in the trachea were up-regulated in the infected chickens compared with the uninfected control during C. baileyi infection. Significant increased IL-17 mRNA level in the trachea was observed as early as 12 h post infection (pi), peaking at 24 h pi and 10 d pi, and declining thereafter. The transcription levels of IL-17 and Th17 response relative cytokines in spleen were also significantly increased at different time points during the infection.

CONCLUSIONS

IL-17 was indicated to participate in the induction of inflammation during infection of some intracellular protozoan parasites. The results in the present study suggest that IL-17 may play a role in immunity against Cryptosporidium infection, and provide basic information for determining the role of Th17 cell in Cryptosporidium infection.

Prospects for immunotherapy and vaccines against Cryptosporidium

Cryptosporidium spp is a ubiquitous parasite that has long been recognized as a frequent cause of protozoal diarrhea in humans. While infections in immunocompetent hosts are usually self-limiting, immunocompromised individuals can develop severe, chronic, and life-threatening illness. Vaccine development or immunotherapy that prevents disease or reduces the severity of infection is a relevant option since efficacious drug treatments are lacking. In particular, children in developing countries might benefit the most from a vaccine since cryptosporidiosis in early childhood has been reported to be associated with subsequent impairment in growth, physical fitness, and intellectual capacity. In this review, immunotherapies that have been used clinically are described as well as experimental vaccines and their evaluation in vivo.

Dendritic cells play a role in host susceptibility to Cryptosporidium parvum infection

Our previous studies have described dendritic cells (DCs) to be important sources of Th1 cytokines such as IL-12 and IL-2 in vitro, following stimulation with Cryptosporidium parvum antigens. We further established the role of DCs during cryptosporidiosis using a diphtheria toxin promoter regulated transgenic CD11c-DTR/EGFP mouse model. In vivo depletion of CD11c(+) cells in CD11c-DTR-Tg mice significantly increased susceptibility to C. parvum infection. Adoptive transfer of unstimulated or antigen stimulated DCs into CD11c(+) depleted CD11c-DTR-Tg mice resulted in an early decrease in parasite load at 4 days post infection. However, this response was transient since parasite load increased in mice engrafted with either unstimulated DCs or DCs stimulated with solubilized antigen by 6 days post infection. In contrast, in mice engrafted with DCs stimulated with live sporozoites, parasite load remained low during the entire period, suggesting the development of a more effective and sustained response. A corresponding increase in IFN-γ expression in T cells from spleen and mesenteric lymph nodes was also noted. Consistent with the in vivo engraftment study, DCs that are pulsed with live sporozoites in vitro and co-cultured with CD4(+) and CD8(+) T cells produced higher IFN-γ levels. Our study establishes the importance of DCs in susceptibility to infection by C. parvum and as important mediators of immune responses.

Innate immune responses against Cryptosporidium parvum infection

Cryptosporidium parvum infects intestinal epithelial cells and is commonly the parasite species involved in mammalian cryptosporidiosis, a major health problem for humans and neonatal livestock. In mice, immunologically mediated elimination of C. parvum requires CD4+ T cells and IFN-γ. However, innate immune responses also have a significant protective role in both adult and neonatal mice. NK cells and IFN-γ have been shown to be important components in immunity in T and B cell-deficient mice, but IFN-γ-dependent resistance has also been demonstrated in alymphocytic mice. Epithelial cells may play a vital role in immunity as once infected these cells have increased expression of inflammatory chemokines and cytokines and demonstrate antimicrobial killing mechanisms, including production of NO and antimicrobial peptides. Toll-like receptors facilitate the establishment of immunity in mice and are involved in the development of inflammatory responses of infected epithelial cells and also dendritic cells.

Cryptosporidium parvum antigens induce mouse and human dendritic cells to generate Th1-enhancing cytokines

Cryptosporidium parvum is an opportunistic intracellular parasite that causes mild to severe diarrhoea, which can be life-threatening in an immunocompromised host. To increase our understanding of the mechanisms that play a role in host immune responses, we investigated the effects of C. parvum antigens on the phenotype of mouse and human dendritic cells (DCs). Cryptosporidium parvum antigens induced DC activation as indicated by upregulation of the maturation marker CD209, as well as by the production of the cytokines interleukin-12 p70, IL-2, IL-1beta, IL-6. In particular, significant increases in the expression of IL-12 p70 were observed from mouse DCs derived from bone marrow in response to solubilized sporozoite antigen and the recombinant cryptosporidial antigens, Cp40 and Cp23. We observed a small but significant increase in IL-18 expression following the exposure to Cp40. We found that the induction of Th1 cytokines was MyD88 dependent (MyD88 knockout mouse DCs were unresponsive). Additionally, both sporozoite preparations (solubilized and live) significantly induced IL-12 production by human monocytic dendritic cells (MoDCs). This finding indicates that solubilized as well as recombinant antigens can induce the maturation of DCs and subsequently initiate an innate immune response.

IL-12p40 deficiency leads to uncontrolled Trypanosoma cruzi dissemination in the spinal cord resulting in neuronal death and motor dysfunction

Chagas’ disease is a protozoosis caused by Trypanosoma cruzi that frequently shows severe chronic clinical complications of the heart or digestive system. Neurological disorders due to T. cruzi infection are also described in children and immunosuppressed hosts. We have previously reported that IL-12p40 knockout (KO) mice infected with the T. cruzi strain Sylvio X10/4 develop spinal cord neurodegenerative disease. Here, we further characterized neuropathology, parasite burden and inflammatory component associated to the fatal neurological disorder occurring in this mouse model. Forelimb paralysis in infected IL-12p40KO mice was associated with 60% (p<0.05) decrease in spinal cord neuronal density, glutamate accumulation (153%, p<0.05) and strong demyelization in lesion areas, mostly in those showing heavy protein nitrosylation, all denoting a neurotoxic degenerative profile. Quantification of T. cruzi 18S rRNA showed that parasite burden was controlled in the spinal cord of WT mice, decreasing from the fifth week after infection, but progressive parasite dissemination was observed in IL-12p40KO cords concurrent with significant accumulation of the astrocytic marker GFAP (317.0%, p<0.01) and 8-fold increase in macrophages/microglia (p<0.01), 36.3% (p<0.01) of which were infected. Similarly, mRNA levels for CD3, TNF-α, IFN-γ, iNOS, IL-10 and arginase I declined in WT spinal cords about the fourth or fifth week after infection, but kept increasing in IL-12p40KO mice. Interestingly, compared to WT tissue, lower mRNA levels for IFN-γ were observed in the IL-12p40KO spinal cords up to the fourth week of infection. Together the data suggest that impairments of parasite clearance mechanisms in IL-12p40KO mice elicit prolonged spinal cord inflammation that in turn leads to irreversible neurodegenerative lesions.

A protective role for interleukin 18 in interferon γ-mediated innate immunity to Cryptosporidium parvum that is independent of natural killer cells

Innate immunity against some intracellular parasitic protozoa involves interleukin 18 (IL-18)-mediated interferon γ (IFN-γ) production by natural killer (NK) cells, but the role of IL-18 in innate resistance to Cryptosporidium infection is unknown. Adult Rag2(-/-)γc(-/-) mice that lack NK cells, T cells, and B cells demonstrated resistance to Cryptosporidium parvum infection that was IFN-γ dependent. Treatment with anti-IL-18-neutralizing antibodies resulted in loss of resistance correlating with reduced intestinal IFN-γ expression. Intestinal mature IL-18 expression increased in vivo during infection and also in the intestinal epithelial cell line CMT-93 following combined IFN-γ treatment/infection. Peritoneal macrophages produced IFN-γ when stimulated with IL-18 combined with interleukin 12, and the latter was expressed in vivo during infection. Macrophage depletion in infected mice caused a rapid growth of infection with no increase in IFN-γ expression. These findings provide evidence of an NK cell-independent, IFN-γ-mediated innate immune pathway against C. parvum in which IL-18 and macrophages play prominent parts.

Induction of protective immunity against Eimeria tenella, Eimeria maxima, and Eimeria acervulina infections using dendritic cell-derived exosomes

This study describes a novel immunization strategy against avian coccidiosis using exosomes derived from Eimeria parasite antigen (Ag)-loaded dendritic cells (DCs). Chicken intestinal DCs were isolated and pulsed in vitro with a mixture of sporozoite-extracted Ags from Eimeria tenella, E. maxima, and E. acervulina, and the cell-derived exosomes were isolated. Chickens were nonimmunized or immunized intramuscularly with exosomes and subsequently noninfected or coinfected with E. tenella, E. maxima, and E. acervulina oocysts. Immune parameters compared among the nonimmunized/noninfected, nonimmunized/infected, and immunized/infected groups were the numbers of cells secreting T(h)1 cytokines, T(h)2 cytokines, interleukin-16 (IL-16), and Ag-reactive antibodies in vitro and in vivo readouts of protective immunity against Eimeria infection. Cecal tonsils, Peyer's patches, and spleens of immunized and infected chickens had increased numbers of cells secreting the IL-16 and the T(h)1 cytokines IL-2 and gamma interferon, greater Ag-stimulated proliferative responses, and higher numbers of Ag-reactive IgG- and IgA-producing cells following in vitro stimulation with the sporozoite Ags compared with the nonimmunized/noninfected and nonimmunized/infected controls. In contrast, the numbers of cells secreting the T(h)2 cytokines IL-4 and IL-10 were diminished in immunized and infected chickens compared with the nonimmunized/noninfected and the nonimmunized/infected controls. Chickens immunized with Ag-loaded exosomes and infected in vivo with Eimeria oocysts had increased body weight gains, reduced feed conversion ratios, diminished fecal oocyst shedding, lessened intestinal lesion scores, and reduced mortality compared with the nonimmunized/infected controls. These results suggest that successful field vaccination against avian coccidiosis using exosomes derived from DCs incubated with Ags isolated from Eimeria species may be possible.

Cryptosporidiosis: host immune responses and the prospects for effective immunotherapies

Cryptosporidium spp. that develop in intestinal epithelial cells are responsible for the diarrhoeal disease cryptosporidiosis, which is common in humans of all ages and in neonatal livestock. Following infection, parasite reproduction increases for a number of days before it is blunted and then impeded by innate and adaptive immune responses. Immunocompromised hosts often cannot establish strong immunity and develop chronic infections that can lead to death. Few drugs consistently inhibit parasite reproduction in the host, and chemotherapy might be ineffective in immunodeficient hosts. Future options for prevention or treatment of cryptosporidiosis might include vaccines or recombinant immunological molecules, but this will probably require a better understanding of both the mucosal immune system and intestinal immune responses to the parasite.

Cryptosporidiosis-an overview

Apicomplexan protozoan parasites of the genus Cryptosporidium infect the gastrointestinal tract and lungs of a wide variety of animals, including humans. The majority of human infections are due to either Cryptosporidium hominis (C. hominis) and/or Cryptosporidium parvum (C. parvum). The parasite has a complex life cycle that includes both asexual and sexual stages. While there are invasive free living stages, proliferation and differentiation take place within a unique parasitrophorous vacuole under the host cell brush border but outside the host cell cytoplasm. Infection is spread by environmentally resistant spores that primarily contaminate drinking water and occasionally food sources, which may cause significant outbreaks of diarrhea that generally lasts less than 2 w in immunocompetent individuals. In immunodeficient or immunosuppressed individuals, diarrhea may be copious and can result in significant morbidity and mortality, particularly in AIDS patients. Although diagnosis is relatively simple, effective drug treatment, particulary for infections in immunodeficient patients, has not been uniformly successful. This overview summarizes the species known to infect humans, aspects of the parasite life cycle, sources of infection, the pathophysiology of cryptosporidiosis, the immune response to infection, diagnosis, treatment and some aspects of cryptosporidiosis in China.

Host immune response to Cryptosporidium parvum infection

Species of the genus Cryptosporidium are protozoan parasites (Apicomplexa) that cause gastroenteritis in animals and humans. Of these Cryptosporidium parvum and Cryptosporidium hominis are the major causative agents of human cryptosporidiosis. Whereas infection is self-limiting in the immunocompetent hosts, immunocompromised individuals develop a chronic, life-threatening disease. As specific therapeutic or preventive interventions are not yet available, better understanding of the immune response to the parasite is required. This minireview briefly summarizes the factors involved in the innate and acquired immune response in this pathogen-host interaction with an emphasis on more recent data from mouse models of infection.

Roles for NK cells and an NK cell-independent source of intestinal gamma interferon for innate immunity to Cryptosporidium parvum infection

A gamma interferon (IFN-gamma)-dependent innate immune response operates against the intestinal parasite Cryptosporidium parvum in T- and B-cell-deficient SCID mice. Although NK cells are a major source of IFN-gamma in innate immunity, their protective role against C. parvum has been unclear. The role of NK cells in innate immunity was investigated using Rag2-/- mice, which lack T and B cells, and Rag2-/- gammac-/- mice, which, in addition, lack NK cells. Adult mice of both knockout lines developed progressive chronic infections; however, on most days the level of oocyst excretion was higher in Rag2-/- gammac-/- mice and these animals developed morbidity and died, whereas within the same period the Rag2-/- mice appeared healthy. Neonatal mice of both mouse lines survived a rapid onset of infection that reached a higher intensity in Rag2-/- gammac-/- mice. Significantly, similar levels of intestinal IFN-gamma mRNA were expressed in Rag2-/- and Rag2-/- gammac-/- mice. Also, infections in each mouse line were exacerbated by treatment with anti-IFN-gamma neutralizing antibodies. These results support a protective role for NK cells and IFN-gamma in innate immunity against C. parvum. In addition, the study implies that an intestinal cell type other than NK cells may be an important source of IFN-gamma during infection and that NK cells may have an IFN-gamma-independent protective role.