Intestine Of Infected Mice Research Articles

Therapeutic effects of myrrh extract and myrrh-based silver nanoparticles on Trichinella spiralis-infected mice: parasitological, histopathological, and immunological (IFN-γ, IL-10, and MMP-9) investigations.

Trichinellosis, caused by Trichinella spiralis (T. spiralis), remains a prevalent parasitic zoonosis. Developing new drugs targeting and understanding the immune response against the infection is imperative. Previous research has inadequately explored the efficacy of crude myrrh extract and myrrh-based silver nanoparticles (AgNPs) against trichinellosis, as well as their impact on histopathological, and immunological factors. This study evaluated the effects of silver nanoparticles biosynthesized using myrrh, crude myrrh extracts, and albendazole on the intestinal phase of T. spiralis. It also examined the associated histopathological changes and alterations in key immunological markers, including Interferon-gamma (IFN-γ), Interleukin-10 (IL-10), and Matrix Metalloproteinase-9 (MMP-9). Five groups of 12 mice were allocated as follows: group 1: non-infected, non-treated (negative control), group 2: infected, non-treated (positive control), group 3: infected and treated with biosynthesized silver nanoparticles (40 μg/mL), group 4: infected and treated with myrrh crude extract (800 mg/kg), and group 5: infected and treated with albendazole (50 mg/kg). Treatment was orally administered starting on the 2nd day post-infection and continued for three successive days. Mice of all groups were euthanized on the 6th day post-infection, and the intestine of each was isolated for parasitological, histopathological, and immunohistochemistry evaluation of MMP-9, as well as assessment of cytokines level (IFN-γ and IL-10 gene expressions) via Real-time PCR technique. The present study showed a considerable reduction in adult worm count among the treated groups. The mortality rates of adult worms were 88.64% in the silver nanoparticles treated group, 85.17% in the myrrh crude extract group, and 94.07% in the albendazole-treated group. Histopathological examination revealed prominent alterations in the intestine of the infected non-treated mice, which were markedly restored by treatment. Immunohistochemical examination accompanied by significant reduction in MMP-9 expression in the infected mice treated with AgNPs compared to the infected non-treated group, reflecting the role of AgNPs in downgrading the inflammatory reaction in the intestine of infected mice. Collectively, this study demonstrates the novel antiparasitic potential of silver nanoparticles biosynthesized with myrrh against T. spiralis in infected mice. The treatment was associated with moderate rise in IFN-γ gene expression and IL-10 expression, highlighting its therapeutic efficacy against T. spiralis.

Effect of Algae Chlorella extracts for treatment of intestinal tissues of mice infected with Cryptosporidium spp.

Cryptosporidium is a protozoan parasite of medical importance that causes gastroenteritis in a variety of vertebrate hosts, so the study was conducted to evaluate the anti-cryptosporidiosis efficacy of alcoholic and aqueous Chlorella algae extracts in comparison with Azithromycin in the intestines of infected mice. Fecal samples were collected from patients at Al-Kut Hospital suffering from diarrhea in the period December 2021 to end of March 2022, and 90 microscopic samples of both sexes were examined using a modified Ziell-Nelson stain to detect oocysts infected with the parasite. Isolation and flotation purification with Sheather's sugar solution and preservation in potassium dichromate for the purpose of infection in mice. The Experimental study was on groups of 57 mice by dealing with oral parasite oral oocysts within 104 oocyst/ ml except for the negative group addressed by a fishery saline solution. To strict injury, the detailed mice has been examined with microscopic parasites using Ziehl-Nelson Stain, and molecular screening was performed using Multiplex PCR technology. After the mice were divided into five groups with the uninfected and untreated group kept as a healthy negative control. The first group which included 21 mice was treated after it was divided into three subgroups A, B, C for each secondary group 7 mice they were treated with alcoholic extract of Chlorella at different concentrations 50, 100, 150 mg/ml on the respectively, while the second group which included 21 mice on three groups A, B, and C was treated with aqueous extract of Chlorella at the previous concentrations for three consecutive days for each concentration. The third group was treated with azithromycin at a concentration of 500 ml, and the positive control group remained infected with the parasite and was not treated. After treatment a microscopic examination was performed by evaluating the excretion average of parasite oocysts using a hematocytometer slide. The results of histological examination showed that treatment with alcoholic and aqueous Chlorella algae extracts led to remarkable repair and regeneration with restructuring in all sections of the small intestine infected with Cryptosporidium spp. parasite to varying degrees according to the concentrations used. Whereas the groups treated with Chlorella algae extracts showed epithelial layers renewed with the formation of non-enlarged cells and less edema, in addition less infiltration of inflammatory cells was observed in the submucosal layer. There was a slight inflammation in the tissues of the duodenum, jejunum, and ileum with a clear decrease in inflation and the degree of inflammation as well as less severe lesions in the intestinal tissues treated with alcoholic and aqueous extract of Chlorella algae in the highest concentrations with complete disappearance of parasite oocysts.Key words: Intestine, Cryptosporidium spp., Chlorella

Effect of Algae Spirulina Extraction in treatment of intestinal tissues of mice infected with Cryptosporidium spp.

Cryptosporidiosis caused by Cryptosporidium spp. It is a zoonotic disease that is the most prevalent, so the study was conducted to evaluate the anti-cryptosporidiosis efficacy of alcoholic and aqueous spirulina algae extracts in comparison with Azithromycin in the intestines of infected mice. Fecal samples were collected from patients at Al-Kout Hospital suffering from diarrhea in the period November 2021 to February 2022, and 124 microscopic samples of both sexes were examined using a modified Ziell-Nelson stain to detect eggs infected with the parasite. Isolation and flotation purification with shither sugar solution and preservation in potassium dichromate for the purpose of infection in mice. The Experimental study was on groups of 57 mice by dealing with oral parasite oral oocysts within 104 oocyst/ ml except for the negative group addressed by a fishery saline solution. To strict injury, the detailed mice has been examined with microscopic parasites using Ziehl-Nelson Stain, and molecular screening was performed using Multiplex PCR technology. After the mice were divided into five groups with the uninfected and untreated group kept as a healthy negative control. The first group which included 21 mice was treated after it was divided into three subgroups A, B, C for each secondary group 7 mice they were treated with alcoholic extract of Spirulina at different concentrations 50, 100, 150 mg/ml on the respectively, while the second group which included 21 mice on three groups A, B, and C was treated with aqueous extract of Spirulina at the previous concentrations for three consecutive days for each concentration. The third group was treated with azithromycin at a concentration of 500 ml, and the positive control group remained infected with the parasite and was not treated. After treatment a microscopic examination was performed by evaluating the excretion average of parasite oocysts using a hematocytometer slide. The results of histological examination showed that treatment with alcoholic and aqueous Spirulina algae extracts led to remarkable repair and regeneration with restructuring in all sections of the small intestine infected with Cryptosporidium spp. parasite to varying degrees according to the concentrations used. Whereas the groups treated with Spirulina algae extracts showed epithelial layers renewed with the formation of non-enlarged cells and less edema, in addition less infiltration of inflammatory cells was observed in the submucosal layer. There was a slight inflammation in the tissues of the duodenum, jejunum and ileum with a clear decrease in inflation and the degree of inflammation as well as less severe lesions in the intestinal tissues treated with alcoholic and aqueous extract of Spirulina algae in the highest concentrations with complete disappearance of parasite oocysts.

Bat-Origin Swine Acute Diarrhea Syndrome Coronavirus Is Lethal to Neonatal Mice.

Bats are reservoirs for diverse coronaviruses, including swine acute diarrhea syndrome coronavirus (SADS-CoV). SADS-CoV has been reported to have broad cell tropism and inherent potential to cross host species barriers for dissemination. We rescued synthetic wild-type SADS-CoV using one-step assembly of a viral cDNA clone by homologous recombination in yeast. Furthermore, we characterized SADS-CoV replication in vitro and in neonatal mice. We found that SADS-CoV caused severe watery diarrhea, weight loss, and a 100% fatality rate in 7- and 14-day-old mice after intracerebral infection. We also detected SADS-CoV-specific N protein in the brain, lungs, spleen, and intestines of infected mice. Furthermore, SADS-CoV infection triggers excessive cytokine expression that encompasses a broad array of proinflammatory mediators, including interleukin 1β (IL-1β), IL-6, IL-8, tumor necrosis factor alpha (TNF-α), C-X-C motif chemokine ligand 10 (CXCL10), interferon beta (IFN-β), IFN-γ, and IFN-λ3. This study highlights the importance of identifying neonatal mice as a model for developing vaccines or antiviral drugs against SADS-CoV infection. IMPORTANCE SADS-CoV is the documented spillover of a bat coronavirus that causes severe disease in pigs. Pigs are in frequent contact with both humans and other animals and theoretically possess a greater chance, compared to many other species, of promoting cross-species viral transmission. SADS-CoV has been reported to have broad cell tropism and inherent potential to cross host species barriers for dissemination. Animal models are an essential feature of the vaccine design toolkit. Compared with neonatal piglets, the mouse is small, making it an economical choice for animal models for SADS-CoV vaccine design. This study showed the pathology of neonatal mice infected with SADS-CoV, which should be very useful for vaccine and antiviral studies.

The Colombian Strain of Trypanosoma cruzi Induces a Proinflammatory Profile, Neuronal Death, and Collagen Deposition in the Intestine of C57BL/6 Mice Both during the Acute and Early Chronic Phase.

The objective of this study was to evaluate the histopathological changes caused by infection with the Colombian strain of Trypanosoma cruzi (T. cruzi) in the acute and chronic experimental phases. C57Bl/6 mice were infected with 1000 trypomastigote forms of the Colombian strain of T. cruzi. After 30 days (acute phase) and 90 days (early chronic phase) of infection, the animals were euthanized, and the colon was collected and divided into two parts: proximal and distal. The distal portion was used for histopathological analysis, whereas the proximal portion was used for quantification of pro- and anti-inflammatory cytokines. In addition, the weight of the animals and parasitemia were assessed. The infection induced gradual weight loss in the animals. In addition, the infection induced an increase in interferon gamma (IFNγ) and tumor necrosis factor-alpha (TNF-α) in the intestine in the acute phase, in which this increase continued until the early chronic phase. The same was observed in relation to the presence of intestinal inflammatory infiltrates. In relation to interleukin (IL)-10, there was an increase only in the early chronic phase. The Colombian strain infection was also able to induce neuronal loss in the myenteric plexus and deposition of the collagen fibers during the acute phase. The Colombian strain of T. cruzi is capable of causing histopathological changes in the intestine of infected mice, especially in inducing neuronal destructions. Thus, this strain can also be used to study the intestinal form of Chagas disease in experimental models.

The ethanolic extract of the fungus Trichoderma stromaticum decreases the Toxoplasma gondii replication in vitro and ameliorates the experimental toxoplasmosis in vivo

Trichoderma are fungi that are well-known to inhibit the growth of a variety of plant pathogens. Currently, there is an increasing search for new drugs to treat toxoplasmosis. The aims of this study were to investigate the effect of ExtTs in the control of Toxoplasma gondii proliferation in vitro and the course of toxoplasmosis in a mouse model. Firstly, the cytotoxicity of the ExtTs was evaluated by cultivating macrophages with different concentrations of the extract and cell viability was assessed by the MTT assay. Next, the infectivity of the T. gondii treated with extract was analyzed by infecting J774 macrophages. To evaluate the effect of the ExtTs in vivo, C57BL/6 mice were infected orally with T. gondii, ME-49, treated daily with ExtTs, and clinical, biochemical and histological changes were monitored. It was demonstrated that the extract did not affect the host cellular viability and, the treatment of parasites with ExtTs altered their morphology and decreased their ability to proliferate inside macrophages. Additionally, the treatment of mice with ExtTs decreased the parasitism and inflammation in the small intestine and liver of infected mice in parallel with increased IL-10/TNF ratio systemically and prevented alterations to serum VLDL and triglyceride levels. Thus, ExtTs could be considered an alternative/complementary therapy to control toxoplasmosis.

Evaluation of host and bacterial gene modulation during Lawsonia intracellularis infection in immunocompetent C57BL/6 mouse model.

BackgroundProliferative enteritis caused by Lawsonia intracellularis undermines the economic stability of the swine industry worldwide. The development of cost-effective animal models to study the pathophysiology of the disease will help develop strategies to counter this bacterium.ObjectivesThis study focused on establishing a model of gastrointestinal (GI) infection of L. intracellularis in C57BL/6 mice to evaluate the disease progression and lesions of proliferative enteropathy (PE) in murine GI tissue.MethodsWe assessed the murine mucosal and cell-mediated immune responses generated in response to inoculation with L. intracellularis.ResultsThe mice developed characteristic lesions of the disease and shed L. intracellularis in the feces following oral inoculation with 5 × l07 bacteria. An increase in L. intracellularis 16s rRNA and groEL copies in the intestine of infected mice indicated intestinal dissemination of the bacteria. The C57BL/6 mice appeared capable of modulating humoral and cell-mediated immune responses to L. intracellularis infection. Notably, the expression of genes for the vitamin B12 receptor and for secreted and membrane-bound mucins were downregulated in L. intracellularis -infected mice. Furthermore, L. intracellularis colonization of the mouse intestine was confirmed by the immunohistochemistry and western blot analyses.ConclusionsThis is the first study demonstrating the contributions of bacterial chaperonin and host nutrient genes to PE using an immunocompetent mouse model. This mouse infection model may serve as a platform from which to study L. intracellularis infection and develop potential vaccination and therapeutic strategies to treat PE.

Interleukin (IL)-33 is dispensable for Schistosoma mansoni worm maturation and the maintenance of egg-induced pathology in intestines of infected mice

BackgroundSchistosomes are trematode worms that dwell in their definitive host’s blood vessels, where females lay eggs that need to be discharged into the environment with host excreta to maintain their life-cycle. Both worms and eggs require type 2 immunity for their maturation and excretion, respectively. However, the immune molecules that orchestrate such immunity remain unclear. Interleukin (IL)-33 is one of the epithelium-derived cytokines that induce type 2 immunity in tissues. The aim of this study was to determine the role of IL-33 in the maturation, reproduction and excretion of Schistosoma mansoni eggs, and in the maintenance of egg-induced pathology in the intestines of mice.MethodsThe morphology of S. mansoni worms and the number of eggs in intestinal tissues were studied at different time points post-infection in S. mansoni-infected IL-33-deficient (IL-33−/−) and wild-type (WT) mice. IL-5 and IL-13 production in the spleens and mesenteric lymph nodes were measured. Tissue histology was performed on the terminal ilea of both infected and non-infected mice.ResultsWorms from IL-33−/− and WT mice did not differ morphologically at 4 and 6 weeks post-infection (wpi). The number of eggs in intestinal tissues of IL-33−/− and WT mice differed only slightly. At 6 wpi, IL-33−/− mice presented impaired type 2 immunity in the intestines, characterized by a decreased production of IL-5 and IL-13 in mesenteric lymph nodes and fewer inflammatory infiltrates with fewer eosinophils in the ilea. There was no difference between IL-33−/− and WT mice in the levels of IL-25 and thymic stromal lymphopoietin (TSLP) in intestinal tissues.ConclusionsDespite its ability to initiate type 2 immunity in tissues, IL-33 alone seems dispensable for S. mansoni maturation and its absence may not affect much the accumulation of eggs in intestinal tissues. The transient impairment of type 2 immunity observed in the intestines, but not spleens, highlights the importance of IL-33 over IL-25 and TSLP in initiating, but not maintaining, locally-induced type 2 immunity in intestinal tissues during schistosome infection. Further studies are needed to decipher the role of each of these molecules in schistosomiasis and clarify the possible interactions that might exist between them.Graphical

Gut Microbiota Modulates Intestinal Pathological Injury in Schistosoma japonicum-Infected Mice.

Trapping of Schistosoma japonicum (S. japonicum) eggs in host tissue, mainly in the intestine and liver, causes severe gastrointestinal and hepatic granulomatous immune responses and irreversible fibrosis. Although the gut microbiota plays a central role in regulating pathological responses in several diseases, the effect of the gut microbiota on the pathologenesis progression of schistosomiasis remains largely unknown. In this study, we aimed to investigate the regulatory function of the gut microbiota in schistosomiasis japonica. We found that the depletion of the gut microbiota significantly ameliorated egg granulomas formation and fibrosis in the intestine of infected mice. This role of the gut microbiota in intestinal granuloma formation and fibrosis was reinforced when normal and infected mice were housed together in one cage. Notably, changes in the gut microbiota induced by S. japonicum infection were partly reversible with microbiota transfer in the cohousing experiment. Transfer of the gut microbiota from normal to infected mice attenuated the intestinal pathological responses. Depletion of the gut microbiota by antibiotics, or transfer of the gut microbiota from normal to infected mice decreased the levels of IL-4, IL-5, and IL-13 and promoted the production of cytokines and mRNA levels of IL-10 and TGF-β in infected mice. Our findings indicated a regulatory effect of the gut microbiota on intestinal pathological injury associated with schistosomiasis japonica in mice, and thus suggested a potential strategy for schistosomiasis treatment.

Phage-delivered sensitisation with subsequent antibiotic treatment reveals sustained effect against antimicrobial resistant bacteria

Temperate phages integrated with clustered regularly interspaced short palindromic repeat (CRISPR)/Cas systems have been gaining attention as potential strategies for combating bacteria resistant to antimicrobials. To further advance this technology, phage recombination procedure should be improved, and the bactericidal effect should be examined in detail and compared with conventional lytic phage strategy. The possibility of the emergence of mutational resistance, a phenomenon commonly observed with lytic phage therapy, should be illustrated.Methods: Here, we developed a novel one-step cloning method to fulfil the recombination of CRISPR/Cas9 system within the genome of a new isolated lysogenic Escherichia coli phage. Then, we proposed and developed a phage-delivered resistance eradication with subsequent antibiotic treatment (PRESA) strategy. The removal efficiency and antimicrobial effect of the plasmids were analysed. Long-term antimicrobial effect was evaluated by continued OD600 monitoring for 240 hours to illustrate the potential mutational resistance, compared with the lytic phage strategy. The treatment effect of PRESA was evaluated in vivo by determining bacterial loads in the skin and intestine of infected mice, in contrast with lytic phage therapy. Genome sequencing was performed to identify mutations in bacterial cells treated with phage strategies.Results: Phage-delivered CRISPR targeting efficiently eradicated and blocked the transfer of the antibiotic resistance plasmid. PRESA decreased the bacterial load by over 6- and 5-logs in vitro and in vivo, respectively. Importantly, while lytic phages induced mutational phage resistance at 24 h in vitro and 48 hours in vivo, PRESA demonstrated a constant effect and revealed no resistant mutants. Genes involved in DNA mismatch repair were upregulated in cells undergoing Cas9-based plasmid cleavage, which may reduce the development of mutations.Conclusion: The PRESA strategy for eradicating resistant bacteria showed high bactericidal efficacy and a sustained inhibition effect against resistant bacteria. By restoring the efficacy of low-cost antibiotics, PRESA could be developed as an efficient and economical therapy for infections of antibiotic resistant bacteria.

Manipulation of the balance between Th2 and Th2/1 hybrid cells affects parasite nematode fitness in mice.

T-helper type 2 (Th2) responses are central to the control of helminth infections, but sensitive to opposing cytokine signals favoring Th1 priming. We previously reported on GATA-3+ T-bet+ Th2/1 hybrid cell differentiation in helminth mono-infections, resulting in a substantial proportion of cells coproducing IFN-γ next to Th2 cytokines. Here, we demonstrate Th2/1 cells as the major source of parasite-specific IFN-γ production in acute and chronic infections with the enteric nematode Heligmosomoides polygyrus. Th2/1 cells differentiated from naive precursors and accumulated in spleen and intestine of infected mice, resulting in increased systemic and mucosal IFN-γ production. IFN-γ supplementation early during infection supported Th2/1 differentiation, associated with elevated parasite fecundity and the maintenance of high worm burdens in the chronic stage of infection, whereas mice lacking IFN-γ signals generated poor Th2/1 responses and restricted parasite fecundity more efficiently. These findings suggest that Th2/1 hybrid responses take part in immune regulation during helminth infection and restrain effective anti-helminth immunity.

A Nonpyroptotic IFN-γ-Triggered Cell Death Mechanism in Nonphagocytic Cells Promotes Salmonella Clearance In Vivo.

The cytokine IFN-γ has well-established antibacterial properties against the bacterium Salmonella enterica in phagocytes, but less is known about the effects of IFN-γ on Salmonella-infected nonphagocytic cells, such as intestinal epithelial cells (IECs) and fibroblasts. In this article, we show that exposing human and murine IECs and fibroblasts to IFN-γ following infection with Salmonella triggers a novel form of cell death that is neither pyroptosis nor any of the major known forms of programmed cell death. Cell death required IFN-γ-signaling via STAT1-IRF1-mediated induction of guanylate binding proteins and the presence of live Salmonella in the cytosol. In vivo, ablating IFN-γ signaling selectively in murine IECs led to higher bacterial burden in colon contents and increased inflammation in the intestine of infected mice. Together, these results demonstrate that IFN-γ signaling triggers release of Salmonella from the Salmonella-containing vacuole into the cytosol of infected nonphagocytic cells, resulting in a form of nonpyroptotic cell death that prevents bacterial spread in the gut.

Transcriptomic analysis of mouse liver reveals a potential hepato-enteric pathogenic mechanism in acute Toxoplasma gondii infection.

BackgroundToxoplasma gondii is a worldwide spread pathogen which can infect all tissues of its host. The transcriptomic responses of infected brain and spleen have been reported. However, our knowledge of the global transcriptomic change in infected liver is limited. Additionally, T. gondii infection represents a highly dynamic process involving complex biological responses of the host at many levels. Herein, we describe such processes at a global level by discovering gene expression changes in mouse livers after acute infection with T. gondii ToxoDB#9 strain.ResultsGlobal transcriptomic analysis identified 2,758 differentially expressed transcripts in infected liver, of which 1,356 were significantly downregulated and 1,402 upregulated. GO and KEGG database analyses showed that host immune responses were upregulated, while the metabolic-related processes/pathways were downregulated, especially xenobiotic metabolism, fatty acid metabolism, energy metabolism, and bile biosynthesis and secretion. The metabolism of more than 800 chemical compounds including anti-Toxoplasma prescribed medicines were predicted to be modulated during acute T. gondii infection due to the downregulation of enzymes involved in xenobiotic metabolism.ConclusionsTo the best of our knowledge, this is the first global transcriptomic analysis of mouse liver infected by T. gondii. The present data indicate that during the early stage of liver infection, T. gondii can induce changes in liver xenobiotic metabolism, upregulating inflammatory response and downregulating hepatocellular PPAR signaling pathway, altering host bile biosynthesis and secretion pathway; these changes could enhance host intestinal dysbacteriosis and thus contribute to the pathological changes of both liver and intestine of infected mice. These findings describe the biological changes in infected liver, providing a potential mechanistic pathway that links hepatic and intestinal pathologies to T. gondii infection.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1716-x) contains supplementary material, which is available to authorized users.

New diagnostic antigens for early trichinellosis: the excretory-secretory antigens of Trichinella spiralis intestinal infective larvae.

The excretory-secretory (ES) antigens from Trichinella spiralis muscle larvae (ML) are the most commonly used diagnostic antigens for trichinellosis, but anti-Trichinella IgG antibodies cannot be detected until 2-3weeks after infection; there is an obvious window period between Trichinella infection and antibody positivity. Intestinal infective larvae (IIL) are the first invasive stage during Trichinella infection, and their ES antigens are firstly exposed to the immune system and might be the early diagnostic markers of trichinellosis. The aim of this study was to evaluate the early diagnostic values of IIL ES antigens for trichinellosis. The IIL were collected from intestines of infected mice at 6h postinfection (hpi), and IIL ES antigens were prepared by incubation for 18h. Anti-Trichinella IgG antibodies in mice infected with 100 ML were detectable by ELISA with IIL ES antigens as soon as 10days postinfection (dpi), but ELISA with ML ES antigens did not permit detection of infected mice before 12 dpi. When the sera of patients with trichinellosis at 19 dpi were assayed, the sensitivity (100%) of ELISA with IIL ES antigens was evidently higher than 75% of ELISA with ML ES antigens (P < 0.05) The specificity (96.86%) of ELISA with IIL ES antigens was also higher than 89.31% of ELISA with ML ES antigens (P < 0.05). The IIL ES antigens provided a new source of diagnostic antigens and could be considered as a potential early diagnostic antigen for trichinellosis.

Clostridium difficile-induced colitis in mice is independent of leukotrienes

Clostridium difficile is the major cause of antibiotic-associated diarrhea and pseudomembranous colitis in healthcare settings. However, the host factors involved in the intestinal inflammatory response and pathogenesis of C. difficile infection (CDI) are largely unknown. Here we investigated the role of leukotrienes (LTs), a group of pro-inflammatory lipid mediators, in CDI. Notably, the neutrophil chemoattractant LTB4, but not cysteinyl (cys) LTs, was induced in the intestine of C57BL/6 mice infected with either C. difficile strain VPI 10463 or strain 630. Genetic or pharmacological ablation of LT production did not ameliorate C. difficile colitis or clinical signs of disease in infected mice. Histological analysis demonstrated that intestinal neutrophilic inflammation, edema and tissue damage in mice during acute and severe CDI were not modulated in the absence of LTs. In addition, CDI induced a burst of cytokines in the intestine of infected mice in a LT-independent manner. Serum levels of anti-toxin A immunoglobulin (Ig) G levels were also not modulated by endogenous LTs. Collectively, our results do not support a role for LTs in modulating host susceptibility to CDI in mice.

Giardia muris infection in mice is associated with a protective interleukin 17A response and induction of peroxisome proliferator-activated receptor alpha.

The protozoan parasite Giardia duodenalis (Giardia lamblia) is one of the most commonly found intestinal pathogens in mammals, including humans. In the current study, a Giardia muris-mouse model was used to analyze cytokine transcription patterns and histological changes in intestinal tissue at different time points during infection in C57BL/6 mice. Since earlier work revealed the upregulation of peroxisome proliferator-activated receptors (PPARs) in Giardia-infected calves, a second aim was to investigate the potential activation of PPARs in the intestines of infected mice. The most important observation in all mice was a strong upregulation of il17a starting around 1 week postinfection. The significance of interleukin 17A (IL-17A) in orchestrating a protective immune response was further demonstrated in an infection trial or experiment using IL-17 receptor A (IL-17RA) knockout (KO) mice: whereas in wild-type (WT) mice, cyst secretion dropped significantly after 3 weeks of infection, the IL-17RA KO mice were unable to clear the infection. Analysis of the intestinal response further indicated peroxisome proliferator-activated receptor alpha (PPARα) induction soon after the initial contact with the parasite, as characterized by the transcriptional upregulation of ppara itself and several downstream target genes such as pltp and cpt1. Overall, PPARα did not seem to have any influence on the immune response against G. muris, since PPARα KO animals expressed il-17a and could clear the infection similar to WT controls. In conclusion, this study shows for the first time the importance of IL-17 production in the clearance of a G. muris infection together with an early induction of PPARα. The effect of the latter, however, is still unclear.

MIF Participates in Toxoplasma gondii-Induced Pathology Following Oral Infection

BackgroundMacrophage migration inhibitory factor (MIF) is essential for controlling parasite burden and survival in a model of systemic Toxoplasma gondii infection. Peroral T. gondii infection induces small intestine necrosis and death in susceptible hosts, and in many aspects resembles inflammatory bowel disease (IBD). Considering the critical role of MIF in the pathogenesis of IBD, we hypothesized that MIF participates in the inflammatory response induced by oral infection with T. gondii.Methodology/Principal Findings Mif deficient (Mif−/−) and wild-type mice in the C57Bl/6 background were orally infected with T. gondii strain ME49. Mif−/− mice had reduced lethality, ileal inflammation and tissue damage despite of an increased intestinal parasite load compared to wt mice. Lack of MIF caused a reduction of TNF-α, IL-12, IFN-γ and IL-23 and an increased expression of IL-22 in ileal mucosa. Moreover, suppressed pro-inflammatory responses at the ileal mucosa observed in Mif−/− mice was not due to upregulation of IL-4, IL-10 or TGF-β. MIF also affected the expression of matrix metalloproteinase-9 (MMP-9) but not MMP-2 in the intestine of infected mice. Signs of systemic inflammation including the increased concentrations of inflammatory cytokines in the plasma and liver damage were less pronounced in Mif−/− mice compared to wild-type mice.Conclusion/SignificanceIn conclusion, our data suggested that in susceptible hosts MIF controls T. gondii infection with the cost of increasing local and systemic inflammation, tissue damage and death.

Comparison between morphological and staining characteristics of live and dead eggs of Schistosoma mansoni

Schistosoma mansoni eggs are classified, according to morphological characteristics, as follows: viable mature and immature eggs; dead mature and immature eggs, shells and granulomas. The scope of this study was to compare the staining characteristics of different morphological types of eggs in the presence of fluorescent labels and vital dyes, aiming at differentiating live and dead eggs. The eggs were obtained from the intestines of infected mice, and put into saline 0.85%. The fluorescent labels were Hoechst 33258 and Acridine Orange + Ethidium Bromide and vital dyes (Trypan Blue 0.4% and Neutral Red 1%). When labelled with the probe Hoechst 33258, some immature eggs, morphologically considered viable, presented fluorescence (a staining characteristic detected only in dead eggs); mature eggs did not present fluorescence, and the other types of dead eggs, morphologically defined, showed fluorescence. As far as Acridine Orange + Ethidium Bromide are concerned, either the eggs considered to be live, or the dead ones, presented staining with green color, and only the hatched and motionless miracidium was stained with an orange color. Trypan Blue was not able to stain the eggs, considered to be dead but only dead miracidia which had emerged out of the shell. Neutral Red stained both live and dead eggs. Only the fluorescent Hoechst 33258 can be considered a useful tool for differentiation between dead and live eggs.

Biological variation between two Brazilian geographical isolates of Echinostoma paraensei

The biological behaviour and morphometric data from two allopatric isolates of Echinostoma paraensei (Rio Bonito - RB and Sumidouro - SU) collected from naturally infected Nectomys squamipes from two secluded Atlantic Forest fragments were studied. Mice that had been experimentally infected with ten encysted metacercariae of each isolate were monitored weekly in two trials to analyse worm burden and the kinetics of worm distribution along the intestine. The total number of uterine eggs, wet weights and measurements of the worms and body, acetabulum, testes and ovaries were also analysed. The RB isolate showed a higher worm burden, 7.7+/-0.8, and a longer life span, 16 weeks, compared to a worm burden of 5.8+/-1.1 and life span of 9 weeks for the SU isolate. Worms of the RB isolate were clustered in the duodenum and in the bile duct while the SU isolate worms were dispersed along the small intestine of infected mice. Both isolates developed similarly as regards morphometric data and wet weight, although the total number of uterine eggs was greater in RB. The degree of intraspecific variation observed in the worm distribution along the intestine, worm burden and life span raises questions regarding the use of these criteria for species differentiation. These findings suggest that variation in biological parameters found between the E. paraensei isolates could result from geographical isolation and, in particular, the environmental conditions of transmission. Further studies on E. paraensei polulations from different forest fragments will contribute towards an understanding of the speciation of this parasite.

Mouse Model of Enteropathogenic Escherichia coli Infection

Enteropathogenic Escherichia coli (EPEC) is an important cause of diarrhea in humans. EPEC infection of cultured intestinal epithelial cells induces attaching and effacing (A/E) lesions, alters intestinal ion transport, increases paracellular permeability, and stimulates inflammation. The lack of a small-animal model has restricted in vivo studies examining EPEC-host interactions. The aim of this study was to characterize the C57BL/6J mouse as a model of EPEC infection. We have shown that EPEC can adhere to and colonize the intestinal epithelium of C57BL/6J mice. Animal weight and water intake were not altered during 10 days of EPEC infection. The proximal colon of infected mice contained semisolid stool, with stool pellets forming only in the distal colon. In contrast, the entire colon of control mice contained formed stool. Microvillous effacement and actin rearrangement, characteristic of A/E lesions, were seen in the intestine of infected mice but not control mice. Histological assessment revealed increased numbers of lamina propria neutrophils with occasional crypt abscesses, intraepithelial lymphocytes, and goblet cells in the intestine of EPEC-infected mice. Altogether, these data suggest that the C57BL/6J mouse is susceptible to infection by EPEC and will provide a suitable in vivo model for studying the consequences of EPEC infection.