Metabolic channeling: predictions, deductions, and evidence.

With the elucidation of myriad anabolic and catabolic enzyme-catalyzed cellular pathways crisscrossing each other, an obvious question arose: how could these networks operate with maximal catalytic efficiency and minimal interference? A logical answer was the postulate of metabolic channeling, which in its simplest embodiment assumes that the product generated by one enzyme passes directly to a second without diffusion into the surrounding medium. This tight coupling of activities might increase a pathway's metabolic flux and/or serve to sequester unstable/toxic/reactive intermediates as well as prevent their access to other networks. Here, we present evidence for this concept, commencing with enzymes that feature a physical molecular tunnel, to multi-enzyme complexes that retain pathway substrates through electrostatics or enclosures, and finally to metabolons that feature collections of enzymes assembled into clusters with variable stoichiometric composition. Lastly, we discuss the advantages of reversibly assembled metabolons in the context of the purinosome, the purine biosynthesis metabolon.

φ-OTDR signal compression scheme based on the compressed sensing theory.

In this paper, based on the compressed sensing theory and the orthogonal matching pursuit algorithm, we have designed a data compression scheme, taking the Space-Temporal graph, time domain curve, and its time-frequency spectrum of phase-sensitive optical time-domain reflectometer as the target signals. The compression rates of the three signals were 40%, 35%, and 20%, while the average reconstruction times were 0.74 s, 0.49 s, and 0.32 s. The reconstructed samples effectively retained the characteristic blocks, response pulses, and energy distribution that symbolize the presence of vibrations. The average correlation coefficients of the three kinds of reconstructed signals with the original samples were 0.88, 0.85, and 0.86, respectively, and then a series of quantitative metrics were designed to evaluate the reconstructing efficiency. We have utilized the neural network trained by the original data to identify the reconstructed samples with an accuracy of over 70%, indicating that the reconstructed samples accurately present the vibration characteristics.

Water hammer detection based on FIV online analysis using a distributed fiber optic sensor.

In long-distance oil pipelines, the abnormal flow state of the fluid in the pipeline can cause continuous water hammer effects, which can damage the pipeline and even cause leakage or collapse. Based on this phenomenon, this paper proposes a new, to the best of our knowledge, detection method based on sensing optical fiber and phase-sensitive optical time-domain reflectometry (φ-OTDR) system to solve the problem of continuous water hammer detection in long-distance pipelines. The method uses a non-invasive, low-cost, real-time approach to monitor pipeline wall deformation characteristics and assess flow-induced vibration (FIV) intensity by statistically distinguishing water hammer signals from normal vibration signals and calculating the peak-to-average ratio (PAR) of these signals. Experimental results show that the FIV status of different types of pipelines can be effectively monitored by calculating the PAR of water hammer signals and vibration signals. The measured PAR based on the φ-OTDR system has high consistency with the PAR variation trend of simulation results, the distributed fiber optic sensor is less affected by environmental factors, and its detection distance and anti-interference ability are better than those of high-precision commercial triaxial acceleration sensors.

Promotion Effect of Coexposure to a High-Fat Diet and Nano-Diethylnitrosamine on the Progression of Fatty Liver Malignant Transformation into Liver Cancer.

Overconsumption of high-fat foods increases the risk of fatty liver disease (FLD) and liver cancer with long pathogenic cycles. It is also known that the intake of the chemical poison nitrosamine and its nanopreparations can promote the development of liver injuries, such as FLD, and hepatic fibrosis, and significantly shorten the formation time of the liver cancer cycle. The present work confirmed that the coexposure of a high-fat diet (HFD) and nano-diethylnitrosamine (nano-DEN) altered the tumor microenvironment and studied the effect of this coexposure on the progression of fatty liver malignant transformation into liver cancer. Gene transcriptomics and immunostaining were used to evaluate the tumor promotion effect of the coexposure in mice. After coexposure treatment, tumor nodules were obviously increased, and inflammation levels were elevated. The liver transcriptomics analysis showed that the expression levels of inflammatory, fatty, and fibrosis-related factors in the coexposed group were increased in comparison with the nano-DEN- and high-fat-alone groups. The Kyoto Encyclopedia of Genes and Genomes (KEGG) results showed that coexposure aggravated the high expression of genes related to the carcinomatous pathway and accelerated the formation of the tumor microenvironment. The immunohistochemical staining results showed that the coexposure significantly increased the abnormal changes in proteins related to inflammation, proliferation, aging, and hypoxia in mouse liver tissues. The coexposure of high fat and nano-DEN aggravated the process of steatosis and carcinogenesis. In conclusion, the habitual consumption of pickled foods containing nitrosamines in a daily HFD significantly increases the risk of liver pathology lesions progressing from FLD to liver cancer.

Potential of electronic devices for detection of health problems in older adults at home: A systematic review and meta-analysis.

OBJECTIVE: The aim of this review was to evaluate the overall diagnostic performance of e-devices for detection of health problems in older adults at home. METHODS: A systematic review was conducted following the PRISMA-DTA guidelines. RESULTS: 31 studies were included with 24 studies included in meta-analysis. The included studies were divided into four categories according to the signals detected: physical activity (PA), vital signs (VS), electrocardiography (ECG) and other. The meta-analysis showed the pooled estimates of sensitivity and specificity were 0.94 and 0.98 respectively in the 'VS' group. The pooled sensitivity and specificity were 0.97 and 0.98 respectively in the 'ECG' group. CONCLUSIONS: All kinds of e-devices perform well in diagnosing the common health problems. While ECG-based health problems detection system is more reliable than VS-based ones. For sole signal detection system has limitation in diagnosing specific health problems, more researches should focus on developing new systems combined of multiple signals.

Aptamer-based biosensing through the mapping of encoding upconversion nanoparticles for sensitive CEA detection.

A sensitive detection system based on aptamer-based biosensors for the detection of carcinoembryonic antigen (CEA) by mapping encoding upconversion nanoparticles (UCNPs) was constructed. In this sensor, oligonucleotides with CEA aptamer fragments immobilized on magnetic beads (MBs) were hybridized to complementary DNA modified on UCNPs (cDNA-UCNPs); thus, sandwich-structured probes were formed. In the presence of CEA, due to the stronger interaction between the aptamer and CEA than that of the aptamer and complementary DNA on UCNPs, the cDNA-UCNPs were isolated from the MBs, and the number of isolated UCNPs was directly related to the concentration of CEA. Using an inverted fluorescence microscope, the number of target-dependent UCNPs on a glass slide was counted, enabling the accurate determination of CEA in the solution. The dynamic range for CEA detection in PBS buffer was 0.02-6.0 ng mL-1 (0.1-30 pM) and a limit of detection (LOD) of 65 fM was achieved. We envisage that the system we developed can also have many promising applications in the sensitive detection of other biomarkers for early cancer diagnosis.

Microfluidic synthesis of Janus-structured QD-encoded magnetic microbeads for multiplex immunoassay.

Uniform and monodisperse quantum dot (QD)-encoded magnetic microbeads with Janus structure were produced in a microfluidic device via photopolymerization. UV light through a microscope objective was used to solidify the microbeads which showed sharp interfaces and excellent magnetic responses. QDs with different emission peaks (450 nm for blue and 640 nm for red) were mixed at different ratios to provide three spectral codes. The QD-encoded microbeads can be distinguished by analyzing their fluorescent images in HSV color space. After hydrolysis of the anhydride group in alkaline solution, protein was immobilized on microbeads via activation of carboxyl groups using (1-ethyl-3(3-dimethylaminoprophyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS). A microhole array in polydimethylsiloxane (PDMS) substrates with a specific size was fabricated to trap individual microbeads in a single microhole. The combination of Janus-structured QD-encoded magnetic microbeads and microhole arrays facilitates both flexibility, binding kinetics, sensitivity for suspension assay, and fluorescence mapping analysis for conventional biochips, thus providing a novel platform for multiplex bioanalysis. The capability of this integration for multiplex immunoassays was verified using three kinds of IgG and their corresponding anti-IgG. A detection limit of 0.07 ng/mL was achieved for human IgG, indicating practical applications in various fields.

[Rosmarinic acid bolsters antibacterial immunity activity of macrophages by up-regulating PINK1/Parkin-mediated mitophagy].

This study aims to explore the molecular mechanism through which rosmarinic acid up-regulates mitophagy and enhances antibacterial immunity activity of macrophages. To be specific, RAW264.7 macrophages were treated with rosmarinic acid and then infected with Staphylococcus aureus. The total mRNA and proteins of the cells were then extracted. The mRNA and protein levels of phosphatase and tensin homolog(PTEN)-induced putative kinase 1(PINK1) were detected by q-PCR and Western blot, respectively. Cell mitochondria isolation kit was employed to isolate mitochondria in macrophages. Recruitment of E3 ubiquitin ligase Parkin to mitochondria and the phosphorylation of Parkin were detected by Western blot. Co-immunoprecipitation and laser confocal microscopy were employed to observe the co-localization of PINK1 and Parkin. Mitochondrial division inhibitor 1(Mdivi-1), small interfering RNA(siRNA)-directed gene knockdown, and plate-colony counting were used to detect the levels of inflammatory cytokines and the intracellular antibacterial ability, in an attempt to confirm that rosmarinic acid promotes antibacterial immunity activity of macrophages through strengthening PINK1/Parkin-mediated mitophagy. The results showed that rosmarinic acid up-regulated the mRNA and protein expression of PINK1, promoted the recruitment of Parkin from cytoplasm to mitochondria and the phosphorylation, and enhanced the interaction between PINK1 and Parkin and their co-localization in macrophages. Blocking mitophagy or knocking PINK1 significantly abrogated the promotion of macrophage antibacterial immune response by rosmarinic acid. In summary, rosmarinic acid enhances antibacterial immunity activity of macrophages through up-regulating PINK1/Parkin-mediated mitophagy.

A structure and function relationship study to identify the impact of the R721G mutation in the human mitochondrial lon protease.

Lon is an ATP-dependent protease belonging to the "ATPase associated with diverse cellular activities" (AAA+) protein family. In humans, Lon is translated as a precursor and imported into the mitochondria matrix through deletion of the first 114 amino acid residues. In mice, embryonic knockout of lon is lethal. In humans, some dysfunctional lon mutations are tolerated but they cause a developmental disorder known as the CODAS syndrome. To gain a better understanding on the enzymology of human mitochondrial Lon, this study compares the structure-function relationship of the WT versus one of the CODAS mutants R721G to identify the mechanistic features in Lon catalysis that are affected. To this end, steady-state kinetics were used to quantify the difference in ATPase and ATP-dependent peptidase activities between WT and R721G. The Km values for the intrinsic as well as protein-stimulated ATPase were increased whereas the kcat value for ATP-dependent peptidase activity was decreased in the R721G mutant. The mutant protease also displayed substrate inhibition kinetics. In vitro studies revealed that R721G did not degrade the endogenous mitochondrial Lon substrate pyruvate dehydrogenase kinase isoform 4 (PDK4) effectively like WT hLon. Furthermore, the pyruvate dehydrogenase complex (PDH) protected PDK4 from hLon degradation. Using hydrogen deuterium exchange/mass spectrometry and negative stain electron microscopy, structural perturbations associated with the R721G mutation were identified. To validate the in vitro findings under a physiologically relevant condition, the intrinsic stability as well as proteolytic activity of WT versus R721G mutant towards PDK 4 were compared in cell lysates prepared from immortalized B lymphocytes expressing the respective protease. The lifetime of PDK4 is longer in the mutant cells, but the lifetime of Lon protein is longer in the WT cells, which corroborate the in vitro structure-functional relationship findings.

Establishment and evaluation of an indirect ELISA for detection of antibodies to goat Klebsiella pneumonia.

BACKGROUND: Klebsiella pneumonia, a Gram-negative bacterium belonging to the genus Enterobacter, causes many human and livestock diseases. Notably, infected goats may develop pneumonia, septicemia, which can lead to occasional death, resulting in great economic losses in goat-farming industry. However, there are little systematic methods for detection of goat Klebsiella pneumoniae in livestock production. RESULTS: In this study, we developed a Klebsiella pneumoniae goat polyclonal antibody and established an indirect ELISA method to detect the Klebsiella pneumoniae. After screening and optimizing the conditions for detection, we determined the optimal working dilutions of the coated-bacterial antigen, the polyclonal antibody, and the enzyme-labeled secondary antibody that were 1:800 (2.99 × 107 CFU/ml), 1:6400, and 1:5000, respectively. The optimal condition of coating and blocking were both 4 °C for 12 h. The optimal dilution buffers of bacterial antigen, the antibodies, and the blocking buffer were 0.05 mol/L carbonate buffer, 1% BSA phosphate buffer, and 1.5% BSA carbonate buffer, respectively. The cut-off value was determined to be 0.28, and the analytical sensitivity was 1:800 (dilution of a positive sample). Furthermore, there was no cross-reaction between the coated antigen and goat serum positive for antibodies against other bacteria, indicating that indirect ELISA could detect Klebsiella pneumoniae specifically in most cases. The average coefficients of variation of intra-assay and inter-assay were 4.37 and 5.17% indicating favorable reproducibility of indirect ELISA. In the detection of clinical veterinary samples, the positive rate of indirect ELISA was 6.74%, higher than that of conventional agglutination assays. CONCLUSIONS: Taken together, we successfully established an indirect ELISA method for detecting antibodies against Klebsiella pneumoniae in goats, which can be applied in production.

A Selective Fluorogenic Peptide Substrate for the Human Mitochondrial ATP-Dependent Protease Complex ClpXP.

The goal of this work is to identify differences in the substrate determinants of two human mitochondrial matrix ATP-dependent proteases, human ClpXP (hClpXP) and human Lon (hLon). This information allows the generation of protease-specific peptide substrates that can be used as chemical biology tools to investigate the physiological functions of hClpXP. These enzymes play a role in protein quality control, but currently the physiological functions of human ClpXP are not well defined. In this study, the degradation profile of casein, an alanine positional scanning decapeptide library, and a specific peptide sequence found in an endogenous substrate of bacterial ClpXP by hClpXP as well as hLon were examined. Based on our findings, we generated a specific fluorogenic peptide substrate, FR-Cleptide, for hClpXP with a kcat of 2.44±0.15 s-1 and Km =262±43 µM, respectively. The FR-Cleptide substrate was successfully used to identify a leucine methyl ketone as a potent lead inhibitor, and to detect endogenous hClpXP activity in HeLa cell lysate. We propose that the fluorogenic peptide substrate is a valuable tool for quantitatively monitoring the activity of hClpXP in cell lysate, as well as mechanistic characterization of hClpXP. The peptide-based chemical tools developed in this study will complement the substrates developed for human Lon in aiding the investigation of the physiological functions of the respective protease.

A Proteolytic Site-Directed Affinity Label to Inhibit the Human ATP-Dependent Protease Caseinolytic Complex XP.

Human caseinolytic protease component X and P (hClpXP) is a heterooligomeric ATP-dependent protease. The hClpX subunit catalyzes ATP hydrolysis whereas the hClpP subunit catalyzes peptide bond cleavage. In this study, we generated a peptidyl chloromethyl ketone (dansyl-FAPAL-CMK) that inhibited the hClpP subunit through alkylation of the catalytic His122, which was detected by LC-MS. This inhibitor is composed of a peptide sequence derived from a hydrolyzed peptide product of a substrate cleaved by hClpXP. Binding of FAPAL positions the electrophilic chloromethyl ketone moiety near His122 where alkylation occurs. Dansyl FAPAL-CMK exhibits selectivity for hClpXP over other ATP-dependent proteases such as hLon and the 26S proteasome and abolishes hClpXP activity in HeLa cell lysate. Using the fluorogenic peptide substrate FR-Cleptide as reporter, we detected biphasic inhibition time courses; this supports a slow-binding, time-dependent, covalent inhibition mechanism that is often found in active-site directed affinity labels. Because this inhibitor reacts only with hClpXP but not hLon or the proteasome, it has the potential to serve as a chemical tool to help validate endogenous protein substrates of hClpXP in cell lysate, thereby benefiting investigation of the physiological functions of hClpXP in different cell types or tissue samples.

Phase-sensitive optical time domain reflectometer with ultrafast data processing based on GPU parallel computation.

The sensing performance of a phase-sensitive optical time domain reflectometer (ϕ-OTDR) has been sufficiently improved, thanks to plenty of valuable research in recent years. However, in the literature, there is hardly any attention aimed at enhancing the data processing capability of the system, the necessity and significance of which are undisputed. This paper, for the first time to the best of our knowledge, analyzed the intrinsic superiority of employing GPU parallel computation in ϕ-OTDR for improving the data processing capability and presented a comprehensive performance evaluation. Three typical, frequently implemented algorithms in ϕ-OTDR-moving average, batch fast Fourier transform, and batch correlation dimension computation-are carried out where CPU-based programs and counterpart GPU-based programs are, respectively, developed. Their time-consuming performances in different data scales are experimentally tested and compared. The experiment results show that in each case, employing GPU parallel computation can significantly enhance the system's data processing capacity, thus providing a feasible and efficient way of guaranteeing real-time operation with the growing data scale.

Phase demodulation method in phase-sensitive OTDR without coherent detection.

A phase demodulation method specially developed for direct detection φ-OTDR is proposed and demonstrated. It is the only method to date that can be used for phase demodulation based on pure direct detection system. As a result, this method greatly simplifies the system configuration and lowers the cost. It works by firstly deriving a pair of orthogonal signals from the single-channel intensity and then realizing phase demodulation by means of IQ demodulation. Different forms of PZT induced vibration are applied to the fiber and the phase is correctly demodulated in each case. The experiment results show that this method can effectively perform phase demodulation with extremely simple system configuration.

Yeast Surface Display of Escherichia coli Enterotoxin and Its Effects of Intestinal Microflora and Mucosal Immunity.

Enterotoxigenic Escherichia coli (ETEC) is a significant cause of infectious diarrhea in animals. In this study, yeast surface display technology was employed to investigate the effects of ETEC enterotoxin fusion protein on the intestinal flora and mucosal immunity of rats. ETEC estA, estB, and eltAB (heat-labile and heat-stable toxins) were expressed on the surface of yeast. Rats were divided into normal saline, yeast and display yeast groups. Fecal and jejunal content samples were collected on the 7th, 14th, and 21st days. Rats were then fed ETEC for 3 days before again collecting these samples. Levels of SIgA, IL-2, IL-4, IFN-γ, and microbial population density and diversity were documented by ELISA, T-RFLP and real-time PCR. The results demonstrated that estA, estB, and eltAB fusion proteins were expressed on the surface of yeast. Following ETEC challenge, levels of SIgA, IL-2, IL-4, IFN-γ, and, the numbers and variety of intestinal microbes were significantly increased in rats receiving display yeast and yeast. These factors were significantly decreased in rats given normal saline and yeast. Our results indicate that display yeast and yeast can increase the number and diversity of intestinal microbes in rats and improve intestinal immune function. After ETEC challenge, the display yeast can better maintain the balance of intestinal bacteria and mucosal immunity.

Mechanism study on pH-responsive cyclodextrin capped mesoporous silica: effect of different stalk densities and the type of cyclodextrin.

Cyclodextrin (CD)-capped mesoporous silica nanoparticles (MSN) with pH-responsive properties were synthesized, but little research has been carried out to evaluate the impact of critical factors such as the stalk density and the type of CD on the pH-responsive release behavior. Here, the effect of different stalk densities on the pH-responsive release behavior was investigated. Either too low or too high density of the grafted p-anisidine stalk could result in poor cargo release, and the optimum stalk density for MSN was measured by thermal analysis, and found to be approximately 8.7 stalks nm(-2). To achieve effective release control, the CD capes, α-CD and ß-CD, were also investigated. Isothermal titration calorimetry (ITC) analysis was employed to determine the formation constants (Kf) of the two CD with p-anisidine at different pH values. The results obtained showed that the complex of ß-CD with p-anisidine had excellent pH-responsive behavior as it exhibited the largest changed formation constant (ΔKf) in different pH media. Furthermore, the pH-responsive mechanism between CD and p-anisidine molecules was investigated through ITC and a molecular modeling study. The release of antitumor drug DOX presents a significant prospect toward the development of pH-responsive nanoparticles as a drug delivery vehicle.

miR-125a-3p targets MTA1 to suppress NSCLC cell proliferation, migration, and invasion.

Metastasis-associated gene 1 (MTA1) is associated with cell growth, metastasis, and survival in non-small-cell lung cancer (NSCLC). Several previous reports have demonstrated that microRNAs affect gene expression through interaction between their seed region and the 3'-untranslated region of the target mRNA, resulting in post-transcriptional regulation. The aim of this study was to identify miRNAs that suppress malignancy in NSCLC cells by targeting MTA1. Two human NSCLC cell lines were analyzed for the expression of MTA1 by quantitative RT-PCR and western blotting after transfection with MTA1 mimics. A luciferase reporter assay was established to test the direct connection between MTA1 and its upstream miRNAs. Cell proliferation was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, 5-ethynyl-2'-deoxyuridine analysis, and colony formation assay. Cell migration and invasive capacity were evaluated by wound-healing assay and transwell assay. The miRNA/MTA1 axis was also probed by quantitative RT-PCR and western blotting in samples from eight NSCLC patients. Among the candidate miRNAs, miR-125a-3p was shown to post-transcriptionally regulate MTA1 in NSCLC cells. These data were reinforced by the luciferase reporter assay, in addition to the demonstration that MTA1 is inversely correlated with miR-125a-3p in NSCLC tissues. Furthermore, miR-125a-3p was found to inhibit NSCLC cell proliferation, migration, and invasion, through the same mechanisms of down-regulated MTA1. Our report demonstrates that miR-125a-3p inhibits the proliferation, migration, and invasion of NSCLC cells through down-regulation of MTA1, indicating the role of the miR-125a-3p/MTA1 axis in NSCLC, and may provide novel insight into the molecular mechanisms underpinning the disease and potential therapeutic targets.

Weak Value Amplification-Based Biochip for Highly Sensitive Detection and Identification of Breast Cancer Exosomes.

Exosomes constitute an emerging biomarker for cancer diagnosis because they carry multiple proteins that reflect the origins of the parent cell. The highly sensitive detection of exosomes is a crucial prerequisite for the diagnosis of cancer. In this study, we report an exosome detection system based on quantum weak value amplification (WVA). The WVA detection system consists of a reflection detection light path and a Zr-ionized biochip. Zr-ionized biochips effectively capture exosomes through the specific interaction between zirconium dioxide and the phosphate groups on the lipid bilayer of exosomes. Aptamer-modified gold nanoparticles (Au NPs) are then used to specifically recognize proteins on exosomes to enhance the detection signal. The sensitivity and resolution of the detection system are 2944.07 nm/RIU and 1.22 × 10-5 RIU, respectively. The concentration of exosomes can be directly quantified by the WVA system, ranging from 105-107 particles/mL with the detection limit of 3 × 104 particles/mL. The use of Au NPs-EpCAM for the specific enhancement of breast cancer MDA-MB-231 exosomes is demonstrated. The results indicate that the WVA detection system can be a promising candidate for the detection of exosomes as tumor markers.

Liquid-Liquid phase separation in bacteria.

Cells are the essential building blocks of living organisms, responsible for carrying out various biochemical reactions and performing specific functions. In eukaryotic cells, numerous membrane organelles have evolved to facilitate these processes by providing specific spatial locations. In recent years, it has also been discovered that membraneless organelles play a crucial role in the subcellular organization of bacteria, which are single-celled prokaryotic microorganisms characterized by their simple structure and small size. These membraneless organelles in bacteria have been found to undergo Liquid-Liquid phase separation (LLPS), a molecular mechanism that allows for their assembly. Through extensive research, the occurrence of LLPS and its role in the spatial organization of bacteria have been better understood. Various biomacromolecules have been identified to exhibit LLPS properties in different bacterial species. LLPS which is introduced into synthetic biology applies to bacteria has important implications, and three recent research reports have shed light on its potential applications in this field. Overall, this review investigates the molecular mechanisms of LLPS occurrence and its significance in bacteria while also considering the future prospects of implementing LLPS in synthetic biology.

The relationship between Listeria infections and host immune responses: Listeriolysin O as a potential target.

Listeria monocytogenes (Lm), a foodborne bacterium, can infect people and has a high fatality rate in immunocompromised individuals. Listeriolysin O (LLO), the primary virulence factor of Lm, is critical in regulating the pathogenicity of Lm. This review concludes that LLO may either directly or indirectly activate a number of host cell viral pathophysiology processes, such as apoptosis, pyroptosis, autophagy, necrosis and necroptosis. We describe the invasion of host cells by Lm and the subsequent removal of Lm by CD8 T cells and CD4 T cells upon receipt of the LLO epitopes from major histocompatibility complex class I (MHC-I) and major histocompatibility complex class II (MHC-II). The development of several LLO-based vaccines that make use of the pore-forming capabilities of LLO and the immune response of the host cells is then described. Finally, we conclude by outlining the several natural substances that have been shown to alter the three-dimensional conformation of LLO by binding to particular amino acid residues of LLO, which reduces LLO pathogenicity and may be a possible pharmacological treatment for Lm.