Enteropathogenic Escherichia coli modulates the virulence and pathogenicity of Entamoeba dispar

Amoebiasis is a disease caused by Entamoeba histolytica, affecting the large intestine of humans and occasionally leading to extra-intestinal lesions. Entamoeba dispar is another amoeba species considered commensal, although it has been identified in patients presenting with dysenteric and nondysenteric colitis, as well as amoebic liver abscess. Amoebic virulence factors are essential for the invasion and development of lesions. There is evidence showing that the association of enterobacteria with trophozoites contributes to increased gene expression of amoebic virulence factors. Enteropathogenic Escherichia coli is an important bacterium causing diarrhea, with high incidence rates in the world population, allowing it to interact with Entamoeba sp. in the same host. In this context, this study aims to evaluate the influence of enteropathogenic Escherichia coli on ACFN and ADO Entamoeba dispar strains by quantifying the gene expression of virulence factors, including galactose/N-acetyl-D-galactosamine-binding lectin, cysteine proteinase 2, and amoebapores A and C. Additionally, the study assesses the progression and morphological aspect of amoebic liver abscess and the profile of inflammatory cells. Our results demonstrated that the interaction between EPEC and ACFN Entamoeba dispar strains was able to increase the gene expression of virulence factors, as well as the lesion area and the activity of the inflammatory infiltrate. However, the association with the ADO strain did not influence the gene expression of virulence factors. Together, our findings indicate that the interaction between EPEC, ACFN, and ADO Entamoeba dispar strains resulted in differences in vitro and in vivo gene expression of Gal/GalNAc-binding lectin and CP2, in enzymatic activities of MPO, NAG, and EPO, and consequently, in the ability to cause lesions.

Retrospective cohort study to evaluate the continuous use of anticholesterolemics and diuretics in patients with COVID-19

Purpose

The purpose of this study is to evaluate the interference of the continuous use of drug classes in the expression of biomarkers during the first week of hospitalization and in the prognosis of patients with COVID-19.

Methods

The patients diagnosed with COVID-19 and confirmed with SARS-CoV-2 by RT-qPCR assay underwent the collection of fasting whole blood samples for further analysis. Other data also extracted for this study included age, sex, clinical symptoms, related comorbidities, smoking status, and classes of continuous use. Routine serum biochemical parameters, including alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, C-reactive protein, N-terminal fragment of B-type natriuretic peptide, and cardiac troponin, were measured.

Results

In this cross-sectional study, a total of 176 patients with COVID-19 hospitalizations were included. Among them, 155 patients were discharged (88.5%), and 21 patients died (12%). Among the drug classes evaluated, we verified that the continuous use of diuretic 4.800 (1.853-11.67) (p = 0.0007) and antihypercholesterolemic 3.188 (1.215-7.997) (p = 0.0171) drug classes presented a significant relative risk of death as an outcome when compared to the group of patients who were discharged. We evaluated biomarkers in patients who used continuous antihypercholesterolemic and diuretic drug classes in the first week of hospitalization. We observed significant positive correlations between the levels of CRP with cardiac troponin (r = 0.714), IL-6 (r = 0.600), and IL-10 (r = 0.900) in patients who used continuous anticholesterolemic and diuretic drug classes and were deceased. In these patients, we also evaluated the possible correlations between the biomarkers AST, NT-ProBNP, cardiac troponin, IL-6, IL-8, and IL-10. We observed a significantly negative correlations in AST levels with NT-ProBNP (r = -0.500), cardiac troponin (r = -1.00), IL-6 (r = -1.00), and IL-10 (r = -1.00) and a positive correlation with IL-8 (r = 0.500). We also observed significant negative correlation in the levels of NT-ProBNP with IL-10 (r = -0.800) and a positive correlation with cardiac troponin (r = 0.800). IL-6 levels exhibited positive correlations with cardiac troponin (r = 0.800) and IL-10 (r = 0.700).

Conclusion

In this study, we observed that hospitalized COVID-19 patients who continued using anticholesterolemic and diuretic medications showed a higher number of correlations between biomarkers, indicating a poorer clinical prognosis. These correlations suggest an imbalanced immune response to injuries caused by SARS-CoV-2.

N-(coumarin-3-yl)cinnamamide Promotes Immunomodulatory, Neuroprotective, and Lung Function-Preserving Effects during Severe Malaria

Plasmodium berghei ANKA (PbA) infection in mice resembles several aspects of severe malaria in humans, such as cerebral malaria and acute respiratory distress syndrome. Herein, the effects of N-(coumarin-3-yl)cinnamamide (M220) against severe experimental malaria have been investigated. Treatment with M220 proved to protect cognitive abilities and lung function in PbA-infected mice, observed by an object recognition test and spirometry, respectively. In addition, treated mice demonstrated decreased levels of brain and lung inflammation. The production and accumulation of microglia, and immune cells that produce the inflammatory cytokines TNF and IFN-γ, decreased, while the production of the anti-inflammatory cytokine IL-10 by innate and adaptive immune cells was enhanced. Treatment with M220 promotes immunomodulatory, neuroprotective, and lung function-preserving effects during experimental severe malaria. Therefore, it may be an interesting therapeutic candidate to treat severe malaria effects.

Innate and adaptive immune gene expression in the brain is associated with neuropathological changes after infection with bovine alpha-herpesvirus-5 in mice

Bovine alpha herpesvirus-5 (BoAHV-5) is related to the development of meningoencephalitis in cattle. Very little is known about the molecular pathways involved in the central nervous system (CNS) damage associated with inflammation during BoHV-5 infection in mice. To better identify the specific immunological pathways triggered by BoAHV-5 infection in mice, we evaluated the mRNA expression of 84 genes involved in innate and adaptive immune responses. We compared gene expression changes in the cerebrum from noninfected and infected mice with BoHV-5 at a 1 × 107 TCID50. Then, we analyzed the association of these genes with neurological signs, neuropathology, and activation of glial cells in response to BoHV-5 infection. Three days after BoAHV-5 infection, increased expression of TNF, IL-2, CXCL10, CXCR3, CCR4, CCL5, IFN-γ, IL-10, IRF7, STAT1, MX1, GATA 3 C3, LIZ2, caspase-1 and IL-1b was found. We also observed the upregulated expression of the CD8a, TBX21 and CD40LG genes and the downregulated expression of the CD4 gene after BoAHV-5 infection. In addition, BoHV-5-infected animals showed higher levels of all the evaluated inflammatory mediators (TNF, IFN-γ and IL-10) on day 3 postinfection. BoAHV-5-infected animals showed neurological changes along with meningoencephalitis, neuropil vacuolation, hemorrhage and reactive gliosis. Astrogliosis and microgliosis, indicated by increased expression of glial fibrillary acidic protein (GFAP) and ionized calcium-binding adapter molecule 1 (Iba-1), were found throughout the neuropil in infected brains. Moreover, cleaved caspase-3 immunopositive glio-inflammatory cells were visualized around some blood vessels in areas of neuroinflammation in the cerebrum. In agreement on that we found higher cleaved caspase-3 and Iba-1 expression evaluated by western blot analysis in the brains of infected mice compared to control mice. In conclusion, our results revealed.

Development of chimeric protein as a multivalent vaccine for human Kinetoplastid infections: Chagas disease and leishmaniasis

Leishmania spp. and Trypanosoma cruzi are parasitic kinetoplastids of great medical and epidemiological importance since they are responsible for thousands of deaths and disability-adjusted life-years annually, especially in low- and middle-income countries. Despite efforts to minimize their impact, current prevention measures have failed to fully control their spread. There are still no vaccines available. Taking into account the genetic similarity within the Class Kinetoplastida, we selected CD8+ T cell epitopes preserved among Leishmania spp. and T. cruzi to construct a multivalent and broad-spectrum chimeric polyprotein vaccine. In addition to inducing specific IgG production, immunization with the vaccine was able to significantly reduce parasite burden in the colon, liver and skin lesions from T. cruzi, L. infantum and L. mexicana challenged mice, respectively. These findings were supported by histopathological analysis, which revealed decreased inflammation in the colon, a reduced number of degenerated hepatocytes and an increased proliferation of connective tissue in the skin lesions of the corresponding T. cruzi, L. infantum and L. mexicana vaccinated and challenged mice. Collectively, our results support the protective effect of a polyprotein vaccine approach and further studies will elucidate the immune profile associated with this protection. Noteworthy, our results act as conceptual proof that a single multi-kinetoplastida vaccine can be used effectively to control different infectious etiologies, which in turn can have a profound impact on the development of a new generation of vaccines.

Comorbidities involving parasitic diseases: A look at the benefits and complications

Parasitic infections acquired by the population cause substantial morbidity worldwide, with individuals from developing countries being most affected. Some parasites remain in the host for long periods, settling in different organs, manipulating the flow of nutrients and metabolites, and influencing the immune response, favoring their adaptation. The host attempts to counteract the metabolic and immunological alterations and the possible damage caused by infection. These metabolic and immunological changes experienced by the host can influence the progression of other existing morbidities or those that will be acquired in the future. Cancer and metabolic diseases are also frequent causes of morbidity in the world population. The large numbers of individuals affected by cancer and metabolic diseases and the high prevalence of morbidity caused by parasitic diseases favor the development of comorbidity involving these pathologies. This review provides an overview of major advances in research on cancer and metabolic diseases associated with parasitic infections. Information about hosts and parasites such as alterations of the immune response, metabolism and adaptation mechanisms of the parasites, and parasitic molecules with therapeutic potential is provided, as well as the beneficial results or complications related to the comorbidities discussed herein. We emphasize the need to conduct additional studies addressing comorbidities associated with parasitic infections to improve the understanding of the impact of this association on the progression of morbidities, as well as the possibility of the therapeutic use of and therapeutic approaches involving parasites.

IL-17RA receptor signaling contributes to lung inflammation and parasite burden during Toxocara canis infection in mice

IL-17 is a cytokine produced by innate and acquired immunity cells that have an action against fungi and bacteria. However, its action in helminth infections is unclear, including in Toxocara canis infection. Toxocariasis is a neglected zoonosis representing a significant public health problem with an estimated seroprevalence of 19% worldwide. In the present study, we describe the immunopathological action of IL-17RA in acute T. canis infection. C57BL/6j (WT) and IL-17RA receptor knockout (IL-17RA-/-) mice were infected with 1000 T. canis eggs. Mice were evaluated 3 days post-infection for parasite load and white blood cell count. Lung tissue was harvested for histopathology and cytokine expression. In addition, we performed multiparametric flow cytometry in the BAL and peripheral blood, evaluating phenotypic and functional changes in myeloid and lymphoid populations. We showed that IL-17RA is essential to control larvae load in the lung; however, IL-17RA contributed to pulmonary inflammation, inducing inflammatory nodular aggregates formation and presented higher pulmonary IL-6 levels. The absence of IL-17RA was associated with a higher frequency of neutrophils as a source of IL-4 in BAL, while in the presence of IL-17RA, mice display a higher frequency of alveolar macrophages expressing the same cytokine. Taken together, this study indicates that neutrophils may be an important source of IL-4 in the lungs during T. canis infection. Furthermore, IL-17/IL-17RA axis is important to control parasite load, however, its presence triggers lung inflammation that can lead to tissue damage.

Nitric oxide contributes to liver inflammation and parasitic burden control in Ascaris suum infection

BACKGROUND

Human ascariasis is one of the most prevalent neglected tropical diseases worldwide. The immune response during human ascariasis is characterized by Th2 polarization and a mixed Th2/Th17 response during the pathogenesis of experimental larval ascariasis. Cytokines and other pro-inflammatory mediators, such as nitric oxide (NO), are involved in helminthic infections. However, the role of NO in ascariasis remains unclear.

OBJECTIVES

Given the importance of NO in inflammation, we aimed to determine the immunological and histopathological alterations in the livers of C57BL/6 iNOS^-/- mice during A. suum infection.

METHODS

In this study, parasitic load was evaluated in the livers of wild type C57BL/6 and C57BL/6 iNOS^-/- mice infected with A. suum. Histopathological and morphometric analyses and analysis of serum cytokines via Cytometric Bead Array were performed, and the activity of eosinophil peroxidase and myeloperoxidase of neutrophils in the tissues were determined.

RESULTS

The results showed that NO is important for controlling parasitic load during infection by A. suum. C57BL/6iNOS^-/- mice showed reduced inflammatory processes and less tissue damage during liver larval migration of A. suum, which is associated with a reduction in serum levels of pro-inflammatory cytokines.

CONCLUSIONS

We demonstrated that NO is a crucial inflammatory molecule during Ascaris sp. infection and controls the establishment of the parasite and the development of the host immune response in the liver.

Tissue eosinophilia correlates with mice susceptibility, granuloma formation, and damage during Toxocara canis infection

An increase in peripheral blood eosinophils in helminth infections is expected, and these cells are known to promote immunity against these parasites. However, studies have suggested that in some specific helminths, eosinophils may promote the needs and longevity of these parasites, and their role in these infections remains undefined, including in Toxocara canis infection. Thus, this study aimed to investigate the role of eosinophils in the context of larval migration of T. canis and the immunopathological aspects of infection. For this, we used wild-type mice and mice genetically deficient for the transcription factor GATA-binding factor 1 (GATA1−/−), infected with 1000 eggs of T. canis. At 0, 3, 14 and 63 days post-infection, parasite load, tissue cytokine production, leucocyte profile, bronchoalveolar lavage cells and histopathological analyses were carried out. Collectively, our results demonstrate that the presence of eosinophils mediates susceptibility to T. canis, inducing leucocytosis and the formation of granulomas, increasing the pulmonary and cerebral parasite load, and reducing the number of neutrophils, which may be necessary to control the infection.

Inhalation of dimethyl fumarate-encapsulated solid lipid nanoparticles attenuate clinical signs of experimental autoimmune encephalomyelitis and pulmonary inflammatory dysfunction in mice

RATIONALE

The FDA-approved Dimethyl Fumarate (DMF) as an oral drug for Multiple Sclerosis (MS) treatment based on its immunomodulatory activities. However, it also caused severe adverse effects mainly related to the gastrointestinal system.

OBJECTIVE

Investigated the potential effects of solid lipid nanoparticles (SLNs) containing DMF, administered by inhalation on the clinical signs, central nervous system (CNS) inflammatory response, and lung function changes in mice with experimental autoimmune encephalomyelitis (EAE).

MATERIALS AND METHODS

EAE was induced using MOG35-55 peptide in female C57BL/6J mice and the mice were treated via inhalation with DMF-encapsulated SLN (CTRL/SLN/DMF and EAE/SLN/DMF), empty SLN (CTRL/SLN and EAE/SLN), or saline solution (CTRL/saline and EAE/saline), every 72 h during 21 days.

RESULTS

After 21 days post-induction, EAE mice treated with DMF-loaded SLN, when compared with EAE/saline and EAE/SLN, showed decreased clinical score and weight loss, reduction in brain and spinal cord injury and inflammation, also related to the increased influx of Foxp3+ cells into the spinal cord and lung tissues. Moreover, our data revealed that EAE mice showed signs of respiratory disease, marked by increased vascular permeability, leukocyte influx, production of TNF-α and IL-17, perivascular and peribronchial inflammation, with pulmonary mechanical dysfunction associated with loss of respiratory volumes and elasticity, which DMF-encapsulated reverted in SLN nebulization.

CONCLUSION

Our study suggests that inhalation of DMF-encapsulated SLN is an effective therapeutic protocol that reduces not only the CNS inflammatory process and disability progression, characteristic of EAE disease, but also protects mice from lung inflammation and pulmonary dysfunction.

ASCVac-1, a Multi-Peptide Chimeric Vaccine, Protects Mice Against Ascaris suum Infection

Control of human ascariasis, the most prevalent neglected tropical disease globally affecting 450 million people, mostly relies on mass drug administration of anthelmintics. However, chemotherapy alone is not efficient due to the high re-infection rate for people who live in the endemic area. The development of a vaccine that reduces the intensity of infection and maintains lower morbidity should be the primary target for infection control. Previously, our group demonstrated that immunization with crude Ascaris antigens in mice induced an IgG-mediated protective response with significant worm reduction. Here, we aimed to develop a multipeptide chimera vaccine based on conserved B-cell epitopes predicted from 17 common helminth proteomes using a bioinformatics algorithm. More than 480 B-cell epitopes were identified that are conserved in all 17 helminths. The Ascaris-specific epitopes were selected based on their reactivity to the pooled sera of mice immunized with Ascaris crude antigens or infected three times with A. suum infective eggs. The top 35 peptides with the strongest reactivity to Ascaris immune serum were selected to construct a chimeric antigen connected in sequence based on conformation. This chimera, called ASCVac-1, was produced as a soluble recombinant protein in an Escherichia coli expression system and, formulated with MPLA, was used to immunize mice. Mice immunized with ASCVac-1/MPLA showed around 50% reduced larvae production in the lungs after being challenged with A. suum infective eggs, along with significantly reduced inflammation and lung tissue/function damage. The reduced parasite count and pathology in infected lungs were associated with strong Th2 immune responses characterized by the high titers of antigen-specific IgG and its subclasses (IgG1, IgG2a, and IgG3) in the sera and significantly increased IL-4, IL-5, IL-13 levels in lung tissues. The reduced IL-33 titers and stimulated eosinophils were also observed in lung tissues and may also contribute to the ASCVac-1-induced protection. Taken together, the preclinical trial with ASCVac-1 chimera in a mouse model demonstrated its significant vaccine efficacy associated with strong IgG-based Th2 responses, without IgE induction, thus reducing the risk of an allergic response. All results suggest that the multiepitope-based ASCVac-1 chimera is a promising vaccine candidate against Ascaris sp. infections.

South American Entamoeba dispar strains produce amoebic liver abscesses with different pathogenicities and evolutionary kinetics

Amoebiasis is a protozoan disease caused by Entamoeba histolytica, and presents a geographic distribution of worldwide amplitude, high incidence, sometimes accompanied by severe clinical manifestations such as amoebic colitis and Amoebic Liver Abscess (ALA), remaining as a public health problem in developing countries. Entamoeba dispar is another species of amoeba that infects approximately 12% of the world's population, and it has previously been classified as noninvasive. However, E. dispar has already been isolated from patients with symptomatic non-dysenteric colitis, as well as its DNA sequences were detected and genotyped in samples from patients with dysenteric colitis, and patients with ALA, suggesting that this species could also be involved in the development of lesions in the large intestine and liver of human beings. In this context, this study aims to evaluate the ability of isolated strains of Entamoeba dispar in South America to cause liver damage, and to better characterize histopathological findings in 3, 8, 12 and 16 days after infection (DAI). Firstly, we assessed whether trophozoites from MCR, ACFN, ICS, ADO and VEJ E. dispar strains, and EGG Entamoeba histolytica strain differed in their in vitro phagocytosis ability, being related to greater ability to phagocyte with greater virulence. Then, we investigate and characterize histopathological changes present in the liver of mice induced by different strains of E. dispar. Our results demonstrated that trophozoites from E. dispar strains are capable of phagocyting human erythrocytes, but in lower amounts than Entamoeba histolytica. In addition, we described and characterized the lesions in different periods after infection by different E. dispar strains, and identified ACFN as the most pathogenic strain, followed by MCR. The large areas of necrosis produced by the ACFN strain as the eighth DAI, which also show high parasitism, led to 100% mortality. On the other hand, the ICS, ADO and VEJ strains did not produce mortality, and this was correlated with the presence of well-developed chronic granulomatous inflammation, necrosis absorption throughout the infection, and regeneration of the liver parenchyma. The greater pathogenicity of the ACFN strain strongly suggests that this strain could be producing higher levels of virulence factors. As the experimental infection, the heterogeneity of biological behavior of different Entamoeba dispar strains could be involved in the development of undiagnosed human clinical conditions.

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.

Evaluation of mesalazine polymeric conjugate in the treatment of actinic proctitis in rats

Purpose:

The present study aimed at testing a new formulation of mesalazine linked to chondroitin sulfate and its components alone in the treatment of actinic proctitis in rats.

Methods:

Forty-seven female Wistar rats were submitted to pelvic radiation and divided into eight groups: control A, mesalazine A, chondroitin A, and conjugate A, gavage of the according substance two weeks after irradiation and sacrifice three weeks after oral treatment; control C, mesalazine C, chondroitin C, and conjugate C, sacrifice six weeks after oral treatment. The rectum was submitted to histological characterization for each of the findings: inflammatory infiltrate, epithelial degeneration, mucosal necrosis, and fibrosis.

Results:

The inflammatory infiltrate was more intense in chondroitin A, mesalazine A, and conjugate C. The collagen deposition was less intense in chondroitin A, and mesalazine A, and more intense in control C.

Conclusions:

Mesalazine and chondroitin alone were efficacious in inducing a delayed inflammatory response, hence reducing the late fibrosis. The conjugate was able to induce an ever more delayed inflammatory response.

Detrimental role of IL-33/ST2 pathway sustaining a chronic eosinophil-dependent Th2 inflammatory response, tissue damage and parasite burden during Toxocara canis infection in mice

Toxocariasis is a neglected disease that affects people around the world. Humans become infected by accidental ingestion of eggs containing Toxocara canis infective larvae, which upon reaching the intestine, hatch, penetrate the mucosa and migrate to various tissues such as liver, lungs and brain. Studies have indicated that Th2 response is the main immune defense mechanism against toxocariasis, however, there are still few studies related to this response, mainly the IL-33/ST2 pathway. Some studies have reported an increase in IL-33 during helminth infections, including T. canis. By binding to its ST2 receptor, IL-33 stimulating the Th2 polarized immune cell and cytokine responses. Thus, we aimed to investigate the role of the IL-33/ST2 pathway in the context of T. canis larval migration and the immunological and pathophysiological aspects of the infection in the liver, lungs and brain from Wild-Type (WT) BALB/c background and genetically deficient mice for the ST2 receptor (ST2^-/-). The most important findings revealed that the IL-33/ST2 pathway is involved in eosinophilia, hepatic and cerebral parasitic burden, and induces the formation of granulomas related to tissue damage and pulmonary dysfunction. However, ST2^-/- mice, the immune response was skewed to Th1/Th17 type than Th2, that enhanced the control of parasite burden related to IgG2a levels, tissue macrophages infiltration and reduced lung dysfunction. Collectively, our results demonstrate that the Th2 immune response triggered by IL-33/ST2 pathway mediates susceptibility to T. canis, related to parasitic burden, eosinophilia and granuloma formation in which consequently contributes to tissue inflammation and injury.

Toxocariasis is a neglected disease caused by Toxocara canis, which has 19% worldwide seroprevalence, and is associated with socioeconomic, geographic and environmental factors. Humans become infected by accidental ingestion of T. canis eggs present in contaminated food, water or soil. After ingestion, the larvae hatch in the intestine and can reach various tissues such as liver, lung and brain. Helminth infections usually trigger a Th2 immune response in the host, by releasing cytokines such as IL-4, IL-5, IL-13 and IL-33. IL-33 is an alarmin that binds to the ST2 receptor, and some studies have observed an increase in this cytokine in toxocariasis, however there are no studies regarding the IL-33/ST2 role in this infection. Thus, we evaluated the influence of this pathway by analyzing immunological and pathophysiological aspects in T. canis-infected mice. Our results demonstrated that the IL-33/ST2 pathway is related to parasite burden on the liver and brain and also increases the number of eosinophils in the blood and tissues. In addition, it involved with the pulmonary immune response and granulomas with impact in lung function. In conclusion, the IL-33/ST2 pathway governs the host susceptibility to T. canis in mice.

Concomitant experimental coinfection by Plasmodium berghei NK65-NY and Ascaris suum downregulates the Ascaris-specific immune response and potentiates Ascaris-associated lung pathology

Background

Ascariasis and malaria are highly prevalent parasitic diseases in tropical regions and often have overlapping endemic areas, contributing to high morbidity and mortality rates in areas with poor sanitary conditions. Several studies have previously aimed to correlate the effects of Ascaris-Plasmodium coinfections but have obtained contradictory and inconclusive results. Therefore, the present study aimed to investigate parasitological and immunopathological aspects of the lung during murine experimental concomitant coinfection by Plasmodium berghei and Ascaris suum during larvae ascariasis.

Methods

C57BL/6J mice were inoculated with 1 × 10⁴P. berghei strain NK65-NY-infected red blood cells (iRBCs) intraperitoneally and/or 2500 embryonated eggs of A. suum by oral gavage. P. berghei parasitaemia, morbidity and the survival rate were assessed. On the seventh day postinfection (dpi), A. suum lung burden analysis; bronchoalveolar lavage (BAL); histopathology; NAG, MPO and EPO activity measurements; haematological analysis; and respiratory mechanics analysis were performed. The concentrations of interleukin (IL)-1β, IL-12/IL-23p40, IL-6, IL-4, IL-33, IL-13, IL-5, IL-10, IL-17A, IFN-γ, TNF and TGF-β were assayed by sandwich ELISA.

Results

Animals coinfected with P. berghei and A. suum show decreased production of type 1, 2, and 17 and regulatory cytokines; low leukocyte recruitment in the tissue; increased cellularity in the circulation; and low levels of NAG, MPO and EPO activity that lead to an increase in larvae migration, as shown by the decrease in larvae recovered in the lung parenchyma and increase in larvae recovered in the airway. This situation leads to severe airway haemorrhage and, consequently, an impairment respiratory function that leads to high morbidity and early mortality.

Conclusions

This study demonstrates that the Ascaris-Plasmodium interaction is harmful to the host and suggests that this coinfection may potentiate Ascaris-associated pathology by dampening the Ascaris-specific immune response, resulting in the early death of affected animals.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03824-w.

Co-infection by Salmonella enterica subsp. Enterica serovar typhimurium and Entamoeba dispar pathogenic strains enhances colitis and the expression of amoebic virulence factors

Amebiasis is the most severe protozoan infection affecting the human intestine, and the second leading cause of death among parasitic diseases. The mechanisms of amoebic virulence factors acquisition are poorly understood, and there are few studies showing the interaction between Entamoeba dispar and bacteria. Salmonella enterica subsp. enterica serovar typhimurium is also a common cause of gastroenteritis in humans. Considering the high rates of amebiasis and salmonellosis, it is possible that these diseases may co-exist in the human intestine, leading to co-infection. Due to the scarcity of studies showing the influence of enteropathogenic bacteria on amoebic virulence, our research group proposed to evaluate the impact of S. typhimurium on E. dispar trophozoites. We assessed whether co-infection of S. typhimurium and E. dispar can change the progression of amoebic colitis, and the inflammatory response profile in the caecum mucosa, using a co-infection experimental model in rats. In vitro assays was used to investigate whether S. typhimurium induces changes in amoebic virulence phenotype. In the present work, we found that S. typhimurium co-infection exacerbates amoebic colitis and intestinal inflammation. The in vitro association of S. typhimurium and E. dispar trophozoites contributed to increase the expression of amoebic virulence factors. Also, we demonstrated, for the first time, the cysteine proteinase 5 expression in E. dispar MCR, VEJ and ADO strains, isolated in Brazil. Together, our results show that S. typhimurium and E. dispar co-infection worsens amoebic colitis, possibly by increasing the expression of amoebic virulence factors.

Weissella paramesenteroides WpK4 ameliorate the experimental amoebic colitis by increasing the expression of MUC-2 and the intestinal epithelial regeneration

AIMS

This study evaluates the action of Weissella paramesenteroides WpK4 on amoebic colitis.

METHODS AND RESULTS

Weissella paramesenteroides WpK4 was administered in Entamoeba dispar infected and noninfected mice and clinical parameters were evaluated. Following 7 days, the caeca were collected for histopathology, morphometry and immunohistochemical staining of MUC-2, CDC-47 and IgA. The treatment reduced diarrhoea and the presence of blood in the faeces and diminished the area of necrosis, also causing weight gain. Also, the addition of this bacterium enhanced the expression of the mucin (MUC-2). The reduction in necrosis and increased CDC-47 expression indicates significant epithelial regeneration. The negative correlation between CDC-47 and the necrosis area reveals that the bacterium favoured the recovery of the necrotic regions and the positive correlation found between the expression of MUC-2 and CDC-47 indicates that the epithelial regeneration also supports the synthesis of MUC-2.

CONCLUSIONS

Weissella paramesenteroides WpK4 was able to increase the protection of the intestinal mucosa against experimental amoebic colitis through the increase of MUC-2 and epithelial regeneration.

SIGNIFICANCE AND IMPACT OF THE STUDY

Weissella paramesenteroides WpK4 presents the potential to become a complementary tool in the treatment of amoebic colitis.

Up-regulation of brain cytokines and metalloproteinases 1 and 2 contributes to neurological deficit and brain damage in transient ischemic stroke

Ischemic stroke represents a major cause of adult death and severe neurological disability worldwide. Reperfusion following brain ischemia produces an inflammatory cascade that increases brain damage. In this context, matrix metalloproteinases (MMPs) play an important role as pro-inflammatory mediators. The MMP 2 up-regulation seems to promote matrix degradation, blood-brain barrier (BBB) disruption and facilitates the influx of peripheral inflammatory cells to the brain after stroke. However, there are not studies about MMP-1 in this condition. The aim of this study is to evaluate the association of brain damage, inflammatory response and the immunostaining profile of matrix metalloproteinases 1 and 2 after transient global cerebral ischemia. Mice were submitted to bilateral common carotid arterial occlusion (BCCAo) during 25 min. After three days of reperfusion, the neurological deficit score was evaluated and the animals were euthanized. Brain samples were collected in order to analyze the histopathological damage, MMPs 1 and 2 immunostaining and cytokines and chemokines levels. Ischemic group showed neurological deficits associated with brain lesions, characterized by necrotic core and penumbra zone three days after reperfusion. Higher brain immunostaining of MMP-1 and MMP-2 was observed in BCCAo samples than in sham samples. Ischemic group also exhibited increased brain levels of the cytokines tumoral necrosis factor (TNF) and interleukin 1β (IL-1β), chemokine (C-X-C motif) ligand 1 (CXCL1), and chemokine (C-C motif) ligand 5 (CCL5) in comparison to sham group. Our results suggest that the MMP-1 and MMP-2 raise, associated with the up-regulation of inflammatory mediators, contributes to brain damage and neurological deficits after global brain ischemia followed by three days of reperfusion in mice.

Comorbidity associated to Ascaris suum infection during pulmonary fibrosis exacerbates chronic lung and liver inflammation and dysfunction but not affect the parasite cycle in mice

Ascariasis is considered the most neglected tropical disease, and is a major problem for the public health system. However, idiopathic pulmonary fibrosis (IPF) is a result of chronic extracellular deposition of matrix in the pulmonary parenchyma, and thickening of the alveolar septa, which reduces alveolar gas exchange. Considering the high rates of ascariasis and pulmonary fibrosis, we believe that these two diseases may co-exist and possibly lead to comorbidities. We therefore investigated the mechanisms involved in comorbidity of Ascaris suum (A. suum) infection, which could interfere with the progression of pulmonary fibrosis. In addition, we evaluated whether a previous lung fibrosis could interfere with the pulmonary cycle of A. suum in mice. The most important findings related to comorbidity in which A. suum infection exacerbated pulmonary and liver injury, inflammation and dysfunction, but did not promote excessive fibrosis in mice during the investigated comorbidity period. Interestingly, we found that pulmonary fibrosis did not alter the parasite cycle that transmigrated preferentially through preserved but not fibrotic areas of the lungs. Collectively, our results demonstrate that A. suum infection leads to comorbidity, and contributes to the aggravation of pulmonary dysfunction during pulmonary fibrosis, which also leads to significant liver injury and inflammation, without changing the A. suum cycle in the lungs.

Ascariasis is considered a major problem for the public health system, which has an estimated 800 million infected people worldwide. It occurs in the United States, Africa, Asia, and Latin America, and is generally associated with poverty and precarious health conditions. Pulmonary fibrosis affects 14–63 people per 100,000 habitants/year, and is characterized by collagen deposition and alveolar wall thickening. The comorbidities caused by infections are commonly associated with pulmonary fibrosis exacerbations, poor prognosis, and high mortality. Despite the comorbidities caused by helminth infections, which display a pulmonary parasitic cycle such as that of Ascaris, there is no evidence relating to pulmonary fibrosis progression, possibly because Ascariasis is considered a neglected disease. We evaluated the role of Ascaris during pulmonary fibrosis. We considered two simple questions: (1) Whether Ascaris infection could protect or aggravate fibrosis (comorbidities) and (2) whether pulmonary fibrosis could change the cycle of Ascaris as a result of increased alveolar thickening, larvae retention, and the limitation of influx into airways. We answered both questions as follows: (1) Ascaris infection exacerbates pulmonary and liver injury and inflammation, but not fibrosis; and (2) Pulmonary fibrosis did not alter the course of Ascaris cycle in lungs during transmigration into airways, because Ascaris preferentially seeks and penetrates into the lung areas, which are thought to be preserved, but not into fibrotic areas.

Probiotic effect of Bifidobacterium longum 51A and Weissella paramesenteroides WpK4 on gerbils infected with Giardia lamblia

AIMS

The objective of this study was to assess the probiotic potential of genuine strains of Bifidobacterium longum 5^1A and Weissella paramesenteroides WpK4, in experimental giardiasis.

METHODS AND RESULTS

The bacteria were administered orally to gerbils (Meriones unguiculatus) 10 days before oral infection with trophozoites of Giardia lamblia. After 7 days of infection, the animals were euthanized and portions of the duodenum were processed for histopathologic, histochemical and morphometric assessment. The height of the intestinal crypts and crypt/villi ratio were higher in infected groups (P < 0·05) than in noninfected groups. The area of mucus production was higher (P < 0·05) in infected animals pretreated with B. longum 5^1A than in other groups. The parasitic load of the animals that received both bacteria decreased significantly (P < 0·05) compared to the ones of the control group.

CONCLUSIONS

Our results suggest a probiotic function of B. longum 5^1A and W. paramesenteroides WpK4 and may result in their use as a prophylactic and therapeutic alternative for promoting human and animal health.

SIGNIFICANCE AND IMPACT OF THE STUDY

Bifidobacterium longum 5^1A and W. paramesenteroides WpK4 may constitute prophylactic alternatives, reversing the emergence of side effects and resistance observed in the conventional treatment of giardiasis.

IgG Induced by Vaccination With Ascaris suum Extracts Is Protective Against Infection

Human ascariasis has a global and cosmopolitan distribution, and has been characterized as the most prevalent neglected tropical disease worldwide. The development of a preventive vaccine is highly desirable to complement current measures required for this parasitic infection control and to reduce chronic childhood morbidities. In the present study, we describe the mechanism of protection elicited by a preventive vaccine against ascariasis. Vaccine efficacy was evaluated after immunization with three different Ascaris suum antigen extracts formulated with monophosphoryl lipid A (MPLA) as an adjuvant: crude extract of adult worm (ExAD); crude extract of adult worm cuticle (CUT); and crude extract of infective larvae (L3) (ExL3). Immunogenicity elicited by immunization was assessed by measuring antibody responses, cytokine production, and influx of tissue inflammatory cells. Vaccine efficacy was evaluated by measuring the reductions in the numbers of larvae in the lungs of immunized BALB/c mice that were challenged with A. suum eggs. Moreover, lung physiology and functionality were tested by spirometry to determine clinical efficacy. Finally, the role of host antibody mediated protection was determined by passive transfer of serum from immunized mice. Significant reductions in the total number of migrating larvae were observed in mice immunized with ExL3 61% (p < 0.001), CUT 59% (p < 0.001), and ExAD 51% (p < 0.01) antigens in comparison with non-immunized mice. For the Ascaris antigen-specific IgG antibody levels, a significant and progressive increase was observed with each round of immunization, in association with a marked increase of IgG1 and IgG3 subclasses. Moreover, a significant increase in concentration of IL-5 and IL-10 (pre-challenge) in the blood and IL-10 in the lung tissue (post-challenge) was induced by CUT immunization. Finally, ExL3 and CUT-immunized mice showed a marked improvement in lung pathology and tissue fibrosis as well as reduced pulmonary dysfunction induced by Ascaris challenge, when compared to non-immunized mice. Moreover, the passive transfer of specific IgG antibodies from ExL3, CUT, and ExAD elicited a protective response in naïve mice, with significant reductions in parasite burdens in lungs of 65, 64, and 64%, respectively. Taken together, these studies indicated that IgG antibodies contribute to protective immunity.

Colite necrohemorrágica causada por Entamoeba histolytica em um cão

Background: Intestinal amebiasis with morphological lesions and clinical manifestations is uncommon in dogs. The disease is caused by the protozoan Entamoeba histolytica, which is commonly observed in its natural hosts, humans and some non-human primates. It is occasionally found in the company of animals, usually associated with contact with infected humans. Thus, the objective here is to describe a case of necro-hemorrhagic colitis caused by E. histolytica in a dog infected with the canine distemper virus, in order to characterize the epidemiological and clinicopathological aspects of the disease.Case: An adult, mixed-breed bitch displaying anorexia and ataxia was referred to the veterinary hospital for treatment. Clinical evaluation showed a cachectic animal with 12% dehydration, ocular discharge, and bilateral purulent nasal dis-charge. A clinical diagnosis of distemper was made, and treatment was instituted. The dog’s signs progressed to walking in circles, aimlessly, with lethargy and blindness. After three days of the onset of neurological signs, the dog developed diarrhea with hematochezia. With no improvement noted, we elected to euthanize the dog. At necropsy, edema was present in subcutaneous tissues, and the lungs had yellow areas in the cranio-ventral portions, which the court was flowing purulent discharge. In the large intestine, segmental distention of the distal portion of the descending colon was observed. The segment was approximately 15 cm in length and consisted of irregular reddish areas. There was also slight thickening of the wall with edematous mucosa containing blood clots, fibrin, and multiple areas of ulceration. Microscopically showed necro-hemorrhagic colitis associated with rounded structures, approximately 15 μm in size, containing abundant eosinophilic cytoplasm that was slightly granular or vacuolated. They also contained nuclei and nucleoli that were central or slightly eccentric. These organisms were consistent with amoeba trophozoites. There was also demyelinating encephalitis associated with malacia, corpuscular intranuclear eosinophilic inclusions and / or intracytoplasmic inclusions in ependymal cells, astrocytes, and gemistocytes, characteristic of infection with canine distemper virus. Using immunohistochemistry with polyclonal anti-E. histolytica antibodies in the dilution of 1:1000, trophozoites were immunomarked, confirming the suspected amebiasis.Discussion: The diagnosis of intestinal amebiasis was based on clinical signs and by morphological characteristics on gross and microscopic examination, and was confirmed as E. histolytica by immunohistochemistry. Limited information on theepidemiology and pathological findings of infection with Entamoeba sp. has been reported in the literature, as it is relatively uncommon in pets. Affected animals are usually asymptomatic, but immunosuppression caused by canine distemper virus may have triggered the clinical manifestations of the disease in this dog. Enteritis due Entamoeba sp. should be considered in dogs with chronic weight loss and bloody diarrhea. It should also be included in the differential diagnoses for weight loss and hemorrhagic gastroenteritis, such as canine parvovirus, canine adenovirus 1, Pythium insidiosum, and Giardia sp.

Multiple Exposures to Ascaris suum Induce Tissue Injury and Mixed Th2/Th17 Immune Response in Mice

Ascaris spp. infection affects 800 million people worldwide, and half of the world population is currently at risk of infection. Recurrent reinfection in humans is mostly due to the simplicity of the parasite life cycle, but the impact of multiple exposures to the biology of the infection and the consequences to the host's homeostasis are poorly understood. In this context, single and multiple exposures in mice were performed in order to characterize the parasitological, histopathological, tissue functional and immunological aspects of experimental larval ascariasis. The most important findings revealed that reinfected mice presented a significant reduction of parasite burden in the lung and an increase in the cellularity in the bronchoalveolar lavage (BAL) associated with a robust granulocytic pulmonary inflammation, leading to a severe impairment of respiratory function. Moreover, the multiple exposures to Ascaris elicited an increased number of circulating inflammatory cells as well as production of higher levels of systemic cytokines, mainly IL-4, IL-5, IL-6, IL-10, IL-17A and TNF-α when compared to single-infected animals. Taken together, our results suggest the intense pulmonary inflammation associated with a polarized systemic Th2/Th17 immune response are crucial to control larval migration after multiple exposures to Ascaris.

Infection with CagA-positive Helicobacter pylori strain containing three EPIYA C phosphorylation sites is associated with more severe gastric lesions in experimentally infected Mongolian gerbils (Meriones unguiculatus)

Infection with Helicobacter pylori strains containing high number of EPIYA-C phosphorylation sites in the CagA is associated with significant gastritis and increased risk of developing pre-malignant gastric lesions and gastric carcinoma. However, these findings have not been reproduced in animal models yet. Therefore, we investigated the effect on the gastric mucosa of Mongolian gerbil (Meriones unguiculatus) infected with CagA-positive H. pylori strains exhibiting one or three EPIYA-C phosphorilation sites. Mongolian gerbils were inoculated with H. pylori clonal isolates containing one or three EPIYA-C phosphorylation sites. Control group was composed by uninfected animals challenged with Brucella broth alone. Gastric fragments were evaluated by the modified Sydney System and digital morphometry. Clonal relatedness between the isolates was considered by the identical RAPD-PCR profiles and sequencing of five housekeeping genes, vacA i/d region and of oipA. The other virulence markers were present in both isolates (vacA s1i1d1m1, iceA2, and intact dupA). CagA of both isolates was translocated and phosphorylated in AGS cells. After 45 days of infection, there was a significant increase in the number of inflammatory cells and in the area of the lamina propria in the infected animals, notably in those infected by the CagA-positive strain with three EPIYA-C phosphorylation sites. After six months of infection, a high number of EPIYA-C phosphorylation sites was associated with progressive increase in the intensity of gastritis and in the area of the lamina propria. Atrophy, intestinal metaplasia, and dysplasia were also observed more frequently in animals infected with the CagA-positive isolate with three EPIYA-C sites.  We conclude that infection with H. pylori strain carrying a high number of CagA EPIYA-C phosphorylation sites is associated with more severe gastric lesions in an animal model of H. pylori infection.

Entamoeba dispar: Could it be pathogenic

Amebiasis is a disease caused by the protozoan parasite Entamoeba histolytica. This ameba can colonize the human intestine and persist as a commensal parasite, similar to Entamoeba dispar, an ameba considered to be non-pathogenic. The similarities between E. histolytica and E. dispar make the latter an attractive model for studies aimed at clarifying the pathogenesis of amebiasis. However, in addition to being an interesting experimental model, this relative of E. histolytica remains poorly understood. In the 1990, it was believed that E. dispar was unable to produce significant experimental lesions. This scenario began to change in 1996, when E. dispar strains were isolated from symptomatic patients in Brazil. These strains were able to produce liver and intestinal lesions that were occasionally indistinguishable from those produced by E. histolytica. These and other findings, such as the detection of E. dispar DNA sequences in samples from patients with amebic liver abscess, have revived the possibility that this species can produce lesions in humans. The present paper presents a series of studies on E. dispar that begin to reveal a new facet of this protozoan.

Mechanisms of acute kidney injury induced by experimental Lonomia obliqua envenomation

Lonomia obliqua caterpillar envenomation causes acute kidney injury (AKI), which can be responsible for its deadly actions. This study evaluates the possible mechanisms involved in the pathogenesis of renal dysfunction. To characterize L. obliqua venom effects, we subcutaneously injected rats and examined renal functional, morphological and biochemical parameters at several time points. We also performed discovery-based proteomic analysis to measure protein expression to identify molecular pathways of renal disease. L. obliqua envenomation causes acute tubular necrosis, which is associated with renal inflammation; formation of hematic casts, resulting from intravascular hemolysis; increase in vascular permeability and fibrosis. The dilation of Bowman's space and glomerular tuft is related to fluid leakage and intra-glomerular fibrin deposition, respectively, since tissue factor procoagulant activity increases in the kidney. Systemic hypotension also contributes to these alterations and to the sudden loss of basic renal functions, including filtration and excretion capacities, urinary concentration and maintenance of fluid homeostasis. In addition, envenomed kidneys increase the expression of proteins involved in cell stress, inflammation, tissue injury, heme-induced oxidative stress, coagulation and complement system activation. Finally, the localization of the venom in renal tissue agrees with morphological and functional alterations, suggesting also a direct nephrotoxic activity. In conclusion, the mechanisms of L. obliqua-induced AKI are complex involving mainly glomerular and tubular functional impairment and vascular alterations. These results are important to understand the mechanisms of renal injury and may suggest more efficient ways to prevent or attenuate the pathology of Lonomia's envenomation.

Influence of inflammation on parasitism and area of experimental amoebic liver abscess: an immunohistochemical and morphometric study

The influence of inflammation on the number of trophozoites and on the murine amoebic liver abscess area following infection with Entamoeba histolytica and E. dispar was evaluated. Immunohistochemistry and digital morphometry were used to identify and quantify the trophozoites, neutrophils, macrophages, and lesions. Positive correlation was observed between the number of trophozoites and inflammatory cells. A significant decrease in parasitism and inflammation in groups treated with dexamethasone was observed. The scarceness or absence of trophozoites in the treated groups suggest the importance of the inflammatory response in the production of amoebic hepatic abscesses in spite of the inherent virulence of the parasite being decisive in the establishment of the lesion.