Search Results (59)

Background: The movement of endemic diseases from tropical and disadvantaged areas is gradually spreading to developed countries as well. Amoebiasis, in particular, represents a significant threat to public health, amplified by globalization and increasing contact between humans and animals or vectors. In this way, atypical diseases may emerge in our country, also through an unusual mode of transmission—likely sexual, as “sexually transmitted enteric (STE) diseases”. Objective: We report and discuss the clinic approach to a rare case of dual human infestations by ecto- and endo-parasites with multiple liver abscesses presentation in a young truck driver residing in Northern Italy. Methods: The patient underwent a comprehensive screening with laboratory and microbiological tests, and CT images. Results: In July, the patient was admitted to our hepatology unit following the ultrasound identification of two hypoechoic lesions in the right lobe of the liver. In his medical history, in April, after a seemingly harmless infestation of body lice, effectively treated, he suffered from a prolonged and debilitating episode of acute diarrhea, lasting a month. This status was also accompanied by intestinal cramps, weight loss, and recurring fever episodes. Afterwards also appeared a Quincke’s-like angioedema involving the lips and mouth mucosa, with evening time exacerbation. Conclusions: The differential diagnosis of this complex and unusual clinical picture, together with the temporal evolution of the patient’s signs and symptoms, led us to hypothesize the presence of concomitant infections. These were most likely borreliosis and a STE disease, the latter ultimately diagnosed as amebiasis with hepatic invasion, allowing appropriate treatment and a favorable clinical outcome. Full article

The galactose/N-acetyl-D-galactosamine (Gal/GalNAc)-inhibitable lectin of Entamoeba histolytica plays essential roles in host cell adhesion and cytotoxicity. The intermediate subunit lectin-1 (Igl1) contributes to these functions, but its molecular state under different environmental conditions remains unclear. In this study, we found that Igl1 is present as multiple fragments in the culture supernatant of trophozoites, whereas a single major species corresponding to intact Igl1 was detected in cell lysates. Notably, the molecular sizes of both intact Igl1 and its extracellular fragments differed depending on culture conditions, with larger apparent sizes observed under co-culture with Caco-2 cells. These differences were not explained by changes in transcript levels, protein folding, or N-terminal truncation. Fragmentation of Igl1 was suppressed by a cysteine protease inhibitor, indicating extracellular generation. These findings demonstrate that host-cell-associated conditions alter the molecular size of Igl1 and that extracellular protease-dependent processing generates multiple Igl1 fragments, providing new insights into the regulation of this key virulence factor. The presence of extracellular fragments further suggests a potential contribution to host tissue damage during amoebiasis. Full article

For Entamoeba histolytica to establish an infection, it must employ several mechanisms of pathogenicity to produce and secrete virulence factors that allow the parasite to adhere to and finally colonize and invade the host. However, in the intestinal epithelium, trophozoites (amoebae) encounter lactoferrin (Lf), a glycoprotein of the first line of defense, together with immunoglobulins and other molecules. We previously reported that iron-free bovine Lf (bLf) could kill amoebae both in vitro and in animal models of intestinal and hepatic amoebiasis. In this work, selected pathogenic mechanisms were evaluated in trophozoites by exposing cultures to sublethal concentrations of bLf to determine which amoebic functions could be altered. At a sublethal bLf concentration, this glycoprotein was removed from the trophozoite. In the presence of erythrocytes, bLf colocalized with erythrocytes at the capping site; this was observed by confocal microscopy of living cells. In addition, the erythrophagocytosis rate, proteolytic activity, adhesion, and cytotoxic properties towards Caco2 colonic cancer cells were reduced in the presence of bLf. Lactoferrin could be a particularly important protein that naturally protects colonic epithelial cells from E. histolytica infection. Full article

The retromer is a highly conserved complex that mediates the trafficking of cargo proteins to the plasma membrane or the trans-Golgi network. In pathogenic microorganisms, retromer-dependent transport contributes to the delivery of virulence factors and promotes infection. The retromer consists of a sorting nexin dimer (SNX) and a cargo-selection complex (CSC), formed by Vps26, Vps35, and Vps29. In Entamoeba histolytica, the parasite that causes human amoebiasis, the retromer functions as a Rab7A GTPase effector and participates in phagocytosis and cytotoxicity. Although we previously characterized the roles of EhVps26 and EhVps35, the function of EhVps29 remained unclear. In this study, we analyzed the subcellular localization and functional role of EhVps29 in adhesion, phagocytosis, and cytopathic effect. EhVps29 localized to the plasma membrane, cytosol, vesicles, tubules, Golgi-like structures, MVBs and, for the first time, the nucleus. Immunofluorescence and Western blot assays demonstrated that EhVps29 modulates the localization of EhVps26, EhADH adhesin, and EhCP112 cysteine protease. Ehvps29 gene silencing and overexpression confirmed its involvement in virulence-associated processes. Immunoprecipitation and confocal microscopy results showed the interaction among EhVps29 and the ESCRT machinery members EhVps36 and EhADH. Our results indicate that EhVps29 is involved in parasite virulence and protein trafficking through recycling or degradation pathways. Full article

The coordination between transcription and mRNA processing is essential for eukaryotic gene regulation, yet the structural basis of this coupling remains poorly understood in Entamoeba histolytica, the protozoan parasite responsible for amoebiasis. In this study, we characterized the interaction between the transcriptional coactivator EhPC4 and the polyadenylation factor EhCFIm25 through an integrated in vitro and in silico approach. Far-Western assays confirmed direct physical interaction between both recombinant proteins. To elucidate the molecular mechanism, we performed 500 ns Molecular Dynamics simulations of full-length EhPC4, identifying high flexibility in its N-terminal region. Protein–protein docking analysis revealed a stable EhPC4-EhCFIm25 complex (Cluster C4) with favorable binding energies (∆G = −11.4 kcal/mol). Notably, heatmap analysis of the interaction interface identified a conserved “hotspot” at the C-terminal end of EhCFIm25 (residues 249–255) that mediates the binding with PC4 without occluding DNA-binding domain (K127 in EhPC4) or RNA-recognition motifs in EhCFIm25. Our findings suggest that EhCFIm25 serves as a molecular scaffold that physically couples transcription and polyadenylation, providing a structural framework for the efficient regulation of virulence-related genes in this parasite. Full article

Parasitic infections remain a major global health challenge, particularly in resource-limited settings where they are closely tied to poverty and inadequate sanitation. The increasing emergence of drug resistance and the limited accessibility of current therapies highlight the urgent need for novel, safe, and affordable alternatives. Mangifera indica L. (mango), a widely cultivated fruit tree deeply rooted in traditional medicine, has long been used to treat conditions symptomatic of parasitic diseases, including fever, diarrhea, and dysentery. Phytochemical investigations have revealed a rich spectrum of bioactive compounds, notably mangiferin, phenolic compounds and terpenoids, which exhibit antimicrobial, antioxidant, and immunomodulatory activities. This review critically synthesizes evidence on the antiparasitic potential of M. indica against protozoa, such as Plasmodium, Leishmania, Trypanosoma, Toxoplasma gondii, Entamoeba histolytica, and free-living amoebae, as well as helminths. Strongest evidence exists for malaria and helminth infections, where both crude extracts and isolated compounds demonstrated significant activity in vitro and in vivo. Encouraging but limited findings are available for leishmaniasis and trypanosomiasis, while data on toxoplasmosis and amoebiasis remain largely speculative. Variations in efficacy across studies are influenced by plant parts and extraction methods, with ethanolic extracts and mangiferin often showing superior results. Despite promising findings, mechanistic studies, standardized methodologies, toxicological evaluations, and clinical trials are scarce. Future research should focus on elucidating molecular mechanisms, exploring synergistic interactions with existing drugs, and leveraging advanced delivery systems to enhance bioavailability. Full article

Human milk, especially colostrum, is a biologically complex fluid with potent protective properties against gastrointestinal disturbances in infants. Among intestinal protozoa transmitted via the fecal–oral route, this review focuses on Giardia lamblia and Entamoeba histolytica, as the protective role of milk-derived factors against these parasites is the most extensively documented. Its protective effects result from a wide range of bioactive components, including mucins, lactoferrin, human milk oligosaccharides, melatonin, and secretory IgA, which support the integrity of the intestinal barrier, regulate immune responses, and inhibit the adhesion and activity of pathogens. The composition of human milk can be influenced by maternal factors such as nutritional status, stress, sleep quality, and physical activity, which may modulate its immunological potential. Dietary intake of micronutrients, fermentable fibers, and fermented foods also appears to play a role in shaping the milk’s protective properties. This review discusses the molecular mechanisms by which selected milk components contribute to the defense against protozoan infections in early life and considers how maternal health and lifestyle may affect the effectiveness of these protective mechanisms. Full article

Background: The diameter of mature follicles in donkeys is several times larger than in cattle and sheep, but the key genes responsible for maintaining follicular development and preventing apoptosis remain unclear. Methods: This study observed the process of donkey follicular development using ultrasound and analyzed the changes in common reproductive hormones in serum. Granulosa cells (GCs) were collected from large (mature follicles, diameter ≥ 37 mm) and small (atretic follicles, diameter 10–25 mm) follicles for sequencing to screen differentially expressed genes (DEGs) and signaling pathways influencing the development of mature follicles. The roles of selected genes were further validated in in vitro cultured GCs. Results: Donkey follicles exhibited rapid growth 5–7 days before ovulation, reaching maturity at a diameter of 37 mm. The maximum diameter of ovulatory follicles was approximately 40.7 mm, while non-ovulatory follicles began to undergo atresia when reaching about 25 mm. Serum reproductive hormone levels aligned with follicular developmental status. RNA sequencing identified 3291 DEGs between large and small follicles, with KEGG analysis highlighting enrichment in the PI3K-Akt signaling pathway, focal adhesion, amoebiasis, and cancer pathways. Lentiviral overexpression and interference assays targeting the DEGs EMCN and SYT12 revealed that EMCN positively regulates FOXO3, a key gene in the PI3K-Akt pathway. Conclusions: The EMCN gene in mature donkey follicles regulates FOXO3 in the PI3K-Akt signaling pathway, potentially inhibiting apoptosis in follicular granulosa cells and sustaining follicular development until ovulation. This study provides insights into the mechanisms underlying follicular development in donkeys. Full article

Metronidazole is the preferred drug for treating amoebiasis caused by Entamoeba histolytica. Its antiamoebic activity is primarily attributed to activation by various reductases. This study reports an alternative activation pathway in E. histolytica mediated by the decarboxylating malic enzyme. Functional characterization of this NADPH-dependent enzyme reveals that it is secreted into the extracellular milieu and may play a role in E. histolytica adhesion to human enteric cells. Structural analysis of the E. histolytica malic enzyme (EhME) demonstrates that the protein forms a strict dimer, with the protomers interlocked by a unique knot structure formed by two polypeptide chains. This distinctive structural feature closely aligns EhME with its prokaryotic counterparts. In conclusion, our findings reveal that E. histolytica harbors a deeply entangled dimeric malic enzyme that contributes to metronidazole susceptibility, sharing structural similarities with bacterial malic enzymes. Full article

Entamoeba spp. are common zoonotic intestinal protozoa, which can lead to serious intestinal diseases in both humans and animals through fecal–oral transmission, leading to significant economic losses and public health challenges. To reveal the prevalence of Entamoeba in sheep and cattle in Shanxi Province, North China, fecal samples were collected from 311 sheep, 392 dairy cattle, and 393 beef cattle from three representative counties in the northern, central, and southern regions of Shanxi Province. DNA was extracted from the fecal samples and amplified by PCR with primers targeting the nuclear small subunit ribosomal RNA (SSU rRNA) gene of Entamoeba spp., followed by the sequencing of the positive products. The overall infection rates of Entamoeba were 51.5% (160/311), 82.9% (325/392), and 79.1% (311/393) in sheep, dairy cattle, and beef cattle, respectively. Statistical analysis showed a significant correlation between the infection rate of Entamoeba and the location factor in sheep, dairy cattle, and beef cattle (p < 0.001). According to the obtained SSU rRNA sequences, several Entamoeba species, namely Entamoeba bovis, Entamoeba Ribosomal Lineage (RL) 2, Entamoeba RL4, and Entamoeba RL8, were identified. This study represents the first molecular survey of Entamoeba prevalence in sheep, beef cattle, and dairy cattle in Shanxi Province. The findings extend the geographical distribution of Entamoeba spp. and provide valuable scientific data for the prevention and control of amoebiasis in Shanxi Province. Full article

Several studies with kaempferol (KP) and linearolactone (LL) have demonstrated their antiparasitic activity. However, the toxicity of these treatments is unknown. Therefore, this study aimed to evaluate the possible toxicological effects of intraperitoneal (i.p.) administration of KP or LL on the amoebic liver abscess model (ALA) in Mesocricetus auratus. An ALA was induced in male hamsters with 1.5 × 10⁵Entamoeba histolytica (E. histolytica) trophozoites inoculated in the left hepatic lobe. The lesion evolved for 4 days, and then KP (5 mg/kg body weight/day) or LL (10 mg/kg body weight/day) was administered for 4 consecutive days. Then, magnetic resonance imaging (MRI), paraclinical analyses, and necropsy for histopathological evaluation were performed. There was similar ALA inhibition by KP (19.42%), LL (28.16%), and metronidazole, the antiamoebic control (20.87%) (p ≤ 0.05, analysis of variance [ANOVA]). There were hepatic and renal biochemical alterations in all treatment groups, mainly for KP (aspartate aminotransferase: 347.5 ± 37.5 U/L; blood urea nitrogen: 19.4 ± 1.9 g/dL; p ≤ 0.05, ANOVA). Lesions found in the organs were directly linked to the pathology. In conclusion, KP and LL decreased ALA development and exerted fewer toxicological effects compared with metronidazole. Therefore, both compounds exhibit therapeutic potential as an alternative treatment of amoebiasis caused by E. histolytica. However, additional clinical studies in different contexts are required to reaffirm this assertion. Full article

The need for new drugs to treat human infections is a global health concern. Diseases like tuberculosis, trypanosomiasis, amoebiasis, and AIDS remain significant problems, especially in developing countries like Mexico. Despite existing treatments, issues such as resistance and adverse effects drive the search for new alternatives. Herein, we introduce the NUATEI research consortium, made up of experts from the Institute of Biomedical Research at UNAM, who identify and obtain natural and synthetic compounds and test their effects against human pathogens using in vitro and in vivo models. The consortium has evaluated hundreds of natural extracts and compounds against the pathogens causing tuberculosis, trypanosomiasis, amoebiasis, and AIDS, rendering promising results, including a patent with potential for preclinical studies. This paper presents the rationale behind the formation of this consortium, as well as its objectives and strategies, emphasizing the importance of natural and synthetic products as sources of antimicrobial compounds and the relevance of the diseases studied. Finally, we briefly describe the methods of the evaluation of the compounds in each biological model and the main achievements. The potential of the consortium to screen numerous compounds and identify new therapeutic agents is highlighted, demonstrating its significant contribution to addressing these infectious diseases. Full article

Entamoeba histolytica is the protozoan causative of human amoebiasis. The EhADH adhesin (687 aa) is a protein involved in tissue invasion, phagocytosis and host-cell lysis. EhADH adheres to the prey and follows its arrival to the multivesicular bodies. It is an accessory protein of the endosomal sorting complexes required for transport (ESCRT) machinery. Here, to study the role of different parts of EhADH during virulence events, we produced trophozoites overexpressing the three domains of EhADH, Bro1 (1–400 aa), Linker (246–446 aa) and Adh (444–687 aa) to evaluate their role in virulence. The TrophozBro1_1–400 slightly increased adherence and phagocytosis, but these trophozoites showed a higher ability to destroy cell monolayers, augment the permeability of cultured epithelial cells and mouse colon, and produce more damage to hamster livers. The TrophozLinker_226–446 also increased the virulence properties, but with lower effect than the TrophozBro1_1–400. In addition, this fragment participates in cholesterol transport and GTPase binding. Interestingly, the TrophozAdh_444–687 produced the highest effect on adherence and phagocytosis, but it poorly influenced the monolayers destruction; nevertheless, they augmented the colon and liver damage. To identify the protein partners of each domain, we used recombinant peptides. Pull-down assays and mass spectrometry showed that Bro1 domain interplays with EhADH, Gal/GalNAc lectin, EhCPs, ESCRT machinery components and cytoskeleton proteins. While EhADH, ubiquitin, EhRabB, EhNPC1 and EhHSP70 were associated to the Linker domain, and EhADH, EhHSP70, EhPrx and metabolic enzymes interacted to the Adh domain. The diverse protein association confirms that EhADH is a versatile molecule with multiple functions probably given by its capacity to form distinct molecular complexes. Full article

Human amoebiasis still represents a major health problem worldwide. Metronidazole has been used as the most common drug to treat the disease; however, it is also known that the drug causes undesirable side effects. This has led to the search for new pharmacological alternatives which include phytochemical compounds with antiamoebic effects. We analyzed the amoebicidal activity of stevioside (STV), a diterpene glycoside present in Stevia rebaudiana, on trophozoites of E. histolytica. Different concentrations of STV were tested, and an inhibitory concentration of 50% of cell viability (IC₅₀) was determined with an exposition of 9.53 mM for 24 h. Trophozoites exposed to STV showed morphological changes evidenced by the decrease in the basic structures related to the movement and adherence to the substrate, as well as ultrastructural features characterized by a loss of regularity on the cell membrane, an increase in cytoplasmic granularity, and an increase in apparent autophagic vacuoles. Also, the decrease in cysteine protease expression and the proteolytic activity of trophozoites to degrade the cell monolayer were analyzed. A histological analysis of hamster livers inoculated with trophozoites and treated with STV showed changes related to the granulomatous reaction of the liver parenchymal tissue. Our results constitute the first report related to the possible use of STV as a therapeutic alternative in amoebiasis. Full article

Neutrophils are the most abundant polymorphonuclear granular leukocytes in human blood and are an essential part of the innate immune system. Neutrophils are efficient cells that eliminate pathogenic bacteria and fungi, but their role in dealing with protozoan parasitic infections remains controversial. At sites of protozoan parasite infections, a large number of infiltrating neutrophils is observed, suggesting that neutrophils are important cells for controlling the infection. Yet, in most cases, there is also a strong inflammatory response that can provoke tissue damage. Diseases like malaria, trichomoniasis, leishmaniasis, Chagas disease, and amoebiasis affect millions of people globally. In this review, we summarize these protozoan diseases and describe the novel view on how neutrophils are involved in protection from these parasites. Also, we present recent evidence that neutrophils play a double role in these infections participating both in control of the parasite and in the pathogenesis of the disease. Full article