Arginase promotes immune evasion of Echinococcus granulosus in mice

Echinococcus granulosus sensu lato promotes osteoclast differentiation through DUSP4-MAPK signaling in osseous echinococcosis

Introduction

Osseous echinococcosis, caused by Echinococcus granulosus infection, is characterized by progressive bone destruction driven by abnormal osteoclast activation. Dual-specificity phosphatase 4 (DUSP4), a key negative regulator of the MAPK pathway, inhibits osteoclast differentiation and bone resorption. This study aimed to elucidate the role of DUSP4 in E. granulosus-induced bone loss.

Methods

In vitro, a co-culture system of E. granulosus protoscoleces (PSCs) and bone marrow-derived macrophages (BMMs) was established. Osteoclast differentiation and bone resorption were assessed using TRAP staining and F-actin immunofluorescence. Transcriptome sequencing identified DUSP4 as a key regulator. DUSP4 overexpression was performed to evaluate its effects on osteoclast markers and MAPK signaling (ERK, JNK, p38). In vivo, a mouse model of osseous echinococcosis was developed, and DUSP4 overexpression was achieved via lentiviral transduction. Bone destruction was analyzed using X-ray, micro-CT, and histology.

Results

PSCs significantly enhanced osteoclast differentiation and bone resorption, upregulated osteoclast markers (CTSK, NFATc1), and activated MAPK signaling. DUSP4 overexpression reversed these effects, reducing osteoclast activity and MAPK phosphorylation. In vivo, PSC infection caused severe bone destruction, which was mitigated by DUSP4 overexpression.

Disscussion

This study reveals the molecular mechanism by which Echinococcus granulosus drives abnormal osteoclast activation through the DUSP4-MAPK signaling axis. Parasitic infection suppresses DUSP4 expression, relieving its negative regulation of the MAPK pathway and leading to excessive osteoclast differentiation. Restoring DUSP4 expression effectively reverses abnormal MAPK pathway activation, reducing osteoclast bone resorption activity to physiological levels. These findings not only provide new insights into the pathological mechanisms of bone destruction in osseous echinococcosis but also establish DUSP4 as a critical therapeutic target for pathological bone resorption, laying the groundwork for host-directed treatment strategies for parasitic bone diseases.

Laminated Layer Extract from Echinococcus Granulosus cyst Attenuates Ocular Damages and Inflammatory Responses in an Experimental Autoimmune Uveitis Model

PURPOSE

Since extract of the laminated layer (LL) from E. granulosus showed immuno-modulatory effects in vitro and in vivo, we sought to determine its effect on the onset, development, and evolution of experimental auto-immune uveitis (EAU). The latter is a model of some human diseases with ocular inflammation that can cause blindness.

METHODS

E. granulosus LL extract was either injected before EAU induction for the pretreated group or later for treated group. Ocular exploration was made by retinal histological and immunohistological (CD86, CD4, CD8) analysis. Myeloperoxidase (MPO), Superoxide dismutase (SOD), Catalase enzymatic activities (CAT), and Malondialdehyde (MDA), Nitric oxide (NO), Urea, and TNF-α levels were measured in plasma.

RESULTS

LL injection attenuated retinal histological damage and reduced cells infiltration. Also, LL decreased systemic inflammatory and oxidative markers as well as TNF-α production and increased antioxidant parameters.

CONCLUSIONS

Interestingly, we observed a protective effect of E. granulosus LL extract during EAU. LL appears to ameliorate retinal damage by down-regulating inflammatory responses. Our results support LL immunomodulatory effects during autoimmune diseases and offer a promising prospect for helminthic therapy during autoimmune uveitis.

Unraveling molecular mechanistic disparities in pathogenic visceral Leishmania resistance between reptiles and mammals through comparative transcriptomic analyses

Leishmaniasis is one of the most important neglected tropical parasitic diseases, manifesting various clinical forms depending on the parasite species and the genetic background of the host. In order to elucidate the underlying mechanisms of reptilian defense against pathogenic Leishmania species and to delineate the global gene expression profile alterations during host-pathogen interaction, we established experimental animal and cell models using both heterothermic lizards (Phrynocephalus przewalskii) and homothermic mammals (BALB/c mice) infected with pathogenic Leishmania infantum (high virulence HCZ strain) and Leishmania donovani (low virulence 801 strain). Overall, the lizards didn't show any obvious clinical symptoms or immune responses in vivo. Using RNA-seq methodology, differentially expressed genes identified in the HCZ and 801-comparison groups of P. przewalskii were primarily associated with arginine biosynthesis, the MAPK signaling pathway and the PI3K-Akt signaling pathway. In contrast, higher parasite loads, exacerbated hepatic inflammatory lesions and enhanced immune responses were observed in BALB/c mice, with DEGs predominantly associated with immunological diseases, innate and adaptive immune responses. By integrating transcriptional data from reptile and mammalian hosts, we elucidated the pivotal role of amino acid metabolism and lipid metabolism in parasite control. In contrast to findings from animal experiments, Leishmania parasites effectively infected peritoneal macrophages of lizards in vitro, demonstrating a high infection rate. Furthermore, we used RT-qPCR to detect changes in cytokine expression in macrophages and found that Th1-type cytokines were significantly upregulated in lizards, facilitating the clearance of the HCZ strain 24 hours post-infection. Conversely, cytokine expression was generally suppressed in BALB/c mice, allowing immune evasion by the parasites.

Activating the iNOS regulatory pathway by arginine deprivation targets energy metabolism to induce autophagy-dependent apoptosis against spinal echinococcosis

Spinal echinococcosis is one of the most overlooked zoonotic parasitic diseases worldwide. There is currently no safe and effective treatment to eradicate it, and research based on the physiological-metabolic signature of the disease is lacking. Herein, we repurposed agrimol B as a potent anti-hydatid compound and validated its pharmacological mechanism based on arginine uptake as a target through multi-omics sequencing. This herbal component suppressed energy metabolism and activated ROS aggregation by inducing mitochondrial membrane potential depolarization, which subsequently triggered autophagy-dependent apoptosis leading to parasite death. Moreover, we discovered that arginine deprivation induced metabolic changes led to a shift from ornithine to nitrogen oxide synthesis, thus boosting the iNOS enzyme-regulated dominant metabolic pathway. The excess NO targeted the mitochondrial respiratory chain complex IV to disrupt energy metabolic homeostasis and induced a downstream pathological waterfall effect to kill the hydatid. A novel metabolic regulatory mechanism targeting mitochondrial damage for arginine starvation therapy was discovered. Finally, arginine depletion was found to be superior to the anti-spinal echinococcosis effect of albendazole and accompanied by the potential for disc protection. This study unveils the role of arginine in the physiological metabolism of Echinococcus granulosus and reveals the value of targeting arginine metabolism as a potential therapy. In addition, agrimol B is proposed as a promising therapeutic strategy for spinal echinococcosis to block arginine uptake and break this parasite's metabolic balance.

Arginase inhibitor reduces fungal dissemination in murine pulmonary cryptococcosis by promoting anti-cryptococcal immunity

Elevation of arginase enzyme activity in the lung contributes to the pathogenesis of various chronic inflammatory diseases and infections. Inhibition of arginase expression and activity is able to alleviate those effects. Here, we investigated the immunomodulatory effect of arginase inhibitor in C. neoformans infection. In the pulmonary cryptococcosis model that was shown to recapitulate human infection, we found arginase expression was excessively induced in the lung during the late stage of infection. To inhibit the activity of arginase, we administered a specific arginase inhibitor, nor-NOHA, during C. neoformans infection. Inhibition of arginase reduced eosinophil infiltration and level of IL-13 secretion in the lungs. Whole lung transcriptome RNA-sequencing analysis revealed that treatment with nor-NOHA resulted in shifting the Th2-type gene expression patterns induced by C. neoformans infection to the Th1-type immune profile, with higher expression of cytokines Ifng, Il6, Tnfa, Csf3, chemokines Cxcl9 and Cxcl10 and transcription factor Stat1. More importantly, mice treated with arginase inhibitor had more infiltrating brain leukocytes and enhanced gene expression of Th1-associated cytokines and chemokines that are known to be essential for protection against C. neoformans infection. Inhibition of arginase dramatically attenuated spleen and brain infection, with improved survival. Taken together, these studies demonstrated that inhibiting arginase activity induced by C. neoformans infection can modulate host immune response by enhancing protective type-1 immune response during C. neoformans infection. The inhibition of arginase activity could be an immunomodulatory target to enhance protective anti-cryptococcal immune responses.

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.

Hepatic macrophages play critical roles in the establishment and growth of hydatid cysts in the liver during Echinococcus granulosus sensu stricto infection

Cystic echinococcosis (CE) is a worldwide neglected zoonotic disease caused by infection with the larval stage of the tapeworm Echinococcus granulosus sensu lato (E. granulosus s.l.), which predominantly resides in the liver accompanied by mild inflammation. Macrophages constitute the main cellular component of the liver and play a central role in controlling the progression of inflammation and liver fibrosis. However, the role of hepatic macrophages in the establishment and growth of hydatid cysts in the liver during E. granulosus sensu stricto (E. granulosus s.s.) infection has not been fully elucidated. Here, we showed that CD68+ macrophages accumulated in pericystic areas of the liver and that the expression of CD163, a marker of anti-inflammatory macrophages, was more evident in active CE patients than in inactive CE patients. Moreover, in a mouse model of E. granulosus s.s. infection, the pool of hepatic macrophages expanded dramatically through the attraction of massive amounts of monocyte-derived macrophages (MoMFs) to the infection site. These infiltrating macrophages preferentially polarized toward an iNOS+ proinflammatory phenotype at the early stage and then toward a CD206+ anti-inflammatory phenotype at the late stage. Notably, the resident Kupffer cells (KCs) predominantly maintained an anti-inflammatory phenotype to favor persistent E. granulosus s.s. infection. In addition, depletion of hepatic macrophages promoted E. granulosus s.s. larval establishment and growth partially by inhibiting CD4+ T-cell recruitment and liver fibrosis. The above findings demonstrated that hepatic macrophages play a vital role in the progression of CE, contributing to a better understanding of the local inflammatory responses surrounding hydatid cysts and possibly facilitating the design of novel therapeutic approaches for CE.

Preoperative Nutritional Status and Enhanced Recovery after Surgery (ERAS) Prior to Radical Cystectomy: A Review of the Literature

Preoperative nutritional status is an important and modifiable risk factor of a patient's recovery and outcome after radical cystectomy. There are multiple malnutrition screening tools and treatment options. In this review, we discuss the best indicators of this condition and how to optimize nutrition status prior to radical cystectomy.

Immunology of a unique biological structure: the Echinococcus laminated layer

The larval stages of the cestode parasites belonging to the genus Echinococcus grow within internal organs of humans and a range of animal species. The resulting diseases, collectively termed echinococcoses, include major neglected tropical diseases of humans and livestock. Echinococcus larvae are outwardly protected by the laminated layer (LL), an acellular structure that is unique to this genus. The LL is based on a fibrillar meshwork made up of mucins, which are decorated by galactose-rich O-glycans. In addition, in the species cluster termed E. granulosus sensu lato, the LL features nano-deposits of the calcium salt of myo-inositol hexakisphosphate (Insp6). The main purpose of our article is to update the immunobiology of the LL. Major recent advances in this area are (i) the demonstration of LL "debris" at the infection site and draining lymph nodes, (ii) the characterization of the decoy activity of calcium Insp6 with respect to complement, (iii) the evidence that the LL mucin carbohydrates interact specifically with a lectin receptor expressed in Kupffer cells (Clec4F), and (iv) the characterization of what appear to be receptor-independent effects of LL particles on dendritic cells and macrophages. Much information is missing on the immunology of this intriguing structure: we discuss gaps in knowledge and propose possible avenues for research.

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.

The single-cell landscape of cystic echinococcosis in different stages provided insights into endothelial and immune cell heterogeneity

Introduction

Hydatid cysts and angiogenesis are the key characteristics of cystic echinococcosis, with immune cells and endothelial cells mediating essential roles in disease progression. Recent single-cell analysis studies demonstrated immune cell infiltration after Echinococcus granulosus infection, highlighting the diagnostic and therapeutic potential of targeting certain cell types in the lesion microenvironment. However, more detailed immune mechanisms during different periods of E. granulosus infection were not elucidated.

Methods

Herein, we characterized immune and endothelial cells from the liver samples of mice in different stages by single-cell RNA sequencing.

Results

We profiled the transcriptomes of 45,199 cells from the liver samples of mice at 1, 3, and 6 months after infection (two replicates) and uninfected wild-type mice. The cells were categorized into 26 clusters with four distinct cell types: natural killer (NK)/T cells, B cells, myeloid cells, and endothelial cells. An SPP1⁺ macrophage subset with immunosuppressive and pro-angiogenic functions was identified in the late infection stage. Single-cell regulatory network inference and clustering (SCENIC) analysis suggested that Cebpe, Runx3, and Rora were the key regulators of the SPP1⁺ macrophages. Cell communication analysis revealed that the SPP1⁺ macrophages interacted with endothelial cells and had pro-angiogenic functions. There was an obvious communicative relationship between SPP1⁺ macrophages and endothelial cells via Vegfa-Vegfr1/Vegfr2, and SPP1⁺ macrophages interacted with other immune cells via specific ligand-receptor pairs, which might have contributed to their immunosuppressive function.

Discussion

Our comprehensive exploration of the cystic echinococcosis ecosystem and the first discovery of SPP1⁺ macrophages with infection period specificity provide deeper insights into angiogenesis and the immune evasion mechanisms associated with later stages of infection.

Echinococcus granulosus Protoscoleces-Derived Exosome-like Vesicles and Egr-miR-277a-3p Promote Dendritic Cell Maturation and Differentiation

Cystic echinococcosis, a major parasitic disease caused by Echinococcus granulosus, seriously threatens human health. The excretory–secretory (ES) products of E. granulosus can induce immune tolerance in dendritic cells (DCs) to downregulate the host’s immune response; however, the effect of exosomes in the ES products on the DCs has remained unclear. This study showed that E. granulosus protoscoleces-derived exosome-like vesicles (PSC-ELVs) could be internalized by bone marrow-derived dendritic cells (BMDCs), allowing for the delivery of the parasite microRNAs to the BMDCs. Moreover, PSC-ELVs induced BMDCs to produce the proinflammatory cytokinesinterleukin (IL)-6, IL-12, IL-β, tumor necrosis factor-alpha (TNF-α), and interferon-gamma (IFN-γ). PSC-ELVs also upregulated the BMDCs surface marker major histocompatibility complex class II (MHC II), as well as costimulatory molecules CD40, CD80, and CD86. PSC-ELV-derived egr-miR-277a-3p upregulated the IL-6, IL-12, and TNF-α mRNA levels in BMDCs. Moreover, egr-miR-277a-3p directly targeted Nfkb1 (encoding nuclear factor kappa B 1) to significantly suppress the mRNA and protein levels of NF-κB1 in BMDCs, while the expression of NF-κB p65 significantly increased, suggesting that egr-miR-277a-3p induces the production of proinflammatory cytokines by the modification of the NF-kB p65/p50 ratio in BMDCs. These results demonstrated that PSC-ELVs and egr-miR-277a-3p might enhance DCs maturation and differentiation in a cross-species manner, which in turn may modulate the host immune responses and offer a new approach to echinococcosis prevention and treatment.

Immunization with EmCRT-Induced Protective Immunity against Echinococcus multilocularis Infection in BALB/c Mice

Alveolar echinococcosis (AE) is a severe parasitic zoonosis caused by the larval stage of Echinococcus multilocularis. The identification of the antigens eliciting acquired immunity during infection is important for vaccine development against Echinococcus infection. Here, we identified that E. multilocularis calreticulin (EmCRT), a ubiquitous protein with a Ca²⁺-binding ability, could be recognized by the sera of mice infected with E. multilocularis. The native EmCRT was expressed on the surface of E. multilocularis larvae as well as in the secreted products of metacestode vesicles and protoscoleces (PSCs). The coding DNA for EmCRT was cloned from the mRNA of the E. multilocularis metacestode vesicles and a recombinant EmCRT protein (rEmCRT) was expressed in E. coli. Mice immunized with soluble rEmCRT formulated with Freund’s adjuvant (FA) produced a 43.16% larval vesicle weight reduction against the challenge of E. multilocularis PSCs compared to those that received the PBS control associated with a high titer of IgG, IgG1 and IgG2a antibody responses as well as high levels of Th1 cytokines (IFN-γ and IL-2) and Th2 cytokines (IL-4, IL-5 and IL-10), produced by splenocytes. Our results suggest that EmCRT is an immunodominant protein secreted by E. multilocularis larvae and a vaccine candidate that induces partial protective immunity in vaccinated mice against Echinococcus infection.

Transcriptome analysis of Echinococcus granulosus sensu stricto protoscoleces reveals differences in immune modulation gene expression between cysts found in cattle and sheep

Cystic Echinococcosis (CE), a zoonotic parasitic disease, is caused by the cestode Echinococcus granulosus sensu lato. CE inflicts severe damage in cattle, sheep, and human hosts worldwide. Fertile CE cysts are characterized by the presence of viable protoscoleces. These parasite forms are studied with minimal contamination with host molecules. Hosts, cattle and sheep, show differences in their CE cyst fertility. The effect of the host in protoscolex transcriptome is not known. We genotyped and performed transcriptomic analysis on sheep protoscoleces obtained from liver and lung CE cysts. The transcriptomic data of Echinococcus granulosus sensu stricto protoscoleces from 6 lung CE cysts and 6 liver CE cysts were Collected. For host comparison analysis, 4 raw data files belonging to Echinococcus granulosus sensu stricto protoscoleces from cattle liver CE cysts were obtained from the NCBI SRA database. Principal component and differential expression analysis did not reveal any statistical differences between protoscoleces obtained from liver or lung cysts, either within the same sheep or different sheep hosts. Conversely, there are significant differences between cattle and sheep protoscolex samples. We found differential expression of immune-related genes. In cattle, 7 genes were upregulated in protoscoleces from liver cysts. In sheep, 3 genes were upregulated in protoscoleces from liver and lung CE cysts. Noteworthy, are the differential expression of antigen B, tegument antigen, and arginase-2 in samples obtained from sheep CE cysts, and basigin in samples from cattle CE cysts. These findings suggest that the host species is an important factor involved in the differential expression of immune related genes, which in turn is possibly related to the fertility of Echinococcus granulosus sensu stricto cysts.

Metabolomics Analysis of Splenic CD19+ B Cells in Mice Chronically Infected With Echinococcus granulosus sensu lato Protoscoleces

Background: The larval stages of Echinococcus granulosus sensu lato (E. granulosus s.l) infection can alter B cell function and affect host anti-infective immunity, but the underlying mechanism remains unclear. The newly emerging immunometabolism highlights that several metabolites are key factors in determining the fate of immune cells, which provides a new insight for exploring how larval E. granulosus s.l. infection remodels B cell function. This study investigated the metabolomic profiles of B cells in mice infected with E. granulosus s.l. protoscoleces (PSC).

Results:Total CD19⁺ B cells, purified from the spleen of infected mice, showed significantly increased production of IL-6, TNF-α, and IL-10 after exposure to LPS in vitro. Moreover, the mRNA expression of metabolism related enzymes in B cells was remarkably disordered post infection. In addition, differential metabolites were identified in B cells after infection. There were 340 differential metabolites (83 upregulated and 257 downregulated metabolites) identified in the positive ion model, and 216 differential metabolites (97 upregulated and 119 downregulated metabolites) identified in the negative ion mode. Among these, 64 differential metabolites were annotated and involved in 68 metabolic pathways, including thyroid hormone synthesis, the metabolic processes of glutathione, fructose, mannose, and glycerophospholipid. Furthermore, several differential metabolites such as glutathione, taurine, and inosine were validated to regulate the cytokine production in LPS stimulated B cells.

Conclusion:Infection with the larval E. granulosus s.l. causes metabolic reprogramming in the intrinsic B cells of mice, which provides the first evidence for understanding the role and mechanism of B cells in parasite anti-infective immunity from the viewpoint of immunometabolism.