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Food Science and Biotechnology Dec 2023Probiotics are living microorganisms that are beneficial to the host, enhancing the immune response by promoting antibody production, regulating cytokine secretion, and... (Review)
Review
Probiotics are living microorganisms that are beneficial to the host, enhancing the immune response by promoting antibody production, regulating cytokine secretion, and stimulating T cells. However, probiotics have limitations in that they require viability control and have a short shelf life. Recently, the use of paraprobiotics has gained attention. These include dead bacterial cells, bacterial fractions, and cell lysate that have health benefits and are stable and safe for use. Paraprobiotics comprise molecules of bacterial cell wall compounds, such as peptidoglycans, teichoic acids, polysaccharides, and cell surface proteins. Paraprobiotics are manufactured by a diverse range of techniques, including thermal treatments, high pressure, ultraviolet rays, sonication, ionizing radiation, and pH modification. Their beneficial health effects include immunomodulatory, intestinal balancing, anticancer, and antimicrobial activities. Therefore, this review summarizes and discusses the manufacturing methods and bioavailability of paraprobiotics and suggests their potential health advantages.
PubMed: 37860741
DOI: 10.1007/s10068-023-01378-y -
Cytokine & Growth Factor Reviews Jun 2024Pyroptosis, a programmed cell death process, is vital for the immune response against microbial infections and internal danger signals. Recent studies have highlighted... (Review)
Review
Pyroptosis, a programmed cell death process, is vital for the immune response against microbial infections and internal danger signals. Recent studies have highlighted the importance of protein palmitoylation, a modification that involves attaching palmitate to cysteine residues, in regulating key proteins involved in pyroptosis. Palmitoylation of cGAS at residue C474 by ZDHHC18 affects its enzymatic activity and DNA binding ability. Similarly, ZDHHC9 promotes cGAS activity through palmitoylation at residues C404/405. NLRP3 palmitoylation at residue C844, mediated by ZDHHC12, impacts its stability and interactions with other proteins, crucial for activating the NLRP3 inflammasome and triggering inflammation. However, the role of ZDHHC5 in NLRP3 palmitoylation remains uncertain due to conflicting findings. Palmitoylation at C88/91 is essential for STING activation and induction of type I interferons. It modulates the formation of multimeric complexes and downstream signaling pathways. GSDMD palmitoylation at C191 is necessary for pore formation and membrane translocation, while GSDME palmitoylation at C407/408 is associated with drug-induced pyroptosis. Moreover, palmitoylation of NOD1 and NOD2 influences their membrane recruitment and immune signaling pathways in response to bacterial peptidoglycans, acting as upstream regulators of pyroptosis. This review summarizes the important roles for palmitoylation in regulating the function of key pyroptosis-related proteins, shedding light on the intricate mechanisms governing immune responses and inflammation.
Topics: Humans; Pyroptosis; Animals; Lipoylation; NLR Family, Pyrin Domain-Containing 3 Protein; Signal Transduction; Inflammasomes; Membrane Proteins; Nucleotidyltransferases; Inflammation; Acyltransferases
PubMed: 38472042
DOI: 10.1016/j.cytogfr.2024.03.001 -
ELife Apr 2024An enzyme that remodels the cell wall of helps these gut bacteria to divide and generate peptide fragments that enhance the immune response against cancer.
An enzyme that remodels the cell wall of helps these gut bacteria to divide and generate peptide fragments that enhance the immune response against cancer.
PubMed: 38578679
DOI: 10.7554/eLife.97277 -
Proceedings of the National Academy of... Aug 2023The cell envelope of Gram-negative bacteria consists of three distinct layers: the cytoplasmic membrane, a cell wall made of peptidoglycan (PG), and an asymmetric outer...
The cell envelope of Gram-negative bacteria consists of three distinct layers: the cytoplasmic membrane, a cell wall made of peptidoglycan (PG), and an asymmetric outer membrane (OM) composed of phospholipid in the inner leaflet and lipopolysaccharide (LPS) glycolipid in the outer leaflet. The PG layer has long been thought to be the major structural component of the envelope protecting cells from osmotic lysis and providing them with their characteristic shape. In recent years, the OM has also been shown to be a load-bearing layer of the cell surface that fortifies cells against internal turgor pressure. However, whether the OM also plays a role in morphogenesis has remained unclear. Here, we report that changes in LPS synthesis or modification predicted to strengthen the OM can suppress the growth and shape defects of mutants with reduced activity in a conserved PG synthesis machine called the Rod complex (elongasome) that is responsible for cell elongation and shape determination. Evidence is presented that OM fortification in the shape mutants restores the ability of MreB cytoskeletal filaments to properly orient the synthesis of new cell wall material by the Rod complex. Our results are therefore consistent with a role for the OM in the propagation of rod shape during growth in addition to its well-known function as a diffusion barrier promoting the intrinsic antibiotic resistance of Gram-negative bacteria.
Topics: Lipopolysaccharides; Cell Wall; Cell Membrane; Cytoskeleton; Cell Cycle; Escherichia coli; Peptidoglycan
PubMed: 37607228
DOI: 10.1073/pnas.2301987120 -
Annual Review of Entomology Jan 2024Bacteriocytes are host cells specialized to harbor symbionts in certain insect taxa. The adaptation, development, and evolution of bacteriocytes underlie insect... (Review)
Review
Bacteriocytes are host cells specialized to harbor symbionts in certain insect taxa. The adaptation, development, and evolution of bacteriocytes underlie insect symbiosis maintenance. Bacteriocytes carry enriched host genes of insect and bacterial origin whose transcription can be regulated by microRNAs, which are involved in host-symbiont metabolic interactions. Recognition proteins of peptidoglycan, the bacterial cell wall component, and autophagy regulate symbiont abundance in bacteriocytes. Horizontally transferred genes expressed in bacteriocytes influence the metabolism of symbiont peptidoglycan, which may affect the bacteriocyte immune response against symbionts. Bacteriocytes release or transport symbionts into ovaries for symbiont vertical transmission. Bacteriocyte development and death, regulated by transcriptional factors, are variable in different insect species. The evolutionary origin of insect bacteriocytes remains unclear. Future research should elucidate bacteriocyte cell biology, the molecular interplay between bacteriocyte metabolic and immune functions, the genetic basis of bacteriocyte origin, and the coordination between bacteriocyte function and host biology in diverse symbioses.
Topics: Animals; Peptidoglycan; Hemiptera; Insecta; Bacteria; Symbiosis
PubMed: 38270981
DOI: 10.1146/annurev-ento-010323-124159 -
BioRxiv : the Preprint Server For... Sep 2023The role of the intestinal microbiota in host health is increasingly revealed in its contributions to disease states. The host-microbiome interaction is multifactorial...
The role of the intestinal microbiota in host health is increasingly revealed in its contributions to disease states. The host-microbiome interaction is multifactorial and dynamic. One of the factors that has recently been strongly associated with host physiological responses is peptidoglycan from bacterial cell walls. Peptidoglycan from gut commensal bacteria activate peptidoglycan sensors in human cells, including the Nucleotide-binding oligomerization domain containing protein 2 (NOD2). When present in the gastrointestinal tract, both the polymeric form (sacculi) and de-polymerized fragments can modulate host physiology, including checkpoint anticancer therapy efficacy, body temperature and appetite, and postnatal growth. To leverage this growing area of biology towards therapeutic prescriptions, it will be critical to directly analyze a key feature of the host-microbiome interaction from living hosts in a reproducible and non-invasive way. Here we show that metabolically labeled peptidoglycan/sacculi can be readily isolated from fecal samples collected from both mice and humans. Analysis of fecal samples provided a non-invasive route to probe the gut commensal community including the metabolic synchronicity with the host circadian clock. Together, these results pave the way for non-invasive diagnostic tools to interrogate the causal nature of peptidoglycan in host health and disease.
PubMed: 37693563
DOI: 10.1101/2023.07.21.549941 -
Microbiological Research Oct 2023Probiotics are viable microorganisms that provide beneficial health effects when consumed in adequate quantity by the host. Immunomodulation is one of the major... (Review)
Review
Probiotics are viable microorganisms that provide beneficial health effects when consumed in adequate quantity by the host. Immunomodulation is one of the major beneficial effects of probiotics that is a result of the colonization of probiotic microorganisms in the gut, their interaction with the intestinal cells, production of various metabolites and by-products. The last few years have displayed an increasing number of studies on non-viable probiotics (paraprobiotics) and microbial by-products (postbiotics) that prove beneficial to human health by providing positive immune responses even in the inactivated form. The increasing number of research studies compare the effects of viable and non-viable probiotics, their by-products, and metabolites. This review focuses on the ability of different types of paraprobiotics and postbiotics to modulate the immune system. A majority of paraprobiotics are developed from Lactobacillus and Bifidobacterium strains. The postbiotic components that modulate the biological reactions include lipoteichoic acids, bacteriocins, short-chain fatty acids, peptidoglycan, and exopolysaccharides have been reported. We have reviewed paraprobiotics and postbiotics that are commercial as well as in research. Paraprobiotics and postbiotics can be a possible replacement for live probiotics for immunocompromised people. Paraprobiotics display an active role in maintaining T-cell mediated immunity and have been shown to treat colitis. Postbiotic components exhibit properties of pro and anti-immune, anti-tumor, anti-microbial, antioxidant, and anti-biofilm. More research is required on the efficient conversion of probiotics to paraprobiotics, the isolation and purification of different postbiotics, and stability studies during the shelf life. The majority of the articles report the effects of direct ingestion of different '-biotics' without blending in any food product.
PubMed: 37454427
DOI: 10.1016/j.micres.2023.127449 -
Sleep Advances : a Journal of the Sleep... 2023Herein the major accomplishments, trials and tribulations, and epiphanies experienced by James M. Krueger over the course of his career in sleep research are presented....
Herein the major accomplishments, trials and tribulations, and epiphanies experienced by James M. Krueger over the course of his career in sleep research are presented. They include the characterization of a) the supranormal EEG delta waves occurring during NREMS post sleep loss, b) Factor S as a muramyl peptide, c) the physiological roles of cytokines in sleep regulation, d) multiple other sleep regulatory substances, e) the dramatic changes in sleep over the course of infectious diseases, and f) sleep initiation within small neuronal/glial networks. The theory that the preservation of brain plasticity is the primordial sleep function is briefly discussed. These accomplishments resulted from collaborations with many outstanding scientists including James M. Krueger's mentors (John Pappenheimer and Manfred Karnovsky) and collaborators later in life, including Charles Dinarello, Louis Chedid, Mark Opp, Ferenc Obal jr., Dave Rector, Ping Taishi, Linda Toth, Jeannine Majde, Levente Kapas, Eva Szentirmai, Jidong Fang, Chris Davis, Sandip Roy, Tetsuya Kushikata, Fabio Garcia-Garcia, Ilia Karatsoreos, Mark Zielinski, and Alok De, plus many students, e.g. Jeremy Alt, Kathryn Jewett, Erika English, and Victor Leyva-Grado.
PubMed: 37954093
DOI: 10.1093/sleepadvances/zpad039 -
Current Opinion in Microbiology Apr 2024Our ability to control the growth of Gram-negative bacterial pathogens is challenged by rising antimicrobial resistance and requires new approaches. Endolysins are... (Review)
Review
Our ability to control the growth of Gram-negative bacterial pathogens is challenged by rising antimicrobial resistance and requires new approaches. Endolysins are phage-derived enzymes that degrade peptidoglycan and therefore offer potential as antimicrobial agents. However, the outer membrane (OM) of Gram-negative bacteria impedes the access of externally applied endolysins to peptidoglycan. This review highlights recent advances in the discovery and characterization of natural endolysins that can breach the OM, as well as chemical and engineering approaches that increase antimicrobial efficacy of endolysins against Gram-negative pathogens.
Topics: Anti-Bacterial Agents; Peptidoglycan; Endopeptidases; Anti-Infective Agents; Gram-Negative Bacteria; Bacteriophages
PubMed: 38350268
DOI: 10.1016/j.mib.2024.102433 -
Science Advances Jul 2023Semiconductor-based biointerfaces are typically established either on the surface of the plasma membrane or within the cytoplasm. In Gram-negative bacteria, the...
Semiconductor-based biointerfaces are typically established either on the surface of the plasma membrane or within the cytoplasm. In Gram-negative bacteria, the periplasmic space, characterized by its confinement and the presence of numerous enzymes and peptidoglycans, offers additional opportunities for biomineralization, allowing for nongenetic modulation interfaces. We demonstrate semiconductor nanocluster precipitation containing single- and multiple-metal elements within the periplasm, as observed through various electron- and x-ray-based imaging techniques. The periplasmic semiconductors are metastable and display defect-dominant fluorescent properties. Unexpectedly, the defect-rich (i.e., the low-grade) semiconductor nanoclusters produced in situ can still increase adenosine triphosphate levels and malate production when coupled with photosensitization. We expand the sustainability levels of the biohybrid system to include reducing heavy metals at the primary level, building living bioreactors at the secondary level, and creating semi-artificial photosynthesis at the tertiary level. The biomineralization-enabled periplasmic biohybrids have the potential to serve as defect-tolerant platforms for diverse sustainable applications.
Topics: Periplasm; Biomineralization; Cell Membrane; Cytoplasm; Photosynthesis
PubMed: 37478187
DOI: 10.1126/sciadv.adg5858