Liora Wittle

Anal Sci. 2025 Jun;41(6):857-865. doi: 10.1007/s44211-025-00754-4. Epub 2025 Apr 8.

ABSTRACT

We developed PMBiT, an antibody-binding Protein M (PM)-based bioluminescent probe that detects large antigens via luciferase reconstitution by exposing a luciferase fragment. Detection is achieved by exploiting the principle that the antibody, large antigen, and PM cannot form a complex simultaneously. PMBiT was prepared by conjugating PM with a HiBiT-based peptide from split NanoLuc luciferase through an Azide-DBCO click reaction. It retained its binding activity to the antibody and showed bioluminescence upon reconstitution of the luciferase with LgBiT, the other fragment of the split NanoLuc. Mixing PMBiT with various IgG antibodies resulted in decreased bioluminescence. In contrast, when PMBiT was mixed with IgG bound to its large antigen, such as human C-reactive protein, a dose-dependent increase in bioluminescence was obtained. Molecular dynamics simulations of PM showed that two regions in the C-terminus contribute to steric clashes with antigens owing to their relatively rigid structures. Furthermore, in silico analysis of the structure suggested that the antigen size was the primary factor blocking the binding of PMBiT to IgG for antigen detection. An immunoassay utilizing PMBiT does not require genetic manipulation of antibodies, allowing for seamless and scalable antibody replacement, and will advance the future of on-site detection and rapid diagnostics.

PMID:40198526 | DOI:10.1007/s44211-025-00754-4

bioRxiv [Preprint]. 2025 Jul 31:2025.01.21.634180. doi: 10.1101/2025.01.21.634180.

ABSTRACT

Single-cell studies have revealed that intestinal macrophages maintain gut homeostasis through the balanced actions of reactive (inflammatory) and tolerant (non-inflammatory) subpopulations. How such balance is impaired in inflammatory bowel diseases (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), remains unresolved. Here, we define colon-specific macrophage states and reveal the critical role of non-inflammatory colon-associated macrophages (niColAMs) in IBD recovery. Through trans-scale analyses-integrating computational transcriptomics, proteomics, and in vivo interventional studies-we identified GIV (CCDC88A) as a key regulator of niColAMs. GIV emerged as the top-ranked gene in niColAMs that physically and functionally interacts with NOD2, an innate immune sensor implicated in CD and UC. Myeloid-specific GIV depletion exacerbates infectious colitis, prolongs disease, and abolishes the protective effects of the NOD2 ligand, muramyl dipeptide, in colitis and sepsis models. Mechanistically, GIV's C-terminus binds the terminal leucine-rich repeat (LRR#10) of NOD2 and is required for NOD2 to dampen inflammation and clear microbes. The CD-associated 1007fs NOD2-variant, which lacks LRR#10, cannot bind GIV-providing critical insights into how this clinically relevant variant impairs microbial sensing and clearance. These findings illuminate a critical GIV-NOD2 axis essential for gut homeostasis and highlight its disruption as a driver of dysbiosis and inflammation in IBD.

PMID:40766554 | PMC:PMC12324400 | DOI:10.1101/2025.01.21.634180

Front Nutr. 2025 Jun 25;12:1596951. doi: 10.3389/fnut.2025.1596951. eCollection 2025.

ABSTRACT

Food intake is associated with the occurrence of components and metabolites from the gut microbiota in the bloodstream. Using a widely utilised cell-based assay to measure bacterial peptidoglycan via pattern-recognition receptor activation, we found that the performance of this assay is significantly influenced by the presence of other serum components. To address this challenge, an alternative luciferase-based reporter assay protocol was established to accurately measure NOD1 and NOD2 activation by serum samples with high sensitivity. Utilising postprandial human serum samples, we tested this assay and showed that the concentration of NOD2-activating ligands differed in the postprandial phase. Together, we provide a protocol to measure NOD1/2 activation by human serum samples and highlight a role for NOD2 in the postprandial response.

PMID:40635891 | PMC:PMC12237675 | DOI:10.3389/fnut.2025.1596951

RSC Chem Biol. 2025 May 30. doi: 10.1039/d5cb00086f. Online ahead of print.

ABSTRACT

Soluble peptidoglycan fragments produced by the gut bacteria are key effectors in microbiota-host crosstalk. Here, we biochemically characterized BbMep, an NlpC/p60 domain-containing peptidoglycan d,l-endopeptidase from Bifidobacterium bifidum, which efficiently digests Lys- or Orn-type sacculi. Digestion of human stool-derived muropeptides by BbMep enhances NOD2 activation.

PMID:40520142 | PMC:PMC12160582 | DOI:10.1039/d5cb00086f

Nat Commun. 2025 Jul 1;16(1):5577. doi: 10.1038/s41467-025-60678-5.

ABSTRACT

Gut microbiota-derived peptidoglycan fragments (PGNs) are key signaling molecules that regulate multiple aspects of the host's health. Yet the exact structures of natural PGNs in hosts have not been fully elucidated. Herein, we developed an LC-HRMS/MS analytical platform for global quantification and profiling of natural PGN subtypes in host gut and sera, unexpectedly revealing the abundance of PGN-derived saccharide moieties that do not resemble canonical ligands of mammalian NOD1/2 receptors. Focusing on the disaccharide GlcNAc-MurNAc (GM), which does not activate NOD1/2 yet still exhibits immunostimulatory effects in host immune cells, we established GM as a mild TLR4 agonist, illustrating an alternate PGN sensing mechanism other than NOD signaling. Importantly, the administration of GM mitigates colonic inflammation in the DSS-induced colitis model in mice via a TLR4-dependent manner, highlighting the in vivo significance of gut microbiota-derived PGN saccharides in maintaining host intestinal homeostasis.

PMID:40593577 | PMC:PMC12219203 | DOI:10.1038/s41467-025-60678-5

Int J Mol Sci. 2025 Jun 15;26(12):5742. doi: 10.3390/ijms26125742.

ABSTRACT

Aminopeptidase N (APN), an enzyme expressed in the small intestinal mucosa, is involved in dietary protein digestion. Previous studies have shown that oral administration of fermented milk containing lactic acid bacteria (LAB) enhances mucosal APN activity in young mice. This study aimed to investigate whether LAB strains stimulate mucosal APN activity in aged mice and to evaluate its relevance to age-related changes in body composition. The underlying molecular mechanisms were also explored in vitro. Experiment 1: Aged C57BL/6J mice were fed diets supplemented with heat-killed LAB strains-Enterococcus faecalis OU-23 (EF), Leuconostoc mesenteroides OU-03 (LM), or Lactiplantibacillus plantarum SNK12 (LP). Compared to the aged Control group, the ileal APN activity was significantly higher in the LP group. LP administration also elevated serum Gla-osteocalcin levels and decreased serum CTX-1 levels. Experiment 2: IEC-6 cells were co-cultured with LP that had been treated with RNase, DNase, or lysozyme. APN activity was significantly lower in cells co-cultured with DNase- or lysozyme-treated LP compared to those co-cultured with untreated LP. A specific LAB strain may enhance mucosal APN activity in the aged intestine, potentially contributing to improved bone metabolism. This effect may be mediated by bacterial DNA and peptidoglycan.

PMID:40565206 | PMC:PMC12193318 | DOI:10.3390/ijms26125742

Foods. 2025 May 16;14(10):1763. doi: 10.3390/foods14101763.

ABSTRACT

Lactobacilli, as the main member of food microorganisms, is an important component of the intestinal microbial community and plays crucial roles in regulating the immune capacity of the body. This review provides a comprehensive exploration of the key components of Lactobacilli-mediated immune regulation effects, including the immunogenic components (peptidoglycan and lipoteichoic acid) and metabolites (short-chain fatty acids, bacteriocins, and exopolysaccharides), which can interact with host immune cell receptors to initiate complex immune signaling pathways. In addition, the immunomodulatory activity can be influenced by multiple factors including species differences, host-related factors (age, physiological conditions, and gut microbiota), and environmental factors (nutrient substrates, temperatures, etc.), and the application strategies including precision probiotic development, gene-editing driven engineering, and nanocarrier systems have also been proposed to enhance the immunomodulatory potential. Finally, this review provides the theoretical basis for microbial intervention in immune-related diseases and offers prospects for applications in the food and pharmaceutical industries.

PMID:40428542 | PMC:PMC12111133 | DOI:10.3390/foods14101763

Probiotics Antimicrob Proteins. 2025 May 6. doi: 10.1007/s12602-025-10559-6. Online ahead of print.

ABSTRACT

The preservation of cheese has emerged as a significant concern for the international cheese sector, primarily due to microbial spoilage and the implications of chemical preservatives on human health. Contemporary preservation methodologies encompass sophisticated technologies such as non-thermal processing techniques, innovative packaging solutions, and natural preservatives (encompassing probiotics and postbiotics). Postbiotics are defined as soluble entities (either direct products or metabolic byproducts) that are secreted by living bacteria or released subsequent to bacterial lysis; these include enzymes, peptides, teichoic acids, muropeptides derived from peptidoglycan, polysaccharides, cell surface proteins, and organic acids. The interest in these postbiotics is attributed to their well-defined chemical structures, established safe dose thresholds, long shelf lives, and the presence of diverse signaling molecules that may exhibit nutritional properties (such as cholesterol absorption, degradation of undesirable or antioxidative substances along with increased antioxidant potential or antioxidant compounds). They are intended to enhance food quality and safety through biological control of pathogens and fungi in food, degradation, and removal of mycotoxins and bacterial toxins, biofortification of foods, and enhancement of sensory evaluation criteria. This review highlights the potential of postbiotics as natural preservatives in cheese.

PMID:40327312 | DOI:10.1007/s12602-025-10559-6

ACS Nano. 2025 Apr 2. doi: 10.1021/acsnano.5c01930. Online ahead of print.

ABSTRACT

The bacterial cell wall, an essential structure for maintaining cell morphology and protecting against environmental hazards, is predominantly composed of peptidoglycan (PG). This intricate macromolecule undergoes dynamic synthesis and remodeling throughout the cell cycle. Despite its importance, monitoring PG dynamics in live cells, particularly with detailed spatial distribution, poses significant challenges. To this end, we present a series of rhodamine-based fluorogenic probes specifically optimized for real-time and super-resolution imaging of PG synthesis. By fine-tuning the self-aggregation of the probes through the incorporation of hydrophobic linkers, we achieved a substantial reduction in background fluorescence and significant fluorogenicity after labeling. These advancements have enabled us to attain wash-free labeling across a diverse array of bacterial species. Our approach facilitates the direct visualization of PG synthesis patterns, enabling the quantification of septal PG (sPG) synthesis rates in living bacterial cells. Furthermore, it allows for simultaneous imaging of cell division machinery in living cells via both two-dimensional (2D) and three-dimensional (3D) STED microscopy. This study provides a powerful toolkit for investigating the architecture and dynamics of the bacterial cell wall, paving new paths for research on PG-related cellular processes.

PMID:40173278 | DOI:10.1021/acsnano.5c01930

J Oral Biosci. 2025 Mar;67(1):100630. doi: 10.1016/j.job.2025.100630. Epub 2025 Feb 14.

ABSTRACT

OBJECTIVE: Receptor activator of nuclear factor-κB ligand (RANKL) is intimately involved in regulating bone remodeling during osteoclast differentiation and promotion of osteoclast function. Upon binding to its receptor, RANK, RANKL activates various signaling cascades that induce osteoclast differentiation of osteoclast precursor cells into osteoclasts. In the innate immune system, host pattern recognition receptors, such as Toll-like receptors and nucleotide-binding oligomerization domain-like receptors (NLRs), detect pathogen-associated molecular patterns and elicit an immune response. The NLR, nucleotide-binding oligomerization domain 2 (NOD2), is known to bind muramyl dipeptide (MDP) and regulate inflammatory responses via nuclear factor-κB (NF-κB). The objective of this study was to investigate the effect of MDP on RANKL stimulation of osteoclast differentiation to elucidate the mechanism of bone resorption in a bacterial infection-induced inflammation model.

METHODS: The extent of osteoclast formation in MDP-stimulated RAW 264.7 cells was assessed using a tartrate-resistant acid phosphatase activity assay. The protein levels of intracellular signaling molecules were assessed by western blotting.

RESULTS: In RAW 264.7 cells, MDP stimulation did not affect the expression of RANK. MDP enhanced the expression of osteoclast-specific proteins, such as nuclear factor of activated T cells 1 (NFATc1) and cathepsin K, which are osteoclast differentiation markers, in RANKL-stimulated RAW 267.4 cells. Furthermore, JSH23, an NF-κB inhibitor, suppressed the expression of NFATc1 after co-stimulation with MDP and RANKL.

CONCLUSION: MDP promoted osteoclast differentiation in RAW 267.4 cells by upregulating the activators, NF-κB and NFATc1, which are important for osteoclast differentiation, through enhancement of the RANKL signaling pathway.

PMID:39956215 | DOI:10.1016/j.job.2025.100630

J Ethnopharmacol. 2025 Mar 26;344:119457. doi: 10.1016/j.jep.2025.119457. Epub 2025 Feb 8.

ABSTRACT

ETHNOPHARMACOLOGICAL RELEVANCE: As a traditional Chinese herb, Glycyrrhiza uralensis Fisch. exhibits a range of pharmacological activities, including anti-inflammatory, immunomodulatory and antifibrotic, which suggests its therapeutic potential for inflammatory bowel disease, and related mechanisms need to be further clarified.

AIM OF THE STUDY: To evaluate in vivo anti-inflammatory effects of Glycyrrhiza uralensis Fisch. aqueous extract (GE) on 2, 4, 6-trinitrobenzene sulfonic acid (TNBS)-induced acute experimental colitis rat model and its potential mechanisms.

MATERIALS AND METHODS: The protective effects of GE on IBD were evaluated in vivo using a TNBS and 75% ethanol-induced ulcerative colitis (UC) model. The evaluated clinical and anatomical indexes included body weight, colon length, disease activity index (DAI) score, Colonic Mucosal Damage Index (CMDI) score. The percentages of T, B lymphocytes, NK cells, and macrophages in the colon, spleen and peripheral blood were investigated by flow cytometry. Colon tissues were stained with Hematoxylin and Eosin (H&E) for histopathological examination. After using transcriptome sequencing to screen targeted genes, the expression of related genes was detected by Real-Time Quantitative Polymerase Chain Reaction (RT-qPCR) and Western blot (WB).

RESULTS: The decrease of food intake, soft feces, and colon histopathological injury were observed in colitis rats, which were alleviated by GE, with the best therapeutic effect in the 100 mg/kg GE group. The average CMDI scores of colon in UC rats were decreased from 4.0 to 1.5. The percentages of CD161a⁺ NK cells, CD68⁺ total macrophages, CD68⁺/CD161a⁺ M1 type macrophages, CD3⁺ T lymphocytes, and CD45RA⁺ B lymphocytes were decreased in the spleen and colon. The transcriptomics analysis of colon showed that the results were mainly related to the TNF signaling pathway and NF-κB signaling pathway. The RT-qPCR and WB results determined that the upregulated expression of nucleotide-binding oligomerization domain 2 (NOD2), receptor-interacting protein 2 (RIP2), nuclear factor-kappa B (NF-κB), tumor necrosis factor-α (TNF-α) in the colon of the colitis rats were downregulated by GE treatment.

CONCLUSION: The research results indicate that GE can exert therapeutic effects on TNBS-induced UC in rats by alleviating cell injury and inflammatory responses, and its mechanisms may be related to the regulation of NOD2/RIP2/NF-κB signaling pathway.

PMID:39929400 | DOI:10.1016/j.jep.2025.119457

bioRxiv [Preprint]. 2025 Jan 2:2024.12.31.630956. doi: 10.1101/2024.12.31.630956.

ABSTRACT

The recalcitrance of Mycobacterium tuberculosis to antibiotic treatment has been broadly attributed to the impermeability of the organism's outer mycomembrane. However, the studies that support this inference have been indirect and/or reliant on bulk population measurements. We previously developed the P eptidoglycan A ccessibility C lick- M ediated A ssessme N t (PAC-MAN) method to covalently trap azide-modified small molecules in the peptidoglycan cell wall of live mycobacteria, after they have traversed the mycomembrane. Using PAC-MAN we now show that the mycomembrane differentially restricts access of fluorophores and antibiotic derivatives. Mycomembranes of both M. tuberculosis and the model organism M. smegmatis discriminate between divergent classes of antibiotics as well as between antibiotics within a single family, the fluoroquinolones. By analyzing sub-populations of M. tuberculosis and M. smegmatis , we also found that some fluorophores and vancomycin are heterogeneously restricted by the mycomembrane. Our data indicate that the mycomembrane is a molecule- and cell-specific barrier to antibiotic permeation.

PMID:39803531 | PMC:PMC11722283 | DOI:10.1101/2024.12.31.630956

ACS Nano. 2025 Jan 7. doi: 10.1021/acsnano.4c13069. Online ahead of print.

ABSTRACT

Bacterial membrane vesicles (BMVs) are emerging as powerful natural nanoparticles with transformative potential in medicine and industry. Despite their promise, scaling up BMV production and ensuring stable isolation and storage remain formidable challenges that limit their broader application. Inspired by eukaryotic mechanisms of membrane curvature, we engineered Escherichia coli DH5α to serve as a high-efficiency BMV factory. By fusing the ethanolamine utilization microcompartment shell protein EutS with the outer membrane via the ompA signal peptide, we induced dramatic membrane curvatures that drove enhanced vesiculation. Simultaneously, overexpression of fatty acyl reductase led to the production of amphiphilic fatty alcohols, further amplifying the BMV yield. Dynamic modulation of peptidoglycan hydrolase (PGase) expression facilitated efficient BMV release, resulting in a striking 149.11-fold increase in vesicle production. Notably, the high-yield BMVs from our engineered strain, without the need for purification, significantly bolstered innate immune responses and demonstrated therapeutic efficacy in treating inflammatory bowel disease (IBD). This study presents a strategy to overcome BMV production barriers, showcasing the therapeutic potential of engineered bacteria and BMVs for IBD treatment, while highlighting their potential applications in diverse biomedical fields.

PMID:39772458 | DOI:10.1021/acsnano.4c13069

Animals (Basel). 2024 Dec 18;14(24):3661. doi: 10.3390/ani14243661.

ABSTRACT

The innate immune system plays an important role in the defense against pathogens, whereby the ability to rapidly mount an effective inflammatory response is critical in the elimination/containment of the infection. To better understand the nature of the inflammatory responses to bacterial components in chickens, we used the growing feather (GF) cutaneous bioassay together with blood sampling to examine the local and systemic inflammatory responses initiated by intradermal (i.d.) GF-pulp injection of lipopolysaccharide (LPS) from Salmonella Typhimurium or peptidoglycan (PGN) from Staphylococcus aureus. Three studies were conducted in egg-type chickens between 9 and 15 weeks of age; Study 1 and 2 examined the leukocyte response profiles to a 100-fold dose range of LPS or PGN over 24 h or 7 d, respectively; Study 3 examined the leukocyte- and cytokine mRNA-profiles in pulps in response to LPS and PGN concurrently over 72 h. I.d. injection of LPS stimulated a heterophil and monocyte/macrophage dominated response in both GF-pulps and blood that was resolved by 48-72 h and differed based on dose administered. The inflammatory response stimulated by PGN was characterized by rapid infiltration of lymphocytes in GF-pulps with sustained high levels of T and B cells over 5-7 d and was neither affected by PGN dose nor reflected in the blood. Limited cytokine transcriptome analyses did not reveal differences that could explain the divergent response profiles to LPS versus PGN. More research is needed to understand the mechanisms underlying the divergent inflammatory responses to LPS and PGN in chickens.

PMID:39765565 | PMC:PMC11672625 | DOI:10.3390/ani14243661

J Med Chem. 2024 Dec 5. doi: 10.1021/acs.jmedchem.4c02139. Online ahead of print.

ABSTRACT

Helicobacter pylori (H. pylori) infection is characterized by the complex interplay between H. pylori and gastric disorders. It has been established that NOD1 can be activated by the peptidoglycan (PGN) present in the cell wall of H. pylori, serving as a key mediator of inflammation and initiating the RIP2/NF-κB and MAPK inflammatory signaling pathways. In this article, we reported on the development of a 2-chloroquinazolin-4-ol derivative 66 as a potent and selective antagonist of both human and mouse NOD1, which effectively inhibited the expression of inflammatory cytokines (IL-6, TNF-α) and chemokines (CXCL1, CXCL8) in immune and epithelial cells, as well as inflammatory cytokines (KC, IL-6) in a H. pylori-induced murine model of gastritis following oral administration. This study laid a foundation for treating gastritis induced by H. pylori infection.

PMID:39637404 | DOI:10.1021/acs.jmedchem.4c02139

Trends Microbiol. 2024 Nov 28:S0966-842X(24)00286-5. doi: 10.1016/j.tim.2024.11.004. Online ahead of print.

ABSTRACT

During growth and division, the bacterial cell wall is remodeled, resulting in the liberation of peptidoglycan (PG) fragments which are typically reinternalized and recycled. Recycling of PG has been studied in a few model species, but its importance and diversity are not yet well understood. Here, we review how bacteria transport and recycle the components of their PG, highlighting updates and new findings.

PMID:39613687 | DOI:10.1016/j.tim.2024.11.004

ACS Appl Mater Interfaces. 2024 Nov 13;16(45):61655-61663. doi: 10.1021/acsami.4c13041. Epub 2024 Nov 5.

ABSTRACT

The clinical efficacy of cancer vaccines is closely related to immunoadjuvants that play a crucial role in magnifying and prolonging the immune response. Muramyl dipeptide (MDP), a minimal and conserved peptidoglycan found in almost all bacteria, can trigger robust immune activation by uniquely antagonizing the nucleotide-binding oligomerization domain 2 (NOD2) pathway. However, its effectiveness has been hindered by limited solubility, poor membrane penetration, and rapid clearance from the body. Here, we introduce MDP-presenting polymersomes as artificial nanobacteria (NBA) to boost the antitumor immune response. The NBA, featuring abundant MDP molecules, induces superior stimulation of immune cells including macrophages and bone marrow-derived dendritic cells (BMDCs) compared to free MDP, likely via facilitating immune cell uptake and cooperatively stimulating systemic NOD2 signaling. Importantly, systemic administration of NBA significantly enhances the chemo-immunotherapy of B16-F10 melanoma-bearing mice pretreated with doxorubicin by reversing the immunosuppressive tumor microenvironment. Furthermore, NBA carrying ovalbumin and B16-F10 cell lysates induces robust OVA-IgG antibody production and effectively inhibit tumor growth, respectively. The artificial nanobacteria hold great promise as a potent systemic immunoadjuvant for cancer immunotherapy.

PMID:39498882 | DOI:10.1021/acsami.4c13041

bioRxiv [Preprint]. 2024 Oct 12:2024.10.09.617444. doi: 10.1101/2024.10.09.617444.

ABSTRACT

Receptor-interacting serine/threonine protein kinase 2 (RIPK2) is a kinase that plays an essential role in the modulation of innate and adaptive immune responses. As a downstream signaling molecule for nucleotide-binding oligomerization domain 1 (NOD1), NOD2, and Toll-like receptors (TLRs), it is implicated in the signaling triggered by recognition of microbe-associated molecular patterns by NOD1/2 and TLRs. Upon activation of these innate immune receptors, RIPK2 mediates the release of pro-inflammatory factors by activating mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-κB). However, whether RIPK2 is essential for downstream inflammatory signaling following the activation of NOD1/2, TLRs, or both remains controversial. In this study, we examined the role of RIPK2 in NOD2-and TLR4-dependent signaling cascades following stimulation of microglial cells with bacterial muramyl dipeptide (MDP), a NOD2 agonist, or lipopolysaccharide (LPS), a TLR4 agonist. We utilized a highly specific proteolysis targeting chimera (PROTAC) molecule, GSK3728857A, and found dramatic degradation of RIPK2 in a concentration- and time-dependent manner. Importantly, the PROTAC completely abolished MDP-induced increases in iNOS and COX-2 protein levels and pro-inflammatory gene transcription of Nos2, Ptgs2, Il-1β, Tnfα, Il6, Ccl2, and Mmp9. However, increases in iNOS and COX-2 proteins and pro-inflammatory gene transcription induced by the TLR4 agonist, LPS, were only slightly attenuated with the GSK3728857A pretreatment. Further findings revealed that the RIPK2 PROTAC completely blocked the phosphorylation and activation of p65 NF-κB and p38 MAPK induced by MDP, but it had no effects on the phosphorylation of these two mediators triggered by LPS. Collectively, our findings strongly suggest that RIPK2 plays an essential role in the inflammatory responses of microglia to bacterial MDP but not to LPS.

PMID:39416057 | PMC:PMC11482783 | DOI:10.1101/2024.10.09.617444

Mol Biol Rep. 2024 Aug 7;51(1):891. doi: 10.1007/s11033-024-09759-0.

ABSTRACT

BACKGROUND: Peptide transporter 1 (PepT1) transports bacterial oligopeptide products and induces inflammation of the bowel. Nutritional peptides compete for the binding of intestinal bacterial products to PepT1. We investigated the mechanism of short-peptide-based enteral nutrition (SPEN) on the damage to the gut caused by the bacterial oligopeptide product muramyl dipeptide (MDP), which is transported by PepT1. The gut-lung axis is a shared mucosal immune system, and immune responses and disorders can affect the gut-respiratory relationship.

METHODS AND RESULTS: Sprague-Dawley rats were gavaged with solutions containing MDP, MDP + SPEN, MDP + intact-protein-based enteral nutrition (IPEN), glucose as a control, or glucose with GSK669 (a NOD2 antagonist). Inflammation, mitochondrial damage, autophagy, and apoptosis were explored to determine the role of the PepT1-nucleotide-binding oligomerization domain-containing protein 2 (NOD2)-beclin-1 signaling pathway in the small intestinal mucosa. MDP and proinflammatory factors of lung tissue were explored to determine that MDP can migrate to lung tissue and cause inflammation. Induction of proinflammatory cell accumulation and intestinal damage in MDP gavage rats was associated with increased NOD2 and Beclin-1 mRNA expression. IL-6 and TNF-α expression and apoptosis were increased, and mitochondrial damage was severe, as indicated by increased mtDNA in the MDP group compared with controls. MDP levels and expression of proinflammatory factors in lung tissue increased in the MDP group compared with the control group. SPEN, but not IPEN, eliminated these impacts.

CONCLUSIONS: Gavage of MDP to rats resulted in damage to the gut-lung axis. SPEN reverses the adverse effects of MDP. The PepT1-NOD2-beclin-1 pathway plays a role in small intestinal inflammation, mitochondrial damage, autophagy, and apoptosis.

PMID:39110355 | PMC:PMC11306270 | DOI:10.1007/s11033-024-09759-0

Front Immunol. 2024 Jun 11;15:1409333. doi: 10.3389/fimmu.2024.1409333. eCollection 2024.

ABSTRACT

INTRODUCTION: Therapeutic antibodies have become a major strategy to treat oncologic diseases. For chronic lymphocytic leukemia, antibodies against CD20 are used to target and elicit cytotoxic responses against malignant B cells. However, efficacy is often compromised due to a suppressive microenvironment that interferes with cellular immune responses. To overcome this suppression, agonists of pattern recognition receptors have been studied which promote direct cytotoxicity or elicit anti-tumoral immune responses. NOD2 is an intracellular pattern recognition receptor that participates in the detection of peptidoglycan, a key component of bacterial cell walls. This detection then mediates the activation of multiple signaling pathways in myeloid cells. Although several NOD2 agonists are being used worldwide, the potential benefit of these agents in the context of antibody therapy has not been explored.

METHODS: Primary cells from healthy-donor volunteers (PBMCs, monocytes) or CLL patients (monocytes) were treated with versus without the NOD2 agonist L18-MDP, then antibody-mediated responses were assessed. In vivo, the Eµ-TCL1 mouse model of CLL was used to test the effects of L18-MDP treatment alone and in combination with anti-CD20 antibody.

RESULTS: Treatment of peripheral blood mononuclear cells with L18-MDP led to activation of monocytes from both healthy donors and CLL patients. In addition, there was an upregulation of activating FcγR in monocytes and a subsequent increase in antibody-mediated phagocytosis. This effect required the NF-κB and p38 signaling pathways. Treatment with L18-MDP plus anti-CD20 antibody in the Eµ-TCL model of CLL led to a significant reduction of CLL load, as well as to phenotypic changes in splenic monocytes and macrophages.

CONCLUSIONS: Taken together, these results suggest that NOD2 agonists help overturn the suppression of myeloid cells, and may improve the efficacy of antibody therapy for CLL.

PMID:38919608 | PMC:PMC11196781 | DOI:10.3389/fimmu.2024.1409333

Int J Mol Sci. 2024 May 13;25(10):5318. doi: 10.3390/ijms25105318.

ABSTRACT

The lung is prone to infections from respiratory viruses such as Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). A challenge in combating these infections is the difficulty in targeting antiviral activity directly at the lung mucosal tract. Boosting the capability of the respiratory mucosa to trigger a potent immune response at the onset of infection could serve as a potential strategy for managing respiratory infections. This study focused on screening immunomodulators to enhance innate immune response in lung epithelial and immune cell models. Through testing various subfamilies and pathways of pattern recognition receptors (PRRs), the nucleotide-binding and oligomerization domain (NOD)-like receptor (NLR) family was found to selectively activate innate immunity in lung epithelial cells. Activation of NOD1 and dual NOD1/2 by the agonists TriDAP and M-TriDAP, respectively, increased the number of IL-8+ cells by engaging the NF-κB and interferon response pathways. Lung epithelial cells showed a stronger response to NOD1 and dual NOD1/2 agonists compared to control. Interestingly, a less-pronounced response to NOD1 agonists was noted in PBMCs, indicating a tissue-specific effect of NOD1 in lung epithelial cells without inducing widespread systemic activation. The specificity of the NOD agonist pathway was confirmed through gene silencing of NOD1 (siRNA) and selective NOD1 and dual NOD1/2 inhibitors in lung epithelial cells. Ultimately, activation induced by NOD1 and dual NOD1/2 agonists created an antiviral environment that hindered SARS-CoV-2 replication in vitro in lung epithelial cells.

PMID:38791357 | PMC:PMC11121681 | DOI:10.3390/ijms25105318

Nutrients. 2023 Oct 10;15(20):4315. doi: 10.3390/nu15204315.

ABSTRACT

Background Sleep plays a pivotal role in children's mental and physical development and has been linked to the gut microbiota in animals and adults. However, the characteristics of the gut microbiota and metabolites and the relationship to late bedtimes in children remain unclear. Methods In total, 88 eligible children, aged from 3 to 8 years, were recruited and divided into two groups according to the bedtime collected by designed questionnaires (early, before 22:00: n = 48; late, after 22:00, n = 40). Stools and plasma samples were collected to examine the characteristics of the gut microbiota and metabolites by shotgun metagenomics and metabolomics. Results The richness and diversity of the gut microbiota in children with early bedtime were significantly increased compared with the late ones. Coprococcus, Collinsella, Akkermansia muciniphila, and Bifidobacterium adolescentis were significantly more abundant in children with early bedtime, while Bacteroides and Clostridium sp. CAG-253 were obviously enriched in the late ones. A total of 106 metabolic pathways, including biosynthesis of ribonucleotide, peptidoglycan, and amino acids, and starch degradation were enriched in children with early bedtime, while 42 pathways were abundant in those with late bedtime. Notably, more gut microbial metabolites were observed in children with late bedtime, which included aldehyde, ketones, esters, amino acids and their metabolites, benzene and substituted derivatives, bile acids, heterocyclic compounds, nucleotide and metabolites, organic acid and derivatives, sugars and acyl carnitine. In plasma, fatty amides, lipids, amino acids, metabolites, hormones, and related compounds were enriched in children with early bedtime, while bile acids were higher in children with late bedtime. Association studies revealed that the different microbial species were correlated with metabolites from gut microbiota and plasma. Conclusions The results of our study revealed that the gut microbiota diversity and richness, and metabolic pathways were significantly extensive in children with early bedtime, whereas the gut microbial metabolites were significantly decreased, which might be related to gut microbial differences.

PMID:37892391 | PMC:PMC10609417 | DOI:10.3390/nu15204315