Production and immunological characterization of the novel single-chain variable fragment (scFv) antibodies against the epitopes on Opisthorchis viverrini cathepsin F (OvCatF)

BACKGROUND

Opisthorchis viverrini infection is a significant health problem in several countries, especially Southeast Asia. The infection causes acute gastro-hepatic symptoms and also long-term infection leading to carcinogenesis of an aggressive bile duct cancer (cholangiocarcinoma; CCA). Hence, the early diagnosis of O. viverrini infection could be the way out of this situation. Still, stool examination by microscopic-based methods, the current diagnostic procedure is restricted by low parasite egg numbers in the specimen and unprofessional laboratorians. The immunological procedure provides a better chance for diagnosis of the infection. Hence, this study aims to produce single-chain variable fragment (scFv) antibodies for use as a diagnostic tool for O. viverrini infection.

METHODS

This study uses phage display technologies to develop the scFv antibodies against O. viverrini cathepsin F (OvCatF). The OvCatF-deduced amino acid sequence was analyzed and predicted for B-cell epitopes used for short peptide synthesis. The synthetic peptides were used to screen the phage library simultaneously with OvCatF recombinant protein (rOvCatF). The potentiated phages were collected, rescued, and reassembled in XL1-blue Escherichia coli (E. coli) as a propagative host. The positive clones of phagemids were isolated, and the single-chain variable (scFv) fragments were sequenced, computationally predicted, and molecular docked. The complete scFv fragments were digested from the phagemid, subcloned into the pOPE101 expression vector, and expressed in XL1-blue E. coli. Indirect ELISA and Western analysis were used to verify the detection efficiency.

RESULTS

The scFv phages specific to OvCatF were successfully isolated, subcloned, and produced as a recombinant protein. The recombinant scFv antibodies were purified and refolded to make functional scFv. The evaluation of specific recognition of the particular epitopes and detection limit results by both computational and laboratory performances demonstrated that all three recombinant scFv antibodies against OvCatF could bind specifically to rOvCatF, and the lowest detection concentration in this study was only one hundred nanograms.

CONCLUSION

Our produced scFv antibodies will be the potential candidates for developing a practical diagnostic procedure for O. viverrini infection in humans in the future.

Whole Genome Sequencing Reveals Antimicrobial Resistance and Virulence Genes of Both Pathogenic and Non-Pathogenic B. cereus Group Isolates from Foodstuffs in Thailand

Members of the Bacillus cereus group are spore-forming Gram-positive bacilli that are commonly associated with diarrheal or emetic food poisoning. They are widespread in nature and frequently present in both raw and processed food products. Here, we genetically characterized 24 B. cereus group isolates from foodstuffs. Whole-genome sequencing (WGS) revealed that most of the isolates were closely related to B. cereus sensu stricto (12 isolates), followed by B. pacificus (5 isolates), B. paranthracis (5 isolates), B. tropicus (1 isolate), and "B. bingmayongensis" (1 isolate). The most detected virulence genes were BAS_RS06430, followed by bacillibactin biosynthesis genes (dhbA, dhbB, dhbC, dhbE, and dhbF), genes encoding the three-component non-hemolytic enterotoxin (nheA, nheB, and nheC), a gene encoding an iron-regulated leucine-rich surface protein (ilsA), and a gene encoding a metalloprotease (inhA). Various biofilm-associated genes were found, with high prevalences of tasA and sipW genes (matrix protein-encoding genes); purA, purC, and purL genes (eDNA synthesis genes); lytR and ugd genes (matrix polysaccharide synthesis genes); and abrB, codY, nprR, plcR, sinR, and spo0A genes (biofilm transcription regulator genes). Genes related to fosfomycin and beta-lactam resistance were identified in most of the isolates. We therefore demonstrated that WGS analysis represents a useful tool for rapidly identifying and characterizing B. cereus group strains. Determining the genetic epidemiology, the presence of virulence and antimicrobial resistance genes, and the pathogenic potential of each strain is crucial for improving the risk assessment of foodborne B. cereus group strains.

Cardiovascular Protective Effect of Garcinia dulcis Flower Acetone Extract in 2-Kidney-1-Clip Hypertensive Rats

Morelloflavone and camboginol are bioactive compounds purified from Garcinia dulcis (GD), which has anti-inflammatory and antihypertensive properties. The objective of this study was to examine the cardiovascular protective effect of GD flower acetone extract in 2-kidney-1-clip (2K1C) hypertensive rats. Male Wistar rats underwent 2K1C or sham operation (SO) and were housed for 4 weeks. Each group of rats, then, was further divided into 2 subgroups receiving oral administration of either 50 mg/kg BW GD extract or corn oil (vehicle) daily for 4 weeks. Noninvasive blood pressure (BP) and body weight were measured weekly throughout the study. Subsequently, the invasive measurement of arterial BP and the heart rate were determined in all anesthetized rats. The baroreceptor reflex sensitivity (BRS) was investigated by injection of either phenylephrine or sodium nitroprusside for bradycardia or tachycardia response, respectively. Histological examination of the heart and thoracic aorta was also performed in order to investigate the general morphology and the tumor necrosis factor alpha (TNF-α) expression. We found that the GD flower extract significantly diminished the BP and restored the impaired BRS. Moreover, it also decreased the TNF-α expression in the cardiac muscle and thoracic aorta of 2K1C when compared to the SO group. Taken together, our data showed that GD flower extract exhibits the cardiovascular protective effect in the 2K1C hypertensive rats.

Garcinia dulcis Extract Alleviates Inflammation in Kidney and Liver of the 2-Kidney-1-Clip Hypertensive rat

Garcinia dulcis (GD) extract possesses anti-hypertensive property that are poorly characterized. This study aimed to investigate an anti-inflammatory effect of GD flower extract in the 2-kidney-1-clip (2K1C) hypertensive compared to sham operative (SO) rat. Male Wistar rats were divided into 2 groups; the 2K1C group in which a silver clip was placed around renal artery to induce hypertension, and the SO normotensive group. Four weeks later, each group of rats were further divided into 2 subgroups, each subgroup was orally gavaged of either corn oil (vehicle) or 50 mg/kg BW GD extract daily for 4 weeks. The malondialdehyde (MDA) levels in serum, liver, and kidney were determined. Hematoxylin and eosin staining was carried out for histological examination, Periodic acid - Schiff staining for glomerular injury, Masson's trichrome staining for renal fibrosis, and immunohistochemistry for either tumor necrosis factor alpha (TNF-α) or endothelial nitric oxide synthase (eNOS) investigation. Taken together, our results demonstrated that GD flower extract decreased the MDA level in both serum and liver and kidney tissue and suppressed the expression of TNF-α in both liver and kidney of 2K1C hypertensive rats. Mesangial cell proliferation, expansion of mesangial matrix, widening Bowman's capsule space, congestion of glomerular capillary and vessel, cloudy swelling of renal tubular epithelial cell, and renal fibrosis were observed in the kidneys of 2K1C rats. Therefore, we concluded that GD flower extract can alleviate liver and kidney inflammation in which partially attenuates the glomerular injury in the 2K1C rat.

Whole genome sequence analyses of thermotolerant Bacillus sp. isolates from food

The Bacillus cereus group, also known as B. cereus sensu lato (B. cereus s.l.), is composed of various Bacillus species, some of which can cause diarrheal or emetic food poisoning. Several emerging highly heat-resistant Bacillus species have been identified, these include B. thermoamylovorans, B. sporothermodurans, and B. cytotoxicus NVH 391-98. Herein, we performed whole genome analysis of two thermotolerant Bacillus sp. isolates, Bacillus sp. B48 and Bacillus sp. B140, from an omelet with acacia leaves and fried rice, respectively. Phylogenomic analysis suggested that Bacillus sp. B48 and Bacillus sp. B140 are closely related to B. cereus and B. thuringiensis, respectively. Whole genome alignment of Bacillus sp. B48, Bacillus sp. B140, mesophilic strain B. cereus ATCC14579, and thermophilic strain B. cytotoxicus NVH 391-98 using the Mauve program revealed the presence of numerous homologous regions including genes responsible for heat shock in the dnaK gene cluster. However, the presence of a DUF4253 domain-containing protein was observed only in the genome of B. cereus ATCC14579 while the intracellular protease PfpI family was present only in the chromosome of B. cytotoxicus NVH 391-98. In addition, prophage Clp protease-like proteins were found in the genomes of both Bacillus sp. B48 and Bacillus sp. B140 but not in the genome of B. cereus ATCC14579. The genomic profiles of Bacillus sp. isolates were identified by using whole genome analysis especially those relating to heat-responsive gene clusters. The findings presented in this study lay the foundations for subsequent studies to reveal further insights into the molecular mechanisms of Bacillus species in terms of heat resistance mechanisms.

Ethyl Acetate Extract of Halymenia durvillei Induced Apoptosis, Autophagy, and Cell Cycle Arrest in Colorectal Cancer Cells

Colorectal cancer is one of the most death-dealing cancers. However, conventional cancer treatments still have side effects. Therefore, novel chemotherapeutic agents with less side effects are still in search. A marine red seaweed, Halymenia durvillei, is recently interested in its anticancer effects. This study investigated the anticancer effect of ethyl acetate extract of H. durvillei (HDEA) on HT-29 colorectal cancer cells in association with the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway. HDEA-treated HT-29 and OUMS-36 cells were used for cell viability tests by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide assay. The effects of HDEA on apoptosis and cell cycle were evaluated. The nuclear morphology and mitochondrial membrane potential (ΔΨm) were observed by Hoechst 33342 and JC-1 staining, respectively. The gene expression of PI3K, AKT, and mTOR genes was evaluated using a real-time semiquantitative reverse transcription-polymerase chain reaction. The corresponding protein expressions were assessed by western blot analysis. The result revealed that the cell viability of treated HT-29 cells diminished while that of OUMS-36 cells was non-significant. By the down-regulation of cyclin-dependent ki-nase 4 and cyclin D1, HDEA-treated HT-29 cells were arrested in the G0/G1 phase. By the up-regulation of cleaved poly(adenosine diphosphate-ribose) polymerase, caspase-9, caspase-8, caspase-3, and Bax, HDEA-treated HT-29 cells underwent apoptosis, but suppressed Bcl-2, disrupted nuclear morphology and ΔΨm. Furthermore, treated HT-29 cells underwent autophagy by up-regulation of light chain 3-II and beclin-1. Lastly, HDEA suppressed the expression of PI3K, AKT, and mTOR. Therefore, HDEA exerts anticancer effects against HT-29 cells, confirmed by apoptosis, autophagy, and cell cycle arrest induction via regulation of the PI3K/AKT/mTOR signaling pathway.

Anti-Inflammatory Effect of Garcinol Extracted from Garcinia dulcis via Modulating NF-κB Signaling Pathway

Garcinia is a significant medicinal plant with many beneficial phytoconstituents, including garcinol. This study investigated the anti-inflammatory effect of garcinol isolated from Garcinia dulcis fruit in LPS-activated THP-1 and Raw 264.7 macrophages. The results demonstrated that the low concentration of garcinol did not alter cell viability. Furthermore, co-incubation of garcinol with LPS inhibited the production of pro-inflammatory cytokines, including TNF-α, IL-8, IL-6, IL-1β, and pro-inflammatory mediators, including iNOS and COX-2 at the mRNA and protein expression levels. Garcinol also decreased the secretion of TNF-α, IL-6, IL-1β, PGE2, and NO. Moreover, the anti-inflammatory effects involved an alteration in the NF-κB signaling pathway. Downregulation of pIKKα/β, pIκBα, and pNF-κB was observed, hence reducing the translocation of pNF-κB from the cytosol into the nucleus, which subsequently decreased the production of pro-inflammatory molecules. Therefore, garcinol isolated from Garcinia dulcis is a potential candidate as an anti-inflammatory agent for inflammation-related disease treatment.

Garcinia dulcis Flower Extract Alters Gut Microbiota and Fecal Metabolomic Profiles of 2K1C Hypertensive Rats

Garcinia dulcis (GD) extract has been found to have anti-hypertensive properties in animal studies. GD can also alter the colonic microbiota of rats. However, the effects of GD on changes in the gut microbiota and metabolomic profiles of normotensive and hypertensive rats are currently unknown. The purpose of this study was to evaluate changes in the gut microbiota and metabolomic profiles of 2-kidneys-1 clip (2K1C) hypertensive rats after feeding with GD flower extract. Rats were randomly divided into the following 4 groups: sham operation (SO) receiving corn oil (CO) (SO + CO), SO receiving GD (SO + GD), 2K1C receiving corn oil (2K1C + CO) and 2K1C receiving GD (2K1C + GD). Body weight (BW) and systolic blood pressure (SBP) were measured weekly throughout the study. Gut microbiota and fecal metabolites were measured from fresh fecal contents. Alpha diversity results demonstrated a similar microbial richness and diversity between groups. Linear discriminant analysis (LDA) effect size (LEfSe) suggested that GD treatment affected gut microbial community structure in both hypertensive and normotensive rats. Feeding rats with GD caused metabolic alterations that rendered 2K1C + GD rats similar to SO + CO and SO + GD rats. Findings suggest that the impact of GD on gut microbiota and metabolite profiles may be related to its anti-hypertensive properties.

Camboginol and Morelloflavone from Garcinia dulcis (Roxb.) Kurz Flower Extract Promote Autophagic Cell Death against Human Glioblastoma Cells through Endoplasmic Reticulum Stress

Garcinia dulcis is a tropical plant native to Southeast Asia that is traditionally used as a folk remedy to cure several pathological symptoms. Camboginol and morelloflavone have been revealed by previous studies as the principal bioactive compounds from the flower extract of G. dulcis. The disease-preventing properties of camboginol or morelloflavone, including anti-cancer, from various parts of G. dulcis have been revealed by recent studies. Glioblastoma is the aggressive malignant stage of brain cancer and suffers from chemotherapeutic resistance. This study aimed to test the anti-cancer effect of G. dulcis flower extract against the proliferation of A172 human glioblastoma cells. The extract had cytotoxic activity and promoted cell cycle arrest at the S and G2/M phases. Autophagic cell death was promoted by cytotoxic concentrations of the extract, as observed by enhancing autophagic flux and the expression of autophagic markers. Autophagic cell death induced by the extract might be associated with endoplasmic reticulum (ER) stress. Conclusively, it was indicated by this study that the extract from the flower of G. dulcis had a protective effect against the proliferation of A172 human glioblastoma cells through the induction of ER stress-mediated cytotoxic autophagy.

Daily consumption of monosodium glutamate pronounced hypertension and altered renal excretory function in normotensive and hypertensive rats

This study aimed to investigate the effects of monosodium glutamate (MSG) on the levels of arterial blood pressure (ABP) and renal excretory function. Male Wistar rats were divided into 2 groups (n = 24 each) namely sham operation (SO) and 2-kidneys-1-clip (2K1C) to develop the normotensive and hypertensive model, respectively. Four weeks after the operation, each group of rats were further divided into 4 subgroups (n = 6 each) which were orally administered of either distilled water or MSG at the doses of 80, 160, or 320 mg/kg BW/day once a day for 8 weeks. The body weight, the 24-hour water intake, and the 24-hour urine output were recorded weekly. Then, each rat was anesthetized and the ABP was measured via carotid artery. The renal excretory function was examined by using the clearance technique to measure the levels of the glomerular filtration rate and the renal blood flow. The levels of serum malondialdehyde (MDA) as a marker of oxidative stress were analyzed. The expression of tumor necrosis factor alpha (TNF-α) in the kidneys was also investigated using immunohistochemistry. It was found that all doses of MSG significantly increased the ABP in both SO and 2K1C groups. All doses of MSG significantly increased the serum MDA levels and the expression of TNF-α in the kidneys of the SO groups. Long-term intake of 320 mg/kg BW MSG significantly decreased the renal excretion of salt and water in both SO and 2K1C groups. As a whole, this study demonstrated that MSG consumption contributed to an increase in oxidative stress which could lead to alterations in the cardiovascular and renal function.

Heat shock factor 1 regulates heat shock proteins and immune-related genes in Penaeus monodon under thermal stress

Heat shock factors (HSFs) participate in the response to environmental stressors and regulate heat shock protein (Hsp) expression. This study describes the molecular characterization and expression of PmHSF1 in black tiger shrimp Penaeus monodon under heat stress. PmHSF1 expression was detected in several shrimp tissues: the highest in the lymphoid organ and the lowest in the eyestalk. Significant up-regulation of PmHSF1 expression was observed in hemocytes (p < 0.05) following thermal stress. The expression of several PmHsps was rapidly induced following heat stress. Endogenous PmHSF1 protein was expressed in all three types of shrimp hemocyte and strongly induced under heat stress. The suppression of PmHSF1 expression by dsRNA-mediated gene silencing altered the expression of PmHsps, several antimicrobial genes, genes involved in the melanization process, and an antioxidant gene (PmSOD). PmHSF1 plays an important role in the thermal stress response, regulating the expression of Hsps and immune-related genes in P. monodon.

The roles of peroxide protective regulons in protecting Xanthomonas campestris pv. campestris from sodium hypochlorite stress

The exposure of Xanthomonas campestris pv. campestris to sublethal concentrations of a sodium hypochlorite (NaOCl) solution induced the expression of genes that encode peroxide scavenging enzymes within the OxyR and OhrR regulons. Sensitivity testing in various X. campestris mutants indicated that oxyR, katA, katG, ahpC, and ohr contributed to protection against NaOCl killing. The pretreatment of X. campestris cultures with oxidants, such as hydrogen peroxide (H2O2), t-butyl hydroperoxide, and the superoxide generator menadione, protected the bacteria from lethal concentrations of NaOCl in an OxyR-dependent manner. Treating the bacteria with a low concentration of NaOCl resulted in the adaptive protection from NaOCl killing and also provided cross-protection from H2O2 killing. Taken together, the results suggest that the toxicity of NaOCl is partially mediated by the generation of peroxides and other reactive oxygen species that are removed by primary peroxide scavenging enzymes, such as catalases and AhpC, as a part of an overall strategy that protects the bacteria from the lethal effects of NaOCl.

Copper chloride induces antioxidant gene expression but reduces ability to mediate H2O2 toxicity in Xanthomonas campestris

Copper (Cu)-based biocides are currently used as control measures for both fungal and bacterial diseases in agricultural fields. In this communication, we show that exposure of the bacterial plant pathogen Xanthomonas campestris to nonlethal concentrations of Cu2+ ions (75 µM) enhanced expression of genes in OxyR, OhrR and IscR regulons. High levels of catalase, Ohr peroxidase and superoxide dismutase diminished Cu2+-induced gene expression, suggesting that the production of hydrogen peroxide (H2O2) and organic hydroperoxides is responsible for Cu2+-induced gene expression. Despite high expression of antioxidant genes, the CuCl2-treated cells were more susceptible to H2O2 killing treatment than the uninduced cells. This phenotype arose from lowered catalase activity in the CuCl2-pretreated cells. Thus, exposure to a nonlethal dose of Cu2+ renders X. campestris vulnerable to H2O2, even when various genes for peroxide-metabolizing enzymes are highly expressed. Moreover, CuCl2-pretreated cells are sensitive to treatment with the redox cycling drug, menadione. No physiological cross-protection response was observed in CuCl2-treated cells in a subsequent challenge with killing concentrations of an organic hydroperoxide. As H2O2 production is an important initial plant immune response, defects in H2O2 protection are likely to reduce bacterial survival in plant hosts and enhance the usefulness of copper biocides in controlling bacterial pathogens.