Nippostrongylus Brasiliensis Research Articles

Bcl11b is essential for group 2 innate lymphoid cell development.

Group 2 innate lymphoid cells (ILC2s) are often found associated with mucosal surfaces where they contribute to protective immunity, inappropriate allergic responses, and tissue repair. Although we know they develop from a common lymphoid progenitor in the bone marrow (BM), the specific lineage path and transcriptional regulators that are involved are only starting to emerge. After ILC2 gene expression analysis we investigated the role of Bcl11b, a factor previously linked to T cell commitment, in ILC2 development. Using combined Bcl11b-tom and Id2-gfp reporter mice, we show that Bcl11b is expressed in ILC2 precursors in the BM and maintained in mature ILC2s. In vivo deletion of Bcl11b, by conditional tamoxifen-induced depletion or by Bcl11b(-/-) fetal liver chimera reconstitution, demonstrates that ILC2s are wholly dependent on Bcl11b for their development. Notably, in the absence of Bcl11b there is a concomitant expansion of the RORγt(+) ILC3 population, suggesting that Bcl11b may negatively regulate this lineage. Using Nippostrongylus brasiliensis infection, we reveal that the absence of Bcl11b leads to impaired worm expulsion, caused by a deficit in ILC2s, whereas Citrobacter rodentium infection is cleared efficiently. These data clearly establish Bcl11b as a new factor in the differentiation of ILC2s.

B lymphocytes limit the severity of emphysema caused by N. brasiliensis infection in mice (INC4P.332)

Abstract The intestinal nematode parasite, Nippostrongylus brasiliensis (Nb), transiently resides in the lung causing lung damage, resulting in emphysema. However, the mechanisms contributing to this chronic lung pathology remain not well-defined. Here we show that emphysema develops as early as 7 days after Nb inoculation, as measured by alveolar mean linear chord length and is associated with increased neutrophil elastase (NE) and macrophage matrix metalloproteinase 12 (Mmp12) gene expression in the lung. Transfer of sorted Nb-primed neutrophils or macrophages to naïve recipients results in emphysema, indicating that either of these populations can trigger lung emphysema in naïve mice. Parasite infection also results in more severe emphysema in B cell deficient Jh-/- mice compared to wild-type mice or FcRγ-/-mice and is associated with higher numbers of neutrophils and macrophages, as well as increased expression of NE and Mmp12 in the lung. Transfer of B lymphocytes from wild-type mice to the Jh-/- mice can restore control of emphysema. These data suggest that Nb-primed neutrophils and macrophages contribute to lung emphysema. Furthermore, parasite-induced B cells exert regulatory effects that can markedly reduce the severity of emphysema.

The human protein resistin drives detrimental inflammatory monocyte responses in helminth infection (MPF7P.710)

Abstract Resistin-like molecules (RELM) belong to a family of secreted proteins that are expressed in multiple helminth infections with important effects on the host immune response. However the importance of human RELM proteins in helminth infections is less well understood. To investigate this, we utilized transgenic mice that expressed the human resistin gene (Tg+). Following infection with Nippostrongylus brasiliensis, a hookworm that colonizes the lung and intestine, Tg+ mice exhibited significant lung inflammation, characterized by increased inflammatory monocytes and elevated parasite burdens compared to control Tg- mice. Genome-wide transcriptional profiling of the infected lung tissue from Tg+ and Tg- mice revealed that genes associated with cytokine and TLR signaling were significantly elevated in Tg+ mice. To delineate the downstream cellular mediators of resistin, we performed a resistin binding and chemotaxis assay and identified monocytes as the main cell-types that were responsive to resistin. Moreover, monocytes sorted from the infected lung tissue of Tg+ mice expressed significantly higher TNFα compared to Tg- mice. In human studies, increased serum resistin was associated with higher helminth burdens and was positively correlated with inflammatory cytokines. Together, these studies identify a detrimental role for human resistin in instigating a non-protective inflammatory response that may be mediated by monocytes.

Utilizing CX3CR1GFP/PGRPdsRed reporter mice to monitor myeloid and granulocyte responses during helminth infection (MPF6P.652)

Abstract CX3CR1GFP/PGRPdsRed reporter mice have previously been used to monitor trafficking of monocytes and neutrophils, respectively. With this new tool, we examined myeloid cell and neutrophil behavior during murine infection with the helminth, Nippostrongylus brasiliensis (Nb). Nb acutely infects the lungs leading to significant infiltration of PGRPdsRed neutrophils and CX3CR1GFP monocytes compared to naïve mice. Using ex vivo time-lapse confocal microscopy, we discovered that Nb infection increased chemotaxis of CX3CR1GFP monocytes and PGRPdsRed neutrophils. Because CX3CR1GFP expression is a loss of function knock-in mutation, we tested the function of CX3CR1 in the immune response to Nb. After inoculation with infective larvae, CX3CR1GFP mice were less susceptible to infection compared to wild-type mice and had lower worm counts and parasite eggs in the feces. Additionally, ATP cell viability assay revealed that worms recovered from reporter mice were less viable than worms isolated from wild-type mice. Taken together, CX3CR1GFP/PGRPdsRed mice make it possible to monitor myeloid cell and neutrophil behavior, and reveal a previously unrecognized role for CX3CR1 in impairing Nb expulsion.

Macrophages are critical to the maintenance of IL-13-dependent lung inflammation and fibrosis.

The roles of macrophages in type 2-driven inflammation and fibrosis remain unclear. Here, using CD11b-Diphtheria Toxin Receptor (DTR) transgenic mice and three models of IL-13-dependent inflammation, fibrosis, and immunity, we show that CD11b+ F4/80+ Ly6C+ macrophages are required for the maintenance of type-2 immunity within affected tissues but not secondary lymphoid organs. Direct depletion of macrophages during the maintenance or resolution phases of secondary S. mansoni egg-induced granuloma formation caused a profound decrease in inflammation, fibrosis, and type-2 gene expression. Additional studies with CD11c-DTR and CD11b/CD11c-DTR double transgenic mice suggested that macrophages but not dendritic cells were critical. Mechanistically, macrophage depletion impaired effector CD4+ Th2 cell homing and activation within the inflamed lung. Depletion of CD11b+ F4/80+ Ly6C+ macrophages similarly reduced house dust mite-induced allergic lung inflammation and suppressed IL-13-dependent immunity to the nematode parasite Nippostrongylus brasiliensis. Consequently, therapeutic strategies targeting macrophages offer a novel approach to ameliorate established type-2 inflammatory diseases.

ILC2s and T cells cooperate to ensure maintenance of M2 macrophages for lung immunity against hookworms.

Defining the immune mechanisms underlying protective immunity to helminth infection remains an important challenge. Here we report that lung CD4(+) T cells and Group 2 innate lymphoid cells (ILC2s) work in concert to block Nippostrongylus brasiliensis (Nb) development in the parenchyma within 48 h in mice. Immune-damaged larvae have a striking morphological defect that is dependent on the expansion of IL-13-producing ILC2 and CD4(+) T cells, and the activation of M2 macrophages. This T-cell requirement can be bypassed by administration of IL-2 or IL-33, resulting in expansion of IL-13-producing ILC2s and larval killing. Depletion of ILC2s inhibits larval killing in IL-2-treated mice. Our results broaden understanding of ILC2's role in immunity to helminths by demonstrating that they not only act as alarmin sensors, but can also be sustained by CD4(+) T cells, ensuring both the prompt activation and the maintenance of IL-13-dependent M2 macrophage immunity in the lung.

A Survey of Zoonotic Pathogens Carried by Non-Indigenous Rodents at the Interface of the Wet Tropics of North Queensland, Australia

In 1964, Brucella was isolated from rodents trapped in Wooroonooran National Park (WNP), in Northern Queensland, Australia. Genotyping of bacterial isolates in 2008 determined that they were a novel Brucella species. This study attempted to reisolate this species of Brucella from rodents living in the boundary area adjacent to WNP and to establish which endo- and ecto-parasites and bacterial agents were being carried by non-indigenous rodents at this interface. Seventy non-indigenous rodents were trapped [Mus musculus (52), Rattus rattus (17) and Rattus norvegicus (1)], euthanized and sampled on four properties adjacent to the WNP in July 2012. Organ pools were screened by culture for Salmonella, Leptospira and Brucella species, real-time PCR for Coxiella burnetii and conventional PCR for Leptospira. Collected ecto- and endo-parasites were identified using morphological criteria. The percentage of rodents carrying pathogens were Leptospira (40%), Salmonella choleraesuis ssp. arizonae (14.29%), ectoparasites (21.42%) and endoparasites (87%). Brucella and C.burnetii were not identified, and it was concluded that their prevalences were below 12%. Two rodent-specific helminthic species, namely Syphacia obvelata (2.86%) and Nippostrongylus brasiliensis (85.71%), were identified. The most prevalent ectoparasites belonged to Laelaps spp. (41.17%) followed by Polyplax spp. (23.53%), Hoplopleura spp. (17.65%), Ixodes holocyclus (17.64%) and Stephanocircus harrisoni (5.88%), respectively. These ectoparasites, except S.harrisoni, are known to transmit zoonotic pathogens such as Rickettsia spp. from rat to rat and could be transmitted to humans by other arthropods that bite humans. The high prevalence of pathogenic Leptospira species is of significant public health concern. This is the first known study of zoonotic agents carried by non-indigenous rodents living in the Australian wet-tropical forest interface.

Development of novel valerolactam-benzimidazole hybrids anthelmintic derivatives: Diffusion and biotransformation studies in helminth parasites

In the search for new anthelmintics able to overcome the resistance problem against all available drugs in livestock, the synthesis of novel valerolactam-benzimidazole hybrid compounds was reported. This allowed us to obtain these in vitro and in vivo bioactive compounds using Nippostrongylus brasiliensis rat model by integrating physiology-based assays and ex vivo diffusion studies. In order to further study those novel hybrid molecules, Haemonchus contortus (a sheep gastrointestinal nematode of interest) and Mesocestoides vogae tetrathyridia (a useful system to study the efficacy of anthelmintic drugs against cestoda) were used as parasite models to compare the ex vivo patterns of diffusion and biotransformation of benzimidazoles and their valerolactam-benzimidazole hybrid derivatives. On average, a nine-fold higher intraparasitic concentration of compounds was found in M. vogae compared with H.contortus, with similarities regarding the order of entry of compounds, highlighting febendazole (FEB) and its hybrid compound 10, while valerolactam compound 2 practically did not penetrate the parasites. Interestingly, sulphoxidation drug metabolism was observed and measured, revealing percentages of oxidation of 8.2% and 14.5% for albendazole (ABZ) and febendazole respectively in M. vogae, while this effect was more relevant in H. contortus parasite. More importantly, significant differences were observed between anthelmintic-susceptible adult parasites (Hc S) and those from sheep farms (Hc U). In fact, the percentages of oxidation of FEB and the hybrid compound 8 were higher in Hc U (25.5%, 54.1%, respectively) than in Hc S (8.8%, 38.2%). Interestingly, sulphoxidation of hybrid compound 10 was neither observed in M. vogae nor in H. contortus parasites, suggesting that increased drug metabolism (oxidation reactions) could not be used by these parasites as a defense mechanism against this novel drug.

Induction of Sda-sialomucin and sulfated H-sulfomucin in mouse small intestinal mucosa by infection with parasitic helminth

Mucin is a major component of mucus on gastrointestinal mucosa. Mucin alteration in the host is considered to be the principal event for expulsion of intestinal helminths. However, it is unclear what mucin alterations are induced by various helminth infections. In this study, the alterations of mouse small intestinal mucin after infection with two nematodes, Nippostrongylus brasiliensis and Heligmosomoides polygyrus, which parasitize the jejunal epithelium, and a cestode, Vampirolepis nana, which parasitizes the ileal epithelium, were examined biochemically and histologically using two anti-mucin monoclonal antibodies (mAbs), HCM31 and PGM34, which recognize Sda antigen, NeuAcα2–3(GalNAcβ1–4)Galβ1-4GlcNAcβ-, and sulphated H type 2 antigen, Fucα1-2Galβ1-4GlcNAc(6SO3H)β-, respectively. The goblet cell mucins that reacted with HCM31 increased conspicuously on the jejunal mucosa concurrently with expulsion of N. brasiliensis. Increased levels of HCM31-reactive mucins were observed in the jejunal mucosa after H. polygyrus infection, despite the ongoing parasitism. Goblet cell mucins that reacted with PGM34 increased on the ileal mucosa during V. nana parasitism. Small intestinal goblet cells reacting with the two mAbs were not observed in non-infected mice, although sialomucins and sulfomucins were abundantly present. Additionally, the number of ileal goblet cells that reacted with the two mAbs was increased at the time of expulsion of heterophyid trematode. These results indicate that the type of specific acidic mucins expressed after infection varies among species of intestinal helminth, and, furthermore, that the relationship with worm expulsion is also different.

Impairment of host resistance to helminthes with age in murine small intestine.

Age-associated alterations of Th2 immune responses against nematode parasites are largely unknown. We investigated primary and memory responses against two types of gastrointestinal nematode parasites, Heligmosomoides polygyrus (Hp) and Nippostrongylus brasiliensis (Nb), in aged mice. The small intestinal gene expression of Th2 cytokines was almost unchanged after primary (Nb and Hp) and secondary infection (Hp) in aged mice in contrast to strongly increased small intestinal gene expression of Th2 cytokines in young (3-month-old) mice. Mucus production decreased (Nb), and worm expulsion was impaired (Nb and Hp) compared with the young mice. Immunofluorescent staining revealed that after Hp infection, the number of alternatively activated macrophages, which are induced by Th2 cytokines, was lower in the aged mice. On the other hand, the number of CD4(+) T cells recruited to the worm cysts was normal compared with the young mice. These results suggest that migration of CD4(+) T cells to the host-parasite interface is not affected by ageing. Alterations in Th2 immune responses in aged mice might be due to inappropriate or insufficient activation of CD4(+) T cells in the submucosa.

Intestinal nematodes from small mammals captured near the demilitarized zone, Gyeonggi province, Republic of Korea.

A total of 1,708 small mammals (1,617 rodents and 91 soricomorphs), including Apodemus agrarius (n = 1,400), Microtus fortis (167), Crocidura lasiura (91), Mus musculus (32), Myodes (= Eothenomys) regulus (9), Micromys minutus (6), and Tscherskia (= Cricetulus) triton (3), were live-trapped at US/Republic of Korea (ROK) military training sites near the demilitarized zone (DMZ) of Paju, Pocheon, and Yeoncheon, Gyeonggi Province from December 2004 to December 2009. Small mammals were examined for their intestinal nematodes by necropsy. A total of 1,617 rodents (100%) and 91 (100%) soricomorphs were infected with at least 1 nematode species, including Nippostrongylus brasiliensis, Heligmosomoides polygyrus, Syphacia obvelata, Heterakis spumosa, Protospirura muris, Capillaria spp., Trichuris muris, Rictularia affinis, and an unidentified species. N. brasiliensis was the most common species infecting small mammals (1,060; 62.1%) followed by H. polygyrus (617; 36.1%), S. obvelata (370; 21.7%), H. spumosa (314; 18.4%), P. muris (123; 7.2%), and Capillaria spp. (59; 3.5%). Low infection rates (0.1-0.8%) were observed for T. muris, R. affinis, and an unidentified species. The number of recovered worms was highest for N. brasiliensis (21,623 worms; mean 20.4 worms/infected specimen) followed by S. obvelata (9,235; 25.0 worms), H. polygyrus (4,122; 6.7 worms), and H. spumosa (1,160; 3.7 worms). A. agrarius demonstrated the highest prevalence for N. brasiliensis (70.9%), followed by M. minutus (50.0%), T. triton (33.3%), M. fortis (28.1%), M. musculus (15.6%), C. lasiura (13.2%), and M. regulus (0%). This is the first report of nematode infections in small mammals captured near the DMZ in ROK.

The M3 muscarinic receptor is required for optimal adaptive immunity to helminth and bacterial infection.

Innate immunity is regulated by cholinergic signalling through nicotinic acetylcholine receptors. We show here that signalling through the M3 muscarinic acetylcholine receptor (M3R) plays an important role in adaptive immunity to both Nippostrongylus brasiliensis and Salmonella enterica serovar Typhimurium, as M3R-/- mice were impaired in their ability to resolve infection with either pathogen. CD4 T cell activation and cytokine production were reduced in M3R-/- mice. Immunity to secondary infection with N. brasiliensis was severely impaired, with reduced cytokine responses in M3R-/- mice accompanied by lower numbers of mucus-producing goblet cells and alternatively activated macrophages in the lungs. Ex vivo lymphocyte stimulation of cells from intact BALB/c mice infected with N. brasiliensis and S. typhimurium with muscarinic agonists resulted in enhanced production of IL-13 and IFN-γ respectively, which was blocked by an M3R-selective antagonist. Our data therefore indicate that cholinergic signalling via the M3R is essential for optimal Th1 and Th2 adaptive immunity to infection.

Macrophage-derived human resistin is induced in multiple helminth infections and promotes inflammatory monocytes and increased parasite burden.

Parasitic helminth infections can be associated with lifelong morbidity such as immune-mediated organ failure. A better understanding of the host immune response to helminths could provide new avenues to promote parasite clearance and/or alleviate infection-associated morbidity. Murine resistin-like molecules (RELM) exhibit pleiotropic functions following helminth infection including modulating the host immune response; however, the relevance of human RELM proteins in helminth infection is unknown. To examine the function of human resistin (hResistin), we utilized transgenic mice expressing the human resistin gene (hRetnTg+). Following infection with the helminth Nippostrongylus brasiliensis (Nb), hResistin expression was significantly upregulated in infected tissue. Compared to control hRetnTg− mice, hRetnTg+ mice suffered from exacerbated Nb-induced inflammation characterized by weight loss and increased infiltration of inflammatory monocytes in the lung, along with elevated Nb egg burdens and delayed parasite expulsion. Genome-wide transcriptional profiling of the infected tissue revealed that hResistin promoted expression of proinflammatory cytokines and genes downstream of toll-like receptor signaling. Moreover, hResistin preferentially bound lung monocytes, and exogenous treatment of mice with recombinant hResistin promoted monocyte recruitment and proinflammatory cytokine expression. In human studies, increased serum resistin was associated with higher parasite load in individuals infected with soil-transmitted helminths or filarial nematode Wuchereria bancrofti, and was positively correlated with proinflammatory cytokines. Together, these studies identify human resistin as a detrimental factor induced by multiple helminth infections, where it promotes proinflammatory cytokines and impedes parasite clearance. Targeting the resistin/proinflammatory cytokine immune axis may provide new diagnostic or treatment strategies for helminth infection and associated immune-mediated pathology.

Identification and target of Th9 cell molecular signature

Event Abstract Back to Event Identification and target of Th9 cell molecular signature Paula Licona-Limón1, 2*, Jorge Henao-Mejía2, 3 and Richard A. Flavell2, 4 1 UNAM, Biología Celular y del Desarrollo, Mexico 2 YALE UNIVERSITY, Immunobiology, United States 3 University of Pennsylvania, Pathology and Laboratory Medicine, United States 4 Howard Hughes Medical institute, United States Helminth infections and allergies are controlled by the prototypical cytokines IL-4, IL-5, IL-9 and IL-13, however the individual role of this cytokines as well as the cellular sources and the molecular mechanism controlling its expression in vivo are not completely understood. Among these cytokines, IL-9 has gain a lot of attention based on recent in vitro studies suggesting the existence of a T cell subpopulation expressing IL-9 named Th9. Our initial studies focused on determining the cellular sources of IL-9 and its targets in vivo by generating an IL-9 reporter (Interleukin Nine Fluorescent Reporter:INFER) as well as an IL-9 deficient mice. Using a hookworm infection model, we found that IL-9 is a central regulator of type 2 immunity in vivo by promoting IL-5 and IL-13 expression as well as basophilia and eosinophilia in mice infected with Nippostrongylus brasiliensis. We also demonstrated that IL-9 expression is induced in T cells and innate lymphoid cells (ILC2) early upon infection and that T cell derived IL-9 was sufficient to rescue the phenotype observed in IL-9 deficient mice. Furthermore our data also identify for the first time, functional differences between Th9 cells expressing IL-9 and bona fide classical Th2 cells (expressing IL-4). Based on our previous work, we are currently interested in defining the molecular signature of Th9 cells vs Th2 cells. We isolated effector Th2 and Th9 cells generated in vitro with naïve cells from the different reporter mice (INFER and 4get respectively) and compare the expression profile between them by RNA-seq. We identify two candidate molecules highly expressed in Th9 cells and target them for deletion with the CRISPR-Cas9 technology. We are currently analyzing the role of such molecules in Th9 differentiation and function both in vitro and in vivo. Our results will identify the molecular signals controlling Th9 biology and will certainly provide tools to control this important subpopulation in vivo. In the future we are also interested in defining the role of IL-9 in other pathologies such as autoimmune disease and cancer as well as the contribution and regulation of ILC2-derived IL-9 in vivo. Acknowledgements PEW Foundation References Licona-Limón P, Henao-Mejía J, Temann AU, Gagliani N, Licona-Limón I, Ishigame H, Hao L, De Broski H, Flavell RA. Th9 cells drive host immunity against gastrointestinal nematode infection. Immunity. 2013, Oct 17; 39(4):744-757. Keywords: IL-9, Th9 cell, Helminths, RNA sequencing, CRISPR/Cas9 Conference: IMMUNOCOLOMBIA2015 - 11th Congress of the Latin American Association of Immunology - 10o. Congreso de la Asociación Colombiana de Alergia, Asma e Inmunología, Medellin, Colombia, 13 Oct - 16 Oct, 2015. Presentation Type: Oral Presentation Topic: Infectious and parasitic diseases Citation: Licona-Limón P, Henao-Mejía J and Flavell RA (2015). Identification and target of Th9 cell molecular signature. Front. Immunol. Conference Abstract: IMMUNOCOLOMBIA2015 - 11th Congress of the Latin American Association of Immunology - 10o. Congreso de la Asociación Colombiana de Alergia, Asma e Inmunología. doi: 10.3389/conf.fimmu.2015.05.00333 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 09 May 2015; Published Online: 15 Sep 2015. * Correspondence: Dr. Paula Licona-Limón, UNAM, Biología Celular y del Desarrollo, Mexico, DF, 04510, Mexico, plicona@ifc.unam.mx Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Paula Licona-Limón Jorge Henao-Mejía Richard A Flavell Google Paula Licona-Limón Jorge Henao-Mejía Richard A Flavell Google Scholar Paula Licona-Limón Jorge Henao-Mejía Richard A Flavell PubMed Paula Licona-Limón Jorge Henao-Mejía Richard A Flavell Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

IL-25-responsive, lineage-negative KLRG1(hi) cells are multipotential 'inflammatory' type 2 innate lymphoid cells.

Innate lymphoid cells (ILCs) are lymphocyte-like cells lacking T or B cell receptors that mediate protective and repair functions through cytokine secretion. Among them, type 2 ILC (ILC2) cells are capable of producing type 2 cytokines. We report the existence of an inflammatory (i) ILC2 population responsive to IL-25 that complements IL-33-responsive natural (n) ILC2 cells. iILC2 cells developed into nILC2-like cells in vitro and in vivo, contributing to expulsion of Nippostrongylus brasiliensis. They also acquired IL-17-producing capacity, providing partial protection against Candida albicans. We propose that iILC2 cells are transient ILC progenitors mobilized by inflammation and infection that develop into nILC2-like cells or ILC3-like cells and contribute to immunity to both helminths and fungi.

Natural and vaccine-mediated immunity to Salmonella Typhimurium is impaired by the helminth Nippostrongylus brasiliensis.

BackgroundThe impact of exposure to multiple pathogens concurrently or consecutively on immune function is unclear. Here, immune responses induced by combinations of the bacterium Salmonella Typhimurium (STm) and the helminth Nippostrongylus brasiliensis (Nb), which causes a murine hookworm infection and an experimental porin protein vaccine against STm, were examined.Methodology/Principal FindingsMice infected with both STm and Nb induced similar numbers of Th1 and Th2 lymphocytes compared with singly infected mice, as determined by flow cytometry, although lower levels of secreted Th2, but not Th1 cytokines were detected by ELISA after re-stimulation of splenocytes. Furthermore, the density of FoxP3+ T cells in the T zone of co-infected mice was lower compared to mice that only received Nb, but was greater than those that received STm. This reflected the intermediate levels of IL-10 detected from splenocytes. Co-infection compromised clearance of both pathogens, with worms still detectable in mice weeks after they were cleared in the control group. Despite altered control of bacterial and helminth colonization in co-infected mice, robust extrafollicular Th1 and Th2-reflecting immunoglobulin-switching profiles were detected, with IgG2a, IgG1 and IgE plasma cells all detected in parallel. Whilst extrafollicular antibody responses were maintained in the first weeks after co-infection, the GC response was less than that in mice infected with Nb only. Nb infection resulted in some abrogation of the longer-term development of anti-STm IgG responses. This suggested that prior Nb infection may modulate the induction of protective antibody responses to vaccination. To assess this we immunized mice with porins, which confer protection in an antibody-dependent manner, before challenging with STm. Mice that had resolved a Nb infection prior to immunization induced less anti-porin IgG and had compromised protection against infection.ConclusionThese findings demonstrate that co-infection can radically alter the development of protective immunity during natural infection and in response to immunization.

Perinatal exposure to a low dose of bisphenol A impaired systemic cellular immune response and predisposes young rats to intestinal parasitic infection.

Perinatal exposure to the food contaminant bisphenol A (BPA) in rats induces long lasting adverse effects on intestinal immune homeostasis. This study was aimed at examining the immune response to dietary antigens and the clearance of parasites in young rats at the end of perinatal exposure to a low dose of BPA. Female rats were fed with BPA [5 µg/kg of body weight/day] or vehicle from gestational day 15 to pup weaning. Juvenile female offspring (day (D)25) were used to analyze immune cell populations, humoral and cellular responses after oral tolerance or immunization protocol to ovalbumin (OVA), and susceptibility to infection by the intestinal nematode Nippostrongylus brasiliensis (N. brasiliensis). Anti-OVA IgG titers following either oral tolerance or immunization were not affected after BPA perinatal exposure, while a sharp decrease in OVA-induced IFNγ secretion occurred in spleen and mesenteric lymph nodes (MLN) of OVA-immunized rats. These results are consistent with a decreased number of helper T cells, regulatory T cells and dendritic cells in spleen and MLN of BPA-exposed rats. The lack of cellular response to antigens questioned the ability of BPA-exposed rats to clear intestinal infections. A 1.5-fold increase in N. brasiliensis living larvae was observed in the intestine of BPA-exposed rats compared to controls due to an inappropriate Th1/Th2 cytokine production in infected jejunal tissues. These results show that perinatal BPA exposure impairs cellular response to food antigens, and increases susceptibility to intestinal parasitic infection in the juveniles. This emphasized the maturing immune system during perinatal period highly sensitive to low dose exposure to BPA, altering innate and adaptative immune response capacities in early life.

Dusp5 negatively regulates IL-33-mediated eosinophil survival and function.

Mitogen-activated protein kinase (MAPK) activation controls diverse cellular functions including cellular survival, proliferation, and apoptosis. Tuning of MAPK activation is counter-regulated by a family of dual-specificity phosphatases (DUSPs). IL-33 is a recently described cytokine that initiates Th2 immune responses through binding to a heterodimeric IL-33Rα (ST2L)/IL-1α accessory protein (IL-1RAcP) receptor that coordinates activation of ERK and NF-κB pathways. We demonstrate here that DUSP5 is expressed in eosinophils, is upregulated following IL-33 stimulation and regulates IL-33 signaling. Dusp5(-/-) mice have prolonged eosinophil survival and enhanced eosinophil effector functions following infection with the helminth Nippostrongylus brasiliensis. IL-33-activated Dusp5(-/-) eosinophils exhibit increased cellular ERK1/2 activation and BCL-XL expression that results in enhanced eosinophil survival. In addition, Dusp5(-/-) eosinophils demonstrate enhanced IL-33-mediated activation and effector functions. Together, these data support a role for DUSP5 as a novel negative regulator of IL-33-dependent eosinophil function and survival.

Conditional IL-4/IL-13-deficient mice reveal a critical role of innate immune cells for protective immunity against gastrointestinal helminths.

Approximately one-third of the world population is infected with gastrointestinal helminths. Studies in mouse models have demonstrated that the cytokines interleukin (IL)-4 and IL-13 are essential for worm expulsion, but the critical cellular source of these cytokines is poorly defined. Here, we compared the immune response to Nippostrongylus brasiliensis in wild-type, T cell-specific IL-4/IL-13-deficient and general IL-4/IL-13-deficient mice. We show that T cell-derived IL-4/IL-13 promoted T helper 2 (Th2) polarization in a paracrine manner, differentiation of alternatively activated macrophages, and tissue recruitment of innate effector cells. However, innate IL-4/IL-13 played the critical role for induction of goblet cell hyperplasia and secretion of effector molecules like Mucin5ac and RELMβ in the small intestine. Surprisingly, T cell-specific IL-4/IL-13-deficient and wild-type mice cleared the parasite with comparable efficiency, whereas IL-4/IL-13-deficient mice showed impaired expulsion. These findings demonstrate that IL-4/IL-13 produced by cells of the innate immune system is required and sufficient to initiate effective type 2 immune responses resulting in protective immunity against N. brasiliensis.

Secreted Proteomes of Different Developmental Stages of the Gastrointestinal Nematode Nippostrongylus brasiliensis

Hookworms infect more than 700 million people worldwide and cause more morbidity than most other human parasitic infections. Nippostrongylus brasiliensis (the rat hookworm) has been used as an experimental model for human hookworm because of its similar life cycle and ease of maintenance in laboratory rodents. Adult N. brasiliensis, like the human hookworm, lives in the intestine of the host and releases excretory/secretory products (ESP), which represent the major host-parasite interface. We performed a comparative proteomic analysis of infective larval (L3) and adult worm stages of N. brasiliensis to gain insights into the molecular bases of host-parasite relationships and determine whether N. brasiliensis could indeed serve as an appropriate model for studying human hookworm infections. Proteomic data were matched to a transcriptomic database assembled from 245,874,892 Illumina reads from different developmental stages (eggs, L3, L4, and adult) of N. brasiliensis yielding∼18,426 unigenes with 39,063 possible isoform transcripts. From this analysis, 313 proteins were identified from ESPs by LC-MS/MS-52 in the L3 and 261 in the adult worm. Most of the proteins identified in the study were stage-specific (only 13 proteins were shared by both stages); in particular, two families of proteins-astacin metalloproteases and CAP-domain containing SCP/TAPS-were highly represented in both L3 and adult ESP. These protein families are present in most nematode groups, and where studied, appear to play roles in larval migration and evasion of the host's immune response. Phylogenetic analyses of defined protein families and global gene similarity analyses showed that N. brasiliensis has a greater degree of conservation with human hookworm than other model nematodes examined. These findings validate the use of N. brasiliensis as a suitable parasite for the study of human hookworm infections in a tractable animal model.