Interactions between macrophages and helminths

Type 2 cytokines act on enteric sensory neurons to regulate neuropeptide-driven host defense

Enteric nervous system (ENS)-derived neuropeptides modulate immune cell function, yet our understanding of how inflammatory cues directly influence enteric neuron responses during infection is considerably lacking. Here, we characterized a primary enteric sensory neuron (PSN) subset producing the neuropeptides neuromedin U (NMU) and calcitonin gene-related peptide β (CGRPβ) and coexpressing receptors for the type 2 cytokines interleukin-4 (IL-4) and IL-13. Type 2 cytokines amplified NMU and CGRPβ expression in PSNs, in vitro and in vivo, which was abrogated by PSN-specific Il13ra1 deletion. Deletion of Il13ra1 in PSNs impaired host defense to the gastrointestinal helminth Heligmosomoides polygyrus and blunted muscularis immune responses. Co-administration of NMU23 and CGRPβ rescued helminth clearance deficits and restored anti-helminth immunity, highlighting the essential bi-directional neuro-immune crosstalk regulating intestinal type 2 inflammation.

Nerve- and airway-associated interstitial macrophages mitigate SARS-CoV-2 pathogenesis via type I interferon signaling

Despite vaccines, rapidly mutating viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continue to threaten human health due to an impaired immunoregulatory pathway and a hyperactive immune response. Our understanding of the local immune mechanisms used by tissue-resident macrophages to safeguard the host from excessive inflammation during SARS-CoV-2 infection remains limited. Here, we found that nerve- and airway-associated interstitial macrophages (NAMs) are required to control mouse-adapted SARS-CoV-2 (MA-10) infection. Control mice restricted lung viral distribution and survived infection, whereas NAM depletion enhanced viral spread and inflammation and led to 100% mortality. Mechanistically, type I interferon receptor (IFNAR) signaling by NAMs was critical for limiting inflammation and viral spread, and IFNAR deficiency in CD169+ macrophages mirrored NAM-depleted outcomes and abrogated their expansion. These findings highlight the essential protective role of NAMs in regulating viral spread and inflammation, offering insights into SARS-CoV-2 pathogenesis and underscoring the importance of NAMs in mediating host immunity and disease tolerance.

HIV-Helminth Co-Infections and Immune Checkpoints: Implications for Cancer Risk in South Africa

South Africa has the highest HIV prevalence globally, often co-occurring with helminth infections in impoverished regions. The coexistence of these infections leads to immunological interactions, potentially enhancing oncogenesis by upregulating immune checkpoint molecules (ICs) among other effects. Notably, most ICs are overexpressed in cancer and correlated with its progression. Helminth infections trigger Th2-type immunity, increasing immunosuppressive M2 macrophages, regulatory T cells, and associated IC molecules. PD-L2 is reported to contribute to Th2-type immunity induced by helminth infections. Similarly, TIM-3, elevated during chronic viral infections, induces a similar immunosuppressive profile. CTLA-4 and PD-1 impact T-cell function by interacting with CD28, crucial for T-cell function. CD28 is downregulated in chronic infections and cancer. This study investigated the impact of HIV-helminth co-infection on co-stimulatory and co-inhibitory molecule profiles associated with antitumor immunity. Using 78 serum samples collected from March 2020 to May 2021, participants were categorized into uninfected control (no HIV and helminth infections), HIV-infected, helminth-infected, and HIV-helminth co-infected groups. Multiplex immune regulatory molecule assay analysis was conducted. The data were analyzed using multivariate regression analysis and adjusted for confounders (age, gender, BMI, ART, supplements, and other chronic diseases). The uninfected control group was used as the baseline reference group for analysis. HIV-infected individuals had higher PD-1 (adjusted β = 0.12, p = 0.034) and TIM-3 (adjusted β = 23.15, p = 0.052) levels, with the latter showing a trend toward significance. However, lower CD28 levels (adjusted β = -651.95, p = 0.010) were observed. Helminth-infected individuals had higher TIM-3 levels (adjusted β = 20.98, p = 0.020). The co-infected group had higher PD-1 (unadjusted β = 0.18, p = 0.0046) and PD-L2 (adjusted β = 7.95, p = 0.033) levels. A significant decrease in CD28 profile was observed across all infected groups: HIV-infected (adjusted β = -651.95, p = 0.010), helminth-infected (adjusted β = -674.32, p = 0.001), and co-infected (adjusted β = -671.55, p = 0.044). The results suggest that HIV-helminth co-infections alter immune checkpoint markers, potentially increasing cancer risk by promoting an immunosuppressive microenvironment that hinders anti-cancer immunity. CD28's downregulation underscores immune inefficiency in chronic diseases. Addressing these co-infections is crucial for improving HIV care and potentially reducing cancer risks through targeted strategies.

MyD88 inhibitor TJ-M2010-5 alleviates spleen impairment and inflammation by inhibiting the PI3K/miR-136-5p/AKT3 pathway in the early infection of Trichinella spiralis

Trichinella spiralis (T. spiralis) has been reported to induce inflammation, which can cause immune system dysregulation. Myeloid differentiation primary response gene 88 (MyD88) is implicated in inflammation signalling pathways. TJ-M2010-5 is a novel MyD88 inhibitor with remarkable protective effects against several diseases. However, the precise mechanism of TJ-M2010-5's involvement in spleen impairment and inflammation in the early infection of T. spiralis has yet to be fully elucidated. This study analysed histological, inflammation, and macrophage polarisation of the early T. spiralis-infected mice treated with TJ-M2010-5. MyD88 promoter methylation results showed that the methylation levels in the 5 d group were lower compared to the control group (P < 0.05). Furthermore, the methylation led to an imbalance in anti-inflammatory regulation in the infected mice. After TJ-M2010-5 treatment, spleen impairment was reduced. Sequencing analysis showed that TJ-M2010-5 significantly up-regulated 9 and down-regulated 10 miRNAs compared with the 5 d group. A dual-luciferase reporter assay further revealed that miR-136-5p is involved in the TJ-M2010-5 treatment by targeting AKT3. In RAW264.7 cells, TJ-M2010-5 pre-treatment significantly reversed the M1 polarisation and inhibited nitric oxide (NO) production. LC-MS/MS results showed TJ-M2010-5 was hepatosplenic-targeted. In conclusion, the study demonstrates that TJ-M2010-5 could effectively alleviate spleen impairment and reduce inflammation in mice infected with T. spiralis in its early stages by blocking the activation of PI3K/miR-136-5p/AKT3.

The developmental lipidome of Nippostrongylus brasiliensis

BACKGROUND

Nippostrongylus brasiliensis-a nematode of rodents-is commonly used as a model to study the immunobiology of parasitic nematodes. It is a member of the Strongylida-a large order of socioeconomically important parasitic nematodes of animals. Lipids are known to play essential roles in nematode biology, influencing cellular membranes, energy storage and/or signalling.

METHODS

The present investigation provides a comprehensive, untargeted lipidomic analysis of four developmental stages/sexes (i.e. egg, L3, adult female and adult male stages) of N. brasiliensis utilising liquid chromatography coupled to mass spectrometry.

RESULTS

We identified 464 lipid species representing 18 lipid classes and revealed distinct stage-specific changes in lipid composition throughout nematode development. Triacylglycerols (TGs) dominated the lipid profile in the egg stage, suggesting a key role for them in energy storage at this early developmental stage. As N. brasiliensis develops, there was a conspicuous transition toward membrane-associated lipids, including glycerophospholipids (e.g. PE and PC) and ether-linked lipids, particularly in adult stages, indicating a shift toward host adaptation and membrane stabilisation.

CONCLUSIONS

We provide a comprehensive insight into the lipid composition and abundance of key free-living and parasitic stages of N. brasiliensis. This study provides lipidomic resources to underpin the detailed exploration of lipid biology in this model parasitic nematode.

Type I/II Immune Balance Contributes to the Protective Effect of AIF-1 on Hepatic Immunopathology Induced by Schistosoma japonicum in a Transgenic Mouse Model

Schistosomiasis is the second most debilitating neglected tropical disease in the world. Liver egg granuloma and fibrosis are the main damage of schistosomiasis. In this study, the role of allograft inflammatory factor-1 (AIF-1) in liver pathology and its regulation in immune responses were investigated in a transgenic mouse infected with Schistosoma japonicum. We found that AIF-1 overexpression reduced worm burden and decreased egg granuloma sizes and serum alanine aminotransferase levels, along with inhibited hepatic collagen deposition and serum hydroxyproline levels during S. japonicum infection. Moreover, AIF-1 overexpression resulted in an increased ratio of Th1/Th2, increased levels of IFN-γ and T-bet, and lower levels of GATA-3 in the spleen, accompanied by increased M1 percentages, decreased M2 percentages, and thus a higher ratio of M1/M2 in the peritoneal cavity and liver. AIF-1 induced CD68 and iNOS mRNA expression and protein levels of cytoplasmic p-P38 and nuclear NF-κB, along with enhanced levels of TNF-α and TGF-β in macrophages in vitro. Moreover, the hepatic pathology had a negative correlation with Th1/Th2 and M1/M2 ratios in the infected mice. The findings reveal that the beneficial role of AIF-1 in alleviating hepatic damage is related to restoring type I/II immune balance in S. japonicum infection.

The C/EBPβ-SESN2 Axis Promotes M2b Macrophage Polarization Induced by T.cp-MIF to Suppress Inflammation in Thelazia Callipaeda Infection

Infection by the conjunctival sucking nematode Thelazia callipaeda results in ocular inflammation and immune impairment. T.cp-MIF, a macrophage migration inhibitor factor of T. callipaeda, can induce macrophage polarization and is involved in the host innate immune response, but little is known about the regulatory mechanisms and the actual immune effect. Understanding the immunoregulatory mechanisms carries significant clinical relevance for the development of novel preventative and therapeutic strategies. The macrophages were induced by T.cp-MIF in vitro, and the polarization direction at different times and the expression of inflammatory factors were detected by flow cytometry analysis, qPCR and western blotting. The key transcription factors and target genes were screened through transcriptome data, and the functions of transcription factors were verified by inhibition experiments in vitro. T.cp-MIF and T. callipaeda adult worms can cause inflammation of the ocular conjunctiva and macrophage infiltration. T.cp-MIF activated macrophages presenting M2b polarization after 48 h and played a role in inhibiting inflammation. Furthermore, based on the results of transcriptome data analysis and inhibition experiments, we demonstrate that this polarization is dependent on the involvement of the transcription factor C/EBPβ and its target gene SESN2. Our results demonstrated that the C/EBPβ-SESN2 axis plays an important regulatory role in T.cp-MIF-induced macrophage M2b polarization and it provides a new perspective for understanding the immune escape of ocular parasite infection.

Immunization with a Mu-class glutathione transferase from Echinococcus granulosus induces efficient antibody responses and confers long-term protection against secondary cystic echinococcosis

Cystic echinococcosis, a zoonosis caused by cestodes belonging to the Echinococcus granulosus sensu lato (s.l.) genetic complex, affects humans and diverse livestock species. Although a veterinary vaccine exhibiting high levels of antibody-mediated protection has successfully reached the market, the large genetic diversity among parasite isolates and their particular host preferences, makes still necessary the search for novel vaccine candidates. Glutathione transferases (GSTs) constitute attractive targets for immunoprophylaxis due to their outstanding relevance in helminth detoxification processes, against both exogenous and endogenous stressors. Among the six GSTs known to be expressed in E. granulosus s.l., EgGST1 (Mu-class), EgGST2 (Sigma-class), and EgGST3 (a still non-classifiable isoenzyme), show the highest proteomic expression. Therefore, their recombinant forms -rEgGST1, rEgGST2 and rEgGST3- were herein analyzed regarding their potential to induce long-term antiparasite protection in mice. Only immunization with rEgGST1 induced long-lasting protection; and accordingly, rEgGST1-specific antibodies enhanced the parasite killing through both the classical activation of the host complement system and the antibody-dependent cellular cytotoxicity by macrophages. These results support further testing of rEgGST1 as a vaccine candidate in diverse hosts due to the broad expression of EgGST1 in different parasite stages and tissues.

Host resources and parasite traits interact to determine the optimal combination of host parasite-mitigation strategies

Organisms have evolved diverse strategies to manage parasite infections. Broadly, hosts may avoid infection by altering behaviour, resist infection by targeting parasites or tolerate infection by repairing associated damage. The effectiveness of a strategy depends on interactions between, for example, resource availability, parasite traits (virulence, life-history) and the host itself (nutritional status, immunopathology). To understand how these factors shape host parasite-mitigation strategies, we developed a mathematical model of within-host, parasite-immune dynamics in the context of helminth infections. The model incorporated host nutrition and resource allocation to different mechanisms of immune response: larval parasite prevention; adult parasite clearance; damage repair (tolerance). We also considered a non-immune strategy: avoidance via anorexia, reducing intake of infective stages. Resources not allocated to immune processes promoted host condition, whereas harm due to parasites and immunopathology diminished it. Maximising condition (a proxy for fitness), we determined optimal host investment for each parasite-mitigation strategy, singly and combined, across different environmental resource levels and parasite trait values. Which strategy was optimal varied with scenario. Tolerance generally performed well, especially with high resources. Success of the different resistance strategies (larval prevention or adult clearance) tracked relative virulence of larval and adult parasites: slowly maturing, highly damaging larvae favoured prevention; rapidly maturing, less harmful larvae favoured clearance. Anorexia was viable only in the short term, due to reduced host nutrition. Combined strategies always outperformed any lone strategy: these were dominated by tolerance, with some investment in resistance. Choice of parasite mitigation strategy has profound consequences for hosts, impacting their condition, survival and reproductive success. We show that the efficacy of different strategies is highly dependent on timescale, parasite traits and resource availability. Models that integrate such factors can inform the collection and interpretation of empirical data, to understand how those drivers interact to shape host immune responses in natural systems.

Characterization of the immunosuppressive environment induced by larval Echinococcus granulosus during chronic experimental infection

The larval stage of Echinococcus granulosus causes the chronic infection known as cystic echinococcosis, deploying strong inhibitory mechanisms on host immune responses. Using experimental intraperitoneal infection in C57BL/6 mice, we carried out an in-depth analysis of the local changes in macrophage populations associated with chronic infection. In addition, we analyzed T cells and relevant soluble mediators. Infected animals showed an increase in local cell numbers, mostly accounted for by eosinophils, T cells, and macrophages. Within macrophage populations, the largest increases in cell numbers corresponded to resident large peritoneal macrophages (LPM). Monocyte recruitment appeared to be active, as judged by the increased number of monocytes and cells in the process of differentiation towards LPM, including small (SPM) and converting peritoneal macrophages (CPM). In contrast, we found no evidence of macrophage proliferation. Infection induced the expression of M2 markers in SPM, CPM, and LPM. It also enhanced the expression of the co-inhibitor PD-L1 in LPM, SPM, and CPM and induced the co-inhibitor PD-L2 in SPM and CPM. Therefore, local macrophages acquire M2-like phenotypes with probable suppressive capacities. Regarding T cells, infection induced an increase in the percentage of CD4+ cells that are PD-1+, which represent a potential target of suppression by PD-L1+/PD-L2+ macrophages. In possible agreement, CD4+ T cells from infected animals showed blunted proliferative responses to in vitro stimulation with anti-CD3. Further evidence of immune suppression in the parasite vicinity arose from the observation of an expansion in FoxP3+ CD4+ regulatory T cells and increases in the local concentrations of the anti-inflammatory cytokines TGF-β and IL-1Ra.

The knowns and unknowns of helminth-host miRNA cross-kingdom communication

MicroRNAs (miRNAs) are small noncoding RNAs that oversee gene modulation. They are integral to cellular functions and can migrate between species, leading to cross-kingdom gene suppression. Recent breakthroughs in helminth genome studies have sparked curiosity about helminth RNA regulators and their ability to regulate genes across species. Growing data indicate that helminth miRNAs have a significant impact on the host's immune system. Specific miRNAs from helminth parasites can merge with the host's miRNA system, implying that parasites could exploit their host's regulatory machinery and function. This review highlights the role of cross-kingdom helminth-derived miRNAs in the interplay between host and parasite, exploring potential routes for their uptake, processing, and consequences in host interaction.

Ultra-structure, genetic characterization and Immunological approach of fish borne zoonotic trematodes (Family: Heterophyidae) of a redbelly tilapia

Fish-borne zoonotic trematodes (FBZT) are highly significant zoonotic trematodes that can infect humans by eating raw or undercooked fish harboring active metacercaria. In this investigation, FBZT was found in samples of widely cultivated redbelly tilapia (Tilapia zillii) obtained from the Fayum governorate. Encysted metacercaria (EMC) infection was identified in fish belonging to the heterophyid family morphologically. The prevalence of heterophyid EMC was 30.5%. EMC was identified and implemented in a subsequent study on domestic pigeons (Columba livia domestica) carried out to allow adult flukes of Pygidiopsis (P.) genata; P. summa; and Ascocotyle (A.) pindoramensis species in their small intestine. This study presents the first report that combines ultra-structure, molecular approach of three species of heterophyid flukes, ultra-structure using transmission electron microscope in P. genata, and the study of host immunological responses and associated cytokines during Pygidiopsis species infection of pigeons in Egypt. Using Quantitative Real-time PCR (qRT- PCR), the gene expression levels of six cytokines (IL-1, IL-2, IL-6, IL-10, IFN-γ and TGF-β3) were assessed. The molecular confirmation of P. genata, P. summa, and A. pindoramensis have a registration in the GenBank under accession number MT672308.1, OR083433.1, and OR083431.1, respectively. Throughout the infection, the gut produced cytokines in considerably variable amounts. As a result of the Pygidiopsis species infection in pigeons, our data showed distinctive cytokine alterations, which could aid in figuring out the immunological pathogenesis and host defense mechanism against this infection. This study focused on different types of fish-borne trematodes, particularly the zoonotically important ones.

The Roles of Various Immune Cell Populations in Immune Response against Helminths

Helminths are multicellular parasites that are a substantial problem for both human and veterinary medicine. According to estimates, 1.5 billion people suffer from their infection, resulting in decreased life quality and burdens for healthcare systems. On the other hand, these infections may alleviate autoimmune diseases and allergy symptoms. The immune system is programmed to combat infections; nevertheless, its effector mechanisms may result in immunopathologies and exacerbate clinical symptoms. This review summarizes the role of the immune response against worms, with an emphasis on the Th2 response, which is a hallmark of helminth infections. We characterize non-immune cells (enteric tuft cells-ETCs) responsible for detecting parasites, as well as the role of hematopoietic-derived cells (macrophages, basophils, eosinophils, neutrophils, innate lymphoid cells group 2-ILC2s, mast cells, T cells, and B cells) in initiating and sustaining the immune response, as well as the functions they play in granulomas. The aim of this paper is to review the existing knowledge regarding the immune response against helminths, to attempt to decipher the interactions between cells engaged in the response, and to indicate the gaps in the current knowledge.

Exposure to lung-migrating helminth protects against murine SARS-CoV-2 infection through macrophage-dependent T cell activation

Helminth endemic regions report lower COVID-19 morbidity and mortality. Here, we show that lung remodeling from a prior infection with a lung-migrating helminth, Nippostrongylus brasiliensis, enhances viral clearance and survival of human-ACE2 transgenic mice challenged with SARS-CoV-2 (SCV2). This protection is associated with a lymphocytic infiltrate, including increased accumulation of pulmonary SCV2-specific CD8+ T cells, and anti-CD8 antibody depletion abrogated the N. brasiliensis-mediated reduction in viral loads. Pulmonary macrophages with a type 2 transcriptional and epigenetic signature persist in the lungs of N. brasiliensis-exposed mice after clearance of the parasite and establish a primed environment for increased CD8+ T cell recruitment and activation. Accordingly, depletion of macrophages ablated the augmented viral clearance and accumulation of CD8+ T cells driven by prior N. brasiliensis infection. Together, these findings support the concept that lung-migrating helminths can limit disease severity during SCV2 infection through macrophage-dependent enhancement of antiviral CD8+ T cell responses.

How do parasitic worms prevent diabetes? An exploration of their influence on macrophage and β-cell crosstalk

Diabetes is the fastest growing chronic disease globally, with prevalence increasing at a faster rate than heart disease and cancer. While the disease presents clinically as chronic hyperglycaemia, two distinct subtypes have been recognised. Type 1 diabetes (T1D) is characterised as an autoimmune disease in which the insulin-producing pancreatic β-cells are destroyed, and type 2 diabetes (T2D) arises due to metabolic insufficiency, in which inadequate amounts of insulin are produced, and/or the actions of insulin are diminished. It is now apparent that pro-inflammatory responses cause a loss of functional β-cell mass, and this is the common underlying mechanism of both T1D and T2D. Macrophages are the central immune cells in the pathogenesis of both diseases and play a major role in the initiation and perpetuation of the proinflammatory responses that compromise β-cell function. Furthermore, it is the crosstalk between macrophages and β-cells that orchestrates the inflammatory response and ensuing β-cell dysfunction/destruction. Conversely, this crosstalk can induce immune tolerance and preservation of β-cell mass and function. Thus, specifically targeting the intercellular communication between macrophages and β-cells offers a unique strategy to prevent/halt the islet inflammatory events underpinning T1D and T2D. Due to their potent ability to regulate mammalian immune responses, parasitic worms (helminths), and their excretory/secretory products, have been examined for their potential as therapeutic agents for both T1D and T2D. This research has yielded positive results in disease prevention, both clinically and in animal models. However, the focus of research has been on the modulation of immune cells and their effectors. This approach has ignored the direct effects of helminths and their products on β-cells, and the modulation of signal exchange between macrophages and β-cells. This review explores how the alterations to macrophages induced by helminths, and their products, influence the crosstalk with β-cells to promote their function and survival. In addition, the evidence that parasite-derived products interact directly with endocrine cells to influence their communication with macrophages to prevent β-cell death and enhance function is discussed. This new paradigm of two-way metabolic conversations between endocrine cells and macrophages opens new avenues for the treatment of immune-mediated metabolic disease.

The local skin cellular immune response determines the clinical outcome of sarcoptic mange in Iberian ibex (Capra pyrenaica)

Introduction

Sarcoptic mange, caused by Sarcoptes scabiei, is a disease with implications for wildlife conservation and management. Its severity depends on the host's local skin immune response, which is largely unknown in Iberian ibex (Capra pyrenaica), a mountain ungulate dramatically affected by mange. In this species, the clinical outcome of sarcoptic mange varies among individuals, and the local immune response could be key to controlling the infestation. This study aims to characterize the local cellular immune response and its relationship with the clinical outcome.

Methods

Fourteen Iberian ibexes were experimentally infested with S. scabiei and six more served as controls. Clinical signs were monitored, and skin biopsies were collected from the withers at 26, 46, and 103 days post-infection (dpi). The presence and distribution of macrophages (including M1 and M2 phenotypes), T lymphocytes, B lymphocytes, plasma cells, and interleukine 10 were quantitatively evaluated using immunohistochemical techniques.

Results

An inflammatory infiltrate that decreased significantly from 26 to 103 dpi was observed in all the infested ibexes. The predominant inflammatory cell population in the skin of the mangy ibexes was formed by macrophages (mainly the M2 phenotype) followed by T lymphocytes, with lower numbers of B lymphocytes and plasma cells. Three clinical courses were identified: total recovery, partial recovery, and terminal stage. The inflammatory infiltrates were less pronounced in the fully recovered ibexes than in those that progressed to the terminal stage throughout the study.

Discussion

The results suggest an exacerbated but effective Th1-type cellular immune response controlling mange in Iberian ibex. Furthermore, the local immune response appears to determine the variability of the clinical responses to S. scabiei infestation in this species. This first report on the progression of local skin immune cells is relevant not only for individuals but also for population management and conservation.

Single-Cell RNA Sequencing Reveals Microevolution of the Stickleback Immune System

The risk and severity of pathogen infections in humans, livestock, or wild organisms depend on host immune function, which can vary between closely related host populations or even among individuals. This immune variation can entail between-population differences in immune gene coding sequences, copy number, or expression. In recent years, many studies have focused on population divergence in immunity using whole-tissue transcriptomics. But, whole-tissue transcriptomics cannot distinguish between evolved differences in gene regulation within cells, versus changes in cell composition within the focal tissue. Here, we leverage single-cell transcriptomic approaches to document signatures of microevolution of immune system structure in a natural system, the three-spined stickleback (Gasterosteus aculeatus). We sampled nine adult fish from three populations with variability in resistance to a cestode parasite, Schistocephalus solidus, to create the first comprehensive immune cell atlas for G. aculeatus. Eight broad immune cell types, corresponding to major vertebrate immune cells, were identified. We were also able to document significant variation in both abundance and expression profiles of the individual immune cell types among the three populations of fish. Furthermore, we demonstrate that identified cell type markers can be used to reinterpret traditional transcriptomic data: we reevaluate previously published whole-tissue transcriptome data from a quantitative genetic experimental infection study to gain better resolution relating infection outcomes to inferred cell type variation. Our combined study demonstrates the power of single-cell sequencing to not only document evolutionary phenomena (i.e., microevolution of immune cells) but also increase the power of traditional transcriptomic data sets.

Co-Treatment with Human Leukocyte Extract and Albendazole Stimulates Drug's Efficacy and Th1 Biased Immune Response in Mesocestoides vogae (Cestoda) Infection via Modulation of Transcription Factors, Macrophage Polarization, and Cytokine Profiles

The model flatworm Mesocestoides vogae proliferating stage of infection elicits immunosuppression in the host. It was used to investigate the effects of human leukocyte extract (DLE) alone and in combination with anthelmintic albendazole (ABZ) on the reduction in peritoneal infection, peritoneal exudate cells (PECs), their adherent counterparts, and peritoneal exudates after the termination of therapy. Balb/c mice were infected with the larvae of M. vogae. PECs and adherent macrophages were studied via flow cytometry, mRNA transcript levels, and immunofluorescence. The cytokine levels were measured via ELISA and larvae were counted. ABZ significantly reduced larval counts (581.2 ± 65, p < 0.001), but the highest reduction was observed after combined treatment with ABZ and DLE (389.2 ± 119, p < 0.001) in comparison with the control. Compared to an infected group, the proportions of CD11b+CD19- myeloid cells with suppressive ability decreased after albendazole (ABZ) in combination with DLE, which was the most effective in the elevation of B cells and CD11b+F4/80^mid/highMHCII^high macrophages/monocytes (22.2 ± 5.4%). Transcripts of the M2 macrophage markers (arginase 1, FIZZ-1, and Ym-1) were downregulated after DLE and combined therapy but not after ABZ, and the opposite trend was seen for iNOS. This contrasts with reduced ex vivo NO production by LPS-stimulated PECs from DLE and ABZ+DLE groups, where adherent macrophages/monocytes had elevated transcripts of the INF-γ receptor and STAT1 and reduced expression of STAT3, STAT6, and IL-10. Each therapy differentially modulated transcription profiles and concentrations of IFN-γ, TNF-α, IL-12p40, IL-6, IL-10, and TGF-β cytokines. DLE strongly ameliorated ABZ-induced suppression of INF-γ and IL-12 and preserved downregulation for IL-4, IL-10, and TGF-β. Epigenetic study on adherent macrophages from infected mice showed that ABZ, ABZ-sulfoxide, and DLE could interact with the mRNA of examined markers in a dose-dependent pattern. Co-administration of DLE with ABZ seemed to augment the drug's larvicidal effect via modulation of immunity. In comparison with ABZ, combined therapy was the most effective in alleviating parasite-induced Th2/Treg/STAT3/STA6 directed immunosuppression by stimulating the Th1 cytokines, M1 macrophage polarization, and activation of the IFNγ/STAT1 signaling pathway.

Communication is key: Innate immune cells regulate host protection to helminths

Parasitic helminth infections remain a significant global health issue and are responsible for devastating morbidity and economic hardships. During infection, helminths migrate through different host organs, which results in substantial tissue damage and the release of diverse effector molecules by both hematopoietic and non-hematopoietic cells. Thus, host protective responses to helminths must initiate mechanisms that help to promote worm clearance while simultaneously mitigating tissue injury. The specialized immunity that promotes these responses is termed type 2 inflammation and is initiated by the recruitment and activation of hematopoietic stem/progenitor cells, mast cells, basophils, eosinophils, dendritic cells, neutrophils, macrophages, myeloid-derived suppressor cells, and group 2 innate lymphoid cells. Recent work has also revealed the importance of neuron-derived signals in regulating type 2 inflammation and antihelminth immunity. These studies suggest that multiple body systems coordinate to promote optimal outcomes post-infection. In this review, we will describe the innate immune events that direct the scope and intensity of antihelminth immunity. Further, we will highlight the recent progress made in our understanding of the neuro-immune interactions that regulate these pathways and discuss the conceptual advances they promote.

Immune pathogenesis in pigeons during experimental Prohemistomum vivax infection

Prohemistomum vivax is a small trematode belonging to the family Cyathocotylidae, infecting fish-eating birds and mammals, including humans. However, no data on molecular identification and immune pathogenesis are available, challenging effective diagnostic and therapeutic interventions. Here, we identified P. vivax based on combined morphological and molecular data and examined histopathological lesions and the differential cytokines expression in experimentally infected pigeons. Pigeons were orally infected with 500 prohemistomid metacercariae. Intestinal and spleen tissues were harvested 2, 4, 7, 14, 21, and 28 days post-infection (dpi). Gene expression levels of eleven cytokines (IL-1, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12, IL-15, IL-18, IFN-γ, and TGF-β3) were assessed using quantitative reverse-transcription PCR (RT-qPCR). We identified the recovered flukes as Prohemistomum vivax based on morphological features and the sequence and phylogenetic analysis of the internal transcribed spacer 1 (ITS1), 5.8 ribosomal RNA, and ITS2 region. Histopathological lesions were induced as early as 2 dpi, with the intensity of villi atrophy and inflammatory cell infiltration increasing as the infection progressed. An early immunosuppressive state (2 and 4 dpi), with TGF-β3 overexpression, developed to allow parasite colonization. A mixed Th1/Th2 immune response (overexpressed IFN-γ, IL-12, IL-2, IL-4, and IL-5) was activated as the infection progressed from 7 to 28 dpi. Inflammatory cytokines (IL-1, IL-6, IL-18, and IL-15) were generally overexpressed at 7–28 dpi, peaking at 7 or 14 dpi. The upregulated Treg IL-10 expression peaking between 21 and 28 dpi might promote the Th1/Th2 balance and immune homeostasis to protect the host from excessive tissue pathology and inflammation. The intestine and spleen expressed a significantly different relative quantity of cytokines throughout the infection. To conclude, our results presented distinct cytokine alteration throughout P. vivax infection in pigeons, which may aid in understanding the immune pathogenesis and host defense mechanism against this infection.

The role of IgA in gastrointestinal helminthiasis: A systematic review

Immunoglobulin-A (IgA) is an important mediator of immunity and has been associated with protection against several pathogens, although its role in gastrointestinal infections remains unclear. Then, the aim of this systematic review was to synthesize qualitative evidence in respect of IgA as mediator of protective immunity against gastrointestinal helminths. Following recommended guidelines, we searched for articles published between January 1990 and October 2019 that evaluated IgA levels and their association with gastrointestinal helminth infections. Twenty-five articles were included after screening 1,546 titles and abstracts, as well as reading in full 52 selected articles. Consistent associations between higher IgA levels and lower parasitological parameters were only found in mice, rats, and sheep. However, the role of IgA in other host species remains uncertain, making it difficult to create a consensus. Therefore, it is too soon to claim that IgA is an effective protective factor against gastrointestinal helminths, and further studies are still needed.

Exploring the role of macrophages in determining the pathogenesis of liver fluke infection

The food-borne trematodes, Opisthorchis viverrini and Clonorchis sinensis, are classified as group 1 biological carcinogens: definitive causes of cancer. By contrast, infections with Fasciola hepatica, also a food-borne trematode of the phylum Platyhelminthes, are not carcinogenic. This review explores the premise that the differential activation of macrophages during infection with these food-borne trematodes is a major determinant of the pathological outcome of infection. Like most helminths, the latter stages of infection with all 3 flukes induce M2 macrophages, a phenotype that mediates the functional repair of tissue damaged by the feeding and migratory activities of the parasites. However, there is a critical difference in how the development of pro-inflammatory M1 macrophages is regulated during infection with these parasites. While the activation of the M1 macrophage phenotype is largely suppressed during the early stages of infection with F. hepatica, M1 macrophages predominate in the bile ducts following infection with O. viverrini and C. sinensis. The anti-microbial factors released by M1 macrophages create an environment conducive to mutagenesis, and hence the initiation of tumour formation. Subsequently, the tissue remodelling processes induced by the M2 macrophages promote the proliferation of mutated cells, and the expansion of cancerous tissue. This review will also explore the interactions between macrophages and parasite-derived signals, and their contributions to the stark differences in the innate immune responses to infection with these parasites.

RNA sequencing reveals dynamic expression of spleen lncRNAs and mRNAs in Beagle dogs infected by Toxocara canis

BACKGROUND

Toxocara canis is a cosmopolitan parasite with a significant adverse impact on the health of humans and animals. The spleen is a major immune organ that plays essential roles in protecting the host against various infections. However, its role in T. canis infection has not received much attention.

METHODS

We performed sequencing-based transcriptome profiling of long noncoding RNA (lncRNA) and messenger RNA (mRNA) expression in the spleen of Beagle puppies at 24 h post-infection (hpi), 96 hpi and 36 days post-infection (dpi). Deep sequencing of RNAs isolated from the spleen of six puppies (three infected and three control) at each time point after infection was conducted.

RESULTS

Our analysis revealed 614 differentially expressed (DE) lncRNAs and 262 DEmRNAs at 24 hpi; 726 DElncRNAs and 878 DEmRNAs at 96 hpi; and 686 DElncRNAs and 504 DEmRNAs at 36 dpi. Of those, 35 DElncRNA transcripts and 11 DEmRNAs were detected at all three time points post-infection. Many DE genes were enriched in immune response, such as ifit1, ifit2 and rorc. Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed that some genes (e.g. prkx and tnfrsf11a) were involved in the T cell receptor signaling pathway, calcium signaling pathway, Ras signaling pathway and NF-κB signaling pathway.

CONCLUSIONS

The findings of this study show marked alterations in the expression profiles of spleen lncRNAs and mRNAs, with possible implications in the pathophysiology of toxocariasis.

The IL-25-dependent tuft cell circuit driven by intestinal helminths requires macrophage migration inhibitory factor (MIF)

Macrophage migration inhibitory factor (MIF) is a key innate immune mediator with chemokine- and cytokine-like properties in the inflammatory pathway. While its actions on macrophages are well-studied, its effects on other cell types are less understood. Here we report that MIF is required for expansion of intestinal tuft cells during infection with the helminth Nippostrongylus brasiliensis. MIF-deficient mice show defective innate responses following infection, lacking intestinal epithelial tuft cell hyperplasia or upregulation of goblet cell RELMβ, and fail to expand eosinophil, type 2 innate lymphoid cell (ILC2) and macrophage (M2) populations. Similar effects were observed in MIF-sufficient wild-type mice given the MIF inhibitor 4-IPP. MIF had no direct effect on epithelial cells in organoid cultures, and MIF-deficient intestinal stem cells could generate tuft cells in vitro in the presence of type 2 cytokines. In vivo the lack of MIF could be fully compensated by administration of IL-25, restoring tuft cell differentiation and goblet cell expression of RELM-β, demonstrating its requirement upstream of the ILC2-tuft cell circuit. Both ILC2s and macrophages expressed the MIF receptor CXCR4, indicating that MIF may act as an essential co-factor on both cell types to activate responses to IL-25 in helminth infection.

Dynamic changes of macrophage activation in mice infected with Trichinella spiralis

Trichinellosis is a serious food-borne parasitic zoonosis worldwide. Different host macrophage subsets play various roles during helminth infection; however, the dynamic changes in macrophage subsets following Trichinella spiralis infection have not been reported. Here, flow cytometry and immunofluorescence were used to assess macrophage activation in mesenteric lymph nodes (MLN), spleen, intestine, and muscle from T. spiralis-infected mice at 1, 5, 15, and 30 days post infection (dpi). Macrophages in the intestine, MLN, and spleen tended to be activated M1-type at 1 and 5 dpi, while at 15 dpi, M2-type macrophages started to become a major constituent of the spleen macrophage population, and in the intestine and MLN, macrophages were primarily mixed M1 and M2 type. At 30 dpi, macrophages in the intestine, muscle, MLN, and spleen were all mainly activated M2 cells. Additionally, mouse macrophages were cleared and the adult T. spiralis load were determined to evaluate the impact of macrophages on adult parasite expulsion. The results suggested that predominantly M1 macrophages contribute to adult T. spiralis expulsion in the enteral stage of infection. At the newborn larvae migration stage, M2 macrophage-mediated immunity had a weak scavenging effect on adults, but primarily promoted tissue repair and assisted muscle larva immune escape. Our study reveals further details of the interaction between T. spiralis and the host immune system.

Host Liver-Derived Extracellular Vesicles Deliver miR-142a-3p Induces Neutrophil Extracellular Traps via Targeting WASL to Block the Development of Schistosoma japonicum

Schistosomiasis is an important neglected tropical disease. Interactions between the host immune system and schistosomes are complex. Neutrophils contribute to clearance of large pathogens primarily by releasing neutrophil extracellular traps (NETs). However, the functional role of NETs in clearing schistosomes remains unclear. Herein, we report that extracellular vesicles (EVs) derived from the liver of Schistosoma japonicum-infected mice (IL-EVs) induce NET release by delivering miR-142a-3p to target WASL and block the development of S. japonicum. WASL knockout accelerated the formation of NETs that blocked further development of S. japonicum. miR-142a-3p and NETs upregulated the expression of CCL2, which recruits macrophages that block S. japonicum development. However, S. japonicum inhibited NET formation in wild-type mice by upregulating host interleukin-10 (IL-10) expression. In contrast, in WASL knockout mice, IL-10 expression was downregulated, and S. japonicum-mediated inhibition of NET formation was significantly reduced. IL-EV-mediated induction of NET formation is thus an anti-schistosome response that can be counteracted by S. japonicum. These findings suggest that IL-EV-mediated induction of NET formation plays a key role in schistosome infection and that WASL is a potential therapeutic target in schistosomiasis and other infectious diseases.

Helminth and Host Crosstalk: New Insight Into Treatment of Obesity and Its Associated Metabolic Syndromes

Obesity and its associated Metabolic Syndromes (Mets) represent a global epidemic health problem. Metabolic inflammation, lipid accumulation and insulin resistance contribute to the progression of these diseases, thereby becoming targets for drug development. Epidemiological data have showed that the rate of helminth infection negatively correlates with the incidence of obesity and Mets. Correspondingly, numerous animal experiments and a few of clinic trials in human demonstrate that helminth infection or its derived molecules can mitigate obesity and Mets via induction of macrophage M2 polarization, inhibition of adipogenesis, promotion of fat browning, and improvement of glucose tolerance, insulin resistance and metabolic inflammation. Interestingly, sporadic studies also uncover that several helminth infections can reshape gut microbiota of hosts, which is intimately implicated in the pathogenesis of obesity and Mets. Overall, these findings indicate that the crosstalk between helminth and hosts may be a novel direction for obesity and Mets therapy. The present article reviews the molecular mechanism of how helminth masters immunity and metabolism in obesity.

Nematode Orthologs of Macrophage Migration Inhibitory Factor (MIF) as Modulators of the Host Immune Response and Potential Therapeutic Targets

One of the adaptations of nematodes, which allows long-term survival in the host, is the production of proteins with immunomodulatory properties. The parasites secrete numerous homologs of human immune mediators, such as macrophage migration inhibitory factor (MIF), which is a substantial regulator of the inflammatory immune response. Homologs of mammalian MIF have been recognized in many species of nematode parasites, but their role has not been fully understood. The application of molecular biology and genetic engineering methods, including the production of recombinant proteins, has enabled better characterization of their structure and properties. This review provides insight into the current state of knowledge on MIF homologs produced by nematodes, as well as their structure, enzymatic activity, tissue expression pattern, impact on the host immune system, and potential use in the treatment of parasitic, inflammatory, and autoimmune diseases.

cGAS exacerbates Schistosoma japonicum infection in a STING-type I IFN-dependent and independent manner

Schistosomiasis, which is caused by infection with Schistosoma spp., is characterized by granuloma and fibrosis in response to egg deposition. Pattern recognition receptors are important to sense invading Schistosoma, triggering an innate immune response, and subsequently shaping adaptive immunity. Cyclic GMP-AMP synthase (cGAS) was identified as a major cytosolic DNA sensor, which catalyzes the formation of cyclic GMP-AMP (cGAMP), a critical second messenger for the activation of the adaptor protein stimulator of interferon genes (STING). The engagement of STING by cGAMP leads to the activation of TANK-binding kinase 1 (TBK1), interferon regulatory factor 3 (IRF3), and the subsequent type I interferon (IFN) response. cGAS is suggested to regulate infectious diseases, autoimmune diseases, and cancer. However, the function of cGAS in helminth infection is unclear. In this study, we found that Cgas deficiency enhanced the survival of mice infected with S. japonicum markedly, without affecting the egg load in the liver. Consistently, Cgas deletion alleviated liver pathological impairment, reduced egg granuloma formation, and decreased fibrosis severity. In contrast, Sting deletion reduced the formation of egg granulomas markedly, but not liver fibrosis. Notably, Cgas or Sting deficiency reduced the production of IFNβ drastically in mice infected with S. japonicum. Intriguingly, intravenous administration of recombinant IFNβ exacerbated liver damage and promoted egg granuloma formation, without affecting liver fibrosis. Clodronate liposome-mediated depletion of macrophages indicated that macrophages are the major type of cells contributing to the induction of the type I IFN response during schistosome infection. Moreover, cGAS is important for type I IFN production and phosphorylation of TBK1 and IRF3 in response to stimulation with S. japonicum egg- or adult worm-derived DNA in macrophages. Our results clarified the immunomodulatory effect of cGAS in the regulation of liver granuloma formation during S. japonicum infection, involving sensing schistosome-derived DNA and producing type I IFN. Additionally, we showed that cGAS regulates liver fibrosis in a STING-type I–IFN-independent manner.

The sensing of invading pathogens by pattern recognition receptors (PRRs) is important for the host to mount an immune response. Cytosolic DNA receptor cGAS has been documented as critical for the induction of innate immunity, manifesting as a type I IFN response. However, little is known about the role of cGAS or type I IFN in the process of helminth infection. In this study, we identified an important role of the cGAS-STING-type I IFN signaling axis in driving schistosome infection-induced liver inflammation. Moreover, we revealed a hitherto unknown role of cGAS in the regulation of liver fibrosis during Schistosoma infection, a process that is independent of STING. Our study revealed cGAS as a novel functional receptor for the recognition of invading Schistosoma, paving the way for the development of novel strategies to treat schistosomiasis.

IL-33: A central cytokine in helminth infections

IL-33 is an alarmin cytokine which has been implicated in allergy, fibrosis, inflammation, tumorigenesis, metabolism, and homeostasis. However, amongst its strongest roles are in helminth infections, where IL-33 usually (but not always) is central to induction of an effective anti-parasitic immune response. In this review, we will summarise the literature around this fascinating cytokine, its activity on immune and non-immune cells, the unique (and sometimes counterintuitive) responses it induces, and how it can coordinate the immune response during infections by parasitic helminths. Finally, we will summarise some of the ways that parasites have developed to modulate the IL-33 pathway for their own benefit.

Basophils in antihelminth immunity

It has been appreciated that basophilia is a common feature of helminth infections for approximately 50 years. The ability of basophils to secrete IL-4 and other type 2 cytokines has supported the prevailing notion that basophils contribute to antihelminth immunity by promoting optimal type 2 T helper (Th2) cell responses. While this appears to be the case in several helminth infections, emerging studies are also revealing that the effector functions of basophils are extremely diverse and parasite-specific. Further, new reports now suggest that basophils can restrict type 2 inflammation in a manner that preserves the integrity of helminth-affected tissue. Finally, exciting data has also demonstrated that basophils can regulate inflammation by participating in neuro-immune interactions. This article will review the current state of basophil biology and describe how recent studies are transforming our understanding of the role basophils play in the context of helminth infections.

IL-33-induced metabolic reprogramming controls the differentiation of alternatively activated macrophages and the resolution of inflammation

Alternatively activated macrophages (AAMs) contribute to the resolution of inflammation and tissue repair. However, molecular pathways that govern their differentiation have remained incompletely understood. Here, we show that uncoupling protein-2-mediated mitochondrial reprogramming and the transcription factor GATA3 specifically controlled the differentiation of pro-resolving AAMs in response to the alarmin IL-33. In macrophages, IL-33 sequentially triggered early expression of pro-inflammatory genes and subsequent differentiation into AAMs. Global analysis of underlying signaling events revealed that IL-33 induced a rapid metabolic rewiring of macrophages that involved uncoupling of the respiratory chain and increased production of the metabolite itaconate, which subsequently triggered a GATA3-mediated AAM polarization. Conditional deletion of GATA3 in mononuclear phagocytes accordingly abrogated IL-33-induced differentiation of AAMs and tissue repair upon muscle injury. Our data thus identify an IL-4-independent and GATA3-dependent pathway in mononuclear phagocytes that results from mitochondrial rewiring and controls macrophage plasticity and the resolution of inflammation.

Eosinophils mediate SIgA production triggered by TLR2 and TLR4 to control Ascaris suum infection in mice

Human ascariasis is the most prevalent but neglected tropical disease in the world, affecting approximately 450 million people. The initial phase of Ascaris infection is marked by larval migration from the host's organs, causing mechanical injuries followed by an intense local inflammatory response, which is characterized mainly by neutrophil and eosinophil infiltration, especially in the lungs. During the pulmonary phase, the lesions induced by larval migration and excessive immune responses contribute to tissue remodeling marked by fibrosis and lung dysfunction. In this study, we investigated the relationship between SIgA levels and eosinophils. We found that TLR2 and TLR4 signaling induces eosinophils and promotes SIgA production during Ascaris suum infection. Therefore, control of parasite burden during the pulmonary phase of ascariasis involves eosinophil influx and subsequent promotion of SIgA levels. In addition, we also demonstrate that eosinophils also participate in the process of tissue remodeling after lung injury caused by larval migration, contributing to pulmonary fibrosis and dysfunction in re-infected mice. In conclusion, we postulate that eosinophils play a central role in mediating host innate and humoral immune responses by controlling parasite burden, tissue inflammation, and remodeling during Ascaris suum infection. Furthermore, we suggest that the use of probiotics can induce eosinophilia and SIgA production and contribute to controlling parasite burden and morbidity of helminthic diseases with pulmonary cycles.

Fc-conjugated C-type lectin receptors: Tools for understanding host-pathogen interactions

The use of soluble fusion proteins of pattern recognition receptors (PRRs) used in the detection of exogenous and endogenous ligands has helped resolve the roles of PRRs in the innate immune response to pathogens, how they shape the adaptive immune response, and function in maintaining homeostasis. Using the immunoglobulin (Ig) crystallizable fragment (Fc) domain as a fusion partner, the PRR fusion proteins are soluble, stable, easily purified, have increased affinity due to the Fc homodimerization properties, and consequently have been used in a wide range of applications such as flow cytometry, screening of protein and glycan arrays, and immunofluorescent microscopy. This review will predominantly focus on the recognition of pathogens by the cell membrane-expressed glycan-binding proteins of the C-type lectin receptor (CLR) subgroup of PRRs. PRRs bind to conserved pathogen-associated molecular patterns (PAMPs), such as glycans, usually located within or on the outer surface of the pathogen. Significantly, many glycans structures are identical on both host and pathogen (e.g. the Lewis (Le) X glycan), allowing the use of Fc CLR fusion proteins with known endogenous and/or exogenous ligands as tools to identify pathogen structures that are able to interact with the immune system. Screens of highly purified pathogen-derived cell wall components have enabled identification of many unique PAMP structures recognized by CLRs. This review highlights studies using Fc CLR fusion proteins, with emphasis on the PAMPs found in fungi, bacteria, viruses, and parasites. The structure and unique features of the different CLR families is presented using examples from a broad range of microbes whenever possible.

Roles of TLR7 in Schistosoma japonicum Infection-Induced Hepatic Pathological Changes in C57BL/6 Mice

S. japonicum infection can induce granulomatous inflammation in the liver of the host. Granulomatous inflammation limits the spread of infection and plays a role in host protection. Toll-like receptor 7 (TLR7) is an endosomal TLR that recognizes single-stranded RNA (ssRNA). In this study, the role of TLR7 in S. japonicum infection-induced hepatitis was investigated in both normal and TLR7 knockout (KO) C57BL/6 mice. The results indicated that TLR7 KO could aggravate S. japonicum infection-induced damage in the body, with less granuloma formation in the tissue, lower WBCs in blood, and decreased ALT and AST in the serum. Then, the expression of TLR7 was detected in isolated hepatic lymphocytes. The results indicated that the percentage of TLR7⁺ cells was increased in the infected mice. Hepatic macrophages, DCs, and B cells could express TLR7, and most of the TLR7-expressing cells in the liver of infected mice were macrophages. The percentage of TLR7-expressing macrophages was also increased after infection. Moreover, macrophages, T cells, and B cells showed significant changes in the counts, activation-associated molecule expression, and cytokine secretion between S. japonicum-infected WT and TLR7 KO mice. Altogether, this study indicated that TLR7 could delay the progression of S. japonicum infection-induced hepatitis mainly through macrophages. DCs, B cells, and T cells were involved in the TLR7-mediated immune response.

Trichuris muris Model: Role in Understanding Intestinal Immune Response, Inflammation and Host Defense

Several parasites have evolved to survive in the human intestinal tract and over 1 billion people around the world, specifically in developing countries, are infected with enteric helminths. Trichuris trichiura is one of the world’s most common intestinal parasites that causes human parasitic infections. Trichuris muris, as an immunologically well-defined mouse model of T. trichiura, is extensively used to study different aspects of the innate and adaptive components of the immune system. Studies on T. muris model offer insights into understanding host immunity, since this parasite generates two distinct immune responses in resistant and susceptible strains of mouse. Apart from the immune cells, T. muris infection also influences various components of the intestinal tract, especially the gut microbiota, mucus layer, epithelial cells and smooth muscle cells. Here, we reviewed the different immune responses generated by innate and adaptive immune components during acute and chronic T. muris infections. Furthermore, we discussed the importance of studying T. muris model in understanding host–parasite interaction in the context of alteration in the host’s microbiota, intestinal barrier, inflammation, and host defense, and in parasite infection-mediated modulation of other immune and inflammatory diseases.

Intestinal transcriptomes in Kazakh sheep with different haplotypes after experimental Echinococcus granulosus infection

Cystic echinococcosis (CE) is a chronic zoonosis caused by infection with the larval stage of the cestode Echinococcus granulosus. As the intermediate host, sheep are highly susceptible to this disease. Our previous studies have shown that sheep with haplotype MHC Mva Ibc-Sac IIab-Hin1I ab were resistant to CE infection, while their counterparts without this haplotype were not. In order to reveal the molecular mechanism of resistance in Kazakh sheep, after selecting the differential miRNA in our previous study, herein, transcriptome analyses were conducted to detect the differential expression genes in the intestinal tissue of Kazakh sheep with resistant and non-resistant MHC haplotypes, after peroral infection with E. granulosus eggs. A total of 3835 differentially expressed genes were identified between the two groups, with 2229 upregulated and 1606 downregulated. Further function analysis showed that the most significant genes were related to both innate immune response and adaptive response participating in the defense against E. granulosus infection and the metabolic changes associated with it. The results suggest that genes related to lectin receptors, NK cells activation, chemokines, and tumor necrosis factor, may play important roles in the response of intestinal tissue to E. granulosus.

The Two Faces of Nematode Infection: Virulence and Immunomodulatory Molecules From Nematode Parasites of Mammals, Insects and Plants

Helminths stage a powerful infection that allows the parasite to damage host tissue through migration and feeding while simultaneously evading the host immune system. This feat is accomplished in part through the release of a diverse set of molecules that contribute to pathogenicity and immune suppression. Many of these molecules have been characterized in terms of their ability to influence the infectious capabilities of helminths across the tree of life. These include nematodes that infect insects, known as entomopathogenic nematodes (EPN) and plants with applications in agriculture and medicine. In this review we will first discuss the nematode virulence factors, which aid parasite colonization or tissue invasion, and cause many of the negative symptoms associated with infection. These include enzymes involved in detoxification, factors essential for parasite development and growth, and highly immunogenic ES proteins. We also explore how these parasites use several classes of molecules (proteins, carbohydrates, and nucleic acids) to evade the host's immune defenses. For example, helminths release immunomodulatory molecules in extracellular vesicles that may be protective in allergy and inflammatory disease. Collectively, these nematode-derived molecules allow parasites to persist for months or even years in a host, avoiding being killed or expelled by the immune system. Here, we evaluate these molecules, for their individual and combined potential as vaccine candidates, targets for anthelminthic drugs, and therapeutics for allergy and inflammatory disease. Last, we evaluate shared virulence and immunomodulatory mechanisms between mammalian and non-mammalian plant parasitic nematodes and EPNs, and discuss the utility of EPNs as a cost-effective model for studying nematode-derived molecules. Better knowledge of the virulence and immunomodulatory molecules from both entomopathogenic nematodes and soil-based helminths will allow for their use as beneficial agents in fighting disease and pests, divorced from their pathogenic consequences.

Monocyte and Macrophage-Mediated Pathology and Protective Immunity During Schistosomiasis

Infection by Schistosoma parasites culminates in a chronic granulomatous disease characterized by intense tissue fibrosis. Along the course of schistosomiasis, diverse leukocytes are recruited for inflammatory foci. Innate immune cell accumulation in Th2-driven granulomas around Schistosoma eggs is associated with increased collagen deposition, while monocytes and macrophages exert critical roles during this process. Monocytes are recruited to damaged tissues from blood, produce TGF-β and differentiate into monocyte-derived macrophages (MDMs), which become alternatively activated by IL-4/IL-13 signaling via IL-4Rα (AAMs). AAMs are key players of tissue repair and wound healing in response to Schistosoma infection. Alternative activation of macrophages is characterized by the activation of STAT6 that coordinates the transcription of Arg1, Chi3l3, Relma, and Mrc1. In addition to these markers, monocyte-derived AAMs also express Raldh2 and Pdl2. AAMs produce high levels of IL-10 and TGF-β that minimizes tissue damage caused by Schistosoma egg accumulation in tissues. In this review, we provide support to previous findings about the host response to Schistosoma infection reusing public transcriptome data. Importantly, we discuss the role of monocytes and macrophages with emphasis on the mechanisms of alternative macrophage activation during schistosomiasis.