bims-bac4me 2024-11-03 papers

bims-bac4me

Biomed News

on Microbiome and trained immunity

Issue of 2024–11–03
twenty-one papers selected by
Chun-Chi Chang, Universitäts Spital Zürich

Interventions targeting the nasal microbiome to eradicate MRSA.
Metabolites augment oxidative stress to sensitize antibiotic-tolerant Staphylococcus aureus to fluoroquinolones.
Immune Responses to Methicillin-Resistant Staphylococcus aureus Infections and Advances in the Development of Vaccines and Immunotherapies.
Microbial dynamics and pulmonary immune responses in COVID-19 secondary bacterial pneumonia.
The deadly dance of alveolar macrophages and influenza virus.
Bacteria divide to conquer antibiotics.
Priming from within: TLR2 dependent but receptor independent activation of the mammary macrophage inflammasome by Streptococcus uberis.
Immunization with recombinant Streptococcus pneumoniae PgdA protects mice against lung invasion.
Alternations in inflammatory macrophage niche drive phenotypic and functional plasticity of Kupffer cells.
Pseudomonas aeruginosa supports the survival of Prevotella melaninogenica in a cystic fibrosis lung polymicrobial community through metabolic cross-feeding.
High-throughput Bronchus-on-a-Chip system for modeling the human bronchus.
The clinical praxis of bacteriocins as natural anti-microbial therapeutics.
Lactobacillaceae differentially impact butyrate-producing gut microbiota to drive CNS autoimmunity.
Innate memory against viruses.
PGLYRP-1 mediated intracellular peptidoglycan detection promotes mucosal protection.
Pseudomonas aeruginosa faces a fitness trade-off between mucosal colonization and antibiotic tolerance during airway infection.
Direct M2 macrophage co-culture overrides viscoelastic hydrogel mechanics to promote fibroblast activation.
Cytokines Measured in Nasal Lavage Compared to Induced Sputum in Patients with Mild Cystic Fibrosis.
A clinical study on the relationship between chronic rhinosinusitis and bronchial asthma.
A path to better practices in microbiology.
Regenerative Inflammation: The Mechanism Explained from the Perspective of Buffy-Coat Protagonism and Macrophage Polarization.

Clin Microbiol Infect. 2024 Oct 29. pii: S1198-743X(24)00504-4. [Epub ahead of print]

Interventions targeting the nasal microbiome to eradicate MRSA.

Mary T Bessesen.

   BACKGROUND: Staphylococcus aureus is an important pathogen in many sites, including bloodstream, skin and soft tissue, bone and joints. When infection is caused by methicillin resistant S. aureus (MRSA) therapy is more difficult and outcomes are less favorable. Nasal colonization is associated with increased risk for MRSA infections. The nasal microbiome may play a role in risk for nasal colonization and infection.
OBJECTIVES: To review the role of the microbiome in MRSA nasal colonization and infection.
SOURCES: Peer reviewed literature identified in a Medline search using MRSA, S. aureus, prebiotic and microbiota as search terms.
CONTENT: Reduction of S. aureus nasal colonization has been shown to reduce risk of S. aureus infections, but decolonization methods are imperfect. The role of the nasal microbiome in host defense against S. aureus colonization and infection is explored. Numerous organisms have been shown to be negatively associated with S. aureus colonization. Antimicrobial molecules produced by these organisms are an active area of research.
IMPLICATIONS: Future research should focus on development of safe and effective molecules that can inhibit S. aureus in the nasal vestibule. Damage to the diverse nasal microbiota by unnecessary antibiotics should be avoided.

Keywords:  Carrier state; Microbiota; Probiotics; Staphylococcus aureus; prebiotics

DOI:  https://doi.org/10.1016/j.cmi.2024.10.022
mBio. 2024 Oct 30. e0271424

Metabolites augment oxidative stress to sensitize antibiotic-tolerant Staphylococcus aureus to fluoroquinolones.

Jonathan I Batchelder, Andrew J Taylor, Wendy W K Mok.

  If left unchecked, infections involving antibiotic-refractory bacteria are expected to cause millions of deaths per year in the coming decades. Beyond genetically resistant bacteria, persisters, which are genetically susceptible cells that survive antibiotic doses that kill the rest of the clonal population, can potentially contribute to treatment failure and infection relapse. Stationary-phase bacterial cultures are enriched with persisters, and it has been shown that stimulating these populations with exogenous nutrients can reduce persistence to different classes of antibiotics, including topoisomerase-targeting fluoroquinolones (FQs). In this study, we show that adding glucose and amino acids to nutrient-starved Staphylococcus aureus cultures enhanced their sensitivity to FQs, including delafloxacin (Dela)-a drug that was recently approved for treating staphylococcal infections. We found that while the added nutrients increased nucleic acid synthesis, this increase was not required to sensitize S. aureus to FQs. We further demonstrate that addition of these nutrients increases membrane potential and the ability to generate harmful reactive oxygen species (ROS) during FQ treatment. Chelating iron, scavenging hydroxyl radicals, and limiting oxygenation during FQ treatment and during recovery following FQ treatment rescued nutrient-stimulated S. aureus. In all, our data suggest that while nutrient stimulation increases the activity of FQ targets in stationary-phase S. aureus, the resulting generation of ROS, presumably made possible through metabolic upregulation, is the primary driver of increased sensitivity to these drugs.IMPORTANCEStaphylococcus aureus causes many chronic and relapsing infections because of its ability to endure host immunity and antibiotic therapy. While several studies have focused on the nutrient requirements for the formation and maintenance of staphylococcal infections, the effects of the nutrient environment on bacterial responses to antibiotic treatment remain understudied. Here, we show that adding nutrients to starved S. aureus activates biosynthetic processes, including DNA synthesis, but it is the generation of harmful reactive oxidants that sensitizes S. aureus to DNA topoisomerase-targeting FQs. Our results suggest that the development of approaches aimed at perturbing metabolism and increasing oxidative stress can potentiate the bactericidal activity of FQs against antibiotic-tolerant S. aureus.

Keywords:  Staphylococcus aureus; antibiotic persistence; antibiotic stress response; fluoroquinolones; metabolism; oxidative stress

DOI:  https://doi.org/10.1128/mbio.02714-24
Vaccines (Basel). 2024 Sep 27. pii: 1106. [Epub ahead of print]12(10):

Immune Responses to Methicillin-Resistant Staphylococcus aureus Infections and Advances in the Development of Vaccines and Immunotherapies.

John Scully, Abu Salim Mustafa, Asma Hanif, Javed H Tunio, Shumaila Nida Javed Tunio.

  Staphylococcus aureus (SA) is a major bacterial pathogen and causes a wide range of clinical infections in humans leading to severe outcomes including meningitis, endocarditis, and sepsis. This literature review examines studies on host immune responses after infections with SA and methicillin-resistant Staphylococcus aureus (MRSA) and their immune evasion mechanisms. Furthermore, information about vaccines and immunotherapies against SA and MRSA is reviewed. We found promising toxoid vaccine approaches, which deserve further research. We also found support for antitoxin therapies and immunomodulating therapies as high-potential research areas. Although many promising vaccines and immunotherapy candidates have been studied in animal models, more human clinical studies are needed to confirm their long-term safety and efficacy.

Keywords:  MRSA; immune responses; immunotherapies; vaccines

DOI:  https://doi.org/10.3390/vaccines12101106
Nat Commun. 2024 Oct 29. 15(1): 9339

Microbial dynamics and pulmonary immune responses in COVID-19 secondary bacterial pneumonia.

COMET Consortium

Secondary bacterial pneumonia (2°BP) is associated with significant morbidity following respiratory viral infection, yet remains incompletely understood. In a prospective cohort of 112 critically ill adults intubated for COVID-19, we comparatively assess longitudinal airway microbiome dynamics and the pulmonary transcriptome of patients who developed 2°BP versus controls who did not. We find that 2°BP is significantly associated with both mortality and corticosteroid treatment. The pulmonary microbiome in 2°BP is characterized by increased bacterial RNA mass and dominance of culture-confirmed pathogens, detectable days prior to 2°BP clinical diagnosis, and frequently also present in nasal swabs. Assessment of the pulmonary transcriptome reveals suppressed TNFα signaling in patients with 2°BP, and sensitivity analyses suggest this finding is mediated by corticosteroid treatment. Further, we find that increased bacterial RNA mass correlates with reduced expression of innate and adaptive immunity genes in both 2°BP patients and controls. Taken together, our findings provide fresh insights into the microbial dynamics and host immune features of COVID-19-associated 2°BP, and suggest that suppressed immune signaling, potentially mediated by corticosteroid treatment, permits expansion of opportunistic bacterial pathogens.

DOI: https://doi.org/10.1038/s41467-024-53566-x
Eur Respir Rev. 2024 Oct;pii: 240132. [Epub ahead of print]33(174):

The deadly dance of alveolar macrophages and influenza virus.

Camille David, Charles Verney, Mustapha Si-Tahar, Antoine Guillon.

Influenza A virus (IAV) is one of the leading causes of respiratory infections. The lack of efficient anti-influenza therapeutics requires a better understanding of how IAV interacts with host cells. Alveolar macrophages are tissue-specific macrophages that play a critical role in lung innate immunity and homeostasis, yet their role during influenza infection remains unclear. First, our review highlights an active IAV replication within alveolar macrophages, despite an abortive viral cycle. Such infection leads to persistent alveolar macrophage inflammation and diminished phagocytic function, alongside direct mitochondrial damage and indirect metabolic shifts in the alveolar micro-environment. We also discuss the "macrophage disappearance reaction", which is a drastic reduction of the alveolar macrophage population observed after influenza infection in mice but debated in humans, with unclear underlying mechanisms. Furthermore, we explore the dual nature of alveolar macrophage responses to IAV infection, questioning whether they are deleterious or protective for the host. While IAV may exploit immuno-evasion strategies and induce alveolar macrophage alteration or depletion, this could potentially reduce excessive inflammation and allow for the replacement of more effective cells. Despite these insights, the pathophysiological role of alveolar macrophages during IAV infection in humans remains understudied, urging further exploration to unravel their precise contributions to disease progression and resolution.

DOI: https://doi.org/10.1183/16000617.0132-2024
Science. 2024 Nov;386(6721): 494-495

Bacteria divide to conquer antibiotics.

Ewan Harrison.

High-level resistance to methicillin requires a distinct form of cell division.

DOI: https://doi.org/10.1126/science.adt0042
Front Cell Infect Microbiol. 2024 ;14 1444178

Priming from within: TLR2 dependent but receptor independent activation of the mammary macrophage inflammasome by Streptococcus uberis.

Abbie Hinds, Philip Ward, Nathan Archer, James Leigh.

   Introduction: Streptococcus uberis is a member of the pyogenic cluster of Streptococcus commonly associated with intramammary infection and mastitis in dairy cattle. It is a poorly controlled globally endemic pathogen responsible for a significant cause of the disease worldwide. The ruminant mammary gland provides an atypical body niche in which immune cell surveillance occurs on both sides of the epithelial tissue. S. uberis does not cause disease in non-ruminant species and is an asymptomatic commensal in other body niches. S. uberis exploits the unusual niche of the mammary gland to initiate an innate response from bovine mammary macrophage (BMMO) present in the secretion (milk) in which it can resist the host immune responses. As a result - and unexpectedly - the host inflammatory response is a key step in the pathogenesis of S.uberis, without which colonisation is impaired. In contrast to other bacteria pathogenic to the bovine mammary gland, S. uberis does not elicit innate responses from epithelial tissues; initial recognition of infection is via macrophages within milk.
Methods: We dissected the role of the bacterial protein SUB1154 in the inflammasome pathway using ex vivo bovine mammary macrophages isolated from milk, recombinant protein expression, and a panel of inhibitors, agonists, and antagonists. We combine this with reverse-transcription quantitative real-time PCR to investigate the mechanisms underlying SUB1154-mediated priming of the immune response.
Results: Here, we show that SUB1154 is responsible for priming the NLRP3 inflammasome in macrophages found in the mammary gland. Without SUB1154, IL-1β is not produced, and we were able to restore IL-1β responses to a sub1154 deletion S. uberis mutant using recombinant SUB1154. Surprisingly, only by blocking internalisation, or the cytoplasmic TIR domain of TLR2 were we able to block SUB1154-mediated priming.
Discussion: Together, our data unifies several contrasting past studies and provides new mechanistic understanding of potential early interactions between pyogenic streptococci and the host.

Keywords:  NLRP3; Streptococcus; TLR2; inflammasome; mastitis

DOI:  https://doi.org/10.3389/fcimb.2024.1444178
Exp Biol Med (Maywood). 2024 ;249 10119

Immunization with recombinant Streptococcus pneumoniae PgdA protects mice against lung invasion.

Jiangming Xiao, Bichen Liu, Yibing Yin, Xuemei Zhang.

  Current pneumococcal vaccines, including the pneumococcal polysaccharide (PPV23) and conjugate (PCV13) vaccines, offer protection against specific serotypes but pose risks of serotype replacement that can alter the composition of the nasopharyngeal microbiota. To address this challenge, a novel strategy has been proposed to provide effective protection without disrupting the colonization of other bacterial populations. In our study, we found that subcutaneous immunization with recombinant peptidoglycan N-acetylglucosamine deacetylase A (rPgdA) elicited robust humoral and cellular immune responses, significantly reducing the invasion of Streptococcus pneumoniae in the lungs without affecting nasopharyngeal carriage. Furthermore, rPgdA antisera were shown to diminish bacterial invasion of lung epithelial cells in vitro. Notably, sera from patients with invasive pneumococcal infections exhibited higher levels of antibodies against the PgdA protein compared to sera from healthy adults, suggesting that a natural immune response to this protein occurs during infection. These results suggest a promising new target for the development of pneumococcal vaccines.

Keywords:  PgdA; Streptococcus pneumoniae; colonization; novel strategy; vaccine candidate

DOI:  https://doi.org/10.3389/ebm.2024.10119
Nat Commun. 2024 Oct 29. 15(1): 9337

Alternations in inflammatory macrophage niche drive phenotypic and functional plasticity of Kupffer cells.

Han-Ying Huang, Yan-Zhou Chen, Chuang Zhao, Xin-Nan Zheng, Kai Yu, Jia-Xing Yue, Huai-Qiang Ju, Yan-Xia Shi, Lin Tian.

Inflammatory signals lead to recruitment of circulating monocytes and induce their differentiation into pro-inflammatory macrophages. Therefore, whether blocking inflammatory monocytes can mitigate disease progression is being actively evaluated. Here, we employ multiple lineage-tracing models and show that monocyte-derived macrophages (mo-mac) are the major population of immunosuppressive, liver metastasis-associated macrophages (LMAM), while the proportion of Kupffer cells (KC) as liver-resident macrophages is diminished in metastatic nodules. Paradoxically, genetic ablation of mo-macs results in only a marginal decrease in LMAMs. Using a proliferation-recording system and a KC-tracing model in a monocyte-deficient background, we find that LMAMs can be replenished either via increased local macrophage proliferation or by promoting KC infiltration. In the latter regard, KCs undergo transient proliferation and exhibit substantial phenotypic and functional alterations through epigenetic reprogramming following the vacating of macrophage niches by monocyte depletion. Our data thus suggest that a simultaneous blockade of monocyte recruitment and macrophage proliferation may effectively target immunosuppressive myelopoiesis and reprogram the microenvironment towards an immunostimulatory state.

DOI: https://doi.org/10.1038/s41467-024-53659-7
bioRxiv. 2024 Oct 21. pii: 2024.10.21.619475. [Epub ahead of print]

Pseudomonas aeruginosa supports the survival of Prevotella melaninogenica in a cystic fibrosis lung polymicrobial community through metabolic cross-feeding.

Bassam El Hafi, Fabrice Jean-Pierre, George A O'Toole.

Cystic fibrosis (CF) is a multi-organ genetic disorder that affects more than 100,000 individuals worldwide. Chronic respiratory infections are among the hallmark complications associated with CF lung disease, and these infections are often due to polymicrobial communities that colonize the airways of persons with CF (pwCF). Such infections are a significant cause of morbidity and mortality, with studies indicating that pwCF who are co-infected with more than one organism experience more frequent pulmonary exacerbations, leading to a faster decline in lung function. Previous work established an in vitro CF-relevant polymicrobial community model composed of P. aeruginosa , S. aureus , S. sanguinis , and P. melaninogenica . P. melaninogenica cannot survive in monoculture in this model. In this study, we leverage this model to investigate the interactions between P. aeruginosa and P. melaninogenica , allowing us to understand the mechanisms by which the two microbes interact to support the growth of P. melaninogenica specifically in the context of the polymicrobial community. We demonstrate a cross-feeding mechanism whereby P. melaninogenica metabolizes mucin into short-chain fatty acids that are in turn utilized by P. aeruginosa and converted into metabolites (succinate, acetate) that are cross-fed to P. melaninogenica , supporting the survival of this anaerobe in the CF lung-relevant model.
Importance: Polymicrobial interactions impact disease outcomes in pwCF who suffer from chronic respiratory infections. Previous work established a CF-relevant polymicrobial community model that allows experimental probing of these microbial interactions to achieve a better understanding of the factors that govern the mechanisms by which CF lung microbes influence each other. In this study, we investigate the interaction between P. aeruginosa and P. melaninogenica , which are two highly prevalent and abundant CF lung microbes. We uncover a cross-feeding mechanism that requires the metabolism of mucin by P. melaninogenica to generate short-chain fatty acids that are cross-fed to P. aeruginosa , and into metabolized into metabolites which are then cross-fed back to P. melaninogenica to support the growth of this anaerobe.

DOI: https://doi.org/10.1101/2024.10.21.619475
Sci Rep. 2024 Nov 01. 14(1): 26248

High-throughput Bronchus-on-a-Chip system for modeling the human bronchus.

Akina Mori, Marjolein Vermeer, Lenie J van den Broek, Jeroen Heijmans, Arnaud Nicolas, Josse Bouwhuis, Todd Burton, Kazushi Matsumura, Kazuhiro Ohashi, Shigeaki Ito, Bart Kramer.

  Airway inflammation, a protective response in the human body, can disrupt normal organ function when chronic, as seen in chronic obstructive pulmonary disease (COPD) and asthma. Chronic bronchitis induces goblet cell hyperplasia and metaplasia, obstructing airflow. Traditional animal testing is often replaced by in vitro three-dimensional cultures of human epithelial cells to assess chronic cell responses. However, these cells are cultured horizontally, differing from the tubular structure of the human airway and failing to accurately reproduce airway stenosis. To address this, we developed the Bronchus-on-a-Chip (BoC) system. The BoC uses a novel microfluidic design in a standard laboratory plate, embedding 62 chips in one plate. Human bronchial epithelial cells were cultured against a collagen extracellular matrix for up to 35 days. Characterization included barrier integrity assays, microscopy, and histological examination. Cells successfully cultured in a tubular structure, with the apical side air-lifted. Epithelial cells differentiated into basal, ciliated, and secretory cells, mimicking human bronchial epithelium. Upon exposure to inducers of goblet cell hyperplasia and metaplasia, the BoC system showed mucus hyperproduction, replicating chronic epithelial responses. This BoC system enhances in vitro testing for bronchial inflammation, providing a more human-relevant and high-throughput method.

Keywords:  3D-reconstructed airway epithelial cells; Airway-on-a-chip; Organotypic culture

DOI:  https://doi.org/10.1038/s41598-024-77665-3
Arch Microbiol. 2024 Oct 30. 206(11): 451

The clinical praxis of bacteriocins as natural anti-microbial therapeutics.

Safura Nisar, Abdul Haseeb Shah, Ruqeya Nazir.

  In recent decades, the excessive use of antibiotics has resulted in a rise in antimicrobial drug resistance (ADR). Annually, a significant number of human lives are lost due to resistant infectious diseases, leading to around 700,000 deaths, and it is estimated that by 2050, there could be up to 10 million casualties. Apart from their possible application as preservatives in the food sector, bacteriocins are gaining acknowledgment as potential clinical treatments. Not only this, these antimicrobial peptides have revealed in modulating the host immune system producing anti-inflammatory and anti-modulatory responses. At the same time, due to the ever-increasing global threat of antibiotic resistance, bacteriocins have gained attraction among researchers due to their potential clinical applications. Bacteriocins as antimicrobial peptides, represent one of the most important natural defense mechanisms among bacterial species, particularly lactic acid bacteria (LAB), that can fight against infection-causing pathogens. In this review, we are highlighting the potential of bacteriocins as novel therapeutics for inhibiting a wide range of clinically relevant and multi-drug-resistant pathogens (MDR). We also highlight the effectiveness and potential applications of current bacteriocin treatments in combating antimicrobial resistance (AMR), thereby promoting human health.

Keywords:  Antibiotics; Antimicrobial resistance (AMR); Bacteriocins; Lactic acid bacteria; Novel therapeutics; Pathogens

DOI:  https://doi.org/10.1007/s00203-024-04152-8
Gut Microbes. 2024 Jan-Dec;16(1):16(1): 2418415

Lactobacillaceae differentially impact butyrate-producing gut microbiota to drive CNS autoimmunity.

Theresa L Montgomery, Lucinda C Toppen, Korin Eckstrom, Eamonn R Heney, Josephine J Kennedy, Matthew J Scarborough, Dimitry N Krementsov.

   BACKGROUND: Short-chain fatty acids (SCFAs), produced by the gut microbiota, are thought to exert an anti-inflammatory effect on the host immune system. The levels of SCFAs and abundance of the microbiota that produce them are depleted in multiple sclerosis (MS), an autoimmune disease of the central nervous system (CNS). The mechanisms leading to this depletion are unknown. Using experimental autoimmune encephalomyelitis (EAE) as a model for MS, we have previously shown that gut microbiomes divergent in their abundance of specific commensal Lactobacillaceae, Limosilactobacillus reuteri (L. reuteri) and Ligilactobacillus murinus (L. murinus), differentially impact CNS autoimmunity. To determine the underlying mechanisms, we employed colonization by L. reuteri and L. murinus in disparate gut microbiome configurations in vivo and in vitro, profiling their impact on gut microbiome composition and metabolism, coupled with modulation of dietary fiber in the EAE model.
RESULTS: We show that stable colonization by L. reuteri, but not L. murinus, exacerbates EAE, in conjunction with a significant remodeling of gut microbiome composition, depleting SCFA-producing microbiota, including Lachnospiraceae, Prevotellaceae, and Bifidobacterium, with a net decrease in bacterial metabolic pathways involved in butyrate production. In a minimal microbiome culture model in vitro, L. reuteri directly inhibited SCFA-producer growth and depleted butyrate. Genomic analysis of L. reuteri isolates revealed an enrichment in bacteriocins with known antimicrobial activity against SCFA-producing microbiota. Functionally, provision of excess dietary fiber, as the prebiotic substrate for SCFA production, elevated SCFA levels and abrogated the ability of L. reuteri to exacerbate EAE.
CONCLUSTIONS: Our data highlight a potential mechanism for reduced SCFAs and their producers in MS through depletion by other members of the gut microbiome, demonstrating that interactions between microbiota can impact CNS autoimmunity in a diet-dependent manner. These data suggest that therapeutic restoration of SCFA levels in MS may require not only dietary intervention, but also modulation of the gut microbiome.

Keywords:  ASF; Microbiome; SCFA; bacteriocin; butyrate; multiple sclerosis

DOI:  https://doi.org/10.1080/19490976.2024.2418415
Nat Immunol. 2024 Nov;25(11): 1979

Innate memory against viruses.

Paula Jauregui.

DOI: https://doi.org/10.1038/s41590-024-02009-2
Res Sq. 2024 Oct 14. pii: rs.3.rs-5118704. [Epub ahead of print]

PGLYRP-1 mediated intracellular peptidoglycan detection promotes mucosal protection.

Hans-Christian Reinecker, Shuyuan Chen, Rachel Putnik, Xi Li, Alka Diwaker, Marina Vasconcelos, Shuzhen Liu, Junhui Zhou, Lei Guo, Lin Xu, J Sebastian Temme, Klare Bersch, Stephen Hyland, Jianyi Yin, Ezra Burstein, Jeffrey Gildersleeve, Catherine Grimes.

Peptidoglycan recognition proteins (PGRPs or PGLYRPs) are implicated in the control of the intestinal microbiota; however, molecular requirements for peptidoglycan (PGN) binding and receptor signaling mechanisms remain poorly understood. We identified PGLYRP-1 as a receptor for the disaccharide motif of lysine N-acetylglucosamine N-acetylmuramic tripeptide (GMTriP-K) with a newly constructed PGN microarray. Surprisingly, PGLYRP-1 was required for innate immune activation of macrophages by GMTriP-K but not N-acetylglucosamine N-acetylmuramic dipeptide (GMDiP) or muramyl dipeptide (MDP). In macrophages, intracellular PGLYRP-1 complexed with NOD2 and GEF-H1, both of which were required for GMTriP-K-regulated gene expression. PGLYRP-1 localized to the endoplasmic reticulum and interacted at the Golgi with NOD2 upon GMTriP-K stimulation. PGLYRP-1 upregulation and its dependent gene expression signatures were induced in both mouse intestinal inflammation and human ulcerative colitis. Importantly, PGLYRP-1 activation by GMTriP-K resulted in innate immune activation and protection of mice from colitis. Our results show that PGLYRPs can function as intracellular PGN pattern recognition receptors for the control of host defense responses in the intestine.

DOI: https://doi.org/10.21203/rs.3.rs-5118704/v1
Nat Microbiol. 2024 Oct 25.

Pseudomonas aeruginosa faces a fitness trade-off between mucosal colonization and antibiotic tolerance during airway infection.

Lucas A Meirelles, Evangelia Vayena, Auriane Debache, Eric Schmidt, Tamara Rossy, Tania Distler, Vassily Hatzimanikatis, Alexandre Persat.

Pseudomonas aeruginosa frequently causes antibiotic-recalcitrant pneumonia, but the mechanisms driving its adaptation during human infections remain unclear. To reveal the selective pressures and adaptation strategies at the mucosal surface, here we investigated P. aeruginosa growth and antibiotic tolerance in tissue-engineered airways by transposon insertion sequencing (Tn-seq). Metabolic modelling based on Tn-seq data revealed the nutritional requirements for P. aeruginosa growth, highlighting reliance on glucose and lactate and varying requirements for amino acid biosynthesis. Tn-seq also revealed selection against biofilm formation during mucosal growth in the absence of antibiotics. Live imaging in engineered organoids showed that biofilm-dwelling cells remained sessile while colonizing the mucosal surface, limiting nutrient foraging and reduced growth. Conversely, biofilm formation increased antibiotic tolerance at the mucosal surface. Moreover, mutants with exacerbated biofilm phenotypes protected less tolerant but more cytotoxic strains, contributing to phenotypic heterogeneity. P. aeruginosa must therefore navigate conflicting physical and biological selective pressures to establish chronic infections.

DOI: https://doi.org/10.1038/s41564-024-01842-3
bioRxiv. 2024 Oct 15. pii: 2024.10.13.618034. [Epub ahead of print]

Direct M2 macrophage co-culture overrides viscoelastic hydrogel mechanics to promote fibroblast activation.

Leilani R Astrab, Mackenzie L Skelton, Steven R Caliari.

  Fibroblast activation drives fibrotic diseases such as pulmonary fibrosis. However, the complex interplay of how tissue mechanics and macrophage signals combine to influence fibroblast activation is not well understood. Here, we use hyaluronic acid hydrogels as a tunable cell culture system to mimic lung tissue stiffness and viscoelasticity. We applied this platform to investigate the influence of macrophage signaling on fibroblast activation. Fibroblasts cultured on stiff (50 kPa) hydrogels mimicking fibrotic tissue exhibit increased activation as measured by spreading as well as type I collagen and cadherin-11 expression compared to fibroblasts cultured on soft (1 kPa) viscoelastic hydrogels mimicking normal tissue. These trends were unchanged in fibroblasts cultured with macrophage-conditioned media. However, fibroblasts directly co-cultured with M2 macrophages show increased activation, even on soft viscoelastic hydrogels that normally suppress activation. Inhibition of interleukin 6 (IL6) signaling does not change activation in fibroblast-only cultures but ameliorates the pro-fibrotic effects of M2 macrophage co-culture. These results underscore the ability of direct M2 macrophage co-culture to override hydrogel viscoelasticity to promote fibroblast activation in an IL6-dependent manner. This work also highlights the utility of using hydrogels to deconstruct complex tissue microenvironments to better understand the interplay between microenvironmental mechanical and cellular cues.

Keywords:  fibrosis; hydrogels; macrophages; mechanotransduction

DOI:  https://doi.org/10.1101/2024.10.13.618034
Int J Mol Sci. 2024 Oct 15. pii: 11081. [Epub ahead of print]25(20):

Cytokines Measured in Nasal Lavage Compared to Induced Sputum in Patients with Mild Cystic Fibrosis.

Teresa Fuchs, Artemis Vasiliadis, Manuela Zlamy, Anja Siedl, Katharina Niedermayr, Dorothea Appelt, Verena Gasser, Johannes Eder, Helmut Ellemunter.

  The measurement of cytokines in induced sputum and nasal lavage (NL) samples has been performed for years in people with cystic fibrosis (CF). The aim of this study was to directly compare sputum and NL samples and interpret results based on disease severity in patients who were categorized as having mild or severe lung disease. The categorization was based primarily on structural abnormalities detected on lung computed tomography and secondarily on lung function. The serum inflammatory markers neutrophil elastase (NE), IL-1β, 2, 6, 8, 10 and 17a were measured in each sputum and NL sample. Thirty-two sample pairs from 29 patients were included in this study (13 mild, 19 severe). In the patients classified as severe, many systemic inflammatory markers as well as sputum cytokines were significantly higher compared to those in the mild patients. However, all the markers measured in the NL were higher in the mild patients (p =< 0.05 for NE, IL-6 and IL-8). In addition, many cytokines in the NL correlated negatively with those in the sputum samples. Major differences in the cytokine levels were shown although the samples were obtained at the same time in the same patient. Advanced structural lung disease was closely related to systemic and lower airway inflammation, whereas preserved lung function was associated with higher levels in the NL. We hypothesize that the main part of the immune response takes place in the nasal mucosa in patients with minor pulmonary changes. Our results suggest that inflammation must be interpreted individually depending on the compartment in which it is measured. Further research is needed to accurately understand inflammatory markers measured in NL.

Keywords:  cystic fibrosis; cytokines; induced sputum; inflammation; nasal lavage; serum

DOI:  https://doi.org/10.3390/ijms252011081
Front Med (Lausanne). 2024 ;11 1388585

A clinical study on the relationship between chronic rhinosinusitis and bronchial asthma.

Jing Kang, Hui Yong, Zhijuan Zhang, Jing Liu, Xiaoping Gao, Hui Shao, Li Hou.

   Objective: To investigate the correlation between chronic rhinosinusitis (CRS) and bronchial asthma, focusing on the CRS without nasal polyps (CRSsNP) and CRS with nasal polyps (CRSwNP), as well as their impact on lung function.
Methods: A total of 141 patients diagnosed with chronic nasal-sinus inflammation were included in this study. Clinical data, including medical histories, nasal endoscopy scores, CT scores, symptom scores, and quality of life assessments, were collected.
Results: Among the patients with CRSsNP, 23.8% had concomitant bronchial asthma. The incidence of asthma was significantly associated with the severity of sinus involvement in CRSsNP patients (p = 0.049). Pulmonary function impairment was correlated with the severity of sinus inflammation in CRSsNP patients (p = 0.019). Quality of life was significantly affected in patients with concomitant asthma and CRSsNP or CRSwNP.
Conclusion: Chronic rhinosinusitis, both with and without nasal polyps, is closely correlated with bronchial asthma. Pulmonary function impairment is associated with the extent of inflammatory lesions in CRSsNP. Although CRSwNP does not significantly affect pulmonary function, the treatment of sinus diseases can contribute to the control of asthma.

Keywords:  bronchial asthma; chronic rhinosinusitis; inflammation; nasal polyps; sinusitis

DOI:  https://doi.org/10.3389/fmed.2024.1388585
Nat Microbiol. 2024 Nov;9(11): 2763-2764

A path to better practices in microbiology.

DOI: https://doi.org/10.1038/s41564-024-01864-x
Int J Mol Sci. 2024 Oct 21. pii: 11329. [Epub ahead of print]25(20):

Regenerative Inflammation: The Mechanism Explained from the Perspective of Buffy-Coat Protagonism and Macrophage Polarization.

Rubens Andrade Martins, Fábio Ramos Costa, Luyddy Pires, Márcia Santos, Gabriel Silva Santos, João Vitor Lana, Bruno Ramos Costa, Napoliane Santos, Alex Pontes de Macedo, André Kruel, José Fábio Lana.

  The buffy-coat, a layer of leukocytes and platelets obtained from peripheral blood centrifugation, plays a crucial role in tissue regeneration and the modulation of inflammatory responses. This article explores the mechanisms of regenerative inflammation, highlighting the critical role of the buffy-coat in influencing macrophage polarization and its therapeutic potential. Macrophage polarization into M1 and M2 subtypes is pivotal in balancing inflammation and tissue repair, with M1 macrophages driving pro-inflammatory responses and M2 macrophages promoting tissue healing and regeneration. The buffy-coat's rich composition of progenitor cells, cytokines, and growth factors-such as interleukin-10, transforming growth factor-β, and monocyte colony-stimulating factor-supports the transition from M1 to M2 macrophages, enhancing tissue repair and the resolution of inflammation. This dynamic interaction between buffy-coat components and macrophages opens new avenues for therapeutic strategies aimed at improving tissue regeneration and managing inflammatory conditions, particularly in musculoskeletal diseases such as osteoarthritis. Furthermore, the use of buffy-coat-derived therapies in conjunction with other regenerative modalities, such as platelet-rich plasma, holds promise for more effective clinical outcomes.

Keywords:  buffy-coat; macrophage polarization; mesenchymal stem cells; platelet-rich plasma; regenerative inflammation

DOI:  https://doi.org/10.3390/ijms252011329