Biology subjects
Publications and source records attributed to Srutkova, D..
We present a novel protocol for intranasal colonization of germ-free mice with human nasal microbiota, coupled with an optimized DNA extraction method for murine nasal samples compatible with 16S rRNA sequencing. This protocol may facilitate investigation of the functional roles and causal effects of nasal microbial communities in chronic rhinosinusitis and antimicrobial resistance.
Extracellular vesicles (EVs) are key mediators of bacterial communication and adaptation to environmental stress. Their size, cargo, and surface charge are influenced by several factors, including environmental conditions, bacterial physiology, and isolation methods, and are highly strain-specific. Herein, we investigated how exposure to bile, a physiological component of the gut environment, affects the production and properties of EVs released by the probiotic strain Lactiplantibacillus plantarum NCIMB 8826. Through ultracentrifugation followed by size-exclusion chromatography (SEC), we isolated highly purified L. plantarum EVs (LpEVs) and characterized them according to the Minimal Information for Studies of Extracellular Vesicles guidelines. SEC purification significantly reduced the contents of contaminating proteins and peptidoglycans, improving the compositional purity of the isolated EVs. Compared with the parent bacteria, purified LpEVs exhibited distinct surface lipid profiles and zeta potential as well as remarkable stability across varying pH levels, elevated NaCl concentrations, and increasing detergent challenges. Under bile stress, the bacteria released larger LpEVs enriched in bile metabolism-related proteins, suggesting vesicle-mediated adaptation. Fourier-transform infrared spectroscopy further revealed bile-induced molecular alterations in LpEVs that differed from those in the parent bacteria. These findings highlight bacterial EVs as dynamic environmental communicators that respond to stress and may modulate host-microbe interactions before detectable changes occur in the bacterial cells.
Chronic inflammatory and metabolic diseases are major global health issues increasingly linked to dietary factors. Consumption of dietary emulsifiers like polysorbate-80 (p80), common in ultra-processed foods and pharmaceuticals, has raised concerns about gut health. RNA sequencing on intestinal epithelial cells (IECs) exposed to p80 revealed increased expression of ferroptosis-associated genes and disruption of lipid metabolism pathways further demonstrated by mitochondrial dysfunction, including altered membrane potential and architecture, and accumulation of reactive oxygen species, iron, lipid peroxidation, and lipid droplet formation. Lipidomic profiling identified significant alterations in triglyceride species and elevated pro-ferroptotic polyunsaturated fatty acids. These data indicate that p80 disrupts lipid homeostasis in IECs and triggers ferroptotic cell death, mechanisms potentially contributing to the increased incidence of chronic conditions like inflammatory bowel disease and metabolic syndrome. The study highlights critical implications for public health, emphasizing the need for reassessment of emulsifier safety standards while balancing needs with consumer safety.
Allergies have become a growing problem and the number of cases is increasing yearly. Administration of postbiotics, well-defined bacterial molecules, is gaining attention as a novel and promising strategy to ameliorate the allergic burden. The BAP1 polysaccharide (PS) of Bifidobacterium adolescentis CCDM 368, was previously characterized by us regarding its structure and in vitro immunomodulatory properties. Here, to decipher the effect of BAP1 on immune system development, it was intranasally (i.n.) administered to germ-free mice. We observed increased IgA in bronchoalveolar lavage (BAL) fluid, decreased CCL2 production, and higher Rorc gene expression in the lung. The intranasal administration of BAP1 reduced lung inflammation and decreased eosinophils numbers in BAL in the ovalbumin-induced allergy mouse model. Moreover, BAP1 decreased OVA-specific IgE levels in sera and Th2-related cytokines in OVA-stimulated splenocytes and lung cells. Finally, increased Rorc and inhibited Il10 gene expression were observed in lung tissue indicating their possible role in BAP1 function. Our findings support and expand on our previous in vitro and ex vivo studies by demonstrating that BAP1, with a unique chemical structure, induces a specific immunomodulatory effect in the host and could be potentially used for alleviating allergic diseases. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=126 SRC="FIGDIR/small/613063v1_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@16e1d1eorg.highwire.dtl.DTLVardef@39dbe0org.highwire.dtl.DTLVardef@928dd0org.highwire.dtl.DTLVardef@19c8a60_HPS_FORMAT_FIGEXP M_FIG C_FIG
The expression of MHCII by intestinal epithelial cells (IEC) determines the severity of intestinal immunopathological reactions. However, the function of MHCII on IEC under homeostatic conditions remains elusive. Here we report that MHCII expression on IECs is a hallmark of an adaptive wave of homeostatic intestinal immune responses to commensal segmented filamentous bacteria (SFB). Focusing on SFB-driven responses, we describe the expression pattern of MHCII and the associated antigen processing machinery among IEC subpopulations along with the cellular network that regulates MHCII induction. Furthermore, we show that SFB induce the accumulation of SFB-specific intraepithelial lymphocytes (IELs) that originate from conventional CD4+ T-cells. Importantly, induced IELs are dependent on the epithelial MHCII. Finally, we demonstrate that both epithelial MHCII and the IEL functionality regulate the epithelial turnover. This study describes the organization of a commensal-targeted, IEL-driven immune response that is controlled by IEC antigen presentation and ultimately regulates IEC turnover.
Animals form complex symbiotic associations with their gut microbes, whose evolution is determined by an intricate network of host and environmental factors. In many insects, such as Drosophila melanogaster, the microbiome is flexible, environmentally determined and less diverse than in mammals. In contrast, mammals maintain complex multispecies consortia that are able to colonize and persist in the gastrointestinal tract. Understanding the evolutionary and ecological dynamics of gut microbes in different hosts is challenging. This requires disentangling the ecological factors of selection, determining the timescales over which evolution occurs, and elucidating the architecture of such evolutionary patterns. Here, we employ experimental evolution to track the pace of the evolution of a common gut commensal, Lactiplantibacillus plantarum, within invertebrate (Drosophila melanogaster) and vertebrate (Mus musculus) hosts and their respective diets. While the symbiosis between Drosophila and L. plantarum is mainly determined by host diet, with the host influencing the fitness of its gut microbes only over short timescales, bacterial evolution within the mammalian host follows a divergent evolutionary path. Here, the host and its intrinsic factors play a critical role in selection and influence both the phenotypic and genomic evolution of its gut microbes, as well as the outcome of their symbiosis.
BackgroundMucosal mast cells (MC) are key players in IgE-mediated food allergy (FA). The evidence on the interaction between gut microbiota, MC and susceptibility to FA is contradictory.\n\nObjectiveWe tested the hypothesis that commensal bacteria are essential for MC migration to the gut and their maturation impacting the susceptibility to FA.\n\nMethodsThe development and severity of FA symptoms was studied in sensitized germ-free (GF), conventional (CV) and mice mono-colonized with L. plantarum WCFS1 or co-housed with CV mice. MC were phenotypically and functionally characterized.\n\nResultsSystemic sensitization and oral challenge of GF mice with ovalbumin led to increased levels of specific IgE in serum compared to CV mice. Remarkably, despite the high levels of sensitization, GF mice did not develop diarrhea or anaphylactic hypothermia, common symptoms of FA. In the gut, GF mice expressed low levels of the MC tissue-homing markers CXCL1 and CXCL2 and harbored fewer MC which exhibited lower levels of MC protease-1 after challenge. Additionally, MC in GF mice were less mature as confirmed by flow-cytometry and reduced edema formation after injection of degranulation-provoking compound 48/80. Co-housing of GF mice with CV mice fully restored their susceptibility to develop FA. However, this did not occur when GF mice were mono-colonized with L. plantarum.\n\nConclusionOur results demonstrate that microbiota-induced maturation and gut-homing of MC is a critical step for the development of symptoms of experimental FA. This new mechanistic insight into microbiota-MC-FA axis can be exploited in the prevention and treatment of FA in humans.