Search Results (243)

The immune response triggered when plant cell surface receptors recognize pathogen-associated molecular patterns (PAMPs) is known as PAMP-triggered immunity (PTI). Several studies have demonstrated that extracellular plant ferredoxin-like protein (PFLP) can enhance PTI signaling, thereby conferring resistance to bacterial diseases in various plants. The C-terminal casein kinase II (CK2) phosphorylation region of PFLP is essential for strengthening PTI. However, whether phosphorylation at this site directly enhances PTI signaling and consequently increases plant disease resistance remains unclear. To investigate this, site-directed mutagenesis was used to generate PFLPT90A, a non-phosphorylatable mutant, and PFLPT90D, a phospho-mimetic mutant, for functional analysis. Based on the experimental results, none of the recombinant proteins were able to enhance the hypersensitive response induced by the HrpN protein or increase resistance to the soft rot pathogen Pectobacterium carotovorum subsp. carotovorum ECC17. These findings suggest that phosphorylation at the T90 residue might be essential for PFLP-mediated enhancement of plant immune responses, implying that this post-translational modification is likely required for its disease resistance function in planta. To further explore the relationship between PFLP phosphorylation and endogenous CK2, the Arabidopsis insertion mutant cka2 and the complemented line CKA2R were analyzed under treatment with flg22_Pst from Pseudomonas syringae pv. tomato. The effects of PFLP on the hypersensitive response, rapid oxidative burst, callose deposition, and susceptibility to soft rot confirmed that CK2 is required for these immune responses. Furthermore, expression analysis of PTI-related genes FRK1 and WRKY22/29 in the mitogen-activated protein kinase (MAPK) signaling pathway demonstrated that CK2 is necessary for PFLP to enhance flg22_Pst-induced immune signaling. Taken together, these findings suggest that PFLP enhances A. thaliana resistance to bacterial soft rot primarily by promoting the MAPK signaling pathway triggered by PAMP recognition, with CK2-mediated phosphorylation being essential for its function. Full article

Preterm premature rupture of membranes (pPROM) is a leading cause of preterm birth (PTB) and is increasingly recognized for its association with neurodevelopmental disorders (NDDs). The disruption of fetal membrane integrity introduces potential infection and inflammation into the intrauterine environment, triggering immune responses that may affect fetal development. Placental inflammation plays a pivotal role in mediating these effects, exposing the fetus to cytokines, oxidative stress, and potential microbial insults that contribute to adverse neurodevelopmental outcomes. This review examines the current evidence of the mechanistic pathways linking pPROM-induced placental inflammation to NDDs, emphasizing the roles of pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) in the inflammatory responses. We discuss how these immune activations lead to immune cell recruitment and excessive (or uncontrolled) production of inflammatory mediators, leading to an overall inflammatory imbalance that has been linked to disrupted fetal brain development in animal models. Animal models provide critical insights into how both sterile and pathogenic placental inflammation alter fetal neurodevelopment, while human studies, though limited, highlight promising biomarkers and potential therapeutic targets. This review identifies critical knowledge gaps and outlines future directions to mitigate the impact of placental inflammation on long-term infant health. Full article

Sepsis is a life-threatening syndrome characterized by a dysregulated immune response to infection, frequently leading to multiorgan failure and high mortality. Inflammasomes—cytosolic multiprotein complexes of the innate immune system—serve as critical platforms for sensing pathogen- and damage-associated molecular patterns (PAMPs and DAMPs). Key sensors such as NLRP3, AIM2, and IFI16 initiate caspase-1 activation, IL-1β and IL-18 maturation, and gasdermin D–mediated pyroptosis. In sepsis, excessive inflammasome activation drives oxidative stress, endothelial dysfunction, immunothrombosis, and immune exhaustion. This maladaptive cascade is further aggravated by the release of DAMPs and procoagulant factors, compromising vascular integrity and immune homeostasis. Prolonged activation contributes to immunoparalysis, lymphopenia, and increased susceptibility to secondary infections. Inflammasome signaling also intersects with necroptosis and ferroptosis, amplifying systemic inflammation and tissue injury. Additionally, various pathogens exploit immune evasion strategies to modulate inflammasome responses and enhance virulence. Therapeutic interventions under investigation include selective NLRP3 inhibitors, IL-1 blockers, gasdermin D antagonists, and extracorporeal cytokine hemoadsorption. Emerging approaches emphasize biomarker-guided immunomodulation to achieve personalized therapy. While preclinical studies have shown promising results, clinical translation remains limited. Targeting inflammasomes may offer a path toward precision immunotherapy in sepsis, with potential to reduce organ dysfunction and improve survival. Full article

Oxidative stress is key in immune defense against fungal infections, such as those caused by Sporothrix schenckii, the dimorphic fungus responsible for sporotrichosis. Phagocytic cells utilize oxidative stress as a crucial mechanism to control pathogen spread. During S. schenckii infection, phagocytic cells recognize pathogen-associated molecular patterns (PAMPs) on their surface through conserved transmembrane or soluble receptors, known as pattern recognition receptors (PRRs). This recognition triggers a cascade of immune responses, including the generation reactive oxygen species (ROS) essential for pathogen elimination. However, S. schenckii has developed sophisticated mechanisms to evade and counteract this response, contributing to its persistence in the host. These mechanisms include the production of antioxidant enzymes, alterations to its cell wall (CW), and the production of melanin, which helps neutralize oxidative stress. In addition, S. schenckii modulates the production of other proteins, such as moonlighting proteins, suggested to have roles in immune evasion and stress response, helping its survival in the host. These strategies, along with the modulation of gene expression, allow the fungus to survive and persist inside the immune system’s hostile environment, facilitating the progression of the infection. Understanding these interactions between phagocytic cells and S. schenckii is key to developing more effective therapeutic strategies to combat sporotrichosis. Full article

Guanylate-binding proteins (GBPs), encompassing GBP1 through GBP7 in humans, are interferon-inducible large GTPases of the dynamin superfamily, renowned for their pivotal roles in cell-autonomous immunity against intracellular pathogens such as viruses, bacteria, and protozoa. By recognizing pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs), GBPs orchestrate lysosomal targeting, regulate inflammatory cascades, and modulate apoptosis to protect host tissues from immune-mediated damage. Beyond their foundational roles in immunity, GBPs exhibit context-dependent effects in human cancer, promoting malignancy in some tumors through enhanced immune signaling, inhibition of apoptosis, and resistance to therapies, or suppressing tumor growth through immune activation and cell cycle regulation. This comprehensive review explores the structural intricacies, immune functions, and multifaceted contributions of human GBPs to cancer, delving into their molecular mechanisms, prognostic potential, and therapeutic implications. We incorporate the latest insights to highlight how understanding GBP regulation could reshape cancer treatment strategies. Full article

As an evolutionarily conserved and ubiquitous mechanism of host defense, non-immune cells in vertebrates possess the intrinsic ability to autonomously detect and combat intracellular pathogens. This process, termed cell-autonomous immunity, is distinct from classical innate immunity. In this review, we comprehensively examine the defense mechanisms employed by non-immune cells in response to intracellular pathogen invasion. We provide a detailed analysis of the cytosolic sensors that recognize aberrant nucleic acids, lipopolysaccharide (LPS), and other pathogen-associated molecular patterns (PAMPs). Specifically, we elucidate the molecular mechanisms underlying key signaling pathways, including the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, the retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs)-mitochondrial antiviral signaling (MAVS) axis, and the guanylate-binding proteins (GBPs)-mediated pathway. Furthermore, we critically evaluate the involvement of these pathways in the pathogenesis of various diseases, including autoimmune disorders, inflammatory conditions, and malignancies, while highlighting their potential as therapeutic targets. Full article

Orf virus (ORFV) is the type species of Parapoxvirus of the Poxviridae family that induces cutaneous pustular skin lesions in sheep and goats, and causes zoonotic infections in humans. Pattern recognition receptors (PRRs) sense pathogen-associated molecular patterns (PAMPs), leading to the triggering of the innate immune response through multiple signalling pathways involving type I interferons (IFNs). The major PAMPs generated during viral infection are nucleic acids, which are the most important molecules that are recognized by the host. The induction of type l IFNs leads to activation of the Janus kinase (JAK)-signal transducer activator of transcription (STAT) pathway, which results in the induction of hundreds of interferon-stimulated genes (ISGs), many of which encode proteins that have antiviral roles in eliminating virus infection and create an antiviral state. Genetic and functional analyses have revealed that ORFV, as found for other poxviruses, has evolved multiple immunomodulatory genes and strategies that manipulate the innate immune sensing response. Full article

The primary objective of this study was to identify and characterize pathogen defense proteins in the Nicotiana tabacum L. proteome, focusing on their structural, functional, and evolutionary properties, as well as their interactions with pathogen-derived molecules. Specifically, we aimed to comprehensively analyze the proteome to pinpoint potential uncharacterized defense-related protein that has emerging roles in immune responses and antioxidant activity across plants and animals. Through integrated computational approaches, we determined evolutionary relationships, and structural modeling of the selected protein was performed using different modeling software, followed by validation through multiple metrics, including stereochemical checks (Ramachandran plot), MolProbity analysis, and Z-scores. We further investigated the functional binding regions or interaction sites. We performed molecular docking to investigate the molecular interactions between selected proteins and pathogen-associated molecular patterns (PAMPs), specifically β-glucan and peptidoglycan (PGN), to elucidate their defensive mechanisms. Last, normal mode analysis (NMA), molecular dynamics simulation (MDS), and post-simulation analyses were employed to evaluate the stability and mobility of the protein–ligand complexes. Uncharacterized vitellogenin-like protein (VLP: ID A0A1S4CXB2) with the potential defense domain chosen because of its predicted immune-related features, stress response patterns, and unknown pathogen role at new immunity functions. Phylogenetic analysis revealed significant sequence homology with VLPs from other members of the Solanaceae family. Structural modeling showed a high-quality model, with docking studies indicating a stronger affinity for PGN (−10.16 kcal/mol) and β-glucan (−7.19 kcal/mol), highlighting its potential involvement in pathogen defense. NMA, MDS, and post-simulation analyses revealed that PGN exhibits more substantial binding stability and more extensive interactions with VLP than β-glucan. Our findings confirmed that VLPs in N. tabacum may function as pattern recognition receptors (PRRs), capable of recognizing and responding to pathogens by activating immune signaling pathways. Future experimental validation of these interactions could further elucidate the role of VLPs in plant defense and their potential application in biotechnological approaches for sustainable agriculture. Full article

The innate immune response, particularly the interferon-mediated pathway, serves as the first line of defense against viral infections. During virus infection, viral pathogen-associated molecular patterns (PAMPs) are recognized by host pattern recognition receptors (PRRs), triggering downstream signaling pathways. This leads to the activation of transcription factors like IRF3, IRF7, and NF-κB, which translocate to the nucleus and induce the production of type I interferons (IFN-α and IFN-β). Once secreted, type I interferons bind to their receptors (IFNARs) on the surfaces of infected and neighboring cells, activating the JAK-STAT pathway. This results in the formation of the ISGF3 complex (composed of STAT1, STAT2, and IRF9), which translocates to the nucleus and drives the expression of interferon-stimulated genes (ISGs). Some ISGs exert antiviral effects by directly or indirectly blocking infection and replication. Among these ISGs, ISG15 plays a crucial role in the ISGylation process, a ubiquitin-like modification that tags viral and host proteins, regulating immune responses and inhibiting viral replication. However, viruses have evolved counteractive strategies to evade ISG15-mediated immunity and ISGylation. This review first outlines the PAMP-PRR-induced pathways leading to the production of cytokines and ISGs, followed by a summary of ISGylation’s role in antiviral defense and viral evasion mechanisms targeting ISG15 and ISGYlation. Full article

Background: The Catharanthus roseus receptor-like kinase 1-like (CrRLK1L) subfamily, a specialized group within receptor-like kinases (RLKs), was initially identified in C. roseus cell cultures. CrRLK1L plays an important role in the growth, development and stress response of plants. Although CrRLK1L genes have been characterized across multiple plant species, their biological and genetic functions in potatoes (Solanum tuberosum) remains poorly elucidated. Methods: a genome-wide investigation, phylogenetic analysis, chromosome localization, exon–intron structure, conserved motifs, stress-responsive cis-elements, tissue-specific expression patterns, and their effects on pathogen associated molecular patterns (PAMPs) induced reactive oxygen species (ROS) production were analyzed. Results: A total of 29 CrRLK1L genes were identified in the S. tuberosum genome, unevenly distributed across 10 chromosomes and divided into three groups. Tissue-specific expression analysis revealed seven genes highly expressed in all tissues, while CrRLK1L13 was specific to stamens and flowers. Under stress conditions (mannitol, salt, hormone, and heat), StCrRLK1L genes exhibited diverse expression patterns. Functional characterization in Nicotiana benthamiana identified seven ROS suppressors and four ROS enhancers, implicating their roles in PAMP-triggered immunity. Conclusions: This study provides valuable insights into the StCrRLK1L gene family, enhancing our understanding of its functions, particularly in plant innate immunity. Full article

The ubiquitination and degradation of proteins are widely involved in plant biotic and abiotic stress responses. E3 ubiquitin ligases play an important role in the ubiquitination of specific proteins. In this study, we identified the function of a U-box E3 ubiquitin ligase gene OsPUB57 in rice. Expression analyses revealed that OsPUB57 was mainly expressed in the aboveground part of rice. Drought, salt, cold, JA (jasmonic acid), PAMPs (pathogen-associated molecular patterns) or Magnaportheoryzae treatment could significantly suppress the expression of OsPUB57 in rice. Compared with wild-type plants, OsPUB57-overexpressing plants showed a decrease in resistance to M. oryzae, while the mutant plants exhibited an enhancement of M. oryzae resistance. The expression level detection indicated that OsPUB57 negatively regulates rice blast resistance, probably by down-regulating the expression of the defense-related genes OsPR1a and OsAOS2. This study provides a candidate gene for the genetic improvement of rice blast resistance. Full article

Obesity affects the adaptability of adipose tissue (AT), impairing its ability to regulate energy and metabolism. Obesity is associated with many metabolic disorders, including dyslipidemia, hypertension, sleep disorders, non-alcoholic liver disease, and some types of cancer. Toll-like receptors (TLRs) are important in obesity and related metabolic disorders. TLRs are pattern-recognizing receptors (PRRs) involved in the innate immune system and recognize pathogen-associated molecular patterns (PAMPs) and endogenous ligands. TLRs, especially TLR2 and TLR4, are activated by fatty acids, endotoxins, and other ligands. TLR2 and TLR4 activation triggers inflammatory responses. Chronic inflammation driven by TLR activation is a hallmark of obesity and metabolic diseases. The inflammatory response triggered by TLR activation alters insulin signaling, contributing to insulin resistance, a key feature of metabolic syndrome and type 2 diabetes. Modulation of TLR activity through lifestyle changes (diet and exercise), obesity surgery, and pharmacological agents is under study as a possible therapeutic approach to controlling obesity and its complications. Full article

The progression of COVID-19 involves a sophisticated and intricate interplay between the SARS-CoV-2 virus and the host’s immune response. The immune system employs both innate and adaptive mechanisms to combat infection. Innate immunity initiates the release of interferons (IFNs) and pro-inflammatory cytokines, while the adaptive immune response involves CD4+ Th lymphocytes, B lymphocytes, and CD8+ Tc cells. Pattern recognition receptors (PRRs) recognize pathogen-associated molecular patterns (PAMPS) and damage-associated molecular patterns (DAMPs), activating the cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes (cGAS-STING) signaling pathway, a crucial component of the innate immune response to SARS-CoV-2. This pathway fulfills a dual function during infection. In the early phase of infection, the virus can suppress cGAS-STING signaling to avoid immune detection. However, in the late stages, the activation of this pathway may trigger excessive inflammation and tissue damage, exacerbating disease severity. Modulating the cGAS-STING pathway, whether through agonists like dimeric amidobenzimidazole (diABZI) or inhibitors targeting viral proteins, such as 3CLpro, for example, offers a promising approach for personalized therapy to control the immune response and mitigate severe inflammation, ultimately improving clinical outcomes in patients with severe COVID-19. Full article

Interactions between bacteriophages with mammalian immune cells are of great interest and most phages possess at least one molecular pattern (nucleic acid, sugar residue, or protein structure) that is recognizable to the immune system through pathogen associated molecular pattern (PAMP) receptors (i.e., TLRs). Given that phages reside in the same body niches as bacteria, they share the propensity to stimulate or quench immune responses depending on the nature of their interactions with host immune cells. While most in vitro research focuses on the outcomes of direct application of phages to immune cells of interest, the potential impact of their transcytosis through the intestinal barrier has yet to be considered. As transcytosis through intestinal cells is a necessary step in healthy systems for access by phage to the underlying immune cell populations, it is imperative to understand how this step may play a role in immune activation. We compared the activation of macrophages (as measured by TNFα secretion) following direct phage application to those stimulated by incubation with phage transcytosed through a polarized Caco2 epithelial barrier model. Our results demonstrate that phages capable of activating TNFα secretion upon direct contact maintain the stimulatory capability following transcytosis. Furthermore, activation of macrophages by a transcytosed phage is enhanced as compared to that occurring with an equivalent multiplicity of directly applied phage. Full article

The study of nutritional compounds with the potential to train the innate immune response has implications for human health. The objective of the current study was to discover by what means 6 weeks of oral baker’s yeast beta glucan (BYBG) supplementation altered the mRNA expression of genes that reflect innate immune training in the absence of a physical stressor. Nineteen adults were randomly assigned to either a Wellmune^® BYBG or Placebo for 6 weeks. BYBG uniquely altered the expression of 40 mRNAs associated with Dectin-1 and trained innate immunity, the innate immune response, the pathogen-associated (PAMP) and damage-associated molecular pattern (DAMP), and the inflammatory response. The observed changes were classified as immune training rather than immune priming due to the progressive increase in the expression of myeloid immune-associated mRNA. Combined with the findings of previous research, the findings of the present study support the claim that oral BYBG supplementation may be associated with trained innate immunity during resting homeostasis. Further, the key findings associated with BYBG may reflect improved responsiveness to future infection (exogenous) and/or sterile-inflammatory (endogenous) challenge. Full article