Pattern Recognition Receptors Research Articles

Alternaria solani core effector Aex59 is a new member of the Alt a 1 protein family and is recognized as a PAMP

Early blight caused by Alternaria solani is a destructive disease in potato production. Here, through systematically screening of an effector protein pool consisting of 115 small cysteine-containing candidate Aex (Alternariaextracellular proteins) in A. solani, we identified a core effector protein named Aex59, a pathogen-associated molecular pattern (PAMP) molecule. Aex59 is uniquely present in the Ascomycota of fungi and can activate defense responses in multiple plants. Targeted gene disruption showed that Aex59 is a virulence factor and participates in spore development. Perception of Aex59 in Nicotiana benthamiana does not depend on the receptor-like kinases Brassinosteroid-associated kinase1 (BAK1) and Suppressor of BIR1-1 (SOBIR1), which are required for multiple pattern recognition receptors (PRR) pathways. Sequence analysis revealed that Aex59 is a new member of the Alt a 1 protein family and is a potential molecular marker capable of aiding in the classification of the fungi Alternaria spp.

IL-18 signaling is regulated by caspase 6/8 and IL-18BP in turbot (Scophthalmus maximus)

Interleukin (IL)-18 is synthesized as a precursor that requires intracellular processing to become functionally active. In human, IL-18 is processed by caspase 1 (CASP1). In teleost, the maturation and signal transduction mechanisms of IL-18 are unknown. We identified two IL-18 variants, IL-18a and IL-18b, in turbot. IL-18a, but not IL-18b, was processed by CASP6/8 cleavage. Mature IL-18a bound specifically to IL-18 receptor (IL-18R) α-expressing cells and induced IL-18Rα—IL-18Rβ association. Bacterial infection promoted IL-18a maturation in a manner that required CASP6 activation and correlated with gasdermin E activation. The mature IL-18a induced proinflammatory cytokine expression and enhanced bacterial clearance. IL-18a-mediated immune response was suppressed by IL-18 binding protein (IL-18BP), which functioned as a decoy receptor for IL-18a. IL-18BP also functioned as a pathogen pattern recognition receptor and directly inhibited pathogen infection. Our findings revealed unique mechanism of IL-18 maturation and conserved mechanism of IL-18 signaling and regulation in turbot, and provided new insights into the regulation and function of IL-18 related immune signaling.

Nonreducing Sugar Scaffold Enables the Development of Immunomodulatory TLR4‐specific LPS Mimetics with Picomolar Potency

AbstractInnate immune defense mechanisms against infection and cancer encompass the modulation of pattern recognition receptor (PRR)‐mediated inflammation, including upregulation of various transcription factors and the activation of pro‐inflammatory pathways important for immune surveillance. Dysfunction of PRRs‐mediated signaling has been implicated in cancer and autoimmune diseases, while the overactivation of PRRs‐driven responses during infection can lead to devastating consequences such as acute lung injury or sepsis. We used crystal structure‐based design to develop immunomodulatory lipopolysaccharide (LPS) mimetics targeting one of the ubiquitous PRRs, Toll‐like Receptor 4 (TLR4). Taking advantage of an exo‐anomeric conformation and specific molecular shape of synthetic nonreducing β,β‐diglucosamine, which was investigated by NMR, we developed two sets of lipid A mimicking glycolipids capable of either potently activating innate immune responses or inhibiting pro‐inflammatory signaling. Stereoselective 1,1′‐glycosylation towards fully orthogonally protected nonreducing GlcNβ(1↔1′)βGlcN followed by stepwise assembly of differently functionalised phosphorylated glycolipids provided biologically active molecules that were evaluated for their ability to trigger or to inhibit cellular innate immune responses. Two LPS mimetics, identified as potent TLR4‐specific inducers of the intracellular signaling pathways, serve as vaccine adjuvant‐ and immunotherapy candidates, while anionic glycolipids with TLR4‐inhibitory potential hold therapeutic promise for the management of acute or chronic inflammation.

Optimal development of apoptotic cells-mimicking liposomes targeting macrophages

Macrophages are multifunctional innate immune cells that play indispensable roles in homeostasis, tissue repair, and immune regulation. However, dysregulated activation of macrophages is implicated in the pathogenesis of various human disorders, making them a potential target for treatment. Through the expression of pattern recognition and scavenger receptors, macrophages exhibit selective uptake of pathogens and apoptotic cells. Consequently, the utilization of drug carriers that mimic pathogenic or apoptotic signals shows potential for targeted delivery to macrophages. In this study, a series of mannosylated or/and phosphatidylserine (PS) -presenting liposomes were developed to target macrophages via the design of experiment (DoE) strategy and the trial-and-error (TaE) approach. The optimal molar ratio for the liposome formulation was DOPC: DSPS: Chol: PEG-PE = 20:60:20:2 based on the results of cellular uptake and cytotoxicity evaluation on RAW 264.7 and THP-1 in vitro. Results from in vivo distribution showed that, in the DSS-induced colitis model and collagen II-induced rheumatoid arthritis model, PS-presenting liposomes (PS-Lipo) showed the highest accumulation in intestine and paws respectively, which holds promising potential for macrophage target therapy since macrophages are abundant at inflammatory sites and contribute to the progression of corresponding diseases. Organs such as the heart, liver, spleen, lung, and kidney did not exhibit histological alterations such as inflammation or necrosis when exposed to PC-presenting liposomes (PC-Lipo) or PS-Lipo. In addition, liposomes demonstrated hemobiocompatibility and no toxicity to liver or kidney for circulation and did not induce metabolic injury in the animals. Thus, the well-designed PS-Lipo demonstrated the most potential for macrophage target therapy.

Identification of Nonsynonymous SNPs in Immune-Related Genes Associated with Pneumonia Severity in Pigs.

We previously showed that several polymorphisms in genes encoding pattern recognition receptors that cause amino acid substitutions alter pathogen recognition ability and disease susceptibility in pigs. In this study, we expanded our analysis to a wide range of immune-related genes and investigated polymorphism distribution and its influence on pneumonia in multiple commercial pig populations. Among the polymorphisms in 42 genes causing 634 amino acid substitutions extracted from the swine genome database, 80 in 24 genes were found to have a minor allele frequency of at least 10% in Japanese breeding stock pigs via targeted resequencing. Of these, 62 single nucleotide polymorphisms (SNPs) in 23 genes were successfully genotyped in 862 pigs belonging to four populations with data on pneumonia severity. Association analysis using a generalized linear mixed model revealed that 12 SNPs in nine genes were associated with pneumonia severity. In particular, SNPs in the cellular receptor for immunoglobulin G FCGR2B and the intracellular nucleic acid sensors IFI16 and LRRFIP1 were found to be associated with mycoplasmal pneumonia of swine or porcine pleuropneumonia in multiple populations and may therefore have wide applications in the improvement of disease resistance in pigs. Functional analyses at the cellular and animal levels are required to clarify the mechanisms underlying the effects of these SNPs on disease susceptibility.

Molecular characterization and gene expression of pattern recognition receptors in brown-marbled grouper (Epinephelus fuscoguttatus) fingerlings responding to vibriosis infection

The pathogen recognition system involves receptors and genes that play a crucial role in activating innate immune response in brown-marbled grouper (Epinephelus fuscoguttatus) as a control agent against various infections including vibriosis. Here, we report the molecular cloning of partial open reading frames, sequences characterization, and expression profiles of Pattern Recognition Receptors (PRRs) in brown-marbled grouper. The PRRs, namely pglyrp5, tlr5, ctlD, and ctlE in brown-marbled grouper, possess conserved domains and showed shared evolutionary relationships with other fishes, humans, mammals, birds, reptilians, amphibians, and insects. In infection experiments, up to 50% mortality was found in brown-marbled grouper fingerlings infected with Vibrio alginolyticus compared to 27% mortality infected Vibrio parahaemolyticus and 100% survival of control groups. It is also demonstrated that all four PRRs had higher expression in samples infected with V. alginolyticus compared to V. parahaemolyticus. This PRRs gene expression analysis revealed that all four PRRs expressed rapidly at 4-h post-inoculation even though the Vibrio count was only detected earliest at 12-h post-inoculation in samples. The highest expression recorded was from V. alginolyticus inoculated fish spleen with up to 73-fold change for pglyrp5 gene, followed by 14 to 38-fold expression for the same treatment in spleen, head kidney, and blood samples for other PRRs, namely tlr5, ctlD, and ctlE genes. Meanwhile less than a 10% increase in expression of all four genes was detected in spleen, head kidney, and blood samples inoculated with V. parahaemolyticus. These findings indicated that pglyrp5, tlr5, ctlD, and ctlE play important roles in the early immune response to vibriosis infected, brown-marbled grouper fingerlings.

Hypoxia represses pattern-triggered immune responses in Arabidopsis.

Biotic and abiotic stresses frequently co-occur in nature, yet relatively little is known about how plants co-ordinate the response to combined stresses. Protein degradation by the ubiquitin/proteasome system is central to the regulation of multiple independent stress response pathways in plants. The Arg/N-degron pathway is a subset of the ubiquitin/proteasome system that targets proteins based on their N termini and has been specifically implicated in the responses to biotic and abiotic stresses, including hypoxia, via accumulation of group VII ETHYLENE RESPONSE FACTOR (ERF-VII) transcription factors that orchestrate the onset of the hypoxia response program. Here, we investigated the role of the Arabidopsis (Arabidopsis thaliana) Arg/N-degron pathway in mediating the crosstalk between combined abiotic and biotic stresses using hypoxia treatments and the flg22 elicitor of pattern-triggered immunity (PTI), respectively. We uncovered a link between the plant transcriptional responses to hypoxia and flg22. Combined hypoxia and flg22 treatments showed that hypoxia represses the flg22 transcriptional program, as well as the expression of pattern recognition receptors, mitogen-activated protein kinase (MAPK) signalling and callose deposition during PTI through mechanisms that are mostly independent from the ERF-VIIs. These findings improve our understanding of the trade-offs between plant responses to combined abiotic and biotic stresses in the context of our efforts to increase crop resilience to global climate change. Our results also show that the well-known repressive effect of hypoxia on innate immunity in animals also applies to plants.

ISGylation enhances dsRNA-induced interferon response and NFκB signaling in fallopian tube epithelial cells

Heritable mutations in BRCA1 associate with increased risk of high-grade serous tubo-ovarian cancer (HGSTOC). Non-genetic risk factors associated with this cancer, which arises from fallopian tube epithelial (FTE) cells, suggests a role for repetitive ovulation wherein FTE cells are exposed to inflammatory signaling molecules within follicular fluid. We previously reported increased NFκB and EGFR signaling in BRCA1-deficient primary FTE cells, with follicular fluid exposure further increasing abundance of interferon-stimulated gene (ISG) transcripts, including the ubiquitin-like protein ISG15 and other ISGylation pathway members. Both NFκB and type I interferon signaling are upregulated by stimulation of cGAS-STING or MDA5 and RIGI pattern recognition receptors (PRRs). Since some PRRs and their signal transduction pathway members are ISGylated, we tested the impact of ISG15 and ISGylation on IRF3 and NFκB signaling through cGAS-STING or RIGI and MDA5 activation. Expression of ISG15 or UBA7, the E1-like ISG15 activating enzyme, in immortalized FTE cells was disrupted by CRISPR gene editing. Activation of IRF3 by RIGI or MDA5 but not cGAS-STING was attenuated by loss of either ISG15 or UBA7 and this was reflected by a similar effect on NFκB activation and downstream targets. Loss of ISGylation decreased levels of both MDA5 and RIGI, with knock-down of RIGI but not MDA5, decreasing IRF3 and NFκB activation in parental cells. These finding indicate that ISGylation enhances the ability of dsRNA to activate cytokine release and pro-inflammatory signaling. Further work to explore ISGylation as a target for prevention of HGSTOC in BRCA1 mutation carriers is warranted.

Immunobiological effects of lipopolysaccharide derived from Helicobacter pylori and influence of a proton pump inhibitor lansoprazole on human polymorphonuclear leukocytes.

Helicobacter pylori colonizes the human gastric mucosa of more than half of the human population and has a unique lipopolysaccharide (LPS) structure. LPS is the most dominant and suitable pathogen-associated molecular pattern that is detected via pattern recognition receptors. Although the priming effect of H. pylori LPS on reactive oxygen species (ROS) production of PMNs is lower than that of Escherichia coli O111:B4 LPS, LPS released from H. pylori associated with antibiotics eradication therapy may activate PMNs and increase ROS production. In addition, we describe the effects of H. pylori and E. coli O111:B4 LPSs on gene expression and the anti-inflammatory effect of lansoprazole (LPZ) in human polymorphonuclear leukocytes. LPS isolated from H. pylori and E. coli O111:B4 alters toll-like receptor 2 (TLR) and TLR4 expressions similarly. However, LPS from E. coli O111:B4 and H. pylori caused a 1.8-fold and 1.5-fold increase, respectively, in CD14 expression. All LPS subtypes upregulated TNFα and IL6 expression in a concentration-dependent manner. Although E. coli O111:B4 LPS upregulated IL8R mRNA levels, H. pylori LPS did not (≦ 100ng/mL). Gene expression levels of ITGAM demonstrated no significant change on using both LPSs. These different effects on the gene expression in PMNs may depend on variations in LPS structural modifications related to the acquired immunomodulatory properties of H. pylori LPS. Proton pump inhibitors, i.e., LPZ, are used in combination with antibiotics for the eradication therapy of H. pylori. LPZ and its acid-activated sulphenamide form AG-2000 suppress ROS production of PMNs in a dose-dependent manner. These results suggest that LPZ combination with antibiotics for H. pylori eradication reduces gastric inflammation by suppressing ROS release from PMNs.

Salmonid Rickettsial Septicemia (SRS) disease dynamics and Atlantic salmon immune response to Piscirickettsia salmonis LF-89 and EM-90 co-infection

In Chile, Piscirickettsia salmonis contains two genetically isolated genogroups, LF-89 and EM-90. However, the impact of a potential co-infection with these two variants on Salmonid Rickettsial Septicemia (SRS) in Atlantic salmon (Salmo salar) remains largely unexplored. In our study, we evaluated the effect of P. salmonis LF-89-like and EM-90-like co-infection on post-smolt Atlantic salmon after an intraperitoneal challenge to compare changes in disease dynamics and host immune response. Co-infected fish had a significantly lower survival rate (24.1%) at 21 days post-challenge (dpc), compared with EM-90-like single-infected fish (40.3%). In contrast, all the LF-89-like single-infected fish survived. In addition, co-infected fish presented a higher presence of clinical lesions than any of the single-infected fish. The gene expression of salmon immune-related biomarkers evaluated in the head kidney, spleen, and liver showed that the EM-90-like isolate and the co-infection induced the up-regulation of cytokines (e.g., il-1β, ifnγ, il8, il10), antimicrobial peptides (hepdicin) and pattern recognition receptors (PRRs), such as TLR5s. Furthermore, in serum samples from EM-90-like and co-infected fish, an increase in the total IgM level was observed. Interestingly, specific IgM against P. salmonis showed greater detection of EM-90-like antigens in LF-89-like infected fish serum (cross-reaction). These data provide evidence that P. salmonis LF-89-like and EM-90-like interactions can modulate SRS disease dynamics in Atlantic salmon, causing a synergistic effect that increases the severity of the disease and the mortality rate of the fish. Overall, this study contributes to achieving a better understanding of P. salmonis population dynamics.

Therapeutic Targeting of Pattern Recognition Receptors to Modulate Inflammation in Atherosclerosis.

Atherosclerosis (AS), a potentially fatal cardiovascular disease (CVD), is a chronic inflammatory condition. The disease's onset and progression are influenced by inflammatory and immunological mechanisms. The innate immune pathways are essential in the progression of AS, as they are responsible for detecting first danger signals and causing long-term changes in immune cells. The innate immune system possesses distinct receptors known as pattern recognition receptors (PRRs) which can identify both pathogen-associated molecular patterns and danger-associated molecular signals. Activation of PRRs initiates the inflammatory response in various physiological systems, such as the cardiovascular system. This review specifically examines the contribution of the innate immune response and PRRs to the formation and advancement of AS. Studying the role of these particular receptors in AS would enhance our understanding of the development of AS and offer novel approaches for directly improving the inflammatory response associated with it.

Targeting Tumor-Associated Macrophages with the Immune-Activating Nanomedicine for Achieving Strong Antitumor Activity with Rapid Clearance from the Body.

Toll-like receptors (TLRs) are a class of pattern recognition receptors (PRRs) crucial for the detection of infections and activation of downstream signaling pathways that lead to the production of pro-inflammatory cytokines and interferons. The TLR pathway is an attractive actively studied target pathway. Because of their strong immunostimulatory activity, TLRs are thought to be a "double-edged sword" for systemic treatment, even in the cancer field. To solve this, we have developed dextran-based TAM targeting activating conjugate (D-TAC) technology, which successfully uses tumor-associated macrophages (TAMs) to deliver the TLR7 agonist DSP-0509. We used low molecular weight dextran to target CD206 high M2-type macrophages, activate them, and induce a change in phenotype to antitumor M1-type macrophages with rapid clearance from the body and astonishing antitumor activity. We also demonstrated that the antitumor effect of our best drug candidate 5DEX-0509R is dependent on the abundance of TAMs, which is consistent with their mechanism of action. We believe that 5DEX-0509R generated by D-TAC technology can be a clinically applicable immunotherapy targeting the TLR signaling pathway.

Alloreactive memory CD4 T cells promote transplant rejection by engaging DCs to induce innate inflammation and CD8 T cell priming

Alloreactive memory T cells have been implicated as central drivers of transplant rejection. Perplexingly, innate cytokines, such as IL-6, IL-1β, and IL-12, are also associated with rejection of organ transplants. However, the pathways of innate immune activation in allogeneic transplantation are unclear. While the role of microbial and cell death products has been previously described, we identified alloreactive memory CD4 T cells as the primary triggers of innate inflammation. Memory CD4 T cells engaged MHC II-mismatched dendritic cells (DCs), leading to the production of innate inflammatory cytokines. This innate inflammation was independent of several pattern recognition receptors and was primarily driven by TNF superfamily ligands expressed by alloreactive memory CD4 T cells. Blocking of CD40L and TNFα resulted in dampened inflammation, and mice genetically deficient in these molecules exhibited prolonged survival of cardiac allografts. Furthermore, myeloid cell and CD8 T cell infiltration into cardiac transplants was compromised in both CD40L- and TNFα-deficient recipients. Strikingly, we found that priming of naive alloreactive CD8 T cells was dependent on licensing of DCs by memory CD4 T cells. This study unravels the key mechanisms by which alloreactive memory CD4 T cells contribute to destructive pathology and transplant rejection.

Plant resistance to pathogens as a result of gene interaction

Modern information on the genomics of plants and plants’ pathogens as well the achievements of molecular biology have made it possible to state the participation of gene products, proteins, in the organization of molecular complexes that are assembled to implement a certain character of the phenotype. The character of plant “resistance/sensitivity” to a certain biotic factor is also interesting because there is an interaction not only between the genes of one organism, but between the genes of organisms that lie in different kingdoms of life.Plant resistance to pathogens can be passive (provided mainly by characters of plant morphology) and active. Active resistance is formed as a result of the penetration of the pathogen or its elicitors and effectors into the plant. Active protection of the plant at the molecular level is expressed in the launch of the MAPK cascade, the accumulation of reactive oxygen species, and an increase in the flow of calcium ions to the cell. Active protection can be implemented on two levels. The first level, RTI (PAMP Triggered Immunity), develops in response to plant contact with a wide range of non-adapted pathogens. The resistance (immunity) that is formed in this case is called non-specific, or horizontal, or quantitative. The molecular instrument for initiating the defensive reaction is the PRR (Pattern Recognition Receptors). Adapted pathogens are able to overcome RTI by sending effectors to plant cells. These are protein molecules whose function is to create conditions within the cell that are more permissive to the pathogen. The effector can be recognized by the plant’s specific NLR (Nod-Like Receptors), and complementation occurs between the two. There are other specific plant molecules, nonNLR, with a different type of protein product interaction for recognition. In both cases, the second level of protection, ETI (Effector Triggered Immunity), develops. The set of molecular processes that occur at the second level of protection does not differ from the set of the first level, but the processes occur more intensively and are accompanied by the death of the affected cells. This prevents the further spread of the pathogen throughout the plant. The molecular events of the first and second levels of protection are not isolated. The interaction between them involving the products of plant genes and pathogen genes is described by the “zig-zag-zig”-model, invasion model, and the integrated iceberg model. The interaction of plant genes for effector recognition is described by the “guard” and “decoy” models. To initiate a defensive reaction, plant receptors, which can sometimes differentiate into sensors and helpers, form protein complexes, resistosomes.

Molecular identification and functional characterization of a C-type lectin gene in Meretrix meretrix

C-type lectins (CTLs) are a kind of Ca2+-dependent immunoreactive factors, which participated in pathogens recognition and defense. The present study identified a new CTL from hard clam Meretrix meretrix (designated as MmCTL4). The full-length of MmCTL4 cDNA was 608 bp, encoding a presumed signal peptide of 19 bp and a carbohydrate recognition domain (CRD) of 131 bp. The tertiary structure of recombinant MmCTL4 protein (rMmCTL4) was the typical long double-ring structure with three conserved disulfide bonds, and the motifs in Ca2+-binding sites of MmCTL4 were QPN and WSD. The SYBR Green real-time PCR analysis indicated that MmCTL4 was widely expressed in the hemocytes, hepatopancreas and mantle of healthy clams. After Vibrio splendidus stimulation, the temporal expression profile of MmCTL4 mRNA in hemocytes and hepatopancreas increased by 7.8-fold at 6 hpi and 3.9-fold at 12 hpi, respectively. The cDNA fragments encoding MmCTL4 were recombined into pET-32a (+) vectors, and transformed into Escherichia coli BL21 (DE3). The rMmCTL4 with the presence of Ca2+ performed obvious hemagglutination activity, and could agglutinate E. coli, Bacillus subtilis, and Staphylococcus aureus, while it only weakly agglutinate Vibrio parahaemolyticus and fungi P. pastoris. The agglutination activity of rMmCTL4 were significantly inhibited by D-mannose, D-xylose, D-lactose, maltose and lipopolysaccharides. These results indicated that MmCTL4, as a class of typical pattern recognition receptors (PRRs), could protect the host against pathogen invasion in the innate immunity of clams.

Defect in Migration of HSPCs in Nox-2 Deficient Mice Explained by Impaired Activation of Nlrp3 Inflammasome and Impaired Formation of Membrane Lipid Rafts.

NADPH oxidase 2 (Nox2), a superoxide-generating enzyme, is a source of reactive oxygen species (ROS) that regulate the intracellular redox state, self-renewal, and fate of hematopoietic stem/progenitor cells (HSPCs). Nox2 complex expressed on HSPCs associated with several activated cell membrane receptors increases the intracellular level of ROS. In addition, ROS are also released from mitochondria and, all together, are potent activators of intracellular pattern recognition receptor Nlrp3 inflammasome, which regulates the trafficking, proliferation, and metabolism of HSPCs. In the current study, we noticed that Nox2-deficient mice, despite the increased number of HSPCs in the bone marrow (BM), show hematopoietic defects illustrated by delayed recovery of peripheral blood (PB) hematopoietic parameters after sublethal irradiation and mobilize fewer HSPCs after administration of G-CSF and AMD3100. Moreover, Nox2-deficient HSPCs engraft poorly after transplantation into normal syngeneic recipients. To explain these defects at the molecular level, we hypothesized that Nox2-KO decreased ROS level does not efficiently activate Nlrp3 inflammasome, which plays a crucial role in regulating the trafficking of HSPCs. Herein, we report Nox2-deficient HSPCs display i) defective migration to major chemoattractant, ii) impaired intracellular activation of Nlrp3 inflammasome, and iii) a defect in membrane lipid raft (MLRs) formation that is required for a proper chemotactic response to pro-migratory factors. We conclude that Nox2-derived ROS enhances in Nlrp3 inflammasome-dependent manner HSPCs trafficking by facilitating MLRs assemble on the outer cell membranes, and defect in Nox2 expression results in impaired activation of Nlrp3 inflammasome, which affects HSPCs migration.

Dual transcriptomic analysis reveals early induced Castanea defense-related genes and Phytophthora cinnamomi effectors.

Phytophthora cinnamomi Rands devastates forest species worldwide, causing significant ecological and economic impacts. The European chestnut (Castanea sativa) is susceptible to this hemibiotrophic oomycete, whereas the Asian chestnuts (Castanea crenata and Castanea mollissima) are resistant and have been successfully used as resistance donors in breeding programs. The molecular mechanisms underlying the different disease outcomes among chestnut species are a key foundation for developing science-based control strategies. However, these are still poorly understood. Dual RNA sequencing was performed in C. sativa and C. crenata roots inoculated with P. cinnamomi. The studied time points represent the pathogen's hemibiotrophic lifestyle previously described at the cellular level. Phytophthora cinnamomi expressed several genes related to pathogenicity in both chestnut species, such as cell wall-degrading enzymes, host nutrient uptake transporters, and effectors. However, the expression of effectors related to the modulation of host programmed cell death (elicitins and NLPs) and sporulation-related genes was higher in the susceptible chestnut. After pathogen inoculation, 1,556 and 488 genes were differentially expressed by C. crenata and C. sativa, respectively. The most significant transcriptional changes occur at 2 h after inoculation (hai) in C. sativa and 48 hai in C. crenata. Nevertheless, C. crenata induced more defense-related genes, indicating that the resistant response to P. cinnamomi is controlled by multiple loci, including several pattern recognition receptors, genes involved in the phenylpropanoid, salicylic acid and ethylene/jasmonic acid pathways, and antifungal genes. Importantly, these results validate previously observed cellular responses for C. crenata. Collectively, this study provides a comprehensive time-resolved description of the chestnut-P. cinnamomi dynamic, revealing new insights into susceptible and resistant host responses and important pathogen strategies involved in disease development.

A β-1,3/1,6-glucan enhances anti-tumor effects of PD1 antibody by reprogramming tumor microenvironment

Checkpoint blockades have emerged as a frontline approach in cancer management, designed to enhance the adaptive immune response against tumors. However, its clinical efficacy is limited to a narrow range of tumor types, which necessitates the exploration of novel strategies that target another main branch of the immune system. One such potential strategy is the therapeutic modulation of pattern recognition receptors (PRRs) pathways in innate immune cells, which have shown promise in tumor eradication. Previously, a β-1,3/1,6-glucan with high purity from Durvillaea antarctica (BG136) was reported by our group to exhibit pan-antitumor effects. In the current study, we systemically studied the antitumor activity of BG136 in combination with anti-PD1 antibody in MC38 syngeneic tumor model in vivo. Integrated transcriptomic and metabolomic analyses suggested that BG136 enhanced the antitumor immunity of anti-PD1 antibody by reprogramming the tumor microenvironment to become more proinflammatory. In addition, an increase in innate and adaptive immune cell infiltration and activation, enhanced lipid metabolism, and a decrease in ascorbate and aldarate metabolism were also found. These findings provide mechanistic insights that support the potent antitumor efficacy of BG136 when combined with immune checkpoint inhibitor antibodies.

Polysaccharides isolated from Hibiscus sabdariffa L. mitigate intestinal radiation injury through relieving mucosal inflammation and reshaping gut microbiota in mice

Hibiscus sabdariffa L. (H. sabdariffa) shows considerable promise in alleviating oxidative stress injury through its rich content of phytochemicals, especially polysaccharides, yet its efficacy in treating intestinal radiation injury remains unclear. Here, we purified one water-soluble polysaccharides from H. sabdariffa (HSP1), and subsequently explored its role in relieving intestinal radiation injury via a mouse model of abdominal irradiation. The results demonstrated that HSP1 intervention effectively improved gut barrier function by restoring mucus secretion and upregulating tight junction proteins. Additionally, HSP1 mitigated oxidative stress through Nrf2/HO-1 pathway and reduced the inflammatory response through restraining the activation of pattern recognition receptors. Moreover, HSP1 modulated the balance of gut microbiota by suppressing pathogenic bacteria, while promoting the growth of beneficial symbiotic bacteria such as Lactobacillus, Ligilactobacillus, and Lachnospiraceae_NK4A136. Altogether, this study highlights the protective potential of HSP1 against intestinal radiation injury, providing primary data for further applications of H. sabdariffa polysaccharides as radioprotectors.

Mitochondrial Dysfunction is a Crucial Immune Checkpoint for Neuroinflammation and Neurodegeneration: mtDAMPs in Focus.

Neuroinflammation is a pivotal factor in the progression of both age-related and acute neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, and stroke. Mitochondria, essential for neuronal health due to their roles in energy production, calcium buffering, and oxidative stress regulation, become increasingly susceptible to dysfunction under conditions of metabolic stress, aging, or injury. Impaired mitophagy in aged or injured neurons leads to the accumulation of dysfunctional mitochondria, which release mitochondrial-derived damage-associated molecular patterns (mtDAMPs). These mtDAMPs act as immune checkpoints, activating pattern recognition receptors (PRRs) and triggering innate immune signaling pathways. This activation initiates inflammatory responses in neurons and brain-resident immune cells, releasing cytokines and chemokines that damageadjacenthealthy neurons and recruit peripheral immune cells, furtheramplifying neuroinflammation and neurodegeneration. Long-term mitochondrial dysfunction perpetuates a chronic inflammatory state, exacerbating neuronal injury and contributing additional immunogenic components to the extracellular environment. Emerging evidence highlights the critical role of mtDAMPs in initiating and sustaining neuroinflammation, with circulating levels of these molecules potentially serving as biomarkers for disease progression. This review explores the mechanisms of mtDAMP release due to mitochondrial dysfunction, their interaction with PRRs, and the subsequent activation of inflammatory pathways. We also discuss the role of mtDAMP-triggered innate immune responses in exacerbating bothacute and chronic neuroinflammation and neurodegeneration. Targeting dysfunctional mitochondria and mtDAMPs with pharmacological agents presents a promising strategy for mitigating the initiation and progression of neuropathological conditions.