Curli-Containing Enteric Biofilms Inside and Out: Matrix Composition, Immune Recognition, and Disease Implications

Effect of impacted mandibular third molar extraction on periodontal microbiota and clinical parameters of adjacent teeth: A randomized clinical trial

It is urgently necessary to clarify the effect of extraction of impacted mandibular third molar (IMTM) on the periodontal tissue of adjacent second molars (ASMs). In this study, the ASM periodontal condition and pathogenic microbes were assessed before IMTM extraction and at 1, 4, 8 and 12 weeks postoperatively. Based on the inclusion and exclusion criteria, our study revealed that IMTM extractions adversely affected distal － periodontal probing depth (dPPD), attachment loss (dAL), plaque index (dPLI) and bleeding on probing (dBOP) within 8 weeks, but these indices gradually normalize after 12 weeks. The subgingival pathogens near the ASMs distal surface, Porphyromonas and Pseudomonas, were significantly increased postoperatively. Moreover, relevance of ASMs clinical indices and subgingival microbes after IMTM extractions was found. In contrast to the situation in chronic periodontitis, the effects of IMTM extraction on dPPD, dAL, dPLI and dBOP of ASMs were mainly correlated with Pseudomonas. Additionally, while the IMTM extractions have adverse distal periodontal indices of ASMs within 8 weeks and increase subgingival pathogens, the modified triangular flap (MTF) had fewer distal periodontal indices and less Pseudomonas. Compared to the traditional envelope flap and triangular flap, the MTF benefits the periodontal health, which could be considered as the priority option for IMTM extractions.

Biogenic amine tryptamine in human vaginal probiotic isolates mediates matrix inhibition and thwarts uropathogenic E. coli biofilm

Probiotics offer a promising prophylactic approach against various pathogens and represent an alternative strategy to combat biofilm-related infections. In this study, we isolated vaginal commensal microbiota from 54 healthy Indian women to investigate their probiotic traits. We primarily explored the ability of cell-free supernatant (CFS) from Lactobacilli to prevent Uropathogenic Escherichia coli (UPEC) colonization and biofilm formation. Our findings revealed that CFS effectively reduced UPEC's swimming and swarming motility, decreased cell surface hydrophobicity, and hindered matrix production by downregulating specific genes (fimA, fimH, papG, and csgA). Subsequent GC-MS analysis identified Tryptamine, a monoamine compound, as the potent bioactive substance from Lactobacilli CFS, inhibiting UPEC biofilms with an MBIC of 4 µg/ml and an MBEC of 8 µg/ml. Tryptamine induced significant changes in E. coli colony biofilm morphology, transitioning from the Red, Dry, and Rough (RDAR) to the Smooth and White phenotype, indicating reduced extracellular matrix production. Biofilm time-kill assays demonstrated a four-log reduction in UPEC viability when treated with Tryptamine, highlighting its potent antibacterial properties, comparable to CFS treatment. Biofilm ROS assays indicated a significant elevation in ROS generation within UPEC biofilms, suggesting a potential antibacterial mechanism. Gene expression studies with Tryptamine-treated samples showed a reduction in expression of curli gene (csgA), consistent with CFS treatment. This study underscores the potential of Tryptamine from probiotic Lactobacilli CFS as a promising antibiofilm agent against UPEC biofilms.

The menace within: bacterial amyloids as a trigger for autoimmune and neurodegenerative diseases

Bacteria are known to produce amyloids, proteins characterized by a conserved cross-beta sheet structure, which exhibit structural and functional similarities to human amyloids. The deposition of human amyloids into fibrillar plaques within organs is closely linked to several debilitating human diseases, including Alzheimer's and Parkinson's disease. Recently, bacterial amyloids have garnered significant attention as potential initiators of human amyloid-associated diseases as well as autoimmune diseases. This review aims to explore how bacterial amyloid, particularly curli found in gut biofilms, can act as a trigger for neurodegenerative and autoimmune diseases. We will elucidate three primary mechanisms through which bacterial amyloids exert their influence: By delving into these three distinct modes of action, this review will provide valuable insights into the intricate relationship between bacterial amyloids and the onset or progression of neurodegenerative and autoimmune diseases. A comprehensive understanding of these mechanisms may open new avenues for therapeutic interventions and preventive strategies targeting amyloid-associated diseases.

Disease- and stage-specific alterations of the oral and fecal microbiota in Alzheimer's disease

Microbial communities in the intestinal tract are suggested to impact the ethiopathogenesis of Alzheimer's disease (AD). The human microbiome might modulate neuroinflammatory processes and contribute to neurodegeneration in AD. However, the microbial compositions in patients with AD at different stages of the disease are still not fully characterized. We used 16S rRNA analyses to investigate the oral and fecal microbiota in patients with AD and mild cognitive impairment (MCI; n = 84), at-risk individuals (APOE4 carriers; n = 17), and healthy controls (n = 50) and investigated the relationship of microbial communities and disease-specific markers via multivariate- and network-based approaches. We found a slightly decreased diversity in the fecal microbiota of patients with AD (average Chao1 diversity for AD = 212 [SD = 66]; for controls = 215 [SD = 55]) and identified differences in bacterial abundances including Bacteroidetes, Ruminococcus, Sutterella, and Porphyromonadaceae. The diversity in the oral microbiota was increased in patients with AD and at-risk individuals (average Chao1 diversity for AD = 174 [SD = 60], for at-risk group = 195 [SD = 49]). Gram-negative proinflammatory bacteria including Haemophilus, Neisseria, Actinobacillus, and Porphyromonas were dominant oral bacteria in patients with AD and MCI and the abundance correlated with the cerebrospinal fluid biomarker. Taken together, we observed a strong shift in the fecal and the oral communities of patients with AD already prominent in prodromal and, in case of the oral microbiota, in at-risk stages. This indicates stage-dependent alterations in oral and fecal microbiota in AD which may contribute to the pathogenesis via a facilitated intestinal and systemic inflammation leading to neuroinflammation and neurodegeneration.

Disease activity is associated with changes in the innate immune function in patients with systemic lupus erythematosus

OBJECTIVE

To address the relationship between systemic lupus erythematosus (SLE) disease activity and the functional parameters of the innate immunity.

METHODS

We evaluated a cohort of 26 adult SLE patients and 10 sex and age-paired healthy donors. When the patients had a disease flare (baseline) and when they achieve clinical response (follow-up), we assessed the systemic lupus erythematosus disease activity index 2 K (SLEDAI 2 K) and the following parameters with flow cytometry and confocal microscopy: monocyte subsets, their expression of TLR2, phagocytic monocytes and neutrophils using the pHrodo Red E. coli BioParticles, the respiratory burst with 123-dihydrorhodamine in neutrophils, and the spontaneous and lipopolysaccharide (LPS)-induced production of neutrophil extracellular traps (NETs). We used the Wilcoxon test to compare the paired medians with interquartile range (IQR) and the Mann-Whitney U test for independent medians. To assess the effect of prednisone and SLEDAI 2 K on the mentioned parameters, we applied a generalized mixed linear model.

RESULTS

Twenty-three patients (88.4%) were women. The SLEDAI 2 K was higher at baseline 8 (6-14) in comparison to that at follow-up (6 (4-8), P = 0.028). At baseline, SLE patients had a decreased percentage of intermediate monocytes, a higher expression of TLR2 in total monocytes, increased phagocytosis in monocytes and neutrophils, a decreased respiratory burst intensity, and an increased production of NETs. In the mix model, the SLEDAI 2 K was the main factor influencing these functional innate immune parameters.

CONCLUSION

Disease activity regulates the innate immune function in SLE which may contribute to the clinical features and infection predisposition. Key points • This is the first cohort study addressing the effect of disease activity and prednisone use on the innate immune function of lupus patients. • Our results show that the disease activity is a key regulator of the respiratory burst, phagocytosis, and the production of neutrophil extracellular traps. • Also, we observed a differential proportion of monocyte subsets according to SLE disease activity. • We consider that our manuscript contributes to the evidence addressing the intrinsic immune abnormalities of patients with SLE regardless of the use of immunosuppressants and set the bases for new research work considering the disease activity as an element to decide the prescription and duration of antibiotic prophylaxis in SLE patients, which is of interest to all rheumatologists.

Parkinson's disease and gut microbiota: from clinical to mechanistic and therapeutic studies

Parkinson's disease (PD) is one of the most prevalent neurodegenerative diseases. The typical symptomatology of PD includes motor symptoms; however, a range of nonmotor symptoms, such as intestinal issues, usually occur before the motor symptoms. Various microorganisms inhabiting the gastrointestinal tract can profoundly influence the physiopathology of the central nervous system through neurological, endocrine, and immune system pathways involved in the microbiota-gut-brain axis. In addition, extensive evidence suggests that the gut microbiota is strongly associated with PD. This review summarizes the latest findings on microbial changes in PD and their clinical relevance, describes the underlying mechanisms through which intestinal bacteria may mediate PD, and discusses the correlations between gut microbes and anti-PD drugs. In addition, this review outlines the status of research on microbial therapies for PD and the future directions of PD-gut microbiota research.

Spectrum of activity of Salmonella anti-biofilm compounds: Evaluation of activity against biofilm-forming ESKAPE pathogens

The ESKAPE pathogens are a group of bacteria that are a leading cause of health-care associated infections and are known to be agents of chronic, biofilm-mediated infections. These chronic bacterial infections often respond poorly to antibiotics and in some cases may require surgical intervention in order to cure the infection. As biofilms are often the critical mediator of a chronic infection, it is essential to develop therapies that target bacteria within the biofilm state. Herein, we report the development of a rapid, 96-well plate-based assay that employs conditions specific for each species to optimize biofilm production and allow for easy identification of differences in biofilm mass after treatment with anti-biofilm candidates. We used these ESKAPE-specific biofilm assays to test our previously identified Salmonella anti-biofilm small molecule compounds, JG-1 and M4, for anti-biofilm activity. The results demonstrated that JG-1 and M4 have anti-biofilm activity against Enterobacter spp., S. aureus, E. faecium, P. aeruginosa, and A. baumannii. In addition, we identified that M4 has significant antimicrobial activity against S. aureus and E. faecium at concentrations >10 μM (X μg/mL). These findings support the claim that JG-1 and M4 have broad-spectrum anti-biofilm activity, while M4 has antimicrobial activity against the Gram-positive members of the ESKAPE pathogens. Thus, these compounds have the potential to have a significant impact on treating multiple types of commonly encountered biofilm-mediated infections.

Microbial amyloids in neurodegenerative amyloid diseases

Human-disease associated amyloidogenic proteins are not unique in their ability to form amyloid fibrillar structures. Numerous microbes produce amyloidogenic proteins that have distinct functions for their physiology in their amyloid form, rather than solely detrimental. Emerging data indicate associations between various microbial organisms, including those which produce functional amyloids, with neurodegenerative diseases. Here, we review some of the evidence suggesting that microbial amyloids impact amyloid disease in host organisms. Experimental data are building a foundation for continued lines of enquiry and suggest that that direct or indirect interactions between microbial and host amyloids may be a contributor to amyloid pathologies. Inhibiting microbial amyloids or their interactions with the host may therefore represent a tangible target to limit various amyloid pathologies.

Interactions of Neutrophils with the Polymeric Molecular Components of the Biofilm Matrix in the Context of Implant-Associated Bone and Joint Infections

In the presence of orthopedic implants, opportunistic pathogens can easily colonize the biomaterial surfaces, forming protective biofilms. Life in biofilm is a central pathogenetic mechanism enabling bacteria to elude the host immune response and survive conventional medical treatments. The formation of mature biofilms is universally recognized as the main cause of septic prosthetic failures. Neutrophils are the first leukocytes to be recruited at the site of infection. They are highly efficient in detecting and killing planktonic bacteria. However, the interactions of these fundamental effector cells of the immune system with the biofilm matrix, which is the true interface of a biofilm with the host cells, have only recently started to be unveiled and are still to be fully understood. Biofilm matrix macromolecules consist of exopolysaccharides, proteins, lipids, teichoic acids, and the most recently described extracellular DNA. The latter can also be stolen from neutrophil extracellular traps (NETs) by bacteria, who use it to strengthen their biofilms. This paper aims to review the specific interactions that neutrophils develop when they physically encounter the matrix of a biofilm and come to interact with its polymeric molecular components.

TLR2 deficiency is beneficial at the late phase in MPTP-induced Parkinson' disease mice

AIMS

Parkinson's disease (PD) is a progressive neurodegenerative disorder. The etiology of PD is still elusive but neuroinflammation is proved to be an important contributor. Toll-like receptor 2 (TLR2) involves in the release of several inflammatory cytokines. Whether TLR2 serves as a mediator contributing to the damage of DA system in PD remain unclear.

MAIN METHODS

Tlr2 knockout (Tlr2-/-) and wild-type (WT) mice were treated with a subacute regimen of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). At 3, 7 and 14 days after MPTP injection, the behavioral performance, including the Pole test, the Rotarod test, the Rearing test and the Wire hang test was evaluated. Moreover, the PD-like phenotypes, including dopaminergic degeneration, the activation of glial cells and the α-Syn expression were systematically analyzed in the nigrostriatal pathway. Finally, the composition of gut microbiota in the MPTP-treated groups were assessed.

KEY FINDINGS

TLR2 deficiency had no obvious impact on the dopaminergic injury at 3 and 7 days following MPTP administration. On the contrary, at 14 days post injection, TLR2 deficiency not only significantly attenuated motor deficits in the Pole test and the Rotarod test, and the nigrostriatal dopaminergic degeneration, but also mitigated α-Syn abnormality, astrocyte activation and neuroinflammation through the suppressed TLR2/MyD88/TRAF6/NF-κB signaling pathways. Additionally, the alteration of gut microbiota was also detected in the mutant mice.

SIGNIFICANCE

These findings highlight the neuroprotective effect of TLR2-pathways at the late phase in the MPTP-induced PD mouse model.

Amyloid Fibrils Produced by Streptococcus sanguinis Contribute to Biofilm Formation and Immune Evasion

Bacterial surface proteins assembled into amyloids contribute to biofilm formation and host immune evasion. Streptococcus sanguinis, a pioneer colonizer of teeth commonly involved in cardiovascular infections, expresses about thirty-three proteins anchored to the cell wall by sortase A. Here, we characterized the production of amyloid in S. sanguinis strains differing in biofilm and immune evasion phenotypes and investigated the role of sortase A in amyloidogenesis. Amyloid was identified in biofilms formed by nine strains, using Congo red (CR) staining and cross-polarized light microscopy. Additionally, EGCG, an amyloid inhibitor, impaired biofilm maturation in a strain-specific fashion. The amounts of amyloid-like components quantified in culture fluids of nine strains using thioflavin T and fluorimetry negatively correlated with bacterial binding to complement-activating proteins (SAP, C1q), C3b deposition and rates of opsonophagocytosis in PMNs, implying amyloid production in immune evasion. The deletion of the sortase A gene (srtA) in strain SK36 compromised amyloid production and sucrose-independent biofilm maturation. The srtA mutant further showed increased susceptibility to C3b deposition and altered interactions with PMNs as well as reduced persistence in human blood. These findings highlight the contribution of amyloids to biofilm formation and host immune evasion in S. sanguinis strains, further indicating the participation of sortase A substrates in amyloidogenesis.

Extracellular matrix-degrading enzymes as a biofilm control strategy for food-related microorganisms

Biofilm is one of the major problems in food industries and is difficult to be removed or prevented by conventional sanitizers. In this review, we discussed the extracellular matrix-degrading enzymes as a strategy to control biofilms of foodborne pathogenic and food-contaminating bacteria. The biofilms can be degraded by using the enzymes targeting proteins, polysaccharides, extracellular DNA, or lipids which mainly constitute the extracellular polymeric substances of biofilms. However, the efficacy of enzymes varies by the growth medium, bacterial species, strains, or counterpart microorganisms due to a high variation in the composition of extracellular polymeric substances. Several studies demonstrated that the combined treatment using conventional sanitizers or multiple enzymes can synergistically enhance the biofilm removal efficacies. In this review, the application of the immobilized enzymes on solid substrates is also discussed as a potential strategy to prevent biofilm formation on food contact surfaces.

Metagenome-wide association study of gut microbiome features for myositis

PURPOSE

The clinical relevance and pathogenic role of gut microbiome in both myositis and its associated interstitial lung disease (ILD) are still unclear. The purpose of this study was to investigate the role of gut microbiome in myositis through comprehensive metagenomic-wide association studies (MWAS).

METHODS

We conducted MWAS of the myositis gut microbiome in a Chinese cohort by using whole-genome shotgun sequencing of high depth, including 30 myositis patients and 31 healthy controls (HC). Among the myositis patients, 11 developed rapidly progressive interstitial lung disease (RP-ILD) and 10 had chronic ILD (C-ILD).

RESULTS

Analysis for overall distribution level of the bacteria showed Alistipes onderdonkii, Parabacteroides distasonis and Escherichia coli were upregulated, Lachnospiraceae bacterium GAM79, Roseburia intestinalis, and Akkermansia muciniphila were downregulated in patients with myositis compared to HC. Bacteroides thetaiotaomicron, Parabacteroides distasonis and Escherichia coli were upregulated, Bacteroides A1C1 and Bacteroides xylanisolvens were downregulated in RP-ILD cases compared with C-ILD cases. A variety of biological pathways related to metabolism were enriched in the myositis and HC, RP-ILD and C-ILD comparison. And in the analyses for microbial contribution in metagenomic biological pathways, we have found that E. coli played an important role in the pathway expression in both myositis group and myositis-associated RP-ILD group. Anti-PL-12 antibody, anti-Ro-52 antibody, and anti-EJ antibody were found to have positive correlation with bacterial diversity (Shannon-wiener diversity index and Chao1, richness estimator) between myositis group and control groups. The combination of E. coli and R. intestinalis could distinguish myositis group from HC effectively. R. intestinalis can also be applied in the distinguishment of RP-ILD group vs. C-ILD group in myositis patients.

CONCLUSION

Our MWAS study first revealed the link between gut microbiome and pathgenesis of myositis, which may help us understand the role of gut microbiome in the etiology of myositis and myositis-associated RP-ILD.

Persistent Salmonella enterica serovar Typhi sub-populations within host interrogated by whole genome sequencing and metagenomics

Salmonella enterica serovar Typhi (S. Typhi) causes typhoid fever and, in some cases, chronic carriage after resolution of acute disease. This study examined sequential isolates of S. Typhi from a single host with persistent asymptomatic infection. These isolates, along with another S. Typhi isolate recovered from a household contact with typhoid fever, were subjected to whole genome sequencing and analysis. In addition, direct sequencing of the bile fluid from the host with persistent infection was also performed. Comparative analysis of isolates revealed three sub-populations of S. Typhi with distinct genetic patterns. Metagenomic sequencing recognised only two of the three sub-populations within the bile fluid. The detection and investigation of insertion sequences IS10R and associated deletions complemented analysis of single nucleotide polymorphisms. These findings improve our understanding of within-host dynamics of S. Typhi in cases of persistent infection and inform epidemiological investigations of transmission events associated with chronic carriers.

Engineered Curli Nanofilaments as a Self-Adjuvanted Antigen Delivery Platform

Proteinaceous nanoparticles constitute efficient antigen delivery systems in vaccine formulations due to their size and repetitive nature that mimic most invading pathogens and promote immune activation. Nonetheless, the coadministration of an adjuvant with subunit nanovaccines is usually required to induce a robust, long-lasting, and protective immune response. Herein, the protein Curli-specific gene A (CsgA), which is known to self-assemble into nanofilaments contributing to bacterial biofilm, is exploited to engineer an intrinsically immunostimulatory antigen delivery platform. Three repeats of the M2e antigenic sequence from the influenza A virus matrix 2 protein are merged to the N-terminal domain of engineered CsgA proteins. These chimeric 3M2e-CsgA spontaneously self-assemble into antigen-displaying cross-β-sheet nanofilaments that activate the heterodimeric toll-like receptors 2 and 1. The resulting nanofilaments are avidly internalized by antigen-presenting cells and stimulate the maturation of dendritic cells. Without the need of any additional adjuvants, both assemblies show robust humoral and cellular immune responses, which translate into complete protection against a lethal experimental infection with the H1N1 influenza virus. Notably, these CsgA-based nanovaccines induce neither overt systemic inflammation, nor reactogenicity, upon mice inoculation. These results highlight the potential of engineered CsgA nanostructures as self-adjuvanted, safe, and versatile antigen delivery systems to fight infectious diseases.

Endowing textiles with self-repairing ability through the fabrication of composites with a bacterial biofilm

To address the increasing environmental footprint of the fast-growing textile industry, self-repairing textile composites have been developed to allow torn or damaged textiles to restore their morphological, mechanical, and functional features. A sustainable way to create these textile composites is to introduce a coating material that is biologically derived, biodegradable, and can be produced through scalable processes. Here, we fabricated self-repairing textile composites by integrating the biofilms of Escherichia coli (E. coli) bacteria into conventional knitted textiles. The major structural protein component in E. coli biofilm is a matrix of curli fibers, which has demonstrated extraordinary abilities to self-assemble into mechanically strong macroscopic structures and self-heal upon contact with water. We demonstrated the integration of biofilm through three simple, fast, and scalable methods: adsorption, doctor blading, and vacuum filtration. We confirmed that the composites were breathable and mechanically strong after the integration, with improved Young's moduli or elongation at break depending on the fabrication method used. Through patching and welding, we showed that after rehydration, the composites made with all three methods effectively healed centimeter-scale defects. Upon observing that the biofilm strongly attached to the textiles by covering the extruding textile fibers from the self-repair failures, we proposed that the strength of the self-repairs relied on both the biofilm's cohesion and the biofilm-textile adhesion. Considering that curli fibers are genetically-tunable, the fabrication of self-repairing curli-expressing biofilm-textile composites opens new venues for industrially manufacturing affordable, durable, and sustainable functional textiles.

Regulation by cyclic di-GMP attenuates dynamics and enhances robustness of bimodal curli gene activation in Escherichia coli

Curli amyloid fibers are a major constituent of the extracellular biofilm matrix formed by bacteria of the Enterobacteriaceae family. Within Escherichia coli biofilms, curli gene expression is limited to a subpopulation of bacteria, leading to heterogeneity of extracellular matrix synthesis. Here we show that bimodal activation of curli gene expression also occurs in well-mixed planktonic cultures of E. coli, resulting in all-or-none stochastic differentiation into distinct subpopulations of curli-positive and curli-negative cells at the entry into the stationary phase of growth. Stochastic curli activation in individual E. coli cells could further be observed during continuous growth in a conditioned medium in a microfluidic device, which further revealed that the curli-positive state is only metastable. In agreement with previous reports, regulation of curli gene expression by the second messenger c-di-GMP via two pairs of diguanylate cyclase and phosphodiesterase enzymes, DgcE/PdeH and DgcM/PdeR, modulates the fraction of curli-positive cells. Unexpectedly, removal of this regulatory network does not abolish the bimodality of curli gene expression, although it affects dynamics of activation and increases heterogeneity of expression levels among individual cells. Moreover, the fraction of curli-positive cells within an E. coli population shows stronger dependence on growth conditions in the absence of regulation by DgcE/PdeH and DgcM/PdeR pairs. We thus conclude that, while not required for the emergence of bimodal curli gene expression in E. coli, this c-di-GMP regulatory network attenuates the frequency and dynamics of gene activation and increases its robustness to cellular heterogeneity and environmental variation.

Amphiphilic Nano-Swords for Direct Penetration and Eradication of Pathogenic Bacterial Biofilms

Bacterial biofilms are major causes of persistent and recurrent infections and implant failures. Biofilms are formable by most clinically important pathogens worldwide, such as Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, causing recalcitrance to standard antibiotic therapy or anti-biofilm strategies due to amphiphilic impermeable extracellular polymeric substances (EPS) and the presence of resistant and persistent bacteria within the biofilm matrix. Herein, we report our design of an oligoamidine-based amphiphilic "nano-sword" with high structural compacity and rigidity. Its rigid, amphiphilic structure ensures effective penetration into EPS, and the membrane-DNA dual-targeting mechanism exerts strong bactericidal effect on the dormant bacterial persisters within biofilms. The potency of this oligoamidine is shown in two distinct modes of application: it may be used as a coating agent for polycaprolactone to fully inhibit surface biofilm growth in an implant-site mimicking micro-environment; meanwhile, it cures model mice of biofilm infections in various ex vivo and in vivo studies.

Gut Enterobacteriaceae and uraemic toxins - Perpetrators for ageing

Ageing is a complex process that is associated with changes in the composition and functions of gut microbiota. Reduction of gut commensals is the hallmarks of ageing, which favours the expansion of pathogens even in healthy centenarians. Interestingly, gut Enterobacteriaceae have been found to be increased with age and also consistently observed in the patients with metabolic diseases. Thus, they are associated with all-cause mortality, regardless of genetic origin, lifestyle, and fatality rate. Moreover, Enterobacteriaceae are also implicated in accelerating the ageing process through telomere attrition, cellular senescence, inflammasome activation and impairing the functions of mitochondria. However, acceleration of ageing is likely to be determined by intrinsic interactions between Enterobacteriaceae and other associated gut bacteria. Several studies suggested that Enterobacteriaceae possess genes for the synthesis of uraemic toxins. In addition to intestine, Enterobacteriaceae and their toxic metabolites have also been found in other organs, such as adipose tissue and liver and that are implicated in multiorgan dysfunction and age-related diseases. Therefore, targeting Enterobacteriaceae is a nuance approach for reducing inflammaging and enhancing the longevity of older people. This review is intended to highlight the current knowledge of Enterobacteriaceae-mediated acceleration of ageing process.

Gut microbiota of Parkinson's disease in an appendectomy cohort: a preliminary study

In patients with Parkinson's disease (PD), α-synuclein pathology is thought to spread to the brain via the dorsal motor nucleus of the vagus nerve. The link between the gut microbiome and PD has been explored in various studies. The appendix might play an important role in immunity by maintaining the microbiota as a reservoir. In recent times, appendectomy has been linked to a lower risk of PD, possibly owing to the role of the appendix in altering the gut microbiome. We aimed to elucidate whether the gut microbiota affects PD development in the appendectomy cohort. We analyzed the fecal microbial composition in patients with PD and healthy controls with and without a history of appendectomy. The abundance of microbes from the family Enterobacteriaceae was higher in feces samples from patients with Parkinson's disease compared to that in samples collected from healthy controls. Furthermore, there was a significant phylogenetic difference between patients with PD and healthy controls who had undergone appendectomy. There was a significant phylogenetic difference between patients with PD and HCs who had undergone APP. These results suggest the correlation between gut microbiota and PD in patients who have undergone APP.

Bacterial envelope stress responses: Essential adaptors and attractive targets

Millions of deaths a year across the globe are linked to antimicrobial resistant infections. The need to develop new treatments and repurpose of existing antibiotics grows more pressing as the growing antimicrobial resistance pandemic advances. In this review article, we propose that envelope stress responses, the signaling pathways bacteria use to recognize and adapt to damage to the most vulnerable outer compartments of the microbial cell, are attractive targets. Envelope stress responses (ESRs) support colonization and infection by responding to a plethora of toxic envelope stresses encountered throughout the body; they have been co-opted into virulence networks where they work like global positioning systems to coordinate adhesion, invasion, microbial warfare, and biofilm formation. We highlight progress in the development of therapeutic strategies that target ESR signaling proteins and adaptive networks and posit that further characterization of the molecular mechanisms governing these essential niche adaptation machineries will be important for sparking new therapeutic approaches aimed at short-circuiting bacterial adaptation.

Salmonella enterica serovar Typhimurium STM1266 encodes a regulator of curli biofilm formation: the brfS gene

The major biofilm pathway in Salmonella enterica serovar Typhimurium involves specific growth conditions that induce the csgA gene whose product forms surface curli fibers that mediate biofilm formation. We have found that the previously uncharacterized STM1266 gene in S. Typhimurium plays a role in regulating biofilm formation via the curli pathway. S. Typhimurium ΔSTM1266 strains display a biofilm defect, and overexpression of STM1266 results in enhanced biofilm formation. STM1266 deletion resulted in lowered csgA expression using promoter-reporter β-galactosidase assays, and csgA and csgD deletions abrogate the effects of STM1266 overexpression on biofilm formation while deletion of bcsA (encoding an essential enzyme for cellulose formation) has no effect. In a mouse infection model, the ΔSTM1266 strain displayed results similar to those seen for previously reported ΔcsgA strains. The STM1266 gene is predicted to encode a DNA-binding transcriptional regulator of the MerR family and is homologous to the Escherichia coli BluR regulator protein. We respectfully propose to ascribe the name brfS (biofilm regulator for Salmonella Typhimurium) to the STM1266 gene.

Electrostatic interactions mediate the nucleation and growth of a bacterial functional amyloid

Bacterial biofilm formation can have severe impacts on human and environmental health. Enteric bacteria produce functional amyloid fibers called curli that aid in biofilm formation and host colonization. CsgA is the major proteinaceous component of curli amyloid fibers and is conserved in many gram-negative enteric bacteria. The CsgA amyloid core consists of five imperfect repeats (R1-R5). R2, R3, and R4 have aspartic acid (D) and glycine (G) residues that serve as "gatekeeper" residues by modulating the intrinsic aggregation propensity of CsgA. Here, using mutagenesis, salt-mediated charge screening, and by varying pH conditions, we show that the ability of CsgA variants to nucleate and form amyloid fibers is dictated by the charge state of the gatekeeper residues. We report that in Citrobacter youngae CsgA, certain arginine (R) and lysine (K) residues also act as gatekeeper residues. A mechanism of gatekeeping is proposed wherein R and K residues electrostatically interact with negatively charged D residues, tempering CsgA fiber formation.

Systemic exposure to bacterial amyloid curli alters the gut mucosal immune response and the microbiome, exacerbating Salmonella-induced arthritis

The Salmonella biofilm-associated amyloid protein, curli, is a dominant instigator of systemic inflammation and autoimmune responses following Salmonella infection. Systemic curli injections or infection of mice with Salmonella Typhimurium induce the major features of reactive arthritis, an autoimmune disorder associated with Salmonella infection in humans. In this study, we investigated the link between inflammation and microbiota in exacerbating autoimmunity. We studied C57BL/6 mice from two sources, Taconic Farms and Jackson Labs. Mice from Taconic Farms have been reported to have higher basal levels of the inflammatory cytokine IL - 17 than do mice from Jackson Labs due to the differences in their microbiota. When we systemically injected mice with purified curli, we observed a significant increase in diversity in the microbiota of Jackson Labs mice but not in that of the Taconic mice. In Jackson Labs, mice, the most striking effect was the expansion of Prevotellaceae. Furthermore, there were increases in the relative abundance of the family Akkermansiaceae and decreases in families Clostridiaceae and Muribaculaceae in Jackson Labs mice. Curli treatment led to significantly aggravated immune responses in the Taconic mice compared to Jackson Labs counterparts. Expression and production of IL - 1β, a cytokine known to promote IL - 17 production, as well as expression of Tnfa increased in the gut mucosa of Taconic mice in the first 24 hours after curli injections, which correlated with significant increases in the number of neutrophils and macrophages in the mesenteric lymph nodes. A significant increase in the expression of Ccl3 in colon and cecum of Taconic mice injected with curli was detected. Taconic mice injected with curli also had elevated levels of inflammation in their knees. Overall, our data suggest that autoimmune responses to bacterial ligands, such as curli, are amplified in individuals with a microbiome that promote inflammation.

Antibiofilm Action of Plant Terpenes in Salmonella Strains: Potential Inhibitors of the Synthesis of Extracellular Polymeric Substances

Salmonella can form biofilms that contribute to its resistance in food processing environments. Biofilms are a dense population of cells that adhere to the surface, creating a matrix composed of extracellular polymeric substances (EPS) consisting mainly of polysaccharides, proteins, and eDNA. Remarkably, the secreted substances, including cellulose, curli, and colanic acid, act as protective barriers for Salmonella and contribute to its resistance and persistence when exposed to disinfectants. Conventional treatments are mostly ineffective in controlling this problem; therefore, exploring anti-biofilm molecules that minimize and eradicate Salmonella biofilms is required. The evidence indicated that terpenes effectively reduce biofilms and affect their three-dimensional structure due to the decrease in the content of EPS. Specifically, in the case of Salmonella, cellulose is an essential component in their biofilms, and its control could be through the inhibition of glycosyltransferase, the enzyme that synthesizes this polymer. The inhibition of polymeric substances secreted by Salmonella during biofilm development could be considered a target to reduce its resistance to disinfectants, and terpenes can be regarded as inhibitors of this process. However, more studies are needed to evaluate the effectiveness of these compounds against Salmonella enzymes that produce extracellular polymeric substances.

Antibodies against HSV-1 and Curli Show the Highest Correlation in Parkinson's Disease Patients in Comparison to Healthy Controls

Parkinson’s disease (PD) is a neurodegenerative disorder involving the accumulation of alpha-synuclein (α-syn)/Lewy bodies in the brain and -enteric nervous system. The etiology of the disease is not well understood, but bacterial and viral infections may contribute to the pathogenesis of PD. It has been suggested that the gastrointestinal (GI) complications observed in PD patients may arise from bacterial dysbiosis, leading to curli/α-syn deposits in the enteric nervous system. Enteric bacteria secrete curli, a functional amyloid peptide involved in adhesion to surfaces, cell invasion, and biofilm formation. However, these bacterial amyloids can initiate additional α-syn deposits through immune system activation and cross-seeding. In this study, we investigate the humoral response against α-syn, curli peptides, and various bacterial and viral immunogen peptides in PD patients, and compare them with those in healthy controls (HCs). Polyclonal IgG antibodies (Abs) were detected against peptides derived from α-syn (α-syn100−114), curli (Curli133−141), Porphyromonas gingivalis Pg (RgpA800−812, Kpg328−339), Aggregatibacter actinomycetemcomitans (LtxA1429−445, LtxA264−80), Mycobacterium avium subsp. paratuberculosis (MAP3865c125−133, MAP1,4-a-gbp157−173 and MAP_402718−32), Epstein−Barr virus (EBNA1400−413, BOLF1305−320), and Herpes Simplex virus 1 (UI4222−36), as investigated by indirect ELISA of 51 serum samples from PD and 58 sex and age-matched HCs. Significant differences in OD (optical density) values and Abs positivity between PD patients and HCs were observed for Kpg (82.3% vs. 10.3%), followed by RgpA (60.7% vs. 24.1%), curli (51% vs. 22.4%), and UI42 (43.1% vs. 25.8%) in PD, compared to HCs sera (p < 0.001). No significant difference was found in the ODs obtained from other tested peptides in PD patients, compared to HCs. Significant positive correlations between OD values obtained by ELISA were observed for UI42 and curli (r = 0.811, p < 0.0001), Kpg and RgpA (r = 0.659, p < 0.0001), followed by LtxA1 and LtxA2 (r = 0.653, p < 0.0001). The correlation between the HY scale (Hoehn and Yahr Scale) and LtxA1 (r = 0.306, p < 0.028) and HY and Kpg (r = 0.290, p < 0.038) were significantly positive. This study reports a significantly increased humoral response against curli, Pg, and HSV-1 in PD patients, implying that they could be important factors in the pathogenesis of the disease. In addition, the high positive correlation between UI42 and curli may suggest the involvement of HSV-1 in GI dysbiosis. Therefore, the role of each individual pathogen and curli in PD needs to be further investigated.

Anti-biofilm activity of caffeine against uropathogenic E. coli is mediated by curli biogenesis

Biofilms are assemblages of sessile microorganisms that form an extracellular matrix around themselves and mediate attachment to surfaces. The major component of the extracellular matrix of Uropathogenic E. coli and other Enterobacteriaceae are curli fibers, making biofilms robust and resistant to antimicrobials. It is therefore imperative to screen antibiofilm compounds that can impair biofilm formation. In the present study, we investigated the curli-dependent antibiofilm activity of caffeine against UPEC strain CFT073 and commensal strain E. coli K-12MG1655.Caffeine significantly reduced the biofilm formation of both UPEC and E. coli K-12 by 86.58% and 91.80% respectively at 48 mM caffeine as determined by Crystal Violet assay. These results were further confirmed by fluorescence microscopy and Scanning Electron Microscope (SEM). Caffeine significantly reduced the cytotoxicity and survivability of UPEC. Molecular docking analysis revealed a strong interaction between caffeine and curli regulator protein (Csg D) of E. coli. The qRT-PCR data also showed significant downregulation in the expression of CsgBA and the CsgDEFG operon at both 24 mM and 48 mM caffeine. The findings revealed that caffeine could inhibit E. coli biofilm formation by regulating curli assembly and thus may be used as an alternative therapeutic strategy for the treatment of chronic E. coli biofilm-related infections.

Gut instincts in neuroimmunity from the eighteenth to twenty-first centuries

In the past two decades, work on the microbiota-gut-brain axis has led to a renewed appreciation for the interconnectedness between body systems in both clinical and scientific circles. In the USA alone, millions of adults are burdened with non-communicable chronic diseases whose putative etiologies were previously thought to be restricted to either the gut or brain, such as inflammatory bowel disease, irritable bowel syndrome, Parkinson's and Alzheimer's disease, and autism spectrum disorder. However, the recent explosion of research into the impacts of the gut microbiome on diverse aspects of human health has revealed the potentially critical importance of reciprocal interactions between the gut microbiota, the immune system, and the brain in diverse diseases and disorders. In this review, we revisit the history of gut-brain interactions in science and medicine, which dates back to at least the eighteenth century, and outline how concepts in this field have shifted and evolved across eras. Next, we highlight the modern resurgence of gut-brain axis research, focusing on neuro-immune-microbiota interactions and recent progress towards a mechanistic understanding of the diverse impacts of the microbiome on human health. Finally, we offer a forward-looking perspective on the future of microbiota-gut-brain research, which may eventually reveal new paths towards the treatment of diverse diseases influenced by the complex connections between the microbiota and the brain.

Antibiotic Consumption Patterns in European Countries Are Associated with the Prevalence of Parkinson’s Disease; the Possible Augmenting Role of the Narrow-Spectrum Penicillin

Parkinson’s disease: Parkinson’s disease (PD) is the second-most common neurodegenerative disease, affecting at least 0.3% of the worldwide population and over 3% of those over 80 years old. According to recent research (2018), in 2016, 6.1 million (95% uncertainty interval (UI) 5.0–7.3) individuals had Parkinson’s disease globally, compared with 2.5 million (2.0–3.0) in 1990. The pandemic-like spreading of PD is considered a slow-moving disaster. Most recent studies indicated the possible role of an altered microbiome, dysbiosis, in the development of PD, which occurs long before the clinical diagnosis of PD. Antibiotics are considered as major disruptors of the intestinal flora and we have hypothesized that, as different classes of antibiotics might induce different dysbiosis, certain classes of antibiotics could trigger the PD-related dysbiosis as well. Comparative analyses were performed between the average yearly antibiotic consumption of 30 European countries (1997–2016) and the PD prevalence database (estimated for 2016). We divided the time frame of antibiotic consumption of 1997–2016 into four subsections to estimate the possible time lapse between antibiotic exposure and the prevalence, prevalence change, and PD-related death rates estimated for 2016. Our results indicated that countries with high consumption of narrow-spectrum penicillin experienced a higher increase in PD prevalence than the others. Countries reporting a decline in PD from 1990 to 2016 demonstrated a reduction in the consumption of narrow-spectrum penicillin in this period.

Amyloid-containing biofilms and autoimmunity

Bacteria are microscopic, single-celled organisms known for their ability to adapt to their environment. In response to stressful environmental conditions or in the presence of a contact surface, they commonly form multicellular aggregates called biofilms. Biofilms form on various abiotic or biotic surfaces through a dynamic stepwise process involving adhesion, growth, and extracellular matrix production. Biofilms develop on tissues as well as on implanted devices during infections, providing the bacteria with a mechanism for survival under harsh conditions including targeting by the immune system and antimicrobial therapy. Like pathogenic bacteria, members of the human microbiota can form biofilms. Biofilms formed by enteric bacteria contribute to several human diseases including autoimmune diseases and cancer. However, until recently the interactions of immune cells with biofilms had been mostly uncharacterized. Here, we will discuss how components of the enteric biofilm produced in vivo, specifically amyloid curli and extracellular DNA, could be interacting with the host's immune system causing an unpredicted immune response.

Mechanistic insights into accelerated α-synuclein aggregation mediated by human microbiome-associated functional amyloids

The gut microbiome has been shown to have key implications in the pathogenesis of Parkinson's disease (PD). The Escherichia coli functional amyloid CsgA is known to accelerate α-synuclein aggregation in vitro and induce PD symptoms in mice. However, the mechanism governing CsgA-mediated acceleration of α-synuclein aggregation is unclear. Here, we show that CsgA can form stable homodimeric species that correlate with faster α-synuclein amyloid aggregation. Furthermore, we identify and characterize new CsgA homologs encoded by bacteria present in the human microbiome. These CsgA homologs display diverse aggregation kinetics, and they differ in their ability to modulate α-synuclein aggregation. Remarkably, we demonstrate that slowing down CsgA aggregation leads to an increased acceleration of α-synuclein aggregation, suggesting that the intrinsic amyloidogenicity of gut bacterial CsgA homologs affects their ability to accelerate α-synuclein aggregation. Finally, we identify a complex between CsgA and α-synuclein that functions as a platform to accelerate α-synuclein aggregation. Taken together, our work reveals complex interplay between bacterial amyloids and α-synuclein that better informs our understanding of PD causation.

Purification of the Bacterial Amyloid "Curli" from Salmonella enterica Serovar Typhimurium and Detection of Curli from Infected Host Tissues

Microbiologists are learning to appreciate the importance of "functional amyloids" that are produced by numerous bacterial species and have impacts beyond the microbial world. These structures are used by bacteria to link together, presumably to increase survival, protect against harsh conditions, and perhaps to influence cell-cell communication. Bacterial functional amyloids are also beginning to be appreciated in the context of host-pathogen interactions, where there is evidence that they can trigger the innate immune system and are recognized as non-self-molecular patterns. The characteristic three-dimensional fold of amyloids renders them similar across the bacterial kingdom and into the eukaryotic world, where amyloid proteins can be undesirable and have pathological consequences. The bacterial protein curli, produced by pathogenic Salmonella enterica and Escherichia coli strains, was one of the first functional amyloids discovered. Curli have since been well characterized in terms of function, and we are just starting to scratch the surface about their potential impact on eukaryotic hosts. In this manuscript, we present step-by-step protocols with pictures showing how to purify these bacterial surface structures. We have described the purification process from S. enterica, acknowledging that the same method can be applied to E. coli. In addition, we describe methods for detection of curli within animal tissues (i.e., GI tract) and discuss purifying curli intermediates in a S. enterica msbB mutant strain as they are more cytotoxic than mature curli fibrils. Some of these methods were first described elsewhere, but we wanted to assemble them together in more detail to make it easier for researchers who want to purify curli for use in biological experiments. Our aim is to provide methods that are useful for specialists and non-specialists as bacterial amyloids become of increasing importance.

Phenol-Soluble Modulins From Staphylococcus aureus Biofilms Form Complexes With DNA to Drive Autoimmunity

The bacterial amyloid curli, produced by Enterobacteriales including Salmonella species and Escherichia coli, is implicated in the pathogenesis of several complex autoimmune diseases. Curli binds to extracellular DNA, and these complexes drive autoimmunity via production of anti-double-stranded DNA autoantibodies. Here, we investigated immune activation by phenol-soluble modulins (PSMs), the amyloid proteins expressed by Staphylococcus species. We confirmed the amyloid nature of PSMs expressed by S. aureus using a novel specific amyloid stain, (E,E)-1-fluoro-2,5-bis(3-hydroxycarbonyl-4-hydroxy) styrylbenzene (FSB). Direct interaction of one of the S. aureus PSMs, PSMα3, with oligonucleotides promotes fibrillization of PSM amyloids and complex formation with bacterial DNA. Finally, utilizing a mouse model with an implanted mesh-associated S. aureus biofilm, we demonstrated that exposure to S. aureus biofilms for six weeks caused anti-double-stranded DNA autoantibody production in a PSM-dependent manner. Taken together, these results highlight how the presence of PSM-DNA complexes in S. aureus biofilms can induce autoimmune responses, and suggest an explanation for how bacterial infections trigger autoimmunity.

Design of a genetically programmed barnacle-curli inspired living-cell bioadhesive

In nature, barnacles and bacterial biofilms utilize self-assembly amyloid to achieve strong and robust interface adhesion. However, there is still a lack of sufficient research on the construction of macroscopic adhesives based on amyloid-like nanostructures through reasonable molecular design. Here, we report a genetically programmed self-assembly living-cell bioadhesive inspired by barnacle and curli system. Firstly, the encoding genes of two natural adhesion proteins (CsgA and cp19k) derived from E. coli curli and barnacle cement were fused and expressed as a fundamental building block of the bioadhesive. Utilizing the natural curli system of E. coli, fusion protein can be delivered to cell surface and self-assemble into an amyloid nanofibrous network. Then, the E. coli cells were incorporated into the molecular chain network of xanthan gum (XG) through covalent conjugation to produce a living-cell bioadhesive. The shear adhesive strength of the bioadhesive to the surface of the aluminum sheet reaches 278 ​kPa. Benefiting from living cells encapsulated inside, the bioadhesive can self-regenerate with adequate nutrients. This adhesive has low toxicity to organisms, strong resistance to the liquid environment in vivo, easy to pump, exhibiting potential application prospects in biomedical fields such as intestinal soft tissue repair.

Motor and non-motor circuit disturbances in early Parkinson disease: which happens first?

For the last two decades, pathogenic concepts in Parkinson disease (PD) have revolved around the toxicity and spread of α-synuclein. Thus, α-synuclein would follow caudo-rostral propagation from the periphery to the central nervous system, first producing non-motor manifestations (such as constipation, sleep disorders and hyposmia), and subsequently impinging upon the mesencephalon to account for the cardinal motor features before reaching the neocortex as the disease evolves towards dementia. This model is the prevailing theory of the principal neurobiological mechanism of disease. Here, we scrutinize the temporal evolution of motor and non-motor manifestations in PD and suggest that, even though the postulated bottom-up mechanisms are likely to be involved, early involvement of the nigrostriatal system is a key and prominent pathophysiological mechanism. Upcoming studies of detailed clinical manifestations with newer neuroimaging techniques will allow us to more closely define, in vivo, the role of α-synuclein aggregates with respect to neuronal loss during the onset and progression of PD.

T cells, α-synuclein and Parkinson disease

The notion that autoimmune responses to α-synuclein may be involved in the pathogenesis of this disorder stems from reports that mutations in α-synuclein or certain alleles of the major histocompatibility complex (MHC) are associated with the disease and that dopaminergic and norepinephrinergic neurons in the midbrain can present antigenic epitopes. Here, we discuss recent evidence that a defined set of peptides derived from α-synuclein act as antigenic epitopes displayed by specific MHC alleles and drive helper and cytotoxic T cell responses in patients with PD. Moreover, phosphorylated α-synuclein may activate T cell responses in a less restricted manner in PD. While the roles for the acquired immune system in disease pathogenesis remain unknown, preclinical animal models and in vitro studies indicate that T cells may interact with neurons and exert effects related to neuronal death and neuroprotection. These findings suggest that therapeutics that target T cells and ameliorate the incidence or disease severity of inflammatory bowel disorders or CNS autoimmune diseases such as multiple sclerosis may be useful in PD.

Mitochondria-Microbiota Interaction in Neurodegeneration

Alzheimer’s and Parkinson’s are the two best-known neurodegenerative diseases. Each is associated with the excessive aggregation in the brain and elsewhere of its own characteristic amyloid proteins. Yet the two afflictions have much in common and often the same amyloids play a role in both. These amyloids need not be toxic and can help regulate bile secretion, synaptic plasticity, and immune defense. Moreover, when they do form toxic aggregates, amyloids typically harm not just patients but their pathogens too. A major port of entry for pathogens is the gut. Keeping the gut’s microbe community (microbiota) healthy and under control requires that our cells’ main energy producers (mitochondria) support the gut-blood barrier and immune system. As we age, these mitochondria eventually succumb to the corrosive byproducts they themselves release, our defenses break down, pathogens or their toxins break through, and the side effects of inflammation and amyloid aggregation become problematic. Although it gets most of the attention, local amyloid aggregation in the brain merely points to a bigger problem: the systemic breakdown of the entire human superorganism, exemplified by an interaction turning bad between mitochondria and microbiota.

Bacterial Amyloid Curli Associated Gut Epithelial Neuroendocrine Activation Predominantly Observed in Alzheimer's Disease Mice with Central Amyloid-β Pathology

BACKGROUND

Substantial evidence from recent research suggests an influential and underappreciated force in Alzheimer's disease (AD) pathogenesis: the pathological signals originate from outside the brain. Pathogenic bacteria produce amyloid-like proteins "curli" that form biofilms and show functional similarities to human amyloid-β (Aβ). These proteins may contribute to neurological disease progression via signaling cascade from the gut to the brain.

OBJECTIVE

We propose that curli causes neuroendocrine activation from the gut to brain that promotes central Aβ pathology.

METHODS

PGP9.5 and TLR2 levels in response to curli in the lumen of Tg2576 AD mice were analyzed by immunohistochemical and qRT-PCR analysis. Western blot and human 3D in vitro enteroids culture systems were also used. 16S rRNA gene sequencing was used to investigate bacterial dysbiosis.

RESULTS

We found significant increase in bacterial-amyloid curli with elevated TLR2 at the mRNA level in the pre- and symptomatic Tg-AD gut compared to littermate WT controls. This data associates with increased gram-positive bacterial colonization in the ileum of the symptomatic AD mice. We found fundamental evidence for vagus nerve activation in response to bacterial curli. Neuroendocrine marker PGP9.5 was significantly elevated in the gut epithelium of symptomatic AD mice, and this was colocalized with increased TLR2 expression. Enteroids, 3D-human ileal mini-gut monolayer in vitro model system also revealed increase levels of TLR2 upon stimulation with purified bacterial curli fibrils.

CONCLUSION

These findings reveal the importance of pathological changes within the gut-vagus-brain signaling in response to luminal bacterial amyloid that might play a vital role in central Aβ pathogenesis seen in the AD brain.

Intestinal Permeability, Dysbiosis, Inflammation and Enteric Glia Cells: The Intestinal Etiology of Parkinson’s Disease

The scientific and medical communities are becoming more aware of the substantial relationship between the function of the central nervous system (CNS) and the state of the gut environment. Parkinson's disease (PD) is a neurodegenerative disorder that affects the nigrostriatal pathway in the midbrain, presenting not only motor symptoms but also various non-motor manifestations, including neuropsychiatric symptoms and gastrointestinal (GI) symptoms. Over time, our knowledge of PD has progressed from the detection of midbrain dopaminergic deficits to the identification of a multifaceted disease with a variety of central and peripheral manifestations, with increased attention to the intestinal tract. Accumulating evidence has revealed that intestinal disorders are not only the peripheral consequence of PD pathogenesis, but also the possible pathological initiator decades before it progresses to the CNS. Here, we summarized recent research findings on the involvement of the intestinal environment in PD, with an emphasis on the involvement of the intestinal barrier, microbiome and its metabolites, inflammation, and enteric glial cells

Salmonella enterica serovar Enteritidis biofilm lifestyle induces lower pathogenicity and reduces inflammatory response in a murine model compared to planktonic bacteria

Salmonellaenterica serovar Enteritidis (S. Enteritidis) is the most frequent serovar involved in human salmonellosis. It has been demonstrated that about 80% of infections are related to biofilm formation. There is scant information about the pathogenicity of S. Enteritidis and its relationship to biofilm production. In this regard, this study aimed to investigate the differential host response induced by S. Enteritidis biofilm and planktonic lifestyle. To this purpose, biofilm and planktonic bacteria were inoculated to BALB/c mice and epithelial cell culture. Survival studies revealed that biofilm is less virulent than planktonic cells. Reduced signs of intestinal inflammation and lower bacterial translocation were observed in animals inoculated with Salmonella biofilm compared to the planktonic group. Results showed that Salmonella biofilm was impaired for invasion of non-phagocytic cells and induces a lower inflammatory response in vivo and in vitro compared to that of planktonic bacteria. Taken together, the outcome of Salmonella-host interaction varies depending on the bacterial lifestyle.

Shigella flexneri Diguanylate Cyclases Regulate Virulence

Shigella flexneri is an intracellular human pathogen that invades colonic cells and causes bloody diarrhea. S. flexneri evolved from commensal Escherichia coli, and genome comparisons reveal that S. flexneri has lost approximately 20% of its genes through the process of pathoadaptation, including a disproportionate number of genes associated with the turnover of the nucleotide-based second messenger cyclic di-GMP (c-di-GMP); however, the remaining c-di-GMP turnover enzymes are highly conserved. c-di-GMP regulates many behavioral changes in other bacteria in response to changing environmental conditions, including biofilm formation, but this signaling system has not been examined in S. flexneri. In this study, we expressed VCA0956, a constitutively active c-di-GMP synthesizing diguanylate cyclase (DGC) from Vibrio cholerae, in S. flexneri to determine if virulence phenotypes were regulated by c-di-GMP. We found that expressing VCA0956 in S. flexneri increased c-di-GMP levels, and this corresponds with increased biofilm formation and reduced acid resistance, host cell invasion, and plaque size. We examined the impact of VCA0956 expression on the S. flexneri transcriptome and found that genes related to acid resistance were repressed, and this corresponded with decreased survival to acid shock. We also found that individual S. flexneri DGC mutants exhibit reduced biofilm formation and reduced host cell invasion and plaque size, as well as increased resistance to acid shock. This study highlights the importance of c-di-GMP signaling in regulating S. flexneri virulence phenotypes. IMPORTANCE The intracellular human pathogen Shigella causes dysentery, resulting in as many as one million deaths per year. Currently, there is no approved vaccine for the prevention of shigellosis, and the incidence of antimicrobial resistance among Shigella species is on the rise. Here, we explored how the widely conserved c-di-GMP bacterial signaling system alters Shigella behaviors associated with pathogenesis. We found that expressing or removing enzymes associated with c-di-GMP synthesis results in changes in Shigella's ability to form biofilms, invade host cells, form lesions in host cell monolayers, and resist acid stress.

Microbiota in Health and Disease-Potential Clinical Applications

Within the last two decades tremendous efforts in biomedicine have been undertaken to understand the interplay of commensal bacteria living in and on our human body with our own human physiology. It became clear that (1) a high diversity especially of the microbial communities in the gut are important to preserve health and that (2) certain bacteria via nutrition-microbe-host metabolic axes are beneficially affecting various functions of the host, including metabolic control, energy balance and immune function. While a large set of evidence indicate a special role for small chain fatty acids (SCFA) in that context, recently also metabolites of amino acids (e.g., tryptophan and arginine) moved into scientific attention. Of interest, microbiome alterations are not only important in nutrition associated diseases like obesity and diabetes, but also in many chronic inflammatory, oncological and neurological abnormalities. From a clinician’s point of view, it should be mentioned, that the microbiome is not only interesting to develop novel therapies, but also as a modifiable factor to improve efficiency of modern pharmaceutics, e.g., immune-therapeutics in oncology. However, so far, most data rely on animal experiments or human association studies, whereas controlled clinical intervention studies are spare. Hence, the translation of the knowledge of the last decades into clinical routine will be the challenge of microbiome based biomedical research for the next years. This review aims to provide examples for future clinical applications in various entities and to suggest bacterial species and/or microbial effector molecules as potential targets for intervention studies.

Effect of Essential Oils on the Inhibition of Biofilm and Quorum Sensing in Salmonella enteritidis 13076 and Salmonella typhimurium 14028

The emergence of multidrug-resistant microorganisms represents a global challenge that has led to a search for new antimicrobial compounds. Essential oils (EOs) from medicinal aromatic plants are a potential alternative for conventional antibiotics. In this study, the antimicrobial and anti-biofilm potential of 15 EOs was evaluated on planktonic and biofilm-associated cells of Salmonella enterica serovar Enteritidis ATCC 13076 (S. enteritidis) and Salmonella enterica serovar Typhimurium ATCC 14028 (S. typhimurium). In total, 4 out of 15 EOs showed antimicrobial activity and 6 EOs showed anti-biofilm activity against both strains. The EO from the Lippia origanoides chemotype thymol-carvacrol II (LTC II) presented the lowest minimum inhibitory concentration (MIC₅₀ = 0.37 mg mL^-1) and minimum bactericidal concentration (MBC = 0.75 mg mL^-1) values. This EO also presented the highest percentage of biofilm inhibition (>65%) on both microorganisms, which could be confirmed by scanning electron microscopy (SEM) images. Transcriptional analysis showed significant changes in the expression of the genes related to quorum sensing and the formation of the biofilm. EOs could inhibit the expression of genes involved in the quorum sensing mechanism (luxR, luxS, qseB, sdiA) and biofilm formation (csgA, csgB,&nbsp;csgD, flhD, fliZ, and motB), indicating their potential use as anti-biofilm antimicrobial agents. However, further studies are needed to elucidate the action mechanisms of essential oils on the bacterial cells under study.

Structural and Functional Insights into α-Synuclein Fibril Polymorphism

Abnormal accumulation of aggregated α-synuclein (α-Syn) is seen in a variety of neurodegenerative diseases, including Parkinson's disease (PD), multiple system atrophy (MSA), dementia with Lewy body (DLB), Parkinson's disease dementia (PDD), and even subsets of Alzheimer's disease (AD) showing Lewy-body-like pathology. These synucleinopathies exhibit differences in their clinical and pathological representations, reminiscent of prion disorders. Emerging evidence suggests that α-Syn self-assembles and polymerizes into conformationally diverse polymorphs in vitro and in vivo, similar to prions. These α-Syn polymorphs arising from the same precursor protein may exhibit strain-specific biochemical properties and the ability to induce distinct pathological phenotypes upon their inoculation in animal models. In this review, we discuss clinical and pathological variability in synucleinopathies and several aspects of α-Syn fibril polymorphism, including the existence of high-resolution molecular structures and brain-derived strains. The current review sheds light on the recent advances in delineating the structure-pathogenic relationship of α-Syn and how diverse α-Syn molecular polymorphs contribute to the existing clinical heterogeneity in synucleinopathies.

Bacterial Biofilms and Their Implications in Pathogenesis and Food Safety

Biofilm formation is an integral part of the microbial life cycle in nature. In food processing environments, bacterial transmissions occur primarily through raw or undercooked foods and by cross-contamination during unsanitary food preparation practices. Foodborne pathogens form biofilms as a survival strategy in various unfavorable environments, which also become a frequent source of recurrent contamination and outbreaks of foodborne illness. Instead of focusing on bacterial biofilm formation and their pathogenicity individually, this review discusses on a molecular level how these two physiological processes are connected in several common foodborne pathogens such as Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica and Escherichia coli. In addition, biofilm formation by Pseudomonas aeruginosa is discussed because it aids the persistence of many foodborne pathogens forming polymicrobial biofilms on food contact surfaces, thus significantly elevating food safety and public health concerns. Furthermore, in-depth analyses of several bacterial molecules with dual functions in biofilm formation and pathogenicity are highlighted.

The neuromicrobiology of Parkinson's disease: A unifying theory

Recent evidence confirms that PD is indeed a multifactorial disease with different aetiologies and prodromal symptomatology that likely depend on the initial trigger. New players with important roles as triggers, facilitators and aggravators of the PD neurodegenerative process have re-emerged in the last few years, the microbes. Having evolved in association with humans for ages, microbes and their products are now seen as fundamental regulators of human physiology with disturbances in their balance being increasingly accepted to have a relevant impact on the progression of disease in general and on PD in particular. In this review, we comprehensively address early studies that have directly or indirectly linked bacteria or other infectious agents to the onset and progression of PD, from the earliest suspects to the most recent culprits, the gut microbiota. The quest for effective treatments to arrest PD progression must inevitably address the different interactions between microbiota and human cells, and naturally consider the gut-brain axis. The comprehensive characterization of such mechanisms will help design innovative bacteriotherapeutic approaches to selectively shape the gut microbiota profile ultimately to halt PD progression. The present review describes our current understanding of the role of microorganisms and their endosymbiotic relatives, the mitochondria, in inducing, facilitating, or aggravating PD pathogenesis.

Preventing Biofilm Formation and Development on Ear, Nose and Throat Medical Devices

Otorhinolaryngology is a vast domain that requires the aid of many resources for optimal performance. The medical devices utilized in this branch share common problems, such as the formation of biofilms. These structured communities of microbes encased in a 3D matrix can develop antimicrobial resistance (AMR), thus making it a problem with challenging solutions. Therefore, it is of concern the introduction in the medical practice involving biomaterials for ear, nose and throat (ENT) devices, such as implants for the trachea (stents), ear (cochlear implants), and voice recovery (voice prosthetics). The surface of these materials must be biocompatible and limit the development of biofilm while still promoting regeneration. In this respect, several surface modification techniques and functionalization procedures can be utilized to facilitate the success of the implants and ensure a long time of use. On this note, this review provides information on the intricate underlying mechanisms of biofilm formation, the large specter of implants and prosthetics that are susceptible to microbial colonization and subsequently related infections. Specifically, the discussion is particularized on biofilm development on ENT devices, ways to reduce it, and recent approaches that have emerged in this field.

Molecular Communication Between Neuronal Networks and Intestinal Epithelial Cells in Gut Inflammation and Parkinson's Disease

Intestinal symptoms, such as nausea, vomiting, and constipation, are common in Parkinson's disease patients. These clinical signs normally appear years before the diagnosis of the neurodegenerative disease, preceding the occurrence of motor manifestations. Moreover, it is postulated that Parkinson's disease might originate in the gut, due to a response against the intestinal microbiota leading to alterations in alpha-synuclein in the intestinal autonomic nervous system. Transmission of this protein to the central nervous system is mediated potentially via the vagus nerve. Thus, deposition of aggregated alpha-synuclein in the gastrointestinal tract has been suggested as a potential prodromal diagnostic marker for Parkinson's disease. Interestingly, hallmarks of chronic intestinal inflammation in inflammatory bowel disease, such as dysbiosis and increased intestinal permeability, are also observed in Parkinson's disease patients. Additionally, alpha-synuclein accumulations were detected in the gut of Crohn's disease patients. Despite a solid association between neurodegenerative diseases and gut inflammation, it is not clear whether intestinal alterations represent cause or consequence of neuroinflammation in the central nervous system. In this review, we summarize the bidirectional communication between the brain and the gut in the context of Parkinson's disease and intestinal dysfunction/inflammation as present in inflammatory bowel disease. Further, we focus on the contribution of intestinal epithelium, the communication between intestinal epithelial cells, microbiota, immune and neuronal cells, as well as mechanisms causing alterations of epithelial integrity.

Potential strategies to prevent encrustations on urinary stents and catheters - thinking outside the box: a European network of multidisciplinary research to improve urinary stents (ENIUS) initiative

Introduction: Urinary stents have been around for the last 4 decades, urinary catheters even longer. They are associated with infections, encrustation, migration, and patient discomfort. Research efforts to improve them have shifted onto molecular and cellular levels. ENIUS brought together translational scientists to improve urinary implants and reduce morbidity.Methods & materials: A working group within the ENIUS network was tasked with assessing future research lines for the improvement of urinary implants.Topics were researched systematically using Embase and PubMed databases. Clinicaltrials.gov was consulted for ongoing trials.Areas covered: Relevant topics were coatings with antibodies, enzymes, biomimetics, bioactive nano-coats, antisense molecules, and engineered tissue. Further, pH sensors, biodegradable metals, bactericidal bacteriophages, nonpathogenic uropathogens, enhanced ureteric peristalsis, electrical charges, and ultrasound to prevent stent encrustations were addressed.Expert opinion: All research lines addressed in this paper seem viable and promising. Some of them have been around for decades but are yet to proceed to clinical application (i.e. tissue engineering). Others are very recent and, at least in urology, still only conceptual (i.e. antisense molecules). Perhaps the most important learning point resulting from this pan-European multidisciplinary effort is that collaboration between all stakeholders is not only fruitful but also truly essential.

Sulfate Import in Salmonella Typhimurium Impacts Bacterial Aggregation and the Respiratory Burst in Human Neutrophils

During enteric salmonellosis, neutrophil-generated reactive oxygen species alter the gut microenvironment, favoring survival of Salmonella Typhimurium. While type 3 secretion system 1 (T3SS-1) and flagellar motility are potent Salmonella Typhimurium agonists of the neutrophil respiratory burst in vitro, neither of these pathways alone is responsible for stimulation of a maximal respiratory burst. To identify Salmonella Typhimurium genes that impact the magnitude of the neutrophil respiratory burst, we performed a two-step screen of defined mutant libraries in coculture with human neutrophils. We first screened Salmonella Typhimurium mutants lacking defined genomic regions and then tested single-gene deletion mutants representing particular regions under selection. A subset of single-gene deletion mutants was selected for further investigation. Mutants in four genes, STM1696 (sapF), STM2201 (yeiE), STM2112 (wcaD), and STM2441 (cysA), induced an attenuated respiratory burst. We linked the altered respiratory burst to reduced T3SS-1 expression and/or altered flagellar motility for two mutants (ΔSTM1696 and ΔSTM2201). The ΔSTM2441 mutant, defective for sulfate transport, formed aggregates in minimal medium and adhered to surfaces in rich medium, suggesting a role for sulfur homeostasis in the regulation of aggregation/adherence. We linked the aggregation/adherence phenotype of the ΔSTM2441 mutant to biofilm-associated protein A and flagellins and hypothesize that aggregation caused the observed reduction in the magnitude of the neutrophil respiratory burst. Our data demonstrate that Salmonella Typhimurium has numerous mechanisms to limit the magnitude of the neutrophil respiratory burst. These data further inform our understanding of how Salmonella may alter human neutrophil antimicrobial defenses.