Oral administration of immunopotentiator from Pantoea agglomerans 1 (IP-PA1) improves the survival of B16 melanoma-inoculated model mice

Baseline data collections of lipopolysaccharide content in 414 herbal extracts and its role in innate immune activation

Some herbal extracts contain relatively high amounts of lipopolysaccharide (LPS). Because orally administered LPS activates innate immunity without inducing inflammation, it plays a role as an active ingredient in herbal extracts. However, the LPS content in herbal extracts remains extensively unevaluated. This study aimed to create a database of LPS content in herbal extracts; therefore, the LPS content of 414 herbal extracts was measured and the macrophage activation potential was evaluated. The LPS content of these hot water extracts was determined using the kinetic-turbidimetric method. The LPS concentration ranged from a few ng/g to hundreds of μg/g (Standard Escherichia coli LPS equivalent). Twelve samples had a high-LPS-content of > 100 μg/g, including seven samples from roots and three samples from leaves of the herbal extracts. These samples showed high phagocytosis and NO production capacity, and further investigation using polymyxin B, an LPS inhibitor, significantly inhibited macrophage activation. This study suggests that some herbal extracts contain sufficient LPS concentration to activate innate immunity. Therefore, a new approach to evaluate the efficacy of herbal extracts based on their LPS content was proposed. A database listing the LPS content of different herbal extracts is essential for this approach.

Insights into the Potential Role of Plasmids in the Versatility of the Genus Pantoea

In the past two decades, 25 different species of the genus Pantoea within the Enterobacteriaceae family, have been isolated from different environmental niches. These species have a wide range of biological roles. Versatility in functions and hosts indicate that this genus has undergone extensive genetic diversification, which can be attributed to the different extra-chromosomal genetic elements or plasmids found across this genus. We have analyzed the functions of these plasmids and categorized them into four major groups for a better understanding of their future applications. The first and second group includes plasmids that contribute to genetic diversification and pathogenicity, respectively. The third group comprises cryptic plasmids of Pantoea. The last group includes plasmids that play a role in the metabolic versatility of the genus Pantoea. We have analyzed the data available up to May 2023 from two databases (viz; NCBI and PLSDB). In our analysis we have found a vast gap in knowledge. Complete gene annotations are available for only a few of the plasmids. This review highlights these challenges as an avenue for future research.

MEK inhibitors increase the mortality rate in mice with LPS-induced inflammation through IL-12-NO signaling

Lipopolysaccharide (LPS) is an endotoxin that can cause an acute inflammatory response. Nitric oxide (NO) is one of the most important innate immune system components and is synthesized by inducible NOS (iNOS) in macrophages in response to stimulation with LPS. LPS activates the RAS-RAF-mitogen-activated protein kinase/ERK kinase (MEK)-extracellular-signal-regulated kinase (ERK) signaling cascade in macrophages. The purpose of this study was to examine how the combination of LPS and MEK inhibitors, which have been used as anticancer agents in recent years, affects inflammation. We showed that MEK inhibitors enhanced iNOS expression and NO production in LPS-stimulated mouse bone marrow-derived macrophages. A MEK inhibitor increased the mortality rate in mice with LPS-induced inflammation. The expression of the cytokine interleukin-12 (IL-12) in macrophages was enhanced by the MEK inhibitor, as shown by a cytokine array and ELISA. IL-12 enhanced iNOS expression and NO production in response to LPS. We also showed that tumor necrosis factor (TNF-α) was secreted by macrophage after stimulation with LPS and that TNF-α and IL-12 synergistically induced iNOS expression and NO production. An anti-IL-12 neutralizing antibody prevented NO production and mortality in an LPS-induced inflammation mouse model in the presence of a MEK inhibitor. These results suggest that the MEK inhibitor increases the mortality rate in mice with LPS-induced inflammation through IL-12-NO signaling.

Characterization of the Bacterial Microbiome in Natural Populations of Barley Stem Gall Midge, Mayetiola hordei, in Morocco

Mayetiola hordei (Kieffer), known as barley stem gall midge, is one of the most destructive barley pests in many areas around the world, inflicting significant qualitative and quantitative damage to crop production. In this study, we investigate the presence of reproductive symbionts, the effect of geographical origin on the bacterial microbiome's structure, and the diversity associated with natural populations of M. hordei located in four barley-producing areas in Morocco. Wolbachia infection was discovered in 9% of the natural populations using a precise 16S rDNA PCR assay. High-throughput sequencing of the V3-V4 region of the bacterial 16S rRNA gene indicated that the native environments of samples had a substantial environmental impact on the microbiota taxonomic assortment. Briefly, 5 phyla, 7 classes, and 42 genera were identified across all the samples. To our knowledge, this is the first report on the bacterial composition of M. hordei natural populations. The presence of Wolbachia infection may assist in the diagnosis of ideal natural populations, providing a new insight into the employment of Wolbachia in the control of barley midge populations, in the context of the sterile insect technique or other biological control methods.

Oral route lipopolysaccharide as a potential dementia preventive agent inducing neuroprotective microglia

In today's aging society, dementia is an urgent problem to be solved because no treatment or preventive methods have been established. This review focuses on oral administration of lipopolysaccharide (LPS), an outer membrane component of Gram-negative bacteria, as a novel preventive drug for dementia. LPS is also called endotoxin and is well known to induce inflammation when administered systemically. On the other hand, although we humans routinely ingest LPS derived from symbiotic bacteria of edible plants, the effect of oral administration of LPS has hardly been studied. Recently, oral administration of LPS was reported to prevent dementia by inducing neuroprotective microglia. Furthermore, it has been suggested that colony stimulating factor 1 (CSF1) is involved in the dementia prevention mechanism by oral administration of LPS. Thus, in this review, we summarized the previous studies of oral administration of LPS and discussed the predicted dementia prevention mechanism. In addition, we showed the potential of oral LPS administration as a preventive drug for dementia by highlighting research gaps and future issues for clinical application development.

Opposite Sides of Pantoea agglomerans and Its Associated Commercial Outlook

Multifaceted microorganisms such as the bacterium Pantoea colonize a wide range of habitats and can exhibit both beneficial and harmful behaviors, which provide new insights into microbial ecology. In the agricultural context, several strains of Pantoea spp. can promote plant growth through direct or indirect mechanisms. Members of this genus contribute to plant growth mainly by increasing the supply of nitrogen, solubilizing ammonia and inorganic phosphate, and producing phytohormones (e.g., auxins). Several other studies have shown the potential of strains of Pantoea spp. to induce systemic resistance and protection against pests and pathogenic microorganisms in cultivated plants. Strains of the species Pantoea agglomerans deserve attention as a pest and phytopathogen control agent. Several of them also possess a biotechnological potential for therapeutic purposes (e.g., immunomodulators) and are implicated in human infections. Thus, the differentiation between the harmful and beneficial strains of P. agglomerans is mandatory to apply this bacterium safely as a biofertilizer or biocontroller. This review specifically evaluates the potential of the strain-associated features of P. agglomerans for bioprospecting and agricultural applications through its biological versatility as well as clarifying its potential animal and human health risks from a genomic point of view.

Pantoea agglomerans: An Elusive Contributor to Chronic Obstructive Pulmonary Disease Exacerbation

The ubiquitously present gram-negative bacteria Pantoea agglomerans is not a commonly known human pathogen. Recently, increasing recognition of the species as a human pathogen has led to controversy as limited documented cases of P.agglomerans bacteremia and infections have been reported in the literature, with most cases reported among immunocompromised patients or the pediatric population. Here, we present the case of a 54-year-old female with P. agglomerans and Enterococcus faecium bacteremia along with chronic obstructive pulmonary disease.

Lipid A-Mediated Bacterial-Host Chemical Ecology: Synthetic Research of Bacterial Lipid As and Their Development as Adjuvants

Gram-negative bacterial cell surface component lipopolysaccharide (LPS) and its active principle, lipid A, exhibit immunostimulatory effects and have the potential to act as adjuvants. However, canonical LPS acts as an endotoxin by hyperstimulating the immune response. Therefore, LPS and lipid A must be structurally modified to minimize their toxic effects while maintaining their adjuvant effect for application as vaccine adjuvants. In the field of chemical ecology research, various biological phenomena occurring among organisms are considered molecular interactions. Recently, the hypothesis has been proposed that LPS and lipid A mediate bacterial-host chemical ecology to regulate various host biological phenomena, mainly immunity. Parasitic and symbiotic bacteria inhabiting the host are predicted to possess low-toxicity immunomodulators due to the chemical structural changes of their LPS caused by co-evolution with the host. Studies on the chemical synthesis and functional evaluation of their lipid As have been developed to test this hypothesis and to apply them to low-toxicity and safe adjuvants.

Comprehensive genomic analysis reveals virulence factors and antibiotic resistance genes in Pantoea agglomerans KM1, a potential opportunistic pathogen

Pantoea agglomerans is a Gram-negative facultative anaerobic bacillus causing a wide range of opportunistic infections in humans including septicemia, pneumonia, septic arthritis, wound infections and meningitis. To date, the determinants of virulence, antibiotic resistance, metabolic features conferring survival and host-associated pathogenic potential of this bacterium remain largely underexplored. In this study, we sequenced and assembled the whole-genome of P. agglomerans KM1 isolated from kimchi in South Korea. The genome contained one circular chromosome of 4,039,945 bp, 3 mega plasmids, and 2 prophages. The phage-derived genes encoded integrase, lysozyme and terminase. Six CRISPR loci were identified within the bacterial chromosome. Further in-depth analysis showed that the genome contained 13 antibiotic resistance genes conferring resistance to clinically important antibiotics such as penicillin G, bacitracin, rifampicin, vancomycin, and fosfomycin. Genes involved in adaptations to environmental stress were also identified which included factors providing resistance to osmotic lysis, oxidative stress, as well as heat and cold shock. The genomic analysis of virulence factors led to identification of a type VI secretion system, hemolysin, filamentous hemagglutinin, and genes involved in iron uptake and sequestration. Finally, the data provided here show that, the KM1 isolate exerted strong immunostimulatory properties on RAW 264.7 macrophages in vitro. Stimulated cells produced Nitric Oxide (NO) and pro-inflammatory cytokines TNF-α, IL-6 and the anti-inflammatory cytokine IL-10. The upstream signaling for production of TNF-α, IL-6, IL-10, and NO depended on TLR4 and TLR1/2. While production of TNF-α, IL-6 and NO involved solely activation of the NF-κB, IL-10 secretion was largely dependent on NF-κB and to a lesser extent on MAPK Kinases. Taken together, the analysis of the whole-genome and immunostimulatory properties provided in-depth characterization of the P. agglomerans KM1 isolate shedding a new light on determinants of virulence that drive its interactions with the environment, other microorganisms and eukaryotic hosts

Clinical and microbiological characteristics of Pantoea agglomerans infection in children

Pantoea agglomerans is an environmental Gram-negative bacterium that rarely is responsible for the infections in humans but it is often a causative factor of a number of occupational diseases. This study evaluated the clinical and microbiological characteristics and pathogenicity of P. agglomerans in children. We retrospectively reviewed microbiological test results for all children (1 month old to 18 years old) who were admitted to our pediatric hospital between January 2000 to June 2015 and had positive clinical specimen cultures for P. agglomerans. Isolates were identified using conventional tests and the BBL Crystal E/NF ID or MALDI-TOF MS systems. Antibiotic susceptibilities were evaluated using the Kirby-Bauer disc diffusion method. We identified fifteen positive cultures from 14 patients with confirmed infections. The positive specimens included pus, urine, tracheal aspirate, blood, and central venous line samples that yielded P. agglomerans. The median patient age was 8.8 years (range: 1.5 months to 16.5 years), and all patients had underlying comorbidities. Five patients had medical devices, and two devices were removed. The most common P. agglomerans infections involved wound infections (35.7%), pneumonia (21.4%), and urinary tract infections (21.4%). Three patients had concomitant infections (Enterococcus faecium, Pseudomonas aeruginosa, and Aspergillus fumigatus). Five patients had anemia. Three patients (21.4%) died, and all three had carbapenem-resistant P. agglomerans that was detected after the first week of hospitalization; two cases involved pneumonia, which was ineffectively treated. P. agglomerans infections may be life-threatening, especially in young patients with pneumonia. Hospital-acquired P. agglomerans may have different pathogenicity and clinical features, compared to community-acquired P. agglomerans, although further studies are needed to understand the drug-resistance patterns in this bacterium.

A Lipopolysaccharide from Pantoea Agglomerans Is a Promising Adjuvant for Sublingual Vaccines to Induce Systemic and Mucosal Immune Responses in Mice via TLR4 Pathway

A lipopolysaccharide from Pantoea agglomerans (LPSpa) has been applied to various fields for human use as a Toll-like receptor 4 ligand and its safety has been confirmed. Here, we showed for the first time the application of LPSpa as an effective mucosal adjuvant for activating vaccine-induced antigen specific immune responses. Mice sublingually immunized with influenza vaccine (HA split vaccine) with LPSpa induced both HA-specific IgG (systemic) and IgA (mucosal) antibody responses, which led to a significant increase in survival rate against lethal influenza virus challenge compared with subcutaneous vaccination. After sublingual administration of ovalbumin with LPSpa, ovalbumin-specific mucosal IgA responses were induced at both mucosal surfaces close to the immunized site and at remote mucosal surfaces. Sublingual administration of LPSpa evoked local antigen-uptake by dendritic cells in cervical lymph nodes. LPSpa induced cytokine production and the maturation and proliferation of innate immune cells via Toll-like receptor 4 in dendritic cells. Collectively, these results suggest that LPSpa can be used as an effective mucosal adjuvant to stimulate and activate local innate immune cells to improve and enhance mucosal vaccine potency against various pathogens.

The synthetic parasite-derived peptide GK1 increases survival in a preclinical mouse melanoma model

PURPOSE

The therapeutic efficacy of a synthetic parasite-derived peptide GK1, an immune response booster, was evaluated in a mouse melanoma model. This melanoma model correlates with human stage IIb melanoma, which is treated with wide surgical excision; a parallel study employing a surgical treatment was carried out as an instructive goal.

EXPERIMENTAL DESIGN

C57BL/6 mice were injected subcutaneously in the flank with 2×10(5) B16-F10 murine melanoma cells. When the tumors reached 20 mm3, mice were separated into two different groups; the GK1 group, treated weekly with peritumoral injections of GK1 (10 μg/100 μL of sterile saline solution) and the control group, treated weekly with an antiseptic peritumoral injection of 100 μL of sterile saline solution without further intervention. All mice were monitored daily for clinical appearance, tumor size, and survival. Surgical treatment was performed in parallel when the tumor size was 20 mm3 (group A), 500 mm3 (group B), and >500 mm3 (group C).

RESULTS

The GK1 peptide effectively increased the mean survival time by 9.05 days, corresponding to an increase of 42.58%, and significantly delayed tumor growth from day 3 to 12 of treatment. In addition, tumor necrosis was significantly increased (p<0.05) in the treated mice. The overall survival rates obtained with surgical treatment at 6 months were 83.33% for group A, 40% for group B, and 0% for group C, with significant differences (p<0.05) among the groups.

CONCLUSIONS

The GK1 peptide demonstrated therapeutic properties in a mouse melanoma model, as treatment resulted in a significant increase in the mean survival time of the treated animals (42.58%). The potential for GK1 to be used as a primary or adjuvant component of chemotherapeutic cocktails for the treatment of experimental and human cancers remains to be determined, and surgical removal remains a challenge for any new experimental treatment of melanoma in mouse models.

Bacteremia caused by Pantoea agglomerans at a medical center in Taiwan, 2000-2010

BACKGROUND/PURPOSE

There are only three case reports of adult patients with spontaneous Pantoea agglomerans bacteremia in the English literature. The aim of this study was to investigate clinical and microbiologic characteristics patients of P agglomerans bacteremia.

METHODS

We studied all adult patients with P agglomerans bacteremia at a medical center from 2000 to 2010. The isolates were identified using two commercial identification systems.

RESULTS

Of the 18 patients identified, 72% (n = 13) had active gastroesophageal disease treated with antacids. Two-thirds of patients had indwelling central lines and advanced cancers. None of the removed catheter tips yielded P agglomerans and line persistence was not associated with adverse outcomes. Initial disease severity was low, hypotension was uncommon and no patient died of bacteremia. Recurrence of bacteremia occurred in one patient with deep-seated infection. 16srRNA gene sequencing identified only half of the isolates as P agglomerans. The remaining nine isolates were Enterobacter species for six, Pantoea ananatis for two, and Exiguobacterium profundum for one. There were no significant differences between the characteristics of the subgroup molecularly identified as P agglomernas and the overall group characteristics. Eleven (61%) of the 18 isolates were susceptible to cefazolin, six (33%) susceptible to fosfomycin (MIC ≤ 64 mg/ml). Two isolates had colistin MICs ≥ 4 mg/ml.

CONCLUSION

Bacteremia caused by P agglomerans is associated with gastroesophageal reflux disease and receipt of antacids. 16srRNA gene sequencing should not be used as the sole basis for its identification and we have highlighted the need for another molecular-based technique to conclusively characterize P agglomerans.

Report of a rare and aggressive case of oral malignant melanoma

Background

Oral melanoma is a very rare malignancy with unknown etiology. Its higher incidence is between 41 and 60 years of age. A high localization of oral melanoma was found in the maxilla. Gender distribution was reported as 1:1. Oral melanoma represents 0.2% to 8% of the all the total cases of melanoma of the body.

Case report

In this article we report an aggressive case of oral melanoma in a 71-year-old male with chief complaint of black swelling of the gingiva, paresthesia, and denture ill fitting.

Discussion

Most oral melanomas are asymptomatic and painless in early stages and unfortunately diagnosis delayed until symptoms occurred. Early detection of suspected melanotic lesions by patient, dentist, and physician is very important.