Helminths as governors of immune-mediated inflammation

Helminth-derived molecules improve 5-fluorouracil treatment on experimental colon tumorigenesis

Colorectal cancer (CRC) is one of the most prevalent fatal neoplasias worldwide. Despite efforts to improve the early diagnosis of CRC, the mortality rate of patients is still nearly 50%. The primary treatment strategy for CRC is surgery, which may be accompanied by chemotherapy and radiotherapy. The conventional and first-line chemotherapeutic agent utilized is 5-fluorouracil (5FU). However, it has low efficiency. Combination treatment with leucovorin and oxaliplatin or irinotecan improves the effectiveness of 5FU therapy. Unfortunately, most patients develop drug resistance, leading to disease progression. Here, we evaluated the effect of a potential alternative adjuvant treatment for 5FU, helminth-derived Taenia crassiceps (TcES) molecules, on treating advanced colitis-associated colon cancer. The use of TcES enhanced the effects of 5FU on established colonic tumors by downregulating the expression of the immunoregulatory cytokines, Il-10 and Tgf-β, and proinflammatory cytokines, Tnf-α and Il-17a, and reducing the levels of molecular markers associated with malignancy, cyclin D1, and Ki67, both involved in apoptosis inhibition and the signaling pathway of β-catenin. TcES+5FU therapy promoted NK cell recruitment and the release of Granzyme B1 at the tumor site, consequently inducing tumor cell death. Additionally, it restored P53 activity which relates to decreased Mdm2 expression. In vitro assays with human colon cancer cell lines showed that therapy with TcES+5FU significantly reduced cell proliferation and migration by modulating the P53 and P21 signaling pathways. Our findings demonstrate, for the first time in vivo, that helminth-derived excreted/secreted products may potentiate the effect of 5FU on established colon tumors.

Molecular regulation of NLRP3 inflammasome activation during parasitic infection

Parasitic diseases are a serious global health concern, causing many common and severe infections, including Chagas disease, leishmaniasis, and schistosomiasis. The NLRP3 inflammasome belongs to the NLR (nucleotide-binding domain leucine-rich-repeat-containing proteins) family, which are cytosolic proteins playing key roles in the detection of pathogens. NLRP3 inflammasomes are activated in immune responses to Plasmodium, Leishmania, Toxoplasma gondii, Entamoeba histolytica, Trypanosoma cruzi, and other parasites. The role of NLRP3 is not fully understood, but it is a crucial component of the innate immune response to parasitic infections and its functions as a sensor triggering the inflammatory response to the invasive parasites. However, while this response can limit the parasites' growth, it can also result in potentially catastrophic host pathology. This makes it essential to understand how NLRP3 interacts with parasites to initiate the inflammatory response. Plasmodium hemozoin, Leishmania glycoconjugate lipophosphoglycan (LPG) and E. histolytica Gal/GalNAc lectin can stimulate NLRP3 activation, while the dense granule protein 9 (GRA9) of T. gondii has been shown to suppress it. Several other parasitic products also have diverse effects on NLRP3 activation. Understanding the mechanism of NLRP3 interaction with these products will help to develop advanced therapeutic approaches to treat parasitic diseases. This review summarizes current knowledge of the NLRP3 inflammasome's action on the immune response to parasitic infections and aims to determine the mechanisms through which parasitic molecules either activate or inhibit its action.

Immunomodulatory proteins from hookworms reduce cardiac inflammation and modulate regulatory responses in a mouse model of chronic Trypanosoma cruzi infection

Introduction

Hookworms are parasitic helminths that secrete a variety of proteins that induce anti-inflammatory immune responses, stimulating increased CD4 + Foxp3+ regulatory T cells and IL-10 production. Hookworm-derived recombinant proteins AIP-1 and AIP-2 have been shown to reduce inflammation in mouse models of inflammatory bowel disease and inflammatory airway disease by inducing CD4+Foxp3+ cells and IL-10 production. In contrast, chronic infection with the protozoal parasite Trypanosoma cruzi, the causative agent of Chagas disease, leads to chronic inflammation in tissues. Persistence of the parasites in tissues drives chronic low-grade inflammation, with increased infiltration of inflammatory cells into the heart, accompanied by increased production of inflammatory cytokines. There are no current antiparasitic drugs that effectively reduce or prevent chronic myocarditis caused by the onset of Chagas disease, thus new therapies are urgently needed. Therefore, the impact of AIP-1 and AIP-2 on myocarditis was investigated in a mouse model of chronic T. cruzi infection.

Methods

Female BALB/c mice infected with bioluminescent T. cruzi H1 strain trypomastigotes for 70 days were treated once daily for 7 days with 1mg/kg AIP-1 or AIP-2 protein by intraperitoneal injection. Control mice were left untreated or treated once daily for 14 days with 25mg/kg aspirin in drinking water. At 84 days of infection, splenocytes, cardiac tissue and serum were collected for evaluation.

Results

Treatment with both AIP-1 and AIP-2 proteins significantly reduced cardiac cellular infiltration, and reduced cardiac levels of IFNγ, IL-6 and IL-2. AIP-2 treatment reduced cardiac expression of COX-2. Further, while incubation with AIP-1 and AIP-2 proteins did not induce a significant upregulation of an immunoregulatory phenotype in dendritic cells (DC), there was a modest upregulation of CD11c +CD11b+MHCII+SIRPα+ expression, suggesting a regulatory phenotype. Ex-vivo stimulation of splenocytes from the treatment groups with AIP-1 loaded DC induced reduced levels of cytotoxic and pro-inflammatory T cells, stimulation with AIP-2 loaded DC specifically induced enhanced levels of CD4+CD25+Foxp3+ regulatory T cells among treatment groups.

Discussion

All in vivo and in vitro results demonstrate that hookworm-derived AIP-1 and AIP-2 proteins reduce T. cruzi induced cardiac inflammation, possibly through multiple anti-inflammatory mechanisms.

Explanatory integration and integrated explanations in Darwinian medicine and evolutionary medicine

Recently, two research traditions that bring together evolutionary biology and medicine, that is to say, Darwinian medicine and evolutionary medicine, have been identified. In this paper, I analyse these two research traditions with respect to explanatory and interdisciplinary integration. My analysis shows that Darwinian medicine does not integrate medicine and evolutionary biology in any strong sense but does incorporate evolutionary concepts into medicine. I also show that backward-looking explanations in Darwinian medicine are not integrated proximate-and-ultimate explanations but functional explanations that include reference to evolutionary concepts. Nevertheless, explanations in Darwinian medicine have heuristic roles as they potentially contribute to conceptual change and tie pieces of knowledge from different fields of medical research together. I argue that Darwinian medicine is an "interfield" that fosters cross-disciplinary exchange between evolutionary biologists and medical researchers and practitioners based on division of labour and separation, rather than unity. Research in evolutionary medicine, on the other hand, happens at the intersection of evolutionary biology and medicine where the two disciplines are already integrated and is designed to produce entangled proximate-evolutionary explanations. My analysis thus adds another important aspect to the philosophical discussion on the distinction between Darwinian medicine and evolutionary medicine.

Nematode ascarosides attenuate mammalian type 2 inflammatory responses

Animal proof-of-concept studies have shown that roundworms have a protective effect against immune-dysregulated disorders, but it has been difficult to study in human trials without individual nematode-derived molecules to develop and test. We discovered that ascarosides, molecules that are secreted by diverse nematodes, suppress asthma in a rodent model via modulation of expression of Il33, a key epithelial cytokine for induction of type 2 immunity, in addition to decreasing memory-type pathogenic Th2 cells and ILC2s and increasing the Il10-expressing subpopulation of interstitial macrophages in the lung. Thus, ascarosides suppress type 2 immune response by affecting both innate and adaptive immunity and could define a potent class of small molecule drugs to treat allergic airway diseases.

Mounting evidence suggests that nematode infection can protect against disorders of immune dysregulation. Administration of live parasites or their excretory/secretory (ES) products has shown therapeutic effects across a wide range of animal models for immune disorders, including asthma. Human clinical trials of live parasite ingestion for the treatment of immune disorders have produced promising results, yet concerns persist regarding the ingestion of pathogenic organisms and the immunogenicity of protein components. Despite extensive efforts to define the active components of ES products, no small molecules with immune regulatory activity have been identified from nematodes. Here we show that an evolutionarily conserved family of nematode pheromones called ascarosides strongly modulates the pulmonary immune response and reduces asthma severity in mice. Screening the inhibitory effects of ascarosides produced by animal-parasitic nematodes on the development of asthma in an ovalbumin (OVA) murine model, we found that administration of nanogram quantities of ascr#7 prevented the development of lung eosinophilia, goblet cell metaplasia, and airway hyperreactivity. Ascr#7 suppressed the production of IL-33 from lung epithelial cells and reduced the number of memory-type pathogenic Th2 cells and ILC2s in the lung, both key drivers of the pathology of asthma. Our findings suggest that the mammalian immune system recognizes ascarosides as an evolutionarily conserved molecular signature of parasitic nematodes. The identification of a nematode-produced small molecule underlying the well-documented immunomodulatory effects of ES products may enable the development of treatment strategies for allergic diseases.

Recombinant Fasciola hepatica Fatty Acid Binding Protein as a Novel Anti-Inflammatory Biotherapeutic Drug in an Acute Gram-Negative Nonhuman Primate Sepsis Model

Due to their phylogenetic proximity to humans, nonhuman primates (NHPs) are considered an adequate choice for a basic and preclinical model of sepsis. Gram-negative bacteria are the primary causative of sepsis. During infection, bacteria continuously release the potent toxin lipopolysaccharide (LPS) into the bloodstream, which triggers an uncontrolled systemic inflammatory response leading to death. Our previous research has demonstrated in vitro and in vivo using a mouse model of septic shock that Fh15, a recombinant variant of the Fasciola hepatica fatty acid binding protein, acts as an antagonist of Toll-like receptor 4 (TLR4) suppressing the LPS-induced proinflammatory cytokine storm. The present communication is a proof-of concept study aimed to demonstrate that a low-dose of Fh15 suppresses the cytokine storm and other inflammatory markers during the early phase of sepsis induced in rhesus macaques by intravenous (i.v.) infusion with lethal doses of live Escherichia coli. Fh15 was administered as an isotonic infusion 30 min prior to the bacterial infusion. Among the novel findings reported in this communication, Fh15 (i) significantly prevented bacteremia, suppressed LPS levels in plasma, and the production of C-reactive protein and procalcitonin, which are key signatures of inflammation and bacterial infection, respectively; (ii) reduced the production of proinflammatory cytokines; and (iii) increased innate immune cell populations in blood, which suggests a role in promoting a prolonged steady state in rhesus macaques even in the presence of inflammatory stimuli. This report is the first to demonstrate that a F. hepatica-derived molecule possesses potential as an anti-inflammatory drug against sepsis in an NHP model.

IMPORTANCE Sepsis caused by Gram-negative bacteria affects 1.7 million adults annually in the United States and is one of the most important causes of death at intensive care units. Although the effective use of antibiotics has resulted in improved prognosis of sepsis, the pathological and deathly effects have been attributed to the persistent inflammatory cascade. There is a present need to develop anti-inflammatory agents that can suppress or neutralize the inflammatory responses and prevent the lethal consequences of sepsis. We demonstrated here that a small molecule of 14.5 kDa can suppress the bacteremia, endotoxemia, and many other inflammatory markers in an acute Gram-negative sepsis rhesus macaque model. These results reinforce the notion that Fh15 constitutes an excellent candidate for drug development against sepsis.

Intestinal polyparasitism and levels of mucosal anthelmintic SIgA in children from endemic areas in Northeastern Brazil

Interactions between parasites during co-infections are often complex and can impact immunization and treatment programmes, as well as disease outcomes and morbidity. However, little is known about these interactions and the mechanisms involved. In this study, a coproparasitological survey was carried out in school-age children living in endemic areas of parasitic infection in the state of Sergipe, Northeastern Brazil. Anti-helminth-specific and total secretory immunoglobulin-A (SIgA) levels were measured in stool and saliva samples and were compared in children presenting monoparasitism, polyparasitism (helminths and/or intestinal protozoa) and no infections. The survey showed that protozoa were more prevalent than helminths, and that there was a high frequency of polyparasitism in the studied population, mainly from combinations of protozoan species. Although less frequent, combinations between species of protozoa and helminths were also observed. The levels of salivary SIgA in these co-infected individuals were lower than the average observed in infections with helminths alone. Although the children participating in this survey were asymptomatic, and it was, therefore, not possible to evaluate the impact of salivary SIgA reduction on the diseases, and the study highlights the need for further investigations of co-infections by intestinal parasites and the effects on immune response induced by the interactions between different parasites.

Gastrointestinal Nematode-Derived Antigens Alter Colorectal Cancer Cell Proliferation and Migration through Regulation of Cell Cycle and Epithelial-Mesenchymal Transition Proteins

As the global incidences of colorectal cancer rises, there is a growing importance in understanding the interaction between external factors, such as common infections, on the initiation and progression of this disease. While certain helminth infections have been shown to alter the severity and risk of developing colitis-associated colorectal cancer, whether these parasites can directly affect colorectal cancer progression is unknown. Here, we made use of murine and human colorectal cancer cell lines to demonstrate that exposure to antigens derived from the gastrointestinal nematode Heligmosomoides polygyrus significantly reduced colorectal cancer cell proliferation in vitro. Using a range of approaches, we demonstrate that antigen-dependent reductions in cancer cell proliferation and viability are associated with increased expression of the critical cell cycle regulators p53 and p21. Interestingly, H. polygyrus-derived antigens significantly increased murine colorectal cancer cell migration, which was associated with an increased expression of the adherens junction protein β-catenin, whereas the opposite was true for human colorectal cancer cells. Together, these findings demonstrate that antigens derived from a gastrointestinal nematode can significantly alter colorectal cancer cell behavior. Further in-depth analysis may reveal novel candidates for targeting and treating late-stage cancer.

Regulation of immunity and allergy by helminth parasites

There is increasing interest in helminth parasite modulation of the immune system, both from the fundamental perspective of the "arms race" between host and parasite, and equally importantly, to understand if parasites offer new pathways to abate and control untoward immune responses in humans. This article reviews the epidemiological and experimental evidence for parasite down-regulation of host immunity and immunopathology, in allergy and other immune disorders, and recent progress towards defining the mechanisms and molecular mediators which parasites exploit in order to modulate their host. Among these are novel products that interfere with epithelial cell alarmins, dendritic cell activation, macrophage function and T-cell responsiveness through the promotion of an immunoregulatory environment. These modulatory effects assist parasites to establish and survive, while dampening immune reactivity to allergens, autoantigens and microbiome determinants.

Anthelmintic and antimicrobial activity of Indigofera oblongifolia leaf extracts

Due to the endless emergence of drug resistant pathogens, there is a constant need for new therapeutic agents for clinical use. The identification of active components in natural products and determining the efficacy of these active components has become the current focus of pharmacological research. The present study aimed to evaluate the anthelmintic and antimicrobial activities of Indigofera oblongifolia leaf extract (ILE) against the earthworm Allolobophora caliginosa, the gram-positive bacteria (Bacillus cereus, Streptococcus pneumoniae, and Staphylococcus aureus), the gram-negative bacteria (Klebsiella pneumoniae, Pseudomonas aeruginosa and Escherichia coli) and the yeast Candida albicans. Methanolic extract of I. oblongifolia leaf was obtained and the total phenolics and flavonoids in ILE were determined. The anthelmintic study was carried out to determine the time to paralysis and time to death of worms using three doses (100, 200, and 300 mg/mL) of ILE. Also, Kirby-Bauer disk diffusion susceptibility method was used to determine the antimicrobial activity of ILE. The results showed that ILE induces paralysis and death of A. caliginosa at all concentration tested faster than the reference drug, Albendazole. Additionally, ILE exhibited prominent antimicrobial activity against all gram-positive bacteria tested but almost no significant activity against the gram-negative bacteria, except K. pneumoniae. ILE showed close similarity to the spectrum of chloramphenicol and cefoxitin activities. Furthermore, C. albicans was highly susceptible to the leaf extracts. Our results showed that ILE is an effective anthelmintic and antimicrobial agent.

Seroprevalence of Antibodies to Toxocara Species in the United States and Associated Risk Factors, 2011-2014

Background

Toxocariasis results from infection with larval stages of a dog and cat intestinal nematode and causes human morbidity. The current United States estimate of Toxocara exposure is 13.9% (National Health and Nutrition Examination Survey [NHANES] III [1988-1994]).

Methods

We used a multiplex bead-based assay (Tc-CTL-1MBA) with purified Toxocara canis antigen to estimate Toxocara antibody seroprevalence in serum of 13 509 persons aged ≥6 years from NHANES 2011-2014 and identified seropositivity risk factors. We tested a subset of 500 samples with the T. canis enzyme immunoassay used in NHANES III to estimate prior seroprevalence had samples from NHANES III been tested by Tc-CTL-1MBA.

Results

The age-standardized estimate of Toxocara seroprevalence was 5.0% (95% confidence interval [CI], 4.2%-5.8%), lower than previously reported even after adjusting for increased Tc-CTL-1MBA specificity. Risk factors for seropositivity from multiple logistic regression were older age, non-Hispanic black/Hispanic origin, male sex, living below poverty level, households with ≥0.5 persons per room, less than college education, and birth outside of the United States.

Conclusions

Toxocara seroprevalence estimates in 2011-2014 were lower than in a study from NHANES III (1988-1994), but seropositivity risk factors remained the same and should continue to be the focus of prevention efforts.

Genetic Factors and the Intestinal Microbiome Guide Development of Microbe-Based Therapies for Inflammatory Bowel Diseases

The intestinal microbiota is a dynamic community of bacteria, fungi, and viruses that mediates mucosal homeostasis and physiology. Imbalances in the microbiome and aberrant immune responses to gut bacteria can disrupt homeostasis and are associated with inflammatory bowel diseases (IBDs) in humans and colitis in mice. We review genetic variants associated with IBD and their effects on the intestinal microbiome, the immune response, and disease pathogenesis. The intestinal microbiome, which includes microbial antigens, adjuvants, and metabolic products, affects the development and function of the intestinal mucosa, influencing inflammatory responses in the gut. Therefore, strategies to manipulate the microbiome might be used in treatment of IBD. We review microbe-based therapies for IBD and the potential to engineer patients' intestinal microbiota. We discuss how studies of patients with IBD and mouse models have advanced our understanding of the interactions between genetic factors and the gut microbiome, and challenges to the development of microbe-based therapies for IBD.

The therapeutic prospect of crosstalk between prokaryotic and eukaryotic organisms in the human gut

The peaceful phenomenon of the co-evolution between the prokaryotes (microbiota) and the eukaryotes (parasites including protozoa and helminths) in the animal gut has drawn the researchers' attention. Importantly, exploring the potential of helminths for therapeutic uses was one of the reasons behind understanding the physiological and immunological crosstalk existing between them. Here we discuss the interactive immunological associations of helminths and microbial responses individually and in combination with their hosts. Considering that there is probably crosstalk between eukaryotic organisms like helminths and protozoa with their host's gut microbiota, in this review we searched the literature identifying the privileged and favourable relationship generated between them in the host. Understanding the possibilities of the role of helminths along with gut microbiota as a black box would certainly help decode the therapeutic intrusion with helminths in experimental clinical trials, and a successful trial could be used to consider possible future and safe treatments for various immune-inflammatory diseases in humans.

Filarial extract of Litomosoides sigmodontis induces a type 2 immune response and attenuates plaque development in hyperlipidemic ApoE-knockout mice

A type 1 immune response is involved in atherosclerosis progression, whereas the role of a type 2 polarization, especially with regard to an enhanced T helper (T_h)2 cell differentiation, is still unclear. Helminths trigger type 2 immune responses, protecting the host from inflammatory disorders. We investigated whether an increased type 2 polarization by administration of Litomosoides sigmodontis adult worm extract (LsAg) affects atherosclerosis in apolipoprotein E-deficient (ApoE^-/-) mice. Injections of 50 µg LsAg, i.p. into ApoE^-/- mice induced a type 2 immune response shown by increased frequencies of peritoneal eosinophils and alternatively activated macrophages. To analyze the effect of LsAg on atherosclerosis initiation, ApoE^-/- mice received a high-fat diet for 12 wk and weekly injections of 50 µg LsAg from wk 5 to 12. Therapeutic effects on advanced atherosclerosis were analyzed in mice that were fed a high-fat diet for 12 wk followed by 12 wk of normal chow and weekly LsAg injections. Both preventive and therapeutic LsAg application significantly decreased plaque size. Therapeutic treatment even caused regression of plaque size and macrophage density in the aortic root and reduced T_h1-specific gene expression and intraplaque inflammation. In addition, plaque size after therapeutic treatment was inversely correlated with plaque-infiltrated alternatively activated macrophages. In vitro, LsAg treatment of HUVECs reduced intracellular levels of phosphorylated NF-κB-p65, IκB-α, and JNK1/2. In bifurcation flow-through slides, THP-1 cell adhesion to a HUVEC monolayer was decreased by LsAg in regions of nonuniform shear stress. Applying inhibitors of the respective kinases suggests JNK1/2 inhibition is involved in the suppressed cell adhesion. A switch to an enhanced type 2 immune response by LsAg exerts antiatherogenic effects on murine plaque development, indicating a protective role of a hampered type 1 polarization. In vitro, LsAg affects endothelial signaling pathways, among which JNK1/2 inhibition seems to be involved in the suppression of monocytic cell adhesion under proatherogenic shear stress.-Constanze, K., Tauchi, M., Furtmair, R., Urschel, K., Raaz-Schrauder, D., Neumann, A.-L., Frohberger, S. J., Hoerauf, A., Regus, S., Lang, W., Sagban, T. A., Stumpfe, F. M., Achenbach, S., Hübner, M. P., Dietel, B. Filarial extract of Litomosoides sigmodontis induces a type 2 immune response and attenuates plaque development in hyperlipidemic ApoE-knockout mice.

Genetic characterisation and phylogenetic status of whipworms (Trichuris spp.) from captive non-human primates in China, determined by nuclear and mitochondrial sequencing

Background

Whipworms (Nematoda: Trichuridae), among the most common soil-transmitted helminths (STHs), can cause the socioeconomically important disease trichuriasis in various mammalian hosts including humans and non-human primates. For many years, Trichuris from non-human primates has been assigned to the same species as the one infecting humans Trichuris trichiura. More recently, several molecular reports challenged this assumption following recognition of a Trichuris species complex observed in humans and non-human primates. A refined concept for species limits within Trichuris contributes to an understanding of diversity and the potential (zoonotic) transmission among humans and non-human primates. In this study, we expanded previous investigations by exploring the diversity of Trichuris among eight primates including three Asian autochthonous species (i.e. Rhinopithecus roxellana, Rhinopithecus bieti and Nomascus leucogenys). Species-level identification, whether novel or assignable to known lineages of Trichuris, was based on analyses of nuclear internal transcribed spacers (ITS) and mitochondrial cytochrome c oxidase subunit 1 (cox1) genes.

Results

In total, seven genetically distinct subgroups of whipworms were determined to be present among the primates sampled. Most Trichuris lineages, including Subgroups 1, 1’, 3, 5 and 6, showed a broad host range and were not restricted to particular primate species; in addition to T. trichiura, a complex of Trichuris species was shown infecting primates. Furthermore, it was assumed that Trichuris spp. from either N. leucogenys and P. hamadryas or R. roxellana and R. bieti, respectively, were conspecific. Each pair was indicated to be a discrete lineage of Trichuris, designated, respectively, as Subgroups 1 or 1’ and 2, based on integrated genetic and phylogenetic evidence.

Conclusion

These results emphasise that the taxonomy and genetic variations of Trichuris are more complicated than previously acknowledged. These cumulative molecular and phylogenetic data provide a better understanding of the taxonomy, genetics and evolutionary biology of the whipworms.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3100-5) contains supplementary material, which is available to authorized users.

Hookworms Make Us Human: The Microbiome, Eco-immunology, and a Probiotic Turn in Western Health Care

Historians of science have identified an ecological turn underway in immunology, driven by the mapping of the human microbiome and wider environmentalist anxieties. A figure is emerging of the human as a holobiont, composed of microbes and threatened by both microbial excess and microbial absence. Antimicrobial approaches to germ warfare are being supplemented by probiotic approaches to restoring microbial life. This article examines the political ecology of this probiotic turn in Western health care. It focuses on Necator americanus-a species of human hookworm-and its relations with immunologists. The analysis moves from a history of human disentanglement from hookworm, to contemporary anxieties about their absence. It examines the reintroduction of worms for helminthic therapy and explores emerging trajectories for probiotic health care involving the synthesis, modification, and/or restoration of worms and their salutary ecologies. The conclusion differentiates these trajectories and identifies an emerging model of "post-paleo" microbiopolitics.

Relationships Between Gastrointestinal Parasite Infections and the Fecal Microbiome in Free-Ranging Western Lowland Gorillas

Relationships between gastrointestinal parasites (GIPs) and the gastrointestinal microbiome (GIM) are widely discussed topics across mammalian species due to their possible impact on the host's health. GIPs may change the environment determining alterations in GIM composition. We evaluated the associations between GIP infections and fecal microbiome composition in two habituated and two unhabituated groups of wild western lowland gorillas (Gorilla g. gorilla) from Dzanga Sangha Protected Areas, Central African Republic. We examined 43 fecal samples for GIPs and quantified strongylid nematodes. We characterized fecal microbiome composition through 454 pyrosequencing of the V1-V3 region of the bacterial 16S rRNA gene. Entamoeba spp. infections were associated with significant differences in abundances of bacterial taxa that likely play important roles in nutrition and metabolism for the host, besides being characteristic members of the gorilla gut microbiome. We did not observe any relationships between relative abundances of several bacterial taxa and strongylid egg counts. Based on our findings, we suggest that there is a significant relationship between fecal microbiome and Entamoeba infection in wild gorillas. This study contributes to the overall knowledge about factors involved in modulating GIM communities in great apes.

The microbiome and systemic lupus erythematosus

The microbiota, which is comprised of the collective of all microbes inhabiting the gut and its effect on the human host in which it resides, has become a growing field of interest. Various parameters of health and disease have been found to be associated with the variation in the human gut microbiome. In recent years, many studies have demonstrated an important role of gut microbes in the development of various illnesses including autoimmune diseases, such as type 1 diabetes, rheumatoid arthritis, and multiple sclerosis. Although the mechanism of the disease involves both genetic and environmental factors, lupus has been found to be affected by the composition of the microbes lining the intestines. Several recent studies have suggested that alterations of the gut microbial composition may be correlated with SLE disease manifestations, while the exact roles of either symbiotic or pathogenic microbes in this disease have yet to be explored. Elucidation of the roles of gut microbes in SLE will shed light on how this autoimmune disorder develops and provide opportunities for improved biomarkers of the disease and the potential to probe new therapies. This new knowledge, along with that enabling alteration in composition of the gut microbiome, via diet modification, antibiotic, and probiotics, may bring forward a new era in the future of lupus treatment.

Therapeutic Effects of Resiniferatoxin Related with Immunological Responses for Intestinal Inflammation in Trichinellosis

The immune response against Trichinella spiralis at the intestinal level depends on the CD4⁺ T cells, which can both suppress or promote the inflammatory response through the synthesis of diverse cytokines. During the intestinal phase, the immune response is mixed (Th1/Th2) with the initial predominance of the Th1 response and the subsequent domination of Th2 response, which favor the development of intestinal pathology. In this context, the glucocorticoids (GC) are the pharmacotherapy for the intestinal inflammatory response in trichinellosis. However, its therapeutic use is limited, since studies have shown that treatment with GC suppresses the host immune system, favoring T. spiralis infection. In the search for novel pharmacological strategies that inhibit the Th1 immune response (proinflammatory) and assist the host against T. spiralis infection, recent studies showed that resiniferatoxin (RTX) had anti-inflammatory activity, which decreased the serum levels of IL-12, INF-γ, IL-1β, TNF-α, NO, and PGE₂, as well the number of eosinophils in the blood, associated with decreased intestinal pathology and muscle parasite burden. These researches demonstrate that RTX is capable to inhibit the production of Th1 cytokines, contributing to the defense against T. spiralis infection, which places it as a new potential drug modulator of the immune response.

Susceptibility of dendritic cells from individuals with schistosomiasis to infection by Leishmania braziliensis

Coinfection with leishmaniasis and schistosomiasis has been associated with increased time to healing of cutaneous lesions of leishmaniasis. The objective of this study was to evaluate the effect of Leishmania braziliensis infection on co-cultures of monocyte-derived dendritic cells (MoDCs) with autologous lymphocytes from patients with schistosomiasis and patients with cutaneous leishmaniasis. MoDCs were differentiated from peripheral blood monocytes, isolated by magnetic beads, infected with L. braziliensis, and co-cultured with autologous lymphocytes. Expression of HLA-DR, CD1a, CD83, CD80, CD86, CD40, and the IL-10 receptor (IL-10R) on MoDCs as well as CD28, CD40L, CD25, and CTLA-4 on lymphocytes were evaluated by flow cytometry. The production of the cytokines IL-10, TNF, IL-12p40, and IFN-γ were evaluated by sandwich ELISA of the culture supernatant. The infectivity evaluation was performed by light microscopy after concentration of cells by cytospin and Giemsa staining. It was observed that the frequency of MoDCs expressing CD83, CD80, and CD86 as well as the MFI of HLA-DR were smaller in the group of patients with schistosomiasis compared to the group of patients with leishmaniasis. On the other hand, the frequency of IL-10R on MoDCs was higher in patients with schistosomiasis than in patients with leishmaniasis. CD4⁺ and CD8⁺ T lymphocytes from patients with schistosomiasis presented a lower frequency of CD28 and a higher frequency of CTLA-4 compared to lymphocytes from patients with leishmaniasis. Levels of IL-10 were higher in the supernatants of co-cultures from individuals with schistosomiasis compared to those with leishmaniasis. However, levels of TNF, IL-12p40, and IFN-γ were lower in the group of individuals with schistosomiasis. Regarding the frequency of MoDCs infected by L. braziliensis after 72h in culture, it was observed that higher frequencies of cells from patients with schistosomiasis were infected compared to cells from patients with leishmaniasis. It was concluded that MoDCs from patients with schistosomiasis are more likely to be infected by L. braziliensis, possibly due to a lower degree of activation and a regulatory profile.

A structurally distinct TGF-β mimic from an intestinal helminth parasite potently induces regulatory T cells

Helminth parasites defy immune exclusion through sophisticated evasion mechanisms, including activation of host immunosuppressive regulatory T (Treg) cells. The mouse parasite Heligmosomoides polygyrus can expand the host Treg population by secreting products that activate TGF-β signalling, but the identity of the active molecule is unknown. Here we identify an H. polygyrus TGF-β mimic (Hp-TGM) that replicates the biological and functional properties of TGF-β, including binding to mammalian TGF-β receptors and inducing mouse and human Foxp3⁺ Treg cells. Hp-TGM has no homology with mammalian TGF-β or other members of the TGF-β family, but is a member of the complement control protein superfamily. Thus, our data indicate that through convergent evolution, the parasite has acquired a protein with cytokine-like function that is able to exploit an endogenous pathway of immunoregulation in the host.

Heligmosomoides polygyrus can activate mammalian TGF-β signalling pathways, but how it does so is not known. Here the authors identify and isolate a H. polygyrus TFG-β mimic that can bind both mammalian TGF-β receptor subunits, activate Smad signalling and generate inducible regulatory T cells.

Syphacia obvelata: A New Hope to Induction of Intestinal Immunological Tolerance in C57BL/6 Mice

The ability of nematodes to manipulate the immune system of their host towards a Th2 and T regulatory responses has been proposed to suppress the inflammatory response. Clinical trials have proposed a useful effect of helminth infections on improvement of inflammatory disorders. In this study, we investigated the immunomodulatory effect of Syphacia obvelata infection to induce intestinal tolerance in C57BL/6 mice. Mice were infected through the cagemates with self-infected BALB/c mice. Four weeks post-infection, expression levels of IFN-γ, TNF-α, IL-17, and IL-10 were assessed in the supernatant of mesenteric lymph node (MLN) culture. Foxp3⁺Treg were measured in MLN cells by flow cytometry. In the S. obvelata-infected group, the percentage of Tregs (5.2±0.4) was significantly higher than the control (3.6±0.5) (P<0.05). The levels of IL-10 (55.3±2.2 vs 35.2±3.2), IL-17 (52.9±3.8 vs 41±1.8), IFN-γ (44.8±4.8 vs 22.3±2.3) and TNF-α (71.1±5.8 vs 60.1±3.3) were significantly increased in infected mice compared to the control group (P<0.05). The above results showed the potential effects of S. obvelata to induce intestinal tolerance. Therefore, it seems that S. obvelata may increase the immunological suppressive function in the intestinal tract.

Aging, Health, and Quality of Life for Older People Living With HIV in Sub-Saharan Africa: A Review and Proposed Conceptual Framework

OBJECTIVE

The number of people living with HIV (PLWH) over 50 years old in sub-Saharan Africa is predicted to triple in the coming decades, to 6-10 million. Yet, there is a paucity of data on the determinants of health and quality of life for older PLWH in the region.

METHODS

A review was undertaken to describe the impact of HIV infection on aging for PLWH in sub-Saharan Africa.

RESULTS

We (a) summarize the pathophysiology and epidemiology of aging with HIV in resource-rich settings, and (b) describe how these relationships might differ in sub-Saharan Africa, (c) propose a conceptual framework to describe determinants of quality of life for older PLWH, and (d) suggest priority research areas needed to ensure long-term gains in quality of life for PLWH in the region.

CONCLUSIONS

Differences in traditional, lifestyle, and envirnomental risk factors, as well as unique features of HIV epidemiology and care delivery appear to substantially alter the contribution of HIV to aging in sub-Saharan Africa. Meanwhile, unique preferences and conceptualizations of quality of life will require novel measurement and intervention tools. An expanded research and public health infrastructure is needed to ensure that gains made in HIV prevention and treamtent are translated into long-term benefits in this region.

Therapeutic effect of Schistosoma japonicum cystatin on bacterial sepsis in mice

BACKGROUND

Sepsis is a life-threatening complication of an infection and remains one of the leading causes of mortality in surgical patients. Bacteremia induces excessive inflammatory responses that result in multiple organ damage. Chronic helminth infection and helminth-derived materials have been found to immunomodulate host immune system to reduce inflammation against some allergic or inflammatory diseases. Schistosoma japonicum cystatin (Sj-Cys) is a cysteine protease inhibitor that induces regulatory T-cells and a potential immunomodulatory. The effect of Sj-Cys on reducing sepsis inflammation and mortality was investigated.

METHODS

Sepsis was induced in BALB/c mice using cecal ligation and puncture (CLP), followed by intraperitoneal injection of different doses (10, 25 or 50 μg) of recombinant Sj-Cys (rSj-Cys). The therapeutic effect of rSj-Cys on sepsis was evaluated by observing the survival rates of mice for 96 h after CLP and the pathological injury of liver, kidney and lung by measuring the levels of alanine transaminase (ALT), aspartate transaminase (AST), blood urea nitrogen (BUN) and creatinine (Cr) in sera and the tissue sections pathology, and the expression of MyD88 in liver, kidney and lung tissues. The immunological mechanism was investigated by examining pro-inflammatory cytokines (TNF-α, IL-6, IL-1β) and IL-10 and TGF-β1 in mice sera and in culture of macrophages stimulated by lipopolysaccharides (LPS).

RESULTS

rSj-Cys treatment provided significant therapeutic effects on CLP-induced sepsis in mice demonstrated with increased survival rates, alleviated overall disease severity and tissue injury of liver, kidney and lung. The rSj-Cys conferred therapeutic efficacy was associated with upregualted IL-10 and TGF-β1 cytokines and reduced pro-inflammatory cytokines TNF-α, IL-6, IL-1β. MyD88 expression in liver, kidney and lung tissues of rSj-Cys-treated mice was reduced. In vitro assay with macrophages also showed that rSj-Cys inhibited the release of pro-inflammatory cytokines and mediator nitric oxide (NO) after being stimulated by lipopolysaccharide (LPS).

CONCLUSIONS

The results suggest the anti-inflammatory potential of rSj-Cys as a promising therapeutic agent on sepsis. The immunological mechanism underlying its therapeutic effect may involve the downregulation of pro-inflammatory cytokines and upregulation of IL-10 and TGF-β1 cytokines possibly via downregulation of the TLR adaptor-transducer MyD88 pathway. The findings suggest rSj-Cys is a potential therapeutic agent for sepsis and other inflammatory diseases.

Immunomodulation by helminths: Similar impact on type 1 and type 2 diabetes?

The incidence of both type 1 (T1D) and type 2 diabetes (T2D) is drastically increasing, and it is predicted that the global prevalence of diabetes will reach almost 600 million cases by 2035. Even though the pathogenesis of both types of diabetes is distinct, the immune system is actively involved in both forms of the disease. Genetic and environmental factors determine the risk to develop T1D. On the other hand, sedentary life style, surplus of food intake and other lifestyle changes contribute to the increase of T2D incidence. Improved sanitation with high-quality medical treatment is such an environmental factor that has led to a continuous reduction of infectious diseases including helminth infections over the past decades. Recently, a growing body of evidence has implicated a negative association between helminth infections and diabetes in humans as well as animal models. In this review, we discuss studies that have provided evidence for the beneficial impact of helminth infections on T1D and T2D. Possible mechanisms are presented by which helminths prevent T1D onset by mitigating pancreatic inflammation and confer protection against T2D by improving insulin sensitivity, alleviating inflammation, augmenting browning of adipose tissue and improving lipid metabolism and insulin signalling.

Immunopathological response of leukocytes against microfilariae and adult worms in white rats infected with Setaria cervi

AIM

Aim of this study was to see the immunopathological changes against the microfilariae (Mf) and adult worms of a bovine filarid, Setaria cervi in the tissues of vital organs of experimentally infected white rats. The effect of diethylcarbamazine (DEC) was also observed on the Mf, as leukocytes especially lymphocytes produce immunoglobulins which opsonize and increase the efficacy of DEC against circulating Mf. Effect of this drug was also assessed on liver enzymes in the microfilaremic rats.

MATERIALS AND METHODS

Microfilaremia was established by implanting adult worms intraperitoneally and by the infusion of Mf recovered from the uterus of gravid female worms. DEC was administered orally for six consecutive days in the rats having patent infection. Differential leukocyte count was recorded every 3rd day, and liver enzymes were estimated every 10th day in both treated and untreated rats. Pathological changes were observed in HE stained sections of vital organs where Mf or adult worms were trapped.

RESULTS

Destruction and reduction in microfilarial density were noticed in microfilaremic rats treated with DEC. Trapped Mf and embedded worms revealed heavy cellular infiltrations by defensive cells which surrounded and attached with the body surface of the Mf as well as adult worms for their destruction and piece meal clearance. Immune-mediated pathology was observed in the tissue sections of lungs, spleen, and liver. Liver enzymes were elevated during the period of higher parasitemia.

CONCLUSIONS

There was a moderate level of immunopathology against the Mf and adult worms by the leukocytes in experimentally infected microfilaremic rats. Mf were in the process of degeneration where they got trapped. Moderate increase in liver enzyme was noticed which was slightly more in untreated group. Although a fraction of Mf gets killed in the peritoneum, majority of them successfully enter the systemic circulation and survive for about 54 days, which is sufficient enough for conducting immunological and chemotherapeutic studies.

Immune responses to fungal aeroallergen in Heligmosomoides polygyrus-infected mice vary by age

Parasite infections in the developing world have been considered to promote resistance to immune-mediated diseases such as asthma. Mouse studies have shown that helminths and their products reduce the development of allergic asthma. Since epidemiologic studies that show similar protection are in relation to geohelminth infections that occur in early life, we hypothesized that the parasite-mediated protection against asthma may differ by age. Mice infected with Heligmosomoides polygyrus at 3-weeks of age had similar asthma phenotype compared to mice infected at 28-weeks of age wherein airway eosinophilia was unaltered but tissue inflammation and GC metaplasia were reduced. In contrast, mice infected at 18-weeks of age had elevated macrophagic airway inflammation with accompanying tissue pathology. The presence of γδ T cells and T_reg cells in the airways was also regulated by age at worm infection. Our findings demonstrate the importance of age in immune responses that may regulate gut and lung diseases.

Changes in protein expression after treatment with Ancylostoma caninum excretory/secretory products in a mouse model of colitis

Different reports have highlighted the potential use of helminths and their secretions in the treatment of inflammatory bowel disease (IBD) conditions; however, no reports have investigated their effects at a proteome level. Herein, we characterise the protein expression changes that occur in lamina propria (LP) and the intestinal epithelial cells (IEC) of mice with dextran sulfate sodium (DSS)-induced colitis treated with Ancylostoma caninum excretory/secretory (ES) products using a quantitative proteomic approach. We have shown how parasite products can significantly alter the expression of proteins involved in immune responses, cell death and with an antioxidant activity. Interestingly, significant changes in the expression levels of different mucins were observed in this study. MUC13, a mucin implicated in gastrointestinal homeostasis, was upregulated in the LP of mice with DSS-induced colitis treated with ES, while MUC2, a major component of mucus, was upregulated in the IEC. In addition, A. caninum proteins have an important effect on proteins with antioxidant functions and proteins involved in intestinal homeostasis and tissue integrity and regeneration. Understanding how parasites can ameliorate IBD pathogenesis can help us design novel treatments for autoimmune diseases.

Enteric helminth-induced type I interferon signaling protects against pulmonary virus infection through interaction with the microbiota

BACKGROUND

Helminth parasites have been reported to have beneficial immunomodulatory effects in patients with allergic and autoimmune conditions and detrimental consequences in patients with tuberculosis and some viral infections. Their role in coinfection with respiratory viruses is not clear.

OBJECTIVE

Here we investigated the effects of strictly enteric helminth infection with Heligmosomoides polygyrus on respiratory syncytial virus (RSV) infection in a mouse model.

METHODS

A murine helminth/RSV coinfection model was developed. Mice were infected by means of oral gavage with 200 stage 3 H polygyrus larvae. Ten days later, mice were infected intranasally with either RSV or UV-inactivated RSV.

RESULTS

H polygyrus-infected mice showed significantly less disease and pulmonary inflammation after RSV infection associated with reduced viral load. Adaptive immune responses, including T_H2 responses, were not essential because protection against RSV was maintained in Rag1^-/- and Il4rα^-/- mice. Importantly, H polygyrus infection upregulated expression of type I interferons and interferon-stimulated genes in both the duodenum and lung, and its protective effects were lost in both Ifnar1^-/- and germ-free mice, revealing essential roles for type I interferon signaling and microbiota in H polygyrus-induced protection against RSV.

CONCLUSION

These data demonstrate that a strictly enteric helminth infection can have remote protective antiviral effects in the lung through induction of a microbiota-dependent type I interferon response.

The Hygiene Hypothesis and Its Inconvenient Truths about Helminth Infections

Current iterations of the hygiene hypothesis suggest an adaptive role for helminth parasites in shaping the proper maturation of the immune system. However, aspects of this hypothesis are based on assumptions that may not fully account for realities about human helminth infections. Such realities include evidence of causal associations between helminth infections and asthma or inflammatory bowel disease as well as the fact that helminth infections remain widespread in the United States, especially among populations at greatest risk for inflammatory and autoimmune diseases.

Navigating the Microbial Basis of Inflammatory Bowel Diseases: Seeing the Light at the End of the Tunnel

Inflammatory bowel diseases (IBD), such as Crohn's disease and ulcerative colitis, are chronic inflammatory conditions affecting the gastrointestinal tract with variable presentations and disease courses. The cause of IBD is unknown, but it is hypothesized that individuals with a genetic predisposition to disease develop an aberrant immune response to environmental triggers. Evidence suggests that microbiota residing in the gastrointestinal tract play an important role in the development and perpetuation of the disease. In this review, we discuss the role of microbes in the development of a healthy gut, their role in the development of diseases in general, and their role in the development of IBD. Advances in molecular technologies and bioinformatics will continue to further our insight into the structure of the microbial community, the function of the microbial community as a whole, and the interaction of this community with the host immune system. The latter two are crucial to understanding the role of microbes in IBD. The field has advanced significantly in recent years, and the future is very promising as we begin to elucidate the microbial basis of IBD.

Helminth Interaction with the Host Immune System: Short-Term Benefits and Costs in Relation to the Infectious Environment

Chronic infections imply that the parasite and the host immune system closely interact for a long time without a fatal outcome. Environmental changes encountered by hosts and parasites, such as coinfections, can deeply affect the stability of this apparent equilibrium. Our study aimed to determine the effect of the infectious environment on the costs and benefits of chronic infection with the gut nematode Heligmosomoides polygyrus in mice. Heligmosomoides polygyrus is known for its capacity to actively interfere with the host immune response by secreting molecules that can dampen immunity. We simulated bacterial coinfection of H. polygyrus-infected CBA-strain mice during the chronic phase of the infection by injecting them with Escherichia coli lipopolysaccharide. We found that infection by H. polygyrus induced only weak costs for the host (in terms of reproductive investment) and was characterized by the upregulation of both Th1 (interferon-γ) and anti-inflammatory (transforming growth factor-β) cytokines, which is favorable to parasite persistence. However, when co-occurring with the simulated bacterial infection, H. polygyrus infection was associated with a pronounced shift toward a pro-inflammatory status, which was deleterious to both the parasite and the host. Our study highlights the dynamic equilibrium reached during chronic infection, where a rapid environmental change, such as a concomitant bacterial infection, can deeply affect the outcome of the host-parasite interaction.

Parasitic helminths and their beneficial impact on type 1 and type 2 diabetes

It is estimated that by the year 2035 almost 600 million people will suffer from diabetes. In the case of type 2 diabetes, the strongest increase of diabetes incidence occurs in developing and newly industrialized countries. This increase correlates not only with a progressing sedentary lifestyle and nutritional changes, but also environmental changes. Similarly, the increase of type 1 diabetes incidence in industrialized countries over the past decades cannot be explained by genetic factors alone, suggesting that environmental changes are also involved. One such environmental change is a reduced exposure to pathogens because of improved hygiene. Parasitic helminths modulate the immune system of their hosts and induce type 2 as well as regulatory immune responses. As pro-inflammatory immune responses are crucial for the onset of both type 1 and type 2 diabetes, helminth-induced immunomodulation may prevent diabetes onset and ameliorate insulin sensitivity. Several epidemiological studies in human and experimental animal models support such a protective effect of helminths for autoimmune diabetes. Recent studies further suggest that helminths may also provide such a beneficial effect for type 2 diabetes. In this review we summarize studies that investigated parasitic helminths and helminth-derived products and their impact on both type 1 and type 2 diabetes highlighting potential protective mechanisms.

Combination of worm antigen and proinsulin prevents type 1 diabetes in NOD mice after the onset of insulitis

Animal studies demonstrated that administration of helminth products can protect from autoimmune diseases. However, the success of such administrations is limited in the case of type 1 diabetes, as protection is only provided if the administration is started before the development of insulitis. In this study we investigated whether inclusion of helminth antigen administrations to an antigen-specific treatment with proinsulin improves the protective effect by triggering non-specific regulatory immune responses. Using a combination therapy of intraperitoneal Litomosoides sigmodontis antigen and intranasal pro-insulin, onset of diabetes was prevented in NOD mice after insulitis started, while either administration alone failed to protect. This protection was associated with an increased frequency of regulatory T cells within the pancreatic lymph nodes and a reduced inflammation of the pancreatic islets. This suggests that inclusion of helminth antigens improve the protective effect provided by antigen-specific therapies and represent a new potential therapeutic approach against autoimmune diseases.

Regulatory T-cell neutralization in mice during filariasis helps in parasite clearance by enhancing T helper type 17-mediated pro-inflammatory response

Lymphatic filariasis leads to profound impairment of parasite-specific T helper type 1 (Th1) and Th2 immune responses and significantly increases the expression of regulatory networks and regulatory effectors like transforming growth factor-β, CD25, cytotoxic T-lymphocyte antigen 4, glucocorticoid-induced tumour necrosis factor receptor (GITR) and regulatory T (Treg) cells, which together play an important role in immunosuppression. While Treg cells suppress the activity of effector cells, monocyte dysfunction, characterized by an alternatively activated immunoregulatory phenotype, is one hypothesis that explains the lack of an antigen-specific T-cell response in infected individuals. In the present study, we administered neutralizing antibodies against the Treg cell-associated markers CD25 and GITR and observed its effects on filaria-induced immunosuppression. Our results show that administration of anti-CD25 and anti-GITR in infected animals not only arrested the accumulation of Treg cells and reduced arginase activity, but also led to an increase in the percentages of Th17 cells in the secondary lymphoid organs of mice. Elevated levels of interferon-γ and decreased levels of interleukin-10 were also noted in the culture supernatants of mouse splenocytes that were treated with neutralizing antibodies. Furthermore, treatment with neutralizing antibodies enhanced the expression of inducible nitric oxide synthase on host macrophages and CD40 on host dendritic cells with concomitant decreased expression of alternative activation markers Arg1, Ym1 and Fizz1, which together lead to reduced parasite burden in treated animals. In summary, administration of neutralizing antibodies helps in breaking the regulatory network in mice and limits parasite-induced immunosuppression at the earliest host-parasite interface.

Helminth therapy for organic diseases?

Autoimmune and chronic inflammatory organic diseases represent a "postindustrial revolution epidemics," and their frequency has increased dramatically in the last century. Today, it is assumed that the increase in hygiene standards reduced the interactions with helminth parasites that coevolved with the immune system and are crucial for its proper functioning. Several helminths have been proposed and tested in the search of the ideal therapeutic. In this review, the authors summarize the translational and clinical studies and review the caveats and possible solutions for the optimization of helminth therapies.

Helminths and the microbiota: parts of the hygiene hypothesis

In modern societies, diseases that are driven by dysregulated immune responses are increasing at an alarming pace, such as inflammatory bowel diseases and diabetes. There is an urgent need to understand these epidemiological trends, which are likely to be driven by the changing environment of the last few decades. There are complex interactions between human genetic factors and this changing environment that is leading to the increasing prevalence of metabolic and inflammatory diseases. Alterations to human gut bacterial communities (the microbiota) and lowered prevalence of helminth infections are potential environmental factors contributing to immune dysregulation. Helminths have co-evolved with the gut microbiota and their mammalian hosts. This three-way interaction is beginning to be characterized, and the knowledge gained may enable the design of new therapeutic strategies to treat metabolic and inflammatory diseases. However, these complex interactions need to be carefully investigated in the context of host genetic backgrounds to identify optimal treatment strategies. The complex nature of these interactions raises the possibility that only with highly personalized treatment, with knowledge of individual genetic and microbiota communities, will therapeutic interventions be successful for a majority of the individuals suffering from these complex diseases of immune dysregulation.

Identifying the immunomodulatory components of helminths

Immunomodulatory components of helminths offer great promise as an entirely new class of biologics for the treatment of inflammatory diseases. Here, we discuss the emerging themes in helminth-driven immunomodulation in the context of therapeutic drug discovery. We broadly define the approaches that are currently applied by researchers to identify these helminth molecules, highlighting key areas of potential exploitation that have been mostly neglected thus far, notably small molecules. Finally, we propose that the investigation of immunomodulatory compounds will enable the translation of current and future research efforts into potential treatments for autoimmune and allergic diseases, while at the same time yielding new insights into the molecular interface of host-parasite biology.

Variation in Rural African Gut Microbiota Is Strongly Correlated with Colonization by Entamoeba and Subsistence

The human gut microbiota is impacted by host nutrition and health status and therefore represents a potentially adaptive phenotype influenced by metabolic and immune constraints. Previous studies contrasting rural populations in developing countries to urban industrialized ones have shown that industrialization is strongly correlated with patterns in human gut microbiota; however, we know little about the relative contribution of factors such as climate, diet, medicine, hygiene practices, host genetics, and parasitism. Here, we focus on fine-scale comparisons of African rural populations in order to (i) contrast the gut microbiota of populations inhabiting similar environments but having different traditional subsistence modes and either shared or distinct genetic ancestry, and (ii) examine the relationship between gut parasites and bacterial communities. Characterizing the fecal microbiota of Pygmy hunter-gatherers as well as Bantu individuals from both farming and fishing populations in Southwest Cameroon, we found that the gut parasite Entamoeba is significantly correlated with microbiome composition and diversity. We show that across populations, colonization by this protozoa can be predicted with 79% accuracy based on the composition of an individual's gut microbiota, and that several of the taxa most important for distinguishing Entamoeba absence or presence are signature taxa for autoimmune disorders. We also found gut communities to vary significantly with subsistence mode, notably with some taxa previously shown to be enriched in other hunter-gatherers groups (in Tanzania and Peru) also discriminating hunter-gatherers from neighboring farming or fishing populations in Cameroon.

Nuclear and mitochondrial genes for inferring Trichuris phylogeny

Nucleotide sequences of the triose phosphate isomerase (TPI) gene (624 bp) and mitochondrial cytochrome b (cob) gene (520 bp) were obtained by PCR and evaluated for utility in inferring the phylogenetic relationships among Trichuris species. Published sequences of one other nuclear gene (18S or SSU rRNA, 1816-1846 bp) and one additional mitochondrial (mtDNA) gene (cytochrome oxidase 1, cox1, 342 bp) were also analyzed. Maximum likelihood and Bayesian inference methods were used to infer phylogenies for each gene separately but also for the combined mitochondrial data (two genes), the combined nuclear data (two genes), and the total evidence (four gene) dataset. Few Trichuris clades were uniformly resolved across separate analyses of individual genes. For the mtDNA, the cob gene trees had greater phylogenetic resolution and tended to have higher support values than the cox1 analyses. For nuclear genes, the SSU gene trees had slightly greater resolution and support values than the TPI analyses, but TPI was the only gene with reliable support for the deepest nodes in the tree. Combined analyses of genes yielded strongly supported clades in most cases, with the exception of the relationship among Trichuris clades 1, 2, and 3, which showed conflicting results between nuclear and mitochondrial genes. Both the TPI and cob genes proved valuable for inferring Trichuris relationships, with greatest resolution and support values achieved through combined analysis of multiple genes. Based on the phylogeny of the combined analysis of nuclear and mitochondrial genes, parsimony mapping of definitive host utilization depicts artiodactyls as the ancestral hosts for these Trichuris, with host-shifts into primates, rodents, and Carnivora.

Asymptomatic Helminth Infection in Active Tuberculosis Is Associated with Increased Regulatory and Th-2 Responses and a Lower Sputum Smear Positivity

Background

The impact of intestinal helminth infection on the clinical presentation and immune response during active tuberculosis (TB) infection is not well characterized. Our aim was to investigate whether asymptomatic intestinal helminth infection alters the clinical signs and symptoms as well as the cell mediated immune responses in patients with active TB.

Methodology

Consecutive, newly diagnosed TB patients and healthy community controls (CCs) were recruited in North-west Ethiopia. TB-score, body mass index and stool samples were analyzed. Cells from HIV-negative TB patients (HIV-/TB) and from CCs were analyzed for regulatory T-cells (Tregs) and cytokine responses using flow cytometry and ELISPOT, respectively.

Results

A significantly higher ratio of helminth co-infection was observed in TB patients without HIV (Helm+/HIV-/TB) compared to HIV negative CCs, (40% (121/306) versus 28% (85/306), p = 0.003). Helm+/HIV-/TB patients showed significantly increased IL-5 secreting cells compared to Helm-/HIV-/TB (37 SFU (IQR:13–103) versus 2 SFU (1–50); p = 0.02, n = 30). Likewise, levels of absolute Tregs (9.4 (3.2–16.7) cells/μl versus 2.4 (1.1–4.0) cells/μl; p = 0.041) and IL-10 secreting cells (65 SFU (7–196) versus 1 SFU (0–31); p = 0.014) were significantly higher in Helm+/HIV-/TB patients compared to Helm-/HIV-/TB patients. In a multivariate analysis, a lower rate of sputum smear positivity for acid fast bacilli, lower body temperature, and eosinophilia were independently associated with helminth infection in TB patients.

Conclusions

Asymptomatic helminth infection is associated with increased regulatory T-cell and Th2-type responses and a lower rate of sputum smear positivity. Further studies are warranted to investigate the clinical and immunological impact of helminth infection in TB patients.

The effects of helminth infection on chronic infectious diseases such as tuberculosis (TB) merit further characterization. There is limited data regarding the impact of helminth co-infection on clinical and immunological outcomes of TB from clinical field studies in high endemic areas. We tried to address some of these issues in a randomized clinical trial in order to investigate the impact of albendazole treatment on helminth co-infected TB patients. In the present study we focused on the clinical and immunological effects of helminth infection on TB. We found that concomitant asymptomatic helminth infection profoundly affects the immune phenotype of TB patients with a strong leaning towards Th2 types of immune response such as increased regulatory T cells as well as IL-5 and IL-10 secreting cells. Furthermore, helminth co-infection was associated with a significantly lower ratio of sputum smear positivity which correlated to the egg load in helminth positive TB patients. Whether the effect of helminth infection may have an impact on the diagnosis and treatment of active TB remains to be further investigated.

Why is initial bacterial colonization of the intestine important to infants' and children's health?

Microbial colonization of the infant occurs during a critical time window for immune and gastrointestinal development. Infant colonization sets the stage for the adult microbiome. This review is a broad survey of the factors affecting infant colonization and the downstream effects on gastrointestinal health and disease. Major topics affecting colonization include initial inoculation dependent on birth mode, the impact of breast-feeding, and inside-out modulation of the developing microbiome by the immune system. Major outcomes of colonization include the timing-dependent education of the neonatal immune system, which is interconnected with barrier function and metabolism. These all engage in further continuing cross-talk with the microbiome, genetics, and nutrition. This review also briefly examines mechanisms of disease resulting from disrupted colonization as well as nutritional and microbial therapies.

Allergy and worms: let's bring back old friends?

PURPOSE OF REVIEW

In order to survive in their host, parasitic worms (helminths) have evolved cunning strategies to manipulate the host immune system, some of which may lead to protection from immune dysregulatory diseases such as allergy. Thus, loss of exposure to helminths due to a highly hygienic life style might have contributed to the fact that living in an industrialized country is being associated with an increased prevalence of allergic diseases. However, it must be pointed out that certain helminth infections can in fact induce an allergic phenotype. Factors such as different parasite species, timing of infection in relation to allergic sensitization, or duration and intensity of infection may influence the association between helminth infections and the development or clinical course of allergic disease. In the present article, we review studies that have explored the interaction between helminth infections and allergy in epidemiological and experimental studies. Furthermore, the possibility of using helminths or helminth-derived molecules for the treatment of allergic diseases is discussed with a focus on evidence from clinical trials.

RECENT FINDINGS

During the past 10 years, many exciting and important studies have found that certain helminth infections protect against the development of allergic diseases. Not surprisingly, several clinical trials investigated the effects of deliberate exposure to parasites like porcine whipworm (Trichuris suis) or hookworm (Necator americanus) to develop "helminth therapies". Although they proved to be a safe option to control aberrant inflammation, the final goal is to identify the parasite-derived immunnomodulatory molecules responsible for protective effects.

Dendritic cell profile induced by Schistosoma mansoni antigen in cutaneous leishmaniasis patients

The inflammatory response in cutaneous leishmaniasis (CL), although responsible for controlling the infection, is associated with the pathogenesis of disease. Conversely, the immune response induced by S. mansoni antigens is able to prevent immune-mediated diseases. The aim of this study was to evaluate the potential of the S. mansoni Sm29 antigen to change the profile of monocyte-derived dendritic cells (MoDCs) from subjects with cutaneous leishmaniasis (CL) in vitro. Monocytes derived from the peripheral blood mononuclear cells of twelve patients were cultured with GM-CSF and IL-4 for differentiation into dendritic cells and then stimulated with soluble Leishmania antigen (SLA) in the presence or absence of Sm29 antigen. The expression of surface molecules associated with maturation and activation (HLA-DR, CD40, CD83, CD80, and CD86), inflammation (IL-12, TNF), and downregulation (IL-10, IL-10R) was evaluated using flow cytometry. We observed that the frequencies of HLA-DR, CD83, CD80, and CD86 as well as of IL-10 and IL-10R on MoDCs were higher in cultures stimulated with Sm29, compared to the unstimulated cell cultures. Our results indicate that the Sm29 antigen is able to activate regulatory MoDCs in patients with cutaneous leishmaniasis. It might be useful to control the inflammatory process associated with this disease.

Helminth induced suppression of macrophage activation is correlated with inhibition of calcium channel activity

Helminth parasites cause persistent infections in humans and yet many infected individuals are asymptomatic. Neurocysticercosis (NCC), a disease of the central nervous system (CNS) caused by the cestode Taenia solium, has a long asymptomatic phase correlated with an absence of brain inflammation. However, the mechanisms of immune suppression remain poorly understood. Here we report that murine NCC displays a lack of cell surface maturation markers in infiltrating myeloid cells. Furthermore, soluble parasite ligands (PL) failed to induce maturation of macrophages, and inhibited TLR-induced inflammatory cytokine production. Importantly, PL treatment abolished both LPS and thapsigargin-induced store operated Ca2+ entry (SOCE). Moreover, electrophysiological recordings demonstrated PL-mediated inhibition of LPS or Tg-induced currents that were TRPC1-dependent. Concomitantly STIM1-TRPC1 complex was also impaired that was essential for SOCE and sustained Ca2+ entry. Likewise loss of SOCE due to PL further inhibited NFkB activation. Overall, our results indicate that the negative regulation of agonist induced Ca2+ signaling pathway by parasite ligands may be a novel immune suppressive mechanism to block the initiation of the inflammatory response associated with helminth infections.

Genome and transcriptome of the porcine whipworm Trichuris suis

Trichuris (whipworm) infects 1 billion people worldwide and causes a disease (trichuriasis) that results in major socioeconomic losses in both humans and pigs. Trichuriasis relates to an inflammation of the large intestine manifested in bloody diarrhea, and chronic disease can cause malnourishment and stunting in children. Paradoxically, Trichuris of pigs has shown substantial promise as a treatment for human autoimmune disorders, including inflammatory bowel disease (IBD) and multiple sclerosis. Here we report whole-genome sequencing at ∼140-fold coverage of adult male and female T. suis and ∼80-Mb draft assemblies. We explore stage-, sex- and tissue-specific transcription of mRNAs and small noncoding RNAs.