Metabolites Of Bacteria Research Articles

Marine Bacteria: A Source of Novel Bioactive Natural Products.

Marine natural products have great pharmacological potential due to their unique and diverse chemical structures. The marine bacterial biodiversity and the unique marine environment lead to a high level of complexity and ecological interaction among marine species. This results in the production of metabolic pathways and adaptation mechanisms that are different from those of terrestrial organisms, which has drawn significant attention from researchers in the field of natural medicine. This review provides an analysis of the distribution and frequency of keywords in the literature on marine bacterial natural products as well as an overview of the new natural products isolated from the secondary metabolites of marine bacteria in recent years. Finally, it discusses the current research hotspots in this field and speculates on future directions and limitations.

Lactobacillus reuteri metabolites alleviate apple replant disease (ARD) by driving beneficial bacteria to reshape the core root microbiome

Previous studies have shown that the bacterial fertilizer Lactobacillus reuteri (LBR) significantly alleviates apple replant disease (ARD), but the mechanism behind its effectiveness remains unclear. This study investigated the effects of key LBR metabolites on the rhizosphere microbial community. The biocontrol function of extracellular polysaccharides (EPS) was examined and shown to be further enhanced after optimizing the fermentation conditions. The optimized fermentation conditions were found to generate intermediates involved in various plant metabolic pathways, leading to plant growth promotion, increased abundance of beneficial bacteria like Bacillus and Pseudomonas in the rhizosphere soil, and decreased abundance of pathogenic fungi. Through the isolation and identification of rhizosphere microorganisms, a strain of Pseudomonas monteilii with chemotaxis to EPS was isolated, which had growth promotion ability and effectively improved plant resistance and relieves ARD. To further understand the mechanism underlying the inhibitory effect on soil pathogens of microbial aggregations and development in the rhizosphere driven by beneficial bacteria metabolites. These findings offer valuable technical insights for utilizing biocontrol bacteria metabolites in ARD management.

The Effects of Agaro-Oligosaccharides Produced by Marine Bacteria (Rheinheimera sp. (HY)) Possessing Agarose-Degrading Enzymes on Myotube Function.

Agarase and its metabolites are reported to have applications in a variety of fields, but there have been few studies of the effects of agaro-oligosaccharide hydrolysate on muscle function. In this study, we analyzed the functionality of agarase and its metabolites in bacteria isolated from seawater. A bacterium with agar-degrading activity was isolated from Shimabara, Nagasaki, Japan. Through 16S rRNA sequence alignment, it was identified as being closely related to Rheinheimera sp. WMF-1 and was provisionally named Rheinheimera sp. (HY). Crude enzymes derived from this bacterium demonstrated an ability to hydrolyze various polysaccharides, including agar, agarose, and starch, with the highest specificity observed for agarose. The optimum pH and temperature were pH 10 and 50 °C. A glycoside bond specificity analysis of enzymatic activity indicated the cleavage of the α-linkage. Next, we investigated the functional effects of agaro-oligosaccharides on C2C12 myotubes. Treatment with 10-30 kDa oligosaccharides significantly increased the hypertrophy rate, diameter, and expression of myosin heavy-chain genes in C2C12 myotubes. These results indicate that the agaro-oligosaccharides produced by the enzymes identified in this study improve muscle mass, suggesting their potential contribution to muscle function.

High-throughput ecological interaction mapping of dairy microorganisms

To engineer efficient microbial management strategies in the food industry, a comprehensive understanding of microbial interactions is crucial. Microorganisms live in communities where they influence each other in several ways. Although much attention has been paid to the production of antagonistic metabolites in lactic acid bacteria (LAB), research that accounts for the complexity of their ecological interactions and their dynamics remains limited. This study explores binary interactions within a mock community of 94 strains, including 23 LAB from culture collections and 71 isolated from dairy products. Using a colony-picking robot and image analysis, bidirectional interactions were measured at high throughput on solid media, where one test strain was challenged against other mock community members as the target strains. Assays of 15 test strains (14 LAB and one yeast) yielded 1,142 bidirectionally mapped interactions, classified by ecological type over seven days. The results showed variation in the strength, directionality, and type of interactions depending on the origin of the target strains. Cooperation rates increased for strains isolated from raw milk to pasteurized milk and cheese, while exploitation was more common in raw milk strains. Cooperating strains also exhibited more similar ecological behaviors than competing strains, suggesting the presence of microbial cliques. Interestingly, Lactococcus cremoris ATCC 19257 developed pink-red pigmentation when co-cultured with Pseudomonas aeruginosa. Overall, these findings present an unprecedented exploratory data set that significantly improves our understanding of microbial interactions at the system level, with potential applications in strain selection for food processes such as fermentation, bioprotection, and probiotics.

Mechanistic understanding of the biochar-induced inhibition of growth and soil phosphorus solubilization by Bacillus megaterium

Due to the complex composition of biochar and the potential interactions between the components that jointly make up biochar, previous studies have always shown controversial results regarding impacts of biochar on soil phosphorus (P) solubilization. Using a nested experimental design, this study investigated the effects of different components of biochar, i.e. whole biochar (BC), dissolved biochar (DBC) and washed biochar (WBC) on the microbial-mediated P solubilizing process. The growth of Bacillus megaterium, acid/alkaline phosphatase activity, differential metabolites of bacteria and metabolic pathways were measured in treatments with biochar pyrolyzed at 200, 300, 400, 500 and 600 °C. Results showed that BC, DBC and WBC all negatively affected the growth and alkaline phosphatase activity of B. megaterium, and BC500/WBC500 and BC400/WBC400 had the greatest impacts. The negative effects of high-temperature biochar on cell proliferation were caused by persistent free radicals and included down-regulation of histidine metabolism by BC400 and interference in nucleotide metabolism by BC600. The impacts of low-temperature biochar on cell proliferation and alkaline phosphatase activity were highly related to the metal content. Using the independent action model, antagonistic effects were found between DBC and WBC on inhibiting B. megaterium growth, while these biochars had synergistic effects on inhibition of alkaline phosphatase activity. Overall, this study provides insights on how biochar adversely modulates microbial-mediated P solubilization.

Effects of Pine Pollen Polysaccharides and Sulfated Polysaccharides on Ulcerative Colitis in Mice by Regulating Th17/Treg.

This study was to investigate the effects of the polysaccharides (PPM60-III) and sulfated polysaccharides (SPPM60-III) of pine pollen on the Th17/Treg balance, inflammatory cytokines, intestinal microbiota, and metabolite distribution in 3% DSS drinking water-induced UC mice. First of all, the physiological results showed that PPM60-III and SPPM60-III could alleviate UC, which was shown by the reduction in liver Treg cells, the rebalance of Th17/Treg, and the modulation of inflammatory cytokines. In addition, the 16S rRNA results showed that PPM60-III and SPPM60-III could decrease Beijerinck and Bifidobacterium, and increase Akkermansia, Escherichia coli, and Fidobacteria. Finally, the metabonomics results showed that PPM60-III and SPPM60-III also restored purine and glycerolipid metabolism, up-regulated nicotinate and nicotinamide metabolism and caffeine metabolism to inhibit inflammation. In conclusion, PPM60-III and SPPM60-III could inhibit UC by regulating gut bacteria composition and metabolite distribution; SPPM60-III showed better anti-colitis activity.

Effects of priming duration and rhizosphere bacteria metabolite concentration on the germinability of cowpea, soybean, sesame, and okra seeds

Seed priming enhances germination and growth, which are important determinants of crop yield. This study was carried out to assess the effect of priming duration and metabolite concentration on the priming of five (5) crops using the metabolites of five (5) bacterial isolates. The crop seeds were treated in the cold-extracted metabolites of the five isolates at five (5) different priming durations (1, 2, 3, 4, and 5 h) and then in five metabolite concentrations (200, 400, 600, 800, and 1000 mg/L) of the five extracted metabolites at the optimal priming duration determined in the first experiment. Characterization of the cold-extracted metabolites was also carried out using gas-chromatography-mass spectrometry (GC-MS). Results revealed that priming cowpea and soybean seeds for longer durations (< 3 h) could hinder their growth and development. Lower concentrations were observed to be optimal for cowpea and soybean, but for sesame and okra, there was no detectable pattern with metabolite concentration. The GC-MS revealed the presence of some molecules (e.g. hexadecanoic acid) that have shown plant growth promotion potential in other studies. This study showed that seeds with large endosperms, such as those of cowpea and soybean, are more prone to the harmful effects of treatment for longer durations. Further experiments should be undertaken to isolate and purify the bioactive moieties for further studies and application.

Study on the metabolism of Xiao-Jian-Zhong-Tang in rats with chronic atrophic gastritis coupled with bioinformatics.

Xiao-Jian-Zhong-Tang (XJZT) has the effect of warming the middle and tonifying the deficiency, easing the urgency and relieving pain according to the theory of traditional Chinese medicine (TCM), and is able to treat spleen deficiency type chronic atrophic gastritis (CAG). Metabolites of TCM in cecum contents are common metabolites of intestinal bacteria and hosts, which can reflect the metabolic status in disease states. The present work was performed to study the effect of XJZT against CAG coupled with the cecal metabolites analysis and bioinformatics. A total of nine prototypical components and 144 metabolites were firstly identified in the cecum metabolites of XJZT using ultra-high performance liquid chromatography added to the quadrupole-time of flight mass spectrometry (UHPLC-Q-TOF/MS), which underwent the metabolism of oxidation, reduction, methylation, and glucuronic acid reaction Furthermore, different prototypical compounds might metabolize into identical metabolites in the presence of intestinal flora. Bioinformatics was further used to correlate these metabolites with the disease and intestinal flora. Components and targets were screened by Cytoscape, and molecular docking of key targets and core components showed good binding ability. This study provided important information for exploring the mechanism of TCM formulae.

Microbe Profile: Pseudonocardia: antibiotics for every niche.

Pseudonocardia species comprise a genus of filamentous, sporulating bacteria belonging to the phylum Actinomycetota, formerly Actinobacteria. They are found in marine and freshwater sediments and soils and associated with marine animals, insects, and plants. To date, they have mostly been studied because of their mutually beneficial symbiosis with fungus-growing ants in the tribe Attini. They have also attracted interest due to their biosynthetic capabilities, including the production of variably glycosylated polyenes and other novel antifungal compounds, and for their capacity to grow on a variety of hydrocarbons. The majority of clinically used antibiotics are derived from the specialised metabolites of filamentous actinomycete bacteria and most of these come from the genus Streptomyces. However, in the quest for novel chemistry there is increasing interest in studying other filamentous actinomycete genera, including Pseudonocardia. Here we outline the biological properties, genome size and structure and key features of the genus Pseudonocardia, namely their specialised metabolites and ecological roles.

Electro-coagulation pretreatment for improving nanofiltration membrane performance during reclamation of microplastic-contaminated secondary effluent: unexpectedly enhanced membrane fouling and mechanism analysis by MD-DFT simulation

The residue of microplastic in secondary effluent was inevitable with continuous aggravation on nanofiltration membrane fouling. Thus, this study aimed to further evaluate the applicability of electro-coagulation as pretreatment for improving the performance of a nanofiltration-oriented hybrid process during the reclamation of microplastic-contaminated secondary effluent. The electro-coagulation parameters were skillfully optimized and designed for following dynamic nanofiltration experiments. The potential influence of coagulants in different forms as well as their combined effects of microplastics on membrane fouling behaviors and pollutant rejection efficiency was distinguished. Specifically, terminal membrane permeability was reduced by 19% after 0.05 A electro-coagulation, while 0.2 A electro-coagulation almost eliminated the negative effects of microplastics. Mass transfer model analysis excluded the dominance of organic accumulation in the concentration polarization layer on membrane fouling development. Molecular dynamic (MD) simulation and egg-box model demonstrated that humic-Fe network possessed stronger bridging effects and greater porosity. This structure favored the co-deposition of other unlinked bacteria metabolites, which secretion was also facilitated by microplastics as immobilized carriers, on membrane surface. Additionally, density functional theory (DFT) calculation further confirmed that the greater demand for dehydration energy for ferric ions (1124 kcal/mol) inspired the formation of stronger humic-Fe complexes. Besides, residual microplastics in electro-coagulation effluent had different impacts on membrane rejection towards organic and inorganic pollutants, and it depended on the influenced cake-enhanced concentration polarization (CECP) by microplastic affinity with different pollutants.

Hurdle Concept and The Role of Lactic Acid Bacteria

The hurdle idea is a food preservation technique that includes building up a number of barriers to prevent microbes from growing and prolong the shelf life of perishable goods. The idea of using lactic acid bacteria (LAB), which are essential for food preservation, is one that is significant. Through a variety of processes, including fermentation, competitive exclusion, metabolite generation, biofilm formation, nutritional competition, and metabolic activity, LAB support the hurdle concept. Lactic acid bacteria (LAB) ferment glucose to produce lactic acid, which results in an acidic environment that prevents infections and spoiling germs from growing. Additionally, LAB generates antimicrobial substances such as hydrogen peroxide, organic acids, and bacteriocins, which work by competitively excluding harmful germs from growing. Furthermore, metabolites of lactic acid bacteria (LAB) such acetic acid, diacetyl, and carbon dioxide enhance the flavor of fermented foods and serve as organic preservatives. Moreover, LAB have the ability to create biofilms that shield them from antimicrobial agents and environmental stressors, increasing their survival and persistence in food matrices. By means of nutritional competition, LAB outcompetes pathogenic or spoilage bacteria in the consumption of available resources, hence restricting their growth. In addition, LAB produces enzymes and antibacterial substances, among other metabolic activities that further impede the growth of infections.

IDENTIFICATION AND DETERMINATION OF RESISTANCE TO ANTIMYCOTIC FACTORS IN YEAST CLINICAL ISOLATES DURING RESPIRATORY DISEASES

The prevalence of yeast infections has increased significantly over the past few decades, with resistance of isolated pathogens to antimicrobial agents becoming progressively more pressing. Commonly occurring pathogenic yeasts include genus Candida, with C. albicans species being the dominant in both superficial and invasive infectious processes. This report presents data on the identification and determination of antimycotic drug resistance for yeast isolates obtained from clinical material of a patient with chronic bronchitis and a patient with generalized fungal infection. As a result of genomic identification, the strain causing the generalized infection was identified as Candida utilis, confirming the literature data on its increasing prevalence, considered a rare pathogen of invasive processes, as a new dangerous pathogen. Antimycotic susceptibility testing revealed resistance of C. utilis strain to commonly used antifungal drugs such as ketoconazole, itraconazole and fluconazole, weak sensitivity to clotrimazole, nystatin and amphotericin B. The strain from a patient with chronic bronchitis was identified as C. africana, considered to be a C. albicans species. Excepting itraconazole, the strain showed varying sensitivity to the five antimycotic drugs used in the experiment. Both isolated yeast strains actively grew at elevated temperature, were able to form a capsule, hyphal sprouts and biofilms, features which distinguish potentially pathogenic Candida from saprotrophic strains. Combined antifungal therapy includes the use of probiotic preparations based on microorganisms that exhibit antagonism against fungi. The present work shows an effective inhibitory effect from secreted water-soluble metabolites of spore-forming bacteria Bacillus subtilis and Bacillus lichenformis, antiseptics “Octenisept” and “Chlorhexidine”, as well as rosemary and sandalwood oil extracts on growth activity of the studied pathogenic yeast strains and a typical control strain of C. albicans Y-583.

Lactucin reverses liver fibrosis by inhibiting TGF-β1/STAT3 signaling pathway and regulating short-chain fatty acids metabolism

TGF-β1 activation of hepatic stellate cells (HSCs), transcriptional activator 3 (Stat3) activation and short chain fatty acids (SCFAs), metabolite of intestinal bacteria, is closely associated with hepatic fibrosis. Previous studies have shown that Lactucin has significant anti-inflammatory and hepatoprotective effects; however, the mechanism of Lactucin's role in liver fibrosis associated with SCFAs remains unknown. This study was intended to investigate whether effect of Lactucin on liver fibrosis was mediated by TGF-β1/Stat3 and SCFAs. We found that Lactucin induced apoptosis in HSC-T6 cells, and inhibition of nuclear translocation of Stat3 and p-Stat3. And Smad3 and TGF-β1 protein expression was significantly inhibited, while TLR4 and Smad7 protein expression was significantly enhanced. For in vivo experiments, we demonstrated that Lactucin alleviated liver fibrosis in mice, as evidenced by a reduction in inflammatory factors, collagen deposition, liver injury and fibrosis-related factors expression, especially the expression of Smad3 and TGF-β1 proteins was significantly suppressed and Smad7 protein expression was significantly increased in the liver. In addition, the levels of acetic acid, butyric acid and valeric acid in the intestine of Lactucin-treated mice were significantly higher than those in the intestine of liver fibrosis mice. In conclusion, based on the results of in vivo and in vitro experiments, preventive mechanism of Lactucin against liver fibrosis in mice may be to improve the enterohepatic circulation by regulating the metabolites of intestinal microorganisms, acetic acid and butyric acid, and to further regulate the Stat3 and TGF-β1 signaling pathway through the "gut-liver axis" to combat liver fibrosis.

Endophytic bacterial isolate diversity in suboptimal field rice and their potential in sheath blight control

Abstract. Prihatiningsih N, Rahayuniati RF, Djatmiko HA, Lestari P, Wulansari NK, Widnyana IK, Sutanto KD. 2024. Endophytic bacterial isolate diversity in suboptimal field rice and their potential in sheath blight control. Biodiversitas 25: 3359-3367. Rice root endophytic bacteria from suboptimal fields rice are beneficial for controlling plant pathogens. The present research aimed to characterize morphology and biochemical properties, identify secondary metabolites of rice root endophytic bacteria and evaluate their potential as biocontrol for sheath blight caused by Rhizoctonia solani. The present study focused on five endophytic bacteria, specifically Bacillus sp., with white colonies, rod-shaped cells, Gram-positive characteristics, and catalase-positive. These bacteria were selected from rice root samples due to their potential as antagonists against the pathogenic fungus R. solani. The inhibition potential of endophytes against R. solani was determined by measuring the radius of the fungal colony in the presence of the endophytic bacteria isolates. Among them, NP KR4 showed the highest inhibition percentage of 46.00 ± 6.25%, which was attributed to the antibiosis mechanism causing hyphal swelling. A molecular test using the 16S rRNA gene was conducted to determine the isolates' genetic identity. Comparing the gene sequences with those in the genetic database, it was found that NP A5, NP KR4, and NP KR7 isolates were similar to B. subtilis strain 2JKP676166, although with a few base pair differences. NP A6 exhibited a close relation to B. subtilis strain YT2 HQ143571, while NP SB3 was identified as B. subtilis subsp. stercoris strain EG1265MN704551. Further analysis of the endophytic bacteria's secondary metabolites through Gas Chromatography and Mass Spectroscopy revealed the presence of alkaloids, phenols, alcohols, and fatty acids. Among the isolates, NP KR4 demonstrated the highest biocontrol effectiveness against sheath blight, with an efficacy of 58.74%. Overall, the results indicated that the rice root endophytic bacteria isolated from suboptimal fields possess multiple contemporary traits, including antifungal activity and strain-specific differences as Bacillus subtilis. These findings suggest promising prospects for developing bio-fungicide formulations to promote sustainable rice production.

Postbiotics in the Bakery Products: Applications and Nutritional Values.

In recent years, the consumption of postbiotics has gained significant attention due to their potential health benefits. However, their application in the bakery industry remains underutilized. This review focuses on recent advances in the use of postbiotics, specifically the metabolites of lactic acid bacteria, in bakery products. We provide a concise overview of the multifaceted benefits of postbiotics, including their role as natural antioxidants, antimicrobials, and preservatives, and their potential to enhance product quality, extend shelf-life, and contribute to consumer welfare. This review combines information from various sources to provide a comprehensive update on recent advances in the role of postbiotics in bakery products, subsequently discussing the concept of sourdough as a leavening agent and its role in improving the nutritional profile of bakery products. We highlighted the positive effects of postbiotics on bakery items, such as improved texture, flavor, and shelf life, as well as their potential to contribute to overall health through their antioxidant properties and their impact on gut health. Overall, this review emphasizes the promising potential of postbiotics to revolutionize the bakery industry and promote healthier and more sustainable food options. The integration of postbiotics into bakery products represents a promising frontier and offers innovative possibilities to increase product quality, reduce food waste, and improve consumer health. Further research into refining techniques to incorporate postbiotics into bakery products is essential for advancing the health benefits and eco-friendly nature of these vital food items.

Effects of priming duration and rhizosphere bacteria metabolite concentration on the germinability of cowpea, soybean, sesame, and okra seeds.

Seed priming enhances germination and growth, which are important determinants of crop yield. This study was carried out to assess the effect of priming duration and metabolite concentration on the priming of five (5) different crops, using the metabolites of five (5) bacterial isolates. The crop seeds were treated in the cold-extracted metabolites of the five isolates at five (5) different priming durations (1, 2, 3, 4, and 5 h) and then in five metabolite concentrations (200, 400, 600, 800, and 1000 mg/L) of the five extracted metabolites at the optimal priming duration determined in the first experiment. Characterization of the cold-extracted metabolites was also carried out using gas-chromatography-mass spectrometry (GC-MS). Results revealed that priming cowpea and soybean for longer durations (< 3 h) could hinder their growth and development. Lower concentrations were observed to be optimal for cowpea and soybean, but for sesame and okra, there was no detectable pattern with metabolite concentration. The GC-MS revealed the presence of some molecules (e.g. hexadecanoic acid) that have shown plant growth promotion potential in other studies. This study showed that seeds with large endosperm, such as, cowpea and soybean, are more prone to the deleterious effects of treatment for longer durations. Further experiments should be carried out to isolate and purify the bioactive moieties for further studies and onward application.

Ice nucleation active bacteria metabolites as antibiofilm agent to control Aeromonas hydrophila and Streptococcus agalactiae infections in Aquaculture

ObjectivesThe aim of this study was to quantify and identify metabolites of Ice Nucleation Active (INA) bacteria as an anti-biofilm agent against biofilms of fish pathogens such as Aeromonas hydrophila and Streptococcus agalactiae.ResultsIce nucleation active bacteria, which have the ability to catalyze ice nucleation, isolated from rainwater in previous studies, were used. All INA isolates were tested in several assays, including the antimicrobial test, which uses streptomycin as the positive control and none of the isolates were found positive in the antimicrobial test. As for the quorum quenching assay, it was found that four out of ten isolates were able to disturb the communication system in Chromobacterium violaceum wild type, which was used as the indicator bacteria. On the next assay, all ten isolates were tested for Biofilm Inhibition and Destruction and showed anti-biofilm activity with the highest percentage inhibition of 33.49% by isolate A40 against A. hydrophila and 77.26% by isolate A19 against S. agalactiae. C1 performed the highest destruction against A. hydrophila and S. agalactiae, with percentages of 32.11% and 51.88%, respectively. As for the GC-MS analysis, supernatants of INA bacteria contain bioactive compounds such as sarcosine and fatty acids, which are known to have antibiofilm activity against several biofilm-forming bacteria. Through 16s rRNA sequencing, identified bacteria are from the Pantoea, Enterobacter, and Acinetobacter genera. As for the conclusion, ice nucleation active bacteria metabolites tested showed positive results against pathogenic bacteria Aeromonas hydrophila and Streptococcus agalactiae in destructing and inhibiting biofilm growth.

Antibiosis and GC-MS of secondary metabolites of rhizosphere bacteria from Manatee foodplants in the humic freshwater ecosystem of Eniong river, Nigeria

Microorganisms are able to synthesize secondary metabolites of various structures and bioactivities. These metabolites are produced to help the organism compete successfully with other organisms in their natural habitat and adapt with changing environmental milieu. The ability of rhizosphere bacteria (Bacillus subtilis NC_000964.3 and Pseu-domonas aeruginosa NC_002516.2) isolated from the rhizospheric soil of Manatee food plants Mimosa pygra, Ipomeoa aquatica and Pistia stratoites to inhibit the growth of human pathogens (P. aeruginosa, E. coli, S. aureus and B. subtilis) was evaluated using standard methods. It was observed that the growth extracts of B. subtilis strains M5, M8 and P7 and P. aeruginosa strains I3 and M9 contained useful bioactive compound. GC-MS analysis of the cell -free methanol extract of the antibiotic producing bacterial strains was also evaluated and the results showed that their inhibitory potentials against bacterial pathogens are due to the presence of phenylethyl alcohol, 2-ethyl-4-methyl-1,3-dioxolane, bicyclo [4.2.0] octa-1,3,5-triene and 4-amino-2-methyl-5,6-dimethyl pyrimidine for B. subtilis and 3,4-dimethyl tetrahydrofuran, 4,6-dimethyl-4-hydroxy-5- heptenoic acid and 2,4-dimethyl-4-heptanol for Pseudomonas aeruginosa. These strains of rhizosphere bacteria may be exploited to produce new antibiotics.

Interplay between the Chaperone System and Gut Microbiota Dysbiosis in Systemic Lupus Erythematosus Pathogenesis: Is Molecular Mimicry the Missing Link between Those Two Factors?

Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease characterized by self-immune tolerance breakdown and the production of autoantibodies, causing the deposition of immune complexes and triggering inflammation and immune-mediated damage. SLE pathogenesis involves genetic predisposition and a combination of environmental factors. Clinical manifestations are variable, making an early diagnosis challenging. Heat shock proteins (Hsps), belonging to the chaperone system, interact with the immune system, acting as pro-inflammatory factors, autoantigens, as well as immune tolerance promoters. Increased levels of some Hsps and the production of autoantibodies against them are correlated with SLE onset and progression. The production of these autoantibodies has been attributed to molecular mimicry, occurring upon viral and bacterial infections, since they are evolutionary highly conserved. Gut microbiota dysbiosis has been associated with the occurrence and severity of SLE. Numerous findings suggest that proteins and metabolites of commensal bacteria can mimic autoantigens, inducing autoimmunity, because of molecular mimicry. Here, we propose that shared epitopes between human Hsps and those of gut commensal bacteria cause the production of anti-Hsp autoantibodies that cross-react with human molecules, contributing to SLE pathogenesis. Thus, the involvement of the chaperone system, gut microbiota dysbiosis, and molecular mimicry in SLE ought to be coordinately studied.

Fructose aggravating colon barrier dysfunction by decreasing gut bacteria metabolites indole-3-carboxaldehyde and inhibiting activation of aryl hydrocarbon receptor in vivo and in vitro

Fructose aggravating colon barrier dysfunction by decreasing gut bacteria metabolites indole-3-carboxaldehyde and inhibiting activation of aryl hydrocarbon receptor <em>in vivo</em> and <em>in vitro</em>