Pathogen-associated Molecular Patterns Research Articles

Recognition of a Fungal Effector Potentiates Pathogen-Associated Molecular Pattern-Triggered Immunity in Cotton.

Plants are equipped with multi-layered immune systems that recognize pathogen-derived elicitors to activate immunity. Verticillium dahliae is a soil-borne fungus that infects a broad range of plants and causes devastating wilt disease. The mechanisms underlying immune recognition between plants and V. dahliae remain elusive. Here, a V. dahliae secretory protein, elicitor of plant defense gene (VdEPD1), acts as an elicitor that triggers defense responses in both Nicotiana benthamiana and cotton plants is identified. Targeted gene deletion of VdEPD1 enhances V. dahliae virulence in plants. Expression of VdEPD1 triggers the accumulation of reactive oxygen species (ROS) and the activation of cell death in cotton plants. Gossypium barbadense EPD1-interacting receptor-like cytoplasmic kinase (GbEIR5A) and GbEIR5D interact with VdEPD1. Silencing of GbEIR5A/D significantly impairs VdEPD1-triggered cell death in cotton plants, indicating the contribution of GbEIR5A/D to VdEPD1-activated effector-triggered immunity (ETI). VdEPD1 stimulates the expression of GbEIR5A and GbEIR5D in cotton plants. Interestingly, cotton plants with silenced GbEIR5A/D genes exhibit compromised pathogen-associated molecular patterns (PAMPs)-triggered ROS accumulation, whereas overexpression of GbEIR5A or GbEIR5D enhances PAMP-induced ROS. These findings indicate that recognition of VdEPD1 potentiates GbEIRs to enhance cotton PAMP-triggered immunity (PTI), uncovering a cooperative interplay of PTI and ETI in cotton.

Mucus-Penetrable Biomimetic Nanoantibiotics for Pathogen-Induced Pneumonia Treatment.

Bacterial pneumonia has garnered significant attention in the realm of infectious diseases owing to a surge in the incidence of severe infections coupled with the growing scarcity of efficacious therapeutic modalities. Antibiotic treatment is still an irreplaceable method for bacterial pneumonia because of its strong bactericidal activity and good clinical efficacy. However, the mucus layer forming after a bacterial infection in the lungs has been considered as the "Achilles' heels" facing the clinical application of such treatment. Herein, traceable biomimetic nanoantibiotics (BioNanoCFPs) were developed by loading indacenodithieno[3,2-b]thiophene (ITIC) and cefoperazone (CFP) in nanoplatforms coated with natural killer (NK) cell membranes. The BioNanoCFP exhibited excellent demonstrated mucus-penetrating abilities, facilitating their arrival at the infection site. The presence of Toll-like receptors in the NK cell membrane rendered the BioNanoCFP with the capability to recognize pathogen-associated molecular patterns within bacteria, allowing precise targeting of bacterial colonization sites and achieving substantial therapeutic efficacy. Overall, our findings demonstrate the viability and desirability of using NK cell membrane-mediated drug delivery as a promising strategy for precision treatment.

TLR2 Activation as a Marker of Severe COVID-19 and a Potential Therapeutic Target.

SARS-CoV-2-induced COVID-19 has been a serious public health problem, resulting in millions of lives lost over the previous three years. Although the direct infection caused by virus invasion is important for the pathobiology of COVID-19, the hyperinflammatory response and tissue injury are major contributors in critically ill patients. As a host sensor, toll-like receptor 2 (TLR2) recognizes multiple pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs), producing various inflammatory cytokines and inflammatory cell death signals, which are central to the inflammatory pathology observed in COVID-19. The objectives of this narrative review are to summarize the role of TLR2 activation during SARS-CoV-2 infection and emphasize the importance of SARS-CoV-2 viral proteins in TLR2 activation. Additionally, we presented some compounds related to TLR2 regulation clinically or experimentally, which may provide new insights into targets for pharmaceutical discovery and development.

Calcium-Binding Protein and Polymorphism in Musa spp. Somaclones Resistant to Fusarium oxysporum

The fresh fruits of ‘Grande Naine’ (Cavendish AAA—Musa spp.) dominate the world market, especially in countries with a population in a situation of social vulnerability. However, Fusarium wilt, caused by the fungus Fusarium oxysporum f.sp. cubense race 4 Subtropical (Foc ST4), emerges as a serious threat to banana production, requiring the development of resistant cultivars based on biotechnological strategies, such as the induction of mutation in tissue culture. This study aimed to identify and characterize genetic variation in somaclones resistant to Fusarium oxysporum f.sp. cubense subtropical race 4 (Foc ST4), derived from ‘Grand Naine’ bananas, by molecular markers based on retrotransposons IRAP (Inter-retrotransposon Amplified Polymorphism) and REMAP (Retrotransposon-Microsatellite Amplified Polymorphism). Nine combinations of IRAP and six combinations of REMAP primers were used. The low number of polymorphic bands did not allow for genetic diversity studies; however, ten polymorphic bands between the somaclones and control were sequenced. Of these, three presented good base calling and were aligned, namely, 1AF, 2AF, and 3AF bands. Only the 1AF band presented function related to stress response with homology to a calcium-binding protein. These proteins act early in plant infection as secondary messengers activated by pathogen-associated molecular patterns (PAMPs), initiating the cascade of plant defense signals. The fact that this band is present in all somaclones reinforces previous assessments of their resistance to Foc ST4. The use of markers IRAP and REMAP produced polymorphic bands that can, through future primer design and field validations, accelerate the identification of resistant banana genotypes for use in banana genetic breeding programs.

Early inflammation as a footprint of increased mortality risk in infants living with HIV from three African countries

In this work our aim was to identify early biomarkers in plasma samples associated with mortality in children with perinatal HIV treated early in life, to potentially inform early intervention targeting this vulnerable group. 20/215 children (9.3%) with perinatal HIV, enrolled within 3 months of age died prematurely within the first year of the study, despite early ART initiation. Using a propensity score, we selected 40 alive study participants having similar clinical and virological records compared to the deceased group. 13 HIV unexposed (HU) healthy children were additionally used as controls. Baseline plasma samples were analyzed using a targeted proteomic approach, and to assess pathogen-associated and damage-associated molecular patterns (PAMPs, DAMPs) levels. Data from deceased participants were compared to both control groups, with multivariate logistic regression models used to evaluate the association between mortality and plasma proteins. We developed a machine learning model to predict mortality risk, finding that IL-6 and CXCL11 not only were higher in deceased children than Matched-children with HIV (p < 0.001 and p = 0.0034) but also predictive of mortality (accuracy of 77%); levels of PAMPs were higher in deceased children (p = 0.0016). Thus, measuring early inflammatory biomarkers, particularly IL-6, could help mortality risk prediction and potentially guide targeted interventions.

Extracellular DNA as a Strategy to Manage Vascular Wilt Caused by Fusarium oxysporum in Tomato (Solanum lycopersicum L.) Based on Its Action as a Damage-Associated Molecular Pattern (DAMP) or Pathogen-Associated Molecular Pattern (PAMP)

Vascular wilt is an important tomato disease that affects culture yields worldwide, with Fusarium oxysporum (F.o) being the causal agent of this infection. Several management strategies have lost effectiveness due to the ability of this pathogen to persist in soil and its progress in vascular tissues. However, nowadays, research has focused on understanding the plant defense mechanisms to cope with plant diseases. One recent and promising approach is the use of extracellular DNA (eDNA) based on the ability of plants to detect their self-eDNA as damage-associated molecular patterns (DAMPs) and pathogens’ (non-self) eDNA as pathogen-associated molecular patterns (PAMPs). The aim of this work was to evaluate the effect of the eDNA of F.o (as a DAMP for the fungus and a PAMP for tomato plants) applied on soil, and of tomato’s eDNA (as a DAMP of tomato plants) sprayed onto tomato plants, to cope with the disease. Our results suggested that applications of the eDNA of F.o (500 ng/µL) as a DAMP for this pathogen in soil offered an alternative for the management of the disease, displaying significantly lower disease severity levels in tomato, increasing the content of some phenylpropanoids, and positively regulating the expression of some defense genes. Thus, the eDNA of F.o applied in soil was shown to be an interesting strategy to be further evaluated as a new element within the integrated management of vascular wilt in tomato.

Beyond Inflammation: Role of Pyroptosis Pathway Activation by Gram-Negative Bacteria and Their Outer Membrane Vesicles (OMVs) in the Interaction with the Host Cell

Pyroptosis is a gasdermin-mediated pro-inflammatory programmed cell death that, during microbial infections, aims to restrict the spreading of bacteria. Nevertheless, excessive pyroptosis activation leads to inflammation levels that are detrimental to the host. Pathogen-associated molecular patterns (PAMPs) present in bacteria and outer membrane vesicles (OMVs) can trigger pyroptosis pathways in different cell types with different outcomes. Moreover, some pathogens have evolved virulence factors that directly interfere with pyroptosis pathways, like Yersinia pestis YopM and Shigella flexneri IpaH7.8. Other virulence factors, such as those of Neisseria meningitidis, Neisseria gonorrhoeae, Salmonella enterica, and Helicobacter pylori affect pyroptosis pathways indirectly with important differences between pathogenic and commensal species of the same family. These pathogens deserve special attention because of the increasing antimicrobial resistance of S. flexneri and N. gonorrhoeae, the high prevalence of S. enterica and H. pylori, and the life-threatening diseases caused by N. meningitidis and Y. pestis. While inflammation due to macrophage pyroptosis has been extensively addressed, the effects of activation of pyroptosis pathways on modulation of cell cytoskeleton and cell–cell junctions in epithelia and endothelia and on the bacterial crossing of epithelial and endothelial barriers have only been partly investigated. Another important point is the diverse consequences of pyroptosis pathways on calcium influx, like activation of calcium-dependent enzymes and mitochondria dysregulation. This review will discuss the pyroptotic pathways activated by Gram-negative bacteria and their OMVs, analyzing the differences between pathogens and commensal bacteria. Particular attention will also be paid to the experimental models adopted and the main results obtained in the different models. Finally, strategies adopted by pathogens to modulate these pathways will be discussed with a perspective on the use of pyroptosis inhibitors as adjuvants in the treatment of infections.

MdSVWC1, a new pattern recognition receptor triggers multiple defense mechanisms against invading bacteria in Musca domestica

BackgroundSingle-domain von Willebrand factor type C (SVWC) constitute a protein family predominantly identified in arthropods, characterized by a SVWC domain and involved in diverse physiological processes such as host defense, stress resistance, and nutrient metabolism. Nevertheless, the physiological mechanisms underlying these functions remain inadequately comprehended.ResultsA massive expansion of the SVWC gene family in Musca domestica (MdSVWC) was discovered, with a count of 35. MdSVWC1 was selected as the representative of the SVWC family for functional analysis, which led to the identification of the immune function of MdSVWC1 as a novel pattern recognition receptor. MdSVWC1 is highly expressed in both the fat body and intestines and displays acute induction upon bacterial infection. Recombinant MdSVWC1 binds to surfaces of both bacteria and yeast through the recognition of multiple pathogen-associated molecular patterns and exhibits Ca2+-dependent agglutination activity. MdSVWC1 mutant flies exhibited elevated mortality and hindered bacterial elimination following bacterial infection as a result of reduced hemocyte phagocytic capability and weakened expression of antimicrobial peptide (AMP) genes. In contrast, administration of recombinant MdSVWC1 provided protection to flies from bacterial challenges by promoting phagocytosis and AMP genes expression, thereby preventing bacterial colonization. MdSPN16, a serine protease inhibitor, was identified as a target protein of MdSVWC1. It was postulated that the interaction of MdSVWC1 with MdSPN16 would result in the activation of an extracellular proteolytic cascade, which would then initiate the Toll signaling pathway and facilitate the expression of AMP genes.ConclusionsMdSVWC1 displays activity as a soluble pattern recognition receptor that regulates cellular and humoral immunity by recognizing microbial components and facilitating host defense.

A myeloid differentiation–like protein in partnership with Toll5 from the pest insect Spodoptera litura senses baculovirus infection

Many types of viruses infect insects and other arthropods. In contrast, little is known about how arthropods sense viruses, although several innate immune pathways including Toll have antiviral functions. Large DNA viruses in the family Baculoviridae are used to control a number of pest insects. Here, we studied Spodoptera litura and Autographa californica multiple nucleopolyhedrovirus (AcMNPV) to test the hypothesis that one or more myeloid differentiation-like (ML) proteins and Toll family members sense baculoviruses. We identified 11 ML and 12 Toll genes in the S. litura genome. A series of experiments indicated that S. litura ML protein 11 (SlML-11) binds the budded form of AcMNPV and partners with S. litura Toll5 (SlToll5). SlML-11 also bound sphingomyelin (SPM), which is a component of the virion envelope. Disabling SlML-11 and SlToll5 increased susceptibility to infection, while priming larvae with SPM reduced susceptibility as measured by increased survival to the adult stage and clearance of AcMNPV from individuals that emerged as adults. We conclude that SPM is a pathogen-associated molecular pattern molecule while SlML-11 and SlToll5 interact to function as a pattern recognition receptor that senses AcMNPV.

Unraveling the dynamics of Xanthomonas' flagella: insights into host-pathogen interactions.

Understanding the intricate interplay between plants and bacteria is paramount for elucidating mechanisms of immunity and disease. This review synthesizes current knowledge on the role of flagella in bacterial motility and host recognition, shedding light on the molecular mechanisms underlying plant immunity and bacterial pathogenicity. We delve into the sophisticated signaling network of plants, highlighting the pivotal role of pattern recognition receptors (PRRs) in detecting conserved molecular patterns known as microbe-associated molecular patterns (MAMPs), with a particular focus on flagellin as a key MAMP. Additionally, we explore recent discoveries of solanaceous-specific receptors, such as FLAGELLIN SENSING 3 (FLS3), and their implications for plant defense responses. Furthermore, we examine the role of bacterial motility in host colonization and infection, emphasizing the multifaceted relationship between flagella-mediated chemotaxis and bacterial virulence. Through a comprehensive analysis of flagellin polymorphisms within the genus Xanthomonas, we elucidate their potential impact on host recognition and bacterial pathogenicity, offering insights into strategies for developing disease-resistant crops. This review is intended for professionals within the fields of crops sciences and microbiology.

Immunological Strategies in Gastric Cancer: How Toll-like Receptors 2, -3, -4, and -9 on Monocytes and Dendritic Cells Depend on Patient Factors?

(1) Introduction: Toll-like receptors (TLRs) are key in immune response by recognizing pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). In gastric cancer (GC), TLR2, TLR3, TLR4, and TLR9 are crucial for modulating immune response and tumor progression. (2) Objective: This study aimed to assess the percentage of dendritic cells and monocytes expressing TLR2, TLR3, TLR4, and TLR9, along with the concentration of their soluble forms in the serum of GC patients compared to healthy volunteers. Factors such as disease stage, tumor type, age, and gender were also analyzed. (3) Materials and Methods: Blood samples from newly diagnosed GC patients and healthy controls were immunophenotyped using flow cytometry to assess TLR expression on dendritic cell subpopulations and monocytes. Serum-soluble TLRs were measured by ELISA. Statistical analysis considered clinical variables such as tumor type, stage, age, and gender. (4) Results: TLR expression was significantly higher in GC patients, except for TLR3 on classical monocytes. Soluble forms of all TLRs were elevated in GC patients, with significant differences based on disease stage but not tumor type, except for serum TLR2, TLR4, and TLR9. (5) Conclusions: Elevated TLR expression and soluble TLR levels in GC patients suggest a role in tumor pathogenesis and progression, offering potential biomarkers and therapeutic targets.

A bacterial immunity protein directly senses two disparate phage proteins.

Eukaryotic innate immune systems use pattern recognition receptors to sense infection by detecting pathogen-associated molecular patterns, which then triggers an immune response. Bacteria have similarly evolved immunity proteins that sense certain components of their viral predators, known as bacteriophages1-6. Although different immunity proteins can recognize different phage-encoded triggers, individual bacterial immunity proteins have been found to sense only a single trigger during infection, suggesting a one-to-one relationship between bacterial pattern recognition receptors and their ligands7-11. Here we demonstrate that the antiphage defence protein CapRelSJ46 in Escherichia coli can directly bind and sense two completely unrelated and structurally different proteins using the same sensory domain, with overlapping but distinct interfaces. Our results highlight the notable versatility of an immune sensory domain, which may be a common property of antiphage defence systems that enables them to keep pace with their rapidly evolving viral predators. We found that Bas11 phages harbour both trigger proteins that are sensed by CapRelSJ46 during infection, and we demonstrate that such phages can fully evade CapRelSJ46 defence only when both triggers are mutated. Our work shows how a bacterial immune system that senses more than one trigger can help prevent phages from easily escaping detection, and it may allow the detection of a broader range of phages. More generally, our findings illustrate unexpected multifactorial sensing by bacterial defence systems and complex coevolutionary relationships between them and their phage-encoded triggers.

Effect of a loss of the mda5/ifih1 gene on the antiviral resistance in a Chinook salmon Oncorhynchus tshawytscha cell line.

Cells are equipped with intracellular RIG-like Receptors (RLRs) detecting double stranded (ds)RNA, a molecule with Pathogen-Associated Molecular Pattern (PAMPs) generated during the life cycle of many viruses. Melanoma Differentiation-Associated protein 5 (MDA5), a helicase enzyme member of the RLRs encoded by the ifih1 gene, binds to long dsRNA molecules during a viral infection and initiates production of type I interferon (IFN1) which orchestrates the antiviral response. In order to understand the contribution of MDA5 to viral resistance in fish cells, we have isolated a clonal Chinook salmon Oncorhynchus tshawytscha epithelial-like cell line invalidated for the ifih1 gene by CRISPR/Cas9 genome editing. We demonstrated that IFN1 induction is impaired in this cell line after infection with the Snakehead Rhabdovirus (SHRV), the Salmon Alphavirus (SAV) or Nervous Necrosis Virus (NNV). The cell line, however, did not show any increase in cytopathic effect when infected with SHRV or SAV. Similarly, no cytopathic effect was observed in the ifih1-/- cell line when infected with Infectious Pancreatic Necrosis Virus (IPNV), Infectious Haemorrhagic Necrotic Virus (IHNV). These results indicate the redundancy of the antiviral innate defence system in CHSE-derived cells, which helps with circumventing viral evasion strategies.

RIPK2 is crucial for the microglial inflammatory response to bacterial muramyl dipeptide but not to lipopolysaccharide.

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.

Extracellular plant subtilases dampen cold-shock peptide elicitor levels.

Recognizing pathogen-associated molecular patterns on the cell surface is crucial for plant immunity. The proteinaceous nature of many of these patterns suggests that secreted proteases play important roles in their formation and stability. Here we demonstrate that the apoplastic subtilase SBT5.2a inactivates the immunogenicity of cold-shock proteins (CSPs) of the bacterial plant pathogen Pseudomonas syringae by cleaving within the immunogenic csp22 epitope. Consequently, mutant plants lacking SBT5.2a activity retain higher levels of csp22, leading to enhanced immune responses and reduced pathogen growth. SBT5.2 sensitivity is influenced by sequence variation surrounding the cleavage site and probably extends to CSPs from other bacterial species. These findings suggest that variations in csp22 stability among bacterial pathogens are a crucial factor in plant-bacteria interactions and that pathogens exploit plant proteases to avoid pattern recognition.

Damage-associated molecular patterns in bacteraemic infection, including a comparative analysis with bacterial DNA, a pathogen-associated molecular pattern

Damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs) are key triggers of inflammation in sepsis. However, they have rarely been studied simultaneously. Thus, in the present study of patients with bacteraemic infection, we aimed to study how DAMP dynamics are linked to disease severity and outcome and to compare diagnostic and prognostic properties of a DAMP and a previously analysed PAMP (16S rDNA). In a prospective study of adult patients hospitalized with culture-proven community-onset bacteraemic infection, caused by Streptococcus pneumonia (n = 30), Staphylococcus aureus (n = 27), or Escherichia coli (n = 26), dynamics of a PAMP, i.e. 16S rDNA, have previously been presented. For the present study, blood samples obtained on hospital days 1–2 (when blood culture was positive), 3–4, 7 ± 1, 14 ± 2, and 28 ± 4 were analysed for four different DAMPs, i.e., nuclear DNA (nDNA), mitochondrial DNA (mtDNA), heat shock protein 90 alpha (HSP90α), and extracellular high mobility group box 1 (HMGB1). Sepsis was defined according to the Sepsis-3 criteria. The study outcomes were sepsis at admission and negative outcome, defined as intensive care unit (ICU) admission and/or death within 60 days. Of 83 study patients, sepsis was noted in 41 patients (49%) and a negative outcome was noted in 17 patients (20%). nDNA had areas under the receiver operating characteristic (ROC) curves of 0.78 for sepsis and 0.76 for negative outcome, which were higher than those of the other DAMPs and additional biomarkers (CRP, IL-6, IL-8, and IL-10). The nDNA and positive 16S rDNA results on day 1–2 were correlated with each other (r = 0.68, p < 0.001). Multivariate analyses showed that high day 1–2 concentrations of both nDNA and 16S rDNA were independently associated with sepsis. In addition, high day 1–2 concentration of nDNA was independently associated with negative outcomes. While 16S rDNA dissipated from the circulation within days, nDNA concentrations remained elevated throughout the follow-up period in patients with negative outcome. In conclusion, nDNA outperformed the other DAMPs regarding sepsis detection and outcome prediction. Both nDNA (a DAMP) and 16S rDNA (a PAMP) were independently linked to sepsis; nDNA was also associated with negative outcomes and persisted elevated in such cases. This highlights nDNA as an interesting marker within sepsis pathogenesis and as a promising clinical biomarker, warranting further studies.

Unlocking Toll-Like Receptors: Targeting Therapeutics for Respiratory Tract Infections and Inflammatory Disorders

Abstract: The Toll-like Receptors (TLRs) family has significantly enhanced the understanding of innate immune responses by identifying and responding to various microbes or host-derived organisms. TLRs contribute to these responses by increasing the levels of cytokines, interleukins, and other inflammatory mediators through multiple pathways. Located both intracellularly and on the surface of various cells and tissues, including vascular smooth muscles (VSMs) and myocardium cells, TLRs play distinct roles in innate immune activation, such as recognizing pathogen-associated molecular patterns (PAMPs) and activating downstream signaling pathways. In the context of COVID-19, TLRs are critically involved in the pathophysiology by mediating excessive inflammatory responses that exacerbate disease severity, influencing both the acute phase and long-term outcomes. It has been observed that inflammatory diseases such as atherosclerosis, viral myocarditis, and other comorbidities associated with the spread of COVID-19 have increased, although the exact mechanisms remain not fully understood. Nonetheless, there is evidence of TLR-mediated increased pro-inflammatory signaling by different mechanisms in these diseases. This review explains the role of TLRs in various inflammatory diseases related to COVID-19, including viral myocarditis, acute lung infections, and atherosclerosis. Furthermore, the review discusses various herbal drugs, such as Platycodon grandiflorum, Acanthopanax senticosus, Scutellaria baicalensis Georgi, and Engelhardia roxburghiana, and their mechanisms of action on TLRs, including NF-κB, MyD88-dependent, MyD88-independent pathways, and Plasmacytoid DCs. Enhanced clarity on TLRs' specific contributions to COVID-19 pathophysiology and stronger evidence supporting herbal interventions targeting TLRs could improve the impact and applicability of these findings in clinical settings.

Recognition of phylogenetically diverse pathogens through enzymatically amplified recruitment of RNF213.

Innate immunity senses microbial ligands known as pathogen-associated molecular patterns (PAMPs). Except for nucleic acids, PAMPs are exceedingly taxa-specific, thus enabling pattern recognition receptors to detect cognate pathogens while ignoring others. How the E3 ubiquitin ligase RNF213 can respond to phylogenetically distant pathogens, including Gram-negative Salmonella, Gram-positive Listeria, and eukaryotic Toxoplasma, remains unknown. Here we report that the evolutionary history of RNF213 is indicative of repeated adaptation to diverse pathogen target structures, especially in and around its newly identified CBM20 carbohydrate-binding domain, which we have resolved by cryo-EM. We find that RNF213 forms coats on phylogenetically distant pathogens. ATP hydrolysis by RNF213's dynein-like domain is essential for coat formation on all three pathogens studied as is RZ finger-mediated E3 ligase activity for bacteria. Coat formation is not diffusion-limited but instead relies on rate-limiting initiation events and subsequent cooperative incorporation of further RNF213 molecules. We conclude that RNF213 responds to evolutionarily distant pathogens through enzymatically amplified cooperative recruitment.

Metabolic energetic adaptation of Atlantic salmon phagocytes to changes in carbon sources and exposure to PAMPs

Phagocytic cells are pivotal for host homeostasis and infection defense, necessitating metabolic adaptations in glycolysis, the tricarboxylic acid (TCA) cycle, and oxidative phosphorylation (OXPHOS). While mammalian phagocytes shift towards glycolysis and glutaminolysis during polarization, research on fish phagocyte metabolic reprogramming is limited. To address this, the Atlantic salmon phagocytic cell line, SHK-1, serves as a valuable model. Using the Seahorse XFe96 Flux Analyzer, this study compares SHK-1 bioenergetics under glucose-restricted (L-15 medium) and glucose-supplemented (PM) conditions, providing insights into metabolic characteristics and responses to Piscirickettsia salmonis bacterium Pathogen-associated molecular patterns (PAMPs). A standardized protocol for the study of real-time changes in the metabolism study of SHK-1 in PM and L-15 media, determining oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) is shown. Exhibiting metabolic adaptations, SHK-1 cells in the PM medium have higher basal and maximal OCR and spare capacity (SRC), while those grown in the L-15 medium favor OXPHOS, showing minimal glycolytic function. Despite metabolic differences, intracellular ATP levels are comparable, highlighting the metabolic plasticity and adaptability of SHK-1 cells to various carbon sources. Exposure to PAMPs from Piscirickettsia salmonis induces a metabolic shift, increasing glycolysis and OXPHOS, influencing ATP, lactate, glutamine, and glutamate levels. These findings highlight the role of mitochondrial bioenergetics and metabolic plasticity in salmon phagocytes, offering novel nutritional strategies for host-pathogen interventions based on energy metabolism.

Molecular mechanisms of emerging inflammasome complexes and their activation and signaling in inflammation and pyroptosis.

Inflammasomes are multi-protein complexes that assemble within the cytoplasm of mammalian cells in response to pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs), driving the secretion of the pro-inflammatory cytokines IL-1β and IL-18, and pyroptosis. The best-characterized inflammasome complexes are the NLRP3, NAIP-NLRC4, NLRP1, AIM2, and Pyrin canonical caspase-1-containing inflammasomes, and the caspase-11 non-canonical inflammasome. Newer inflammasome sensor proteins have been identified, including NLRP6, NLRP7, NLRP9, NLRP10, NLRP11, NLRP12, CARD8, and MxA. These inflammasome sensors can sense PAMPs from bacteria, viruses and protozoa, or DAMPs in the form of mitochondrial damage, ROS, stress and heme. The mechanisms of action, physiological relevance, consequences in human diseases, and avenues for therapeutic intervention for these novel inflammasomes are beginning to be realized. Here, we discuss these emerging inflammasome complexes and their putative activation mechanisms, molecular and signaling pathways, and physiological roles in health and disease.