Epithelial STAT6 O-GlcNAcylation drives a concerted anti-helminth alarmin response dependent on tuft cell hyperplasia and Gasdermin C.

The epithelium is an integral component of mucosal barrier and host immunity. Following helminth infection, the intestinal epithelial cells secrete "alarmin" cytokines, such as interleukin-25 (IL-25) and IL-33, to initiate the type 2 immune responses for helminth expulsion and tolerance. However, it is unknown how helminth infection and the resulting cytokine milieu drive epithelial remodeling and orchestrate alarmin secretion. Here, we report that epithelial O-linked N-Acetylglucosamine (O-GlcNAc) protein modification was induced upon helminth infections. By modifying and activating the transcription factor STAT6, O-GlcNAc transferase promoted the transcription of lineage-defining Pou2f3 in tuft cell differentiation and IL-25 production. Meanwhile, STAT6 O-GlcNAcylation activated the expression of Gsdmc family genes. The membrane pore formed by GSDMC facilitated the unconventional secretion of IL-33. GSDMC-mediated IL-33 secretion was indispensable for effective anti-helminth immunity and contributed to induced intestinal inflammation. Protein O-GlcNAcylation can be harnessed for future treatment of type 2 inflammation-associated human diseases.

Dairy Heifers Naturally Exposed to Fasciola hepatica Develop a Type 2 Immune Response and Concomitant Suppression of Leukocyte Proliferation.

Fasciola hepatica is a parasitic trematode of global importance in livestock. Control strategies reliant on anthelmintics are unsustainable due to the emergence of drug resistance. Vaccines are under development, but efficacies are variable. Evidence from experimental infection suggests that vaccine efficacy may be affected by parasite-induced immunomodulation. Little is known about the immune response to F. hepatica following natural exposure. Hence, we analyzed the immune responses over time in calves naturally exposed to F. hepatica infection. Cohorts of replacement dairy heifer calves (n = 42) with no prior exposure to F. hepatica, on three commercial dairy farms, were sampled over the course of a grazing season. Exposure was determined through an F. hepatica-specific serum antibody enzyme-linked immunosorbent assay (ELISA) and fluke egg counts. Concurrent changes in peripheral blood leukocyte subpopulations, lymphocyte proliferation, and cytokine responses were measured. Relationships between fluke infection and immune responses were analyzed by using multivariable linear mixed-effect models. All calves from one farm showed evidence of exposure, while cohorts from the remaining two farms remained negative over the grazing season. A type 2 immune response was associated with exposure, with increased interleukin-4 (IL-4) production, IL-5 transcription, and eosinophilia. Suppression of parasite-specific peripheral blood mononuclear cell (PBMC) proliferation was evident, while decreased mitogen-stimulated gamma interferon (IFN-γ) production suggested immunomodulation, which was not restricted to parasite-specific responses. Our findings show that the global immune response is modulated toward a nonproliferative type 2 state following natural challenge with F. hepatica This has implications in terms of the timing of the administration of vaccination programs and for host susceptibility to coinfecting pathogens.

Eosinophilic inflammation in lymph nodes of dogs with visceral leishmaniasis.

Eosinophils are traditionally associated with the immune response against helminth parasites. However, several studies have demonstrated that these cells have a role regarding protective immunity in leishmaniasis. Here, we examined the relationship between the presence of eosinophils and parasite load in biopsy samples from dogs, obtained through fine needle puncture and aspiration of lymph nodes. Histological slides containing biopsy material from lymph nodes of dogs with canine visceral leishmaniasis and healthy dogs were used to obtain baseline eosinophil counts. Subsequently, scrapings were taken from slides for DNA extraction and determination of parasite load, using real-time PCR (qRT-PCR). Additionally, production of nitric oxide (NO) and reactive oxygen species (ROS) levels by eosinophils in the peripheral blood of dogs with canine visceral leishmaniasis and healthy dogs was measured. The eosinophil percentage were higher in lymph nodes of infected group, and the parasite load showed a significant negative correlation with the eosinophil count. The production of NO and ROS by eosinophils in the peripheral blood was higher in the dogs with canine visceral leishmaniasis. All the results together suggest that eosinophils may participate in antileishmanial immunity in canine visceral leishmaniasis.

Antihelminthic niclosamide modulates dendritic cells activation and function.

Dendritic cells (DCs) link the sensing of the environment by the innate immune system to the initiation of adaptive immune responses. Accordingly, DCs are considered to be a major target in the development of immunomodulating compounds. In this study, the effect of niclosamide, a Food and Drug Administration-approved antihelminthic drug, on the activation of lipopolysaccharide (LPS)-stimulated murine bone marrow-derived DCs was examined. Our experimental results show that niclosamide reduced the pro-inflammatory cytokine and chemokine expression of LPS-activated DCs. In addition, niclosamide also affected the expression of MHC and costimulatory molecules and influenced the ability of the cells to take up antigens. Therefore, in mixed cell cultures composed of syngeneic OVA-specific T cells and DCs, niclosamide-treated DCs showed a decreased ability to stimulate T cell proliferation and IFN-γ production. Furthermore, intravenous injection of niclosamide also attenuated contact hypersensitivity (CHS) in mice during sensitization with 2,4-dinitro-1-fluorobenzene. Blocking the LPS-induced activation of MAPK-ERK, JNK and NF-κB may contribute to the inhibitory effect of niclosamide on DC activation. Collectively, our findings suggest that niclosamide can manipulate the function of DCs. These results provide new insight into the immunopharmacological role of niclosamide and suggest that it may be useful for the treatment of chronic inflammatory disorders or DC-mediated autoimmune diseases.

Designing efficient multi-epitope peptide-based vaccine by targeting the antioxidant thioredoxin of bancroftian filarial parasite.

Thioredoxin is a low molecular weight redox-active protein of filarial parasite that plays a crucial role in downregulating the host immune response to prolong the survival of the parasite within the host body. It has the ability to cope up with the oxidative challenges posed by the host. Hence, the antioxidant protein of the filarial parasite has been suggested to be a useful target for immunotherapeutic intervention of human filariasis. In this study, we have designed a multi-epitope peptide-based vaccine using thioredoxin of Wuchereria bancrofti. Different MHC-I and MHC-II epitopes were predicted using various web servers to construct the vaccine model as MHC-I and MHC-II epitopes are crucial for the development of both humoral and cellular immune responses. Moreover, TLRs specific adjuvants were also incorporated into the vaccine candidates as TLRs are the key immunomodulator to execute innate immunity. Protein-protein molecular docking and simulation analysis between the vaccine and human TLR was performed. TLR5 is the most potent receptor to convey the vaccine-mediated inductive signal for eliciting an innate immune response. A satisfactory immunogenic report from an in-silico immune simulation experiment directed us to propose our vaccine model for experimental and clinical validation. The reverse translated vaccine sequence was also cloned in pET28a(+) to apply the concept in a wet lab experiment in near future. Taken together, this in-silico study on the design of a vaccine construct to target W. bancrofti thioredoxin is predicted to be a future hope in saving human-being from the threat of filariasis.

Porcine antibody responses to taenia solium antigens rGp50 and sTs18var1.

Cysticercosis, a disease caused by the larval form of Taenia solium, is diagnosed by detection of specific antibodies or by imaging techniques. Our preferred immunologic assay for cysticercosis is the enzyme-linked immunoelectrodifusion transfer blot, or immunoblot, using the lentil lectin bound antigens from larval cysts. Antibody reactivity with any one of seven glycoproteins is diagnostic for cysticercosis. To develop a simple antibody detection assay for field use, we have synthesized an 8-kD diagnostic antigen, sTs18var1 (a secreted protein with a mature size of 67 amino acids), and expressed a 50-kD membrane protein antigen, rGp50. We used these two diagnostic proteins in a quantitative Falcon assay screening test-enzyme-linked immunosorbent assay (FAST-ELISA) to measure the antibody responses in Peruvian pigs with cysticercosis. Three study designs were used. First, we followed the kinetics of antibody responses against these two diagnostic proteins in pigs with cysticercosis that were treated with oxfendazole. Second, we measured antibody response in naive experimentally infected pigs. Third, we followed the maternal antibodies against rGp50 and sTs18var1 in piglets born from sows with cysticercosis. These studies showed that antibody responses against the two diagnostic proteins in the FAST-ELISA are quantitatively correlated with infection by viable cysts, with anti-sTs18var1 activity being most responsive to the status of infection.

Antibody isotype responses to Schistosoma japonicum antigens in subjects from a schistosomiasis area with repeated praziquantel chemotherapy compared with a new endemic zone in Hunan Province, P.R. China.

To demonstrate the dynamics of specific antibody isotypes against schistosome adult worm (AWA) and soluble egg (SEA) antigens, we evaluated (in 1999-2000) 112 subjects infected with Schistosoma japonicum from 2 regions of Hunan Province, China. Fifty-eight subjects were from Area A, a well-known endemic area with repeated chemotherapy. Area B (n = 54) is a new endemic focus in another part of the same province. Serum samples were collected prior to praziquantel (PZQ) chemotherapy, and at 2 and 12 months post-treatment. IgM, IgA, IgG, IgG2, IgG4 and IgE antibodies to AWA and SEA were measured by quantitative enzyme-linked immunosorbent assay (ELISA). Pre-treatment antibody isotype levels from Area A, except IgA against AWA and SEA, were significantly higher than those from Area B. In response to chemotherapy, most antibody isotype levels fell or remained stable. However, in Area A there was a significant increase in the IgA, IgE and IgG4 responses to AWA 2 months after PZQ--which fell to approach pre-treatment levels by 12 months. A similar response was seen in Area B with IgE and IgG4 to AWA. Levels of all AWA-specific IgE and IgG4 were significantly higher in subjects from Area A compared with Area B at all time-points. AWA-IgE levels demonstrated significant linear correlations with age and number of previous PZQ treatments in Area A only. All SEA-specific isotypes in both areas fell significantly in response to treatment--except IgE, which remained stable in both area. All SEA-specific isotype levels (except IgA) were significantly higher from Area A at baseline. This significant difference was maintained through 12-months follow-up for IgE, IgG2 and IgG4 only. This study suggests that multiple episodes of schistosome infection may be required to generate antibody isotype levels that have been associated with resistance to re-infection in other studies. Further, a surrogate marker of successful chemotherapy (AWA-IgG4) performed less effectively in patients with previous treatment courses.

Induction of protective immunity to Dictyocaulus viviparus in calves while under treatment with endectocides.

Three groups of five parasite-naive calves were used. The treatments were: (a) Group 1 calves were weighed on Day 0 and injected with doramectin at 200 microg/kg. From Day 1 to 19 they were dosed orally with 2000 infective larvae of Dictyocaulus viviparus. On Day 28 they were again injected with doramectin, and infected with D. viviparus larvae from Days 33 to 41. They were then left untreated until Day 81 when they were infected with 20 infective larvae of D. viviparus per kg body weight. They were killed on Day 110 and lungworms were counted; (b) Group 2 calves were immunised with oral lungworm vaccine on Days 0 and 28, and infected and slaughtered as Group 1 on Days 81 and 110, respectively; (c) Group 3 calves acted as infection controls. Blood samples were taken at Days 0, 21, 49, 77 and 110 for antibody tests to D. viviparus. At autopsy there were no significant differences between the number of lungworms from Groups 1 and 2 (Means 17.4 and 31.3, respectively); Group 1 had significantly less value than Group 3 (Mean 228) (p < 0.05). Increased antibody titres to the larval sheath of the infective larvae were observed from Groups 1 and 2, showing that the larvae in Group 1 had penetrated the intestine before being killed by the circulating anthelmintic. This experiment shows that if calves are exposed to infective larvae while under systemic endectocide cover, an immune reaction is stimulated.

Effects of previous suppressive anthelmintic treatments on subsequent nematode infection in fattening cattle in Argentina.

The effect of previous suppressive anthelmintic treatments after weaning on parasitological parameters and weight gain of cattle was studied in the Pampeana region of Argentina. The study was carried out at two grazing fattening periods: April 1995/July 1996 and April 1997/July 1998. During both periods, 60 weaned calves that grazed contaminated pastures, were divided into three groups during the first part of the periods: GY1 group was treated every 2 weeks with doramectin while GY2 and GY3 groups remained untreated. During the second part of the periods, from October onwards GY1 and GY2 remained untreated and GY3 was treated every 2 weeks. In this second period two new groups of 20 weaning young calves were added: TG (treated every 2 weeks) and UG (untreated). Egg counts (EPG), larval cultures, pasture larval counts, serum pepsinogen (Pep) and live weight gain (LWG) were recorded monthly. Ostertagia, Cooperia, Trichostrongylus and Haemonchus were the predominant genera. Despite low levels of previous infection during the first part of the period, slight differences of EPG between GY1 (P<0.09) or UG (P<0.05) and GY2 were detected in the second part of the fattening period in 1995/1996. In 1997/1998 moderate infection levels during the first part of the period were observed. During the second part of this period, GY1 and UG showed higher (P<0.001) EPG than GY2, and only GY3 and TG had (P<0.05) lower Pep levels. Also, during the second part of 1997/1998, LWG responses of GY3 were higher (P<0.001) than those of GY1 and GY2. Live weight gain of GY2 exceeded GY1 by 10.7kg (P<0.006). Higher EPG and lower LWG of GY1 suggest that suppressive treatments negatively affected the level of resistance to infection of yearlings, but these effects were influenced by previous levels of nematode infection. The lack of differences between yearling (GY1) and calves (UG) groups suggest that, under the conditions of this study, there was no evidence that resistance to infection and the related parameters are influenced by the age.

Anti-Dirofilaria immitis antibody levels before and after anthelmintic treatment of experimentally infected dogs.

Antibody to Dirofilaria immitis was measured in 6 dogs before and after treatment with thiacetarsamide. Antibody to microfilarial surface antigens was ascertained with an indirect fluorescent antibody assay (IFA). Various patterns of the production, or presence, of antibody to microfilarial surface antigens were observed. There was no apparent relationship between IFA results and adulticide success. Antibody to adult worm antigen was measured with an enzyme-linked immunosorbent assay (ELISA). ELISA titers increased following infection and decreased transiently at the end of the prepatent period. A marked increase in ELISA titers was noted in all dogs subsequent to an initial thiacetarsamide treatment. In general, ELISA titers returned to low levels in dogs which were successfully treated; however, in dogs with persistent infections or infections which apparently necessitated 2 adulticide treatments ELISA titers remained at pre-treatment levels during the period of observation. Since ELISA titers appeared to decrease to pre-infection levels in successfully treated dogs, the assay should have utility in subsequent antibody determinations and may permit retrospective prediction of chemotherapeutic success.

Synergistic action of praziquantel and host specific immune response against Schistosoma mansoni at different phases of infection.

The interaction between specific immune response to Schistosoma mansoni and praziquantel (PZQ) was studied in mice. In mice harboring concomitant immunity, 6-day-old parasites treated with PZQ were more effectively removed than 24 h treated parasites despite both had a significant worm burden reduction when compared with respective treated controls. These results show that PZQ can be effective at the skin and lung stages of parasite's development mainly acting with a established specific immune response, and particularly at the lung phase.

Effect of heterogeneous mixing and vaccination on the dynamics of anthelmintic resistance: a nested model.

Anthelmintic resistance is a major threat to current measures for helminth control in humans and animals. The introduction of anthelmintic vaccines, as a complement to or replacement for drug treatments, has been advocated as a preventive measure. Here, a computer-based simulation, tracking the dynamics of hosts, parasites and parasite-genes, shows that, depending on the degree of host-population mixing, the frequency of totally recessive autosomes associated with anthelmintic resistance can follow either a fast dynamical regime with a low equilibrium point or a slow dynamical regime with a high equilibrium point. For fully dominant autosomes, only one regime is predicted. The effectiveness of anthelminthic vaccines against resistance is shown to be strongly influenced by the underlying dynamics of resistant autosomes. Vaccines targeting adult parasites, by decreasing helminth fecundity or lifespan, are predicted to be more effective than vaccines targeting parasite larvae, by decreasing host susceptibility to infection, in reducing the spread of resistance. These results may inform new strategies to prevent, monitor and control the spread of anthelmintic resistance, including the development of viable anthelmintic vaccines.

Preparation and characterization of monoclonal antibodies against avermectin.

The coupled antigen, avermectin (AVM) and bovine serum albumin (BSA), was artificially synthesized. Female 8-week-old BALB/c mice were immunized with AVM-BSA emulsified in Freund's adjuvant. Two monoclonal antibodies (MAbs) against AVM, named 2F2 and 2H10, were prepared by lymphocyte hybridoma technique. Ascitic fluid titers of the MAbs 2F2 and 2H10 were, respectively, 1:6400 and 1:25,600, and their subtypes were all IgMkappa. In competitive indirect ELISA (Ci-ELISA), 50% inhibiting concentration (IC(50)) of the MAb 2H10 for avermectin was 101 ng/mL. In specific assay, the MAb 2H10 could not react with ivermectin, doramectin, erythromycin, and albomycin. These data demonstrated that the MAb 2H10 will have a potential use for developing diagnostic reagents of avermectin residues.

Resistência anti-helmíntica de nematóides gastrintestinais em ovinos, Mato Grosso do Sul / Anthelmintic resistance of gastrointestinal nematodes in sheep, Mato Grosso do Sul, Brazil

Entre os métodos de controle da verminose gastrintestinal em ovinos, a utilização de produtos químicos é o mais empregado. Porém, o uso indiscriminado e continuado desses produtos tem selecionado populações de helmintos resistentes aos anti-helmínticos, fenômeno relatado no mundo todo. Este trabalho teve como objetivo identificar as espécies de parasitos gastrintestinais e diagnosticar a situação da resistência anti-helmíntica em ovinos no Estado de Mato Grosso do Sul. Foram realizados testes de redução na contagem de ovos por grama de fezes (OPG) em rebanhos de dezesseis propriedades rurais; as sete formulações utilizadas continham as seguintes bases farmacológicas: Albendazol, Ivermectina, Levamisole, Triclorfon, Moxidectina, Closantel e uma contendo as três primeiras associadas. As espécies identificadas nas necropsias, em ovinos adultos, foram: Haemonchus contortus, Trichostrongylus colubriformis, Cooperia curticei, C. punctata, C. pectinata e Oesophagostomum columbianum; em ordem de prevalência. As formulações contendo Albendazol e Ivermectina não apresentaram eficácia na redução de OPG nos rebanhos testados, com médias de redução de 0,7 e -19,6 por cento, respectivamente. Closantel apresentou eficácia média de 6,7 por cento; Levamisole, Moxidectina e Triclorfon de 28,7, 26,8 e 65 por cento, respectivamente; a associação das três bases (Albendazol, Ivermectina e Levamisole), uma média de eficácia de 55,8 por cento. As percentagens médias de larvas infectantes recuperadas nas coproculturas, tanto no pré como no pós-tratamento, foram semelhantes; indicando que a resistência às bases testadas está presente em todas as espécies citadas, em maior ou menor intensidade. Os dois gêneros predominantemente resistentes são Haemonchus sp., com 86,9 por cento; seguido por Trichostrongylus sp., com média de 47,5 por cento; Strongyloides sp. 33,6 por cento; Oesophagostomum, sp. 21,4 por cento e Cooperia sp. 19,7 por cento.

Among the methods of control of gastrointestinal worms in sheep, the use of chemicals is the most common. However, the continued, and indiscriminate, use of these products has selected populations of resistant helminths to anthelmintics, a phenomenon reported in the whole world. This study aimed to identify the species of gastrointestinal parasites and diagnose the status of anthelmintic resistance in sheep in the State of Mato Grosso do Sul Brazil. Feacal egg count reduction tests (FECRT) were performed in flocks of sixteen farms, and the seven formulations used contained the following pharmacological bases: Albendazole, Ivermectin, Levamizol, Trichlorfon, Moxidectin, Closantel and one containing the first three in association. The species identified at necropsy, in adult sheep, were: Haemonchus contortus, Trichostrongylus colubriformis, Cooperia curticei, C. punctata, C. pectinata and Oesophagostomum columbianum, in order of prevalence. The formulations containing Albendazole and Ivermectin did not show efficacy in reducing the EPG in the flocks tested, with average reductions of 0.7 and -19.6 percent, respectively. Closantel presented an average efficacy of 6.7 percent; Levamisolee, Moxidectin and Trichlorfon, 28.7, 26.8 and 65 percent respectively, the combination of three bases (Albendazole, Ivermectin and Levamizol), an average efficacy of 55.8 percent. The average percentages of infective larvae recovered in the faecal cultures, pre and post treatment were similar, indicating that resistance to the bases tested is present in all species cited, to a greater or lesser degree. The two genera predominantly resistant are Haemonchus sp., with 86.9 percent, followed by Trichostrongylus sp., with an average of 47.5 percent, Strongyloides sp. 33.6 percent, Oesophagostomum sp. 21.4 percent and Cooperia sp. 19.7 percent.

Detection of unwanted residues of ivermectin in bovine milk by dissociation-enhanced lanthanide fluoroimmunoassay.

Avermectins are frequently used to control parasitic infestations in many animal species. Previous studies have shown the long-term persistence of unwanted residues of these drugs in animal tissues and fluids. An immunoassay screening test for the detection and quantification of ivermectin residues in bovine milk has been developed. After an extensive extraction procedure, milk samples were applied to a competitive dissociation-enhanced lanthanide fluoroimmunoassay using a monoclonal antibody against an ivermectin-transferrin conjugate. The monoclonal antibody, raised in Balb C mice, showed cross-reactivity with eprinomectin (92%), abamectin (82%) and doramectin (16%). The limit of detection of the assay (mean + 3 SD), calculated from the analysis of 17 known negative samples, was calculated as 4.6 ng/mL. Intra- and inter-assay RSDs were determined as 11.6% and 15.8%, respectively, using a negative bovine milk sample fortified with 25 ng/mL ivermectin. Six Friesian milking cows were treated with ivermectin, three with a pour-on formulation of the drug and three with an injectable solution at the manufacturer's recommended dose rate. An initial mean peak in ivermectin residue concentration was detected at day 4 (mean level = 47.5 ng/mL) and day 5 post-treatment (mean level = 26.4 ng/mL) with the injectable form and pour-on treatment, respectively. A second peak in residue concentration was observed using the DELFIA procedure 28 days post-treatment in both treatment groups (23.1 ng/mL injectable and 51.9 ng/mL pour-on). These second peaks were not confirmed by HPLC and must at this time be considered to be false-positive results. By day 35 after treatment the mean ivermectin residue concentration of both groups fell below the limit of detection of the assay.