Distribution and virulence of Escherichia coli harboring cyclomodulins and supplementary virulence genes isolates from clinical and environmental samples

This study aimed to determine the prevalence of cyclomodulins (cdt, cnf, pks and cif) in Escherichia coli (E. coli) isolated from clinical and environmental samples, the presence of supplementary virulence genes (SVG), antibiotic resistance, and in vitro cytotoxicity. 413 E. coli were isolated from clinical (stool from obese subjects, normal weight subjects, children with diarrhea, and children without diarrhea; and urine from pregnant and non-pregnant women with urinary tract infections) and environmental (water and different foods) samples. PCR was performed to identify E. coli pathotypes, the four cyclomodulins, and 18 SVG; virulence score, cytotoxic assay, and antibiotic resistance assay were performed. Fifteen percent of E. coli were positive for cyclomodulins and were found in all isolation sources; however, in children with diarrhea, they were more frequent. The most frequent cyclomodulin was cdt. More DEC strains harbor cyclomodulins than non-DEC, and cyclomodulins were most frequent among aEPEC pathotype. SVG ehaC was associated with cyclomodulin-positive strains. Cyclomodulin-positive E. coli had a higher virulence score but no significant cytotoxic activity. They were slightly more resistant to antibiotics. In conclusion, cyclomodulins-positive E. coli was widely distributed in humans, food, and the environment, and they were associated with SVG ehaC, suggesting that these genes may play a role in the pathogenesis of the cyclomodulins. However, more research is needed.

Virulence genes, antimicrobial resistance profile, phylotyping and pathotyping of diarrheagenic Escherichia coli isolated from children in Southwest Mexico

Diarrheagenic E. coli (DEC) strains are one of the most important etiology factors causing diarrhea in children worldwide, especially in developing countries. DEC strains have characteristic virulence factors; however, other supplemental virulence genes (SVG) may contribute to the development of diarrhea in children. Therefore, this study aimed to determine the prevalence of DEC in children with diarrhea in southwestern Mexico and to associate childhood symptoms, SVG, and pathotypes with diarrhea-causing DEC strains. DEC strains were isolated from 230 children with diarrhea aged 0-60 months from the state of Oaxaca, southwestern Mexico; clinical data were collected, and PCR was used to identify SVG and pathotypes. Antibiotic resistance profiling was performed on DEC strains. 63% of samples were DEC positive, single or combined infections (two (21%) or three strains (1.3%)) of aEPEC (51%), EAEC (10.2%), tEPEC (5.4%), DAEC (4.8%), ETEC (4.1%), EIEC (1.4%), or EHEC (0.7%) were found. Children aged ≤ 12 and 49-60 months and symptoms (e.g., fever and blood) were associated with DEC strains. SVG related to colonization (nleB-EHEC), cytotoxicity (sat-DAEC and espC-tEPEC), and proteolysis (pic-aEPEC) were associated with DECs strains. E. coli phylogroup A was the most frequent, and some pathotypes (aEPEC-A, DAEC-B), and SVG (espC-B2, and sat-D) were associated with the phylogroups. Over 79% of the DEC strains were resistant to antibiotics, and 40% were MDR and XDR, respectively. In conclusion aEPEC was the most prevalent pathotype in children with diarrhea in this region. SVG related to colonization, cytotoxicity, and proteolysis were associated with diarrhea-producing DEC strains, which may play an essential role in the development of diarrhea in children in southwestern Mexico.

Virulence-associated genes and antimicrobial resistance patterns in bacteria isolated from pregnant and nonpregnant women with urinary tract infections: the risk of neonatal sepsis

Uropathogenic Escherichia coli (UPEC) is classified as the major causative agent of urinary tract infections (UTIs). UPEC virulence and antibiotic resistance can lead to complications in pregnant women and (or) newborns. Therefore, the aim of this study was to determine the etiological agents of UTIs, as well as to identify genes related to virulence factors in bacteria isolated from pregnant and nonpregnant women. A total of 4506 urine samples were collected from pregnant and nonpregnant women. Urine cultures were performed, and PCR was used to identify phylogroups and virulence-related genes. Antibiotic resistance profiles were determined. The incidence of UTIs was 6.9% (pregnant women, n = 206 and nonpregnant women, n = 57), and UPEC belonging to phylogroup A was the most prevalent. The presence of genes related to capsular protection, adhesins, iron acquisition, and serum protection in UPEC was associated with not being pregnant, while the presence of genes related to adhesins was associated with pregnancy. Bacteria isolated from nonpregnant women were more resistant to antibiotics; 36.5% were multidrug resistant, and 34.9% were extensively drug resistant. Finally, UTIs were associated with neonatal sepsis risk, particularly in pregnant women who underwent cesarean section while having a UTI caused by E. coli. In conclusion, UPEC isolated from nonpregnant women carried more virulence factors than those isolated from pregnant women, and maternal UTIs were associated with neonatal sepsis risk.

Zingiber officinale-Derived Extracellular Vesicles Attenuate Bleomycin-Induced Pulmonary Fibrosis Trough Antioxidant, Anti-Inflammatory and Protease Activity in a Mouse Model

Idiopathic pulmonary fibrosis (IPF) is the most frequent and severe idiopathic interstitial pneumonia. It is a chronic and progressive disease with a poor prognosis and is a major cause of morbidity and mortality. This disease has no cure; therefore, there is a clinical need to search for alternative treatments with greater efficacy. In this study, we aimed to evaluate the effect of extracellular vesicles (EVs) from Zingiber officinale (EVZO) in a murine model of bleomycin (BLM)-induced IPF administered through an osmotic minipump. EVZO had an average size of 373 nm and a spherical morphology, as identified by scanning electron microscopy. Label-free proteomic analysis of EVZOs was performed by liquid chromatography coupled to mass spectrometry, and 20 proteins were identified. In addition, we demonstrated the protease activity of EVZO by gelatin-degrading zymography assay and the superoxide dismutase (SOD) activity of EVZO by an enzymatic assay. In the BLM-induced IPF mouse model, nasal administration of 50 μg of EVZO induced recovery of alveolar space size and decreased cellular infiltrate, collagen deposition, and expression of α-SMA-positive cells. Additionally, EVZO inhibited inflammatory markers such as iNOS and COX-2, lipid peroxidation, and apoptotic cells. These results show that EVZO may represent a novel natural delivery mechanism to treat IPF.

Prevalence of Cyclomodulin-Positive E. coli and Klebsiella spp. Strains in Mexican Patients with Colon Diseases and Antimicrobial Resistance

Colon diseases, such as colorectal cancer (CRC), are multifactor diseases that affect more than one million people per year; recently, the microbiota has been associated with an etiologic factor, specifically bacterial cyclomodulin positivity (CM⁺). Unfortunately, there are no studies from Mexico that detail the presence of bacterial CM⁺ in patients with colon diseases. We therefore performed a comprehensive study to investigate the associations and prevalence of cyclomodulin-positive Diarrheagenic E. coli (DEC), non-DEC, and Klebsiella spp. strains isolated from Mexican subjects with colon diseases. In this work, we analyzed 43 biopsies, 87 different bacteria were isolated, and E. coli was the most frequently noted, followed by Klebsiella spp., and Enterococcus spp. E. coli, non-DEC, and EPEC belonging to phylogroup B2 were the most prevalent. More than 80% of E. coli and Klebsiella were CM⁺. pks, cdt, cnf, and cif were identified. cdt was associated with non-DEC, cif and its combinations with EPEC, as well as cdt and psk with Klebsiella. Lastly, all the CM⁺ bacteria were resistant to at least one antibiotic (34% were MDR, and 48% XDR). In conclusion, the high prevalence of bacterial CM⁺ in colon disease patients suggests that these bacteria play an important role in the genesis of these diseases.

Temporal Dynamics of T Helper Populations in the Proximal Small Intestine after Oral Bovine Lactoferrin Administration in BALB/c Mice

Bovine lactoferrin (bLf), a component of milk and a dietary supplement, modulates intestinal immunity at effector and inductor sites. Considering the regional difference in intestinal compartments and the dynamics of local cytokine-producing cells in the gut across time, the aim of this work was to characterize the effects of bLf on the proximal small intestine in a BALB/c murine model of oral administration. Male BALB/c mice were treated with oral bLf vs. saline control as mock by buccal deposition for 28 days. Intestinal secretions were obtained at different time points and cells were isolated from Peyer's patches (PP) and lamina propria (LP) of the proximal small intestine as representative inductor and effector sites, respectively. Total and specific anti-bLF IgA and IgM were determined by enzyme-immuno assay; the percentages of IgA+ and IgM+ plasma cells (PC) and cytokine-producing CD4+ T cells of PP and LP were analyzed by flow cytometry. We found that total and bLf-specific IgA and IgM levels were increased in the intestinal secretions of the bLf group in comparison to mock group and day 0. LP IgA+ PC and IgM+ PC presented an initial elevation on day 7 and day 21, respectively, followed by a decrease on day 28 in comparison to mock. Higher percentages of CD4+ T cells in LP were found in the bLf group. Cytokines-producing CD4+ T cells populations presented a pattern of increases and decreases in the bLf group in both LP and PP. Transforming growth factor beta (TGF-β)+ CD4+ T cells showed higher percentages after bLf administration with a marked peak at day 21 in both LP and PP in comparison to mock-treated mice. Oral bLf exhibits complex immune properties in the proximal small intestine, where temporal monitoring of the inductor and effector compartments reveals patterns of rises and falls of different cell populations. Exceptionally, TGF-β+ CD4+ T cells show consistent higher numbers after bLf intervention across time. Our work suggests that isolated measurements do not show the complete picture of the modulatory effects of oral bLf in immunological sites as dynamic as the proximal small intestine.

Curcumin Blocks Cytotoxicity of Enteroaggregative and Enteropathogenic Escherichia coli by Blocking Pet and EspC Proteolytic Release From Bacterial Outer Membrane

Pet and EspC are toxins secreted by enteroaggregative (EAEC) and enteropathogenic (EPEC) diarrheagenic Escherichia coli pathotypes, respectively. Both toxins are members of the Serine Protease Autotransporters of Enterobacteriaceae (SPATEs) family. Pet and EspC are important virulence factors that produce cytotoxic and enterotoxic effects on enterocytes. Here, we evaluated the effect of curcumin, a polyphenolic compound obtained from the rhizomes of Curcuma longa L. (Zingiberaceae) on the secretion and cytotoxic effects of Pet and EspC proteins. We found that curcumin prevents Pet and EspC secretion without affecting bacterial growth or the expression of pet and espC. Our results show that curcumin affects the release of these SPATEs from the translocation domain, thereby affecting the pathogenesis of EAEC and EPEC. Curcumin-treated EAEC and EPEC did not induce significant cell damage like the ability to disrupt the actin cytoskeleton, without affecting their characteristic adherence patterns on epithelial cells. A molecular model of docking predicted that curcumin interacts with the determinant residues Asp₁₀₁₈-Asp₁₀₁₉ and Asp₁₀₂₉-Asp₁₀₃₀ of the translocation domain required for the release of Pet and EspC, respectively. Consequently, curcumin blocks Pet and EspC cytotoxicity on epithelial cells by preventing their release from the outer membrane.

Amoebicidal activity of curcumin on Entamoeba histolytica trophozoites

Objectives

This study was undertaken to investigate the amoebicidal potential of curcumin on Entamoeba histolytica, as well as its synergistic effect with metronidazole.

Methods

Entamoeba histolytica trophozoites were exposed to 100, 200 and 300 μm of curcumin, for 6, 12 and 24 h. Consequently, the viability of cells was determined by trypan blue exclusion test. All specimens were further analysed by scanning electron microscopy. For drug combination experiment, the Chou-Talalay method was used.

Key findings

Curcumin affected the growth and cell viability in a time- and dose-dependent manner. The higher inhibitory effects were observed with 300 μm at 24 h; 65.5% of growth inhibition and only 28.8% of trophozoites were viable. Additionally, curcumin also altered adhesion and the morphology of the trophozoites. Scanning electron microscopy revealed treated trophozoites with damages on the membrane, size alterations and parasites with loss of cellular integrity. In addition, the combination of curcumin + metronidazole exhibited a synergistic effect; the activity of both drugs was improved.

Conclusions

This is the first report evaluating the effectiveness of curcumin against E. histolytica. Our results suggest that CUR could be considered for evaluation in future pharmacological studies as a promising amoebicidal agent or as complementary therapy.

Antigiardial Activity of Podophyllotoxin-Type Lignans from Bursera fagaroides var. fagaroides

Giardiasis, a diarrheal disease, is highly prevalent in developing countries. Several drugs are available for the treatment of this parasitosis; unfortunately, all of them have variable efficacies and adverse effects. Bursera fagaroides has been known for its anti-inflammatory and antidiarrheal properties in Mexican traditional medicine. We investigated the in vitro anti-giardial activities of four podophyllotoxin-type lignans from Bursera fagaroides var. fagaroides, namely, 5'-desmethoxy-β-peltatin-A-methylether (5-DES), acetylpodophyllotoxin (APOD), burseranin (BUR), and podophyllotoxin (POD). All lignans affected the Giardia adhesion and electron microscopy images revealed morphological alterations in the caudal region, ventral disk, membrane, and flagella, to different extents. Only 5-DES, APOD, and POD caused growth inhibition. Using the Caco-2 human cell line as a model of the intestinal epithelium, we demonstrated that APOD displayed direct antigiardial killing activity and low toxicity on Caco-2 cells. This finding makes it an attractive potential starting point for new antigiardial drugs.

Pathogenic Lifestyles of E. coli Pathotypes in a Standardized Epithelial Cell Model Influence Inflammatory Signaling Pathways and Cytokines Secretion

Inflammatory response is key for the host defense against diarrheagenic Escherichia coli and contributes to the pathogenesis of the disease but there is not a comparative study among different diarrheagenic pathotypes. We analyzed the inflammatory response induced by five diarrheagenic pathotypes in a HT-29 cell infection model. The model was unified to reproduce the pathogenesis of each pathotype. To compare the inflammatory responses we evaluated: (i) nuclear NF-κB and ERK1/2 translocation by confocal microscopy; (ii) kinetics of activation by each pathway detecting p65 and ERK1/2 phosphorylation by Western blotting; (iii) pathways modulation through bacterial infections with or without co-stimulation with TNF-α or EGF; (iv) cytokine profile induced by each pathotype with and without inhibitors of each pathway. EHEC but mainly EPEC inhibited translocation and activation of p65 and ERK1/2 pathways, as well as cytokines secretion; inhibition of p65 and ERK1/2 phosphorylation prevailed in the presence of TNF-α and EGF, respectively. Intracellular strains, EIEC/Shigella flexneri, caused a strong translocation, activation, and cytokines secretion but they could not inhibit TNF-α and EGF stimulation. ETEC and mainly EAEC caused a moderate translocation, but a differential activation, and high cytokines secretion; interestingly TNF-α and EGF stimulation did no modify p65 and ERK1/2 activation. The use of inhibitors of NF-κB and/or ERK1/2 showed that NF-κB is crucial for cytokine induction by the different pathotypes; only partially depended on ERK1/2 activation. Thus, in spite of their differences, the pathotypes can also be divided in three groups according to their inflammatory response as those (i) that inject effectors to cause A/E lesion, which are able to inhibit NF-κB and ERK1/2 pathways, and cytokine secretion; (ii) with fimbrial adherence and toxin secretion with a moderate inhibition of both pathways but high cytokines secretion through autocrine cytokine regulation; and (iii) the intracellular bacteria that induce the highest pathways activation and cytokines secretion by using different activation mechanisms. This study provides a comprehensive analysis of how the different pathogenesis schemes of E. coli pathotypes manipulate inflammatory signaling pathways, which leads to a specific proinflammatory cytokine secretion in a cell model infection that reproduce the hallmarks of infection of each pathotype.

EspC promotes epithelial cell detachment by enteropathogenic Escherichia coli via sequential cleavages of a cytoskeletal protein and then focal adhesion proteins

EspC is a non-locus of enterocyte effacement (LEE)-encoded autotransporter produced by enteropathogenic Escherichia coli (EPEC) that is secreted to the extracellular milieu by a type V secretion system and then translocated into epithelial cells by the type III secretion system. Here, we show that this efficient EspC delivery into the cell leads to a cytopathic effect characterized by cell rounding and cell detachment. Thus, EspC is the main protein involved in epithelial cell cytotoxicity detected during EPEC adhesion and pedestal formation assays. The cell detachment phenotype is triggered by cytoskeletal and focal adhesion disruption. EspC-producing EPEC is able to cleave fodrin, paxillin, and focal adhesion kinase (FAK), but these effects are not observed when cells are infected with an espC isogenic mutant. Recovery of these phenotypes by complementing the mutant with the espC gene but not with the espC gene mutated in the serine protease motif highlights the role of the protease activity of EspC in the cell detachment phenotype. In vitro assays using purified proteins showed that EspC, but not EspC with an S256I substitution [EspCS256I], directly cleaves these cytoskeletal and focal adhesion proteins. Kinetics of protein degradation indicated that EspC-producing EPEC first cleaves fodrin (within the 11th and 9th repetitive units at the Q1219 and D938 residues, respectively), and this event sequentially triggers paxillin degradation, FAK dephosphorylation, and FAK degradation. Thus, cytoskeletal and focal adhesion protein cleavage leads to the cell rounding and cell detachment promoted by EspC-producing EPEC.