Immune Receptors Research Articles

Role of innate immune receptors in the psoriasis development

Psoriasis is an immune-mediated autoimmune inflammatory skin disease with a prevalence of 2 to 3% worldwide. In the psoriasis development and pathogenesis an important role is played by disorders in the immune system. Disruption of the innate and adaptive immune response mechanisms with the involvement of keratinocytes leads to the initiation and maintenance of inflammation. Immune reactions are activated in the skin, in which various cells participate (macrophages, dendritic cells, mast cells, innate immune lymphoid cells, melanocytes, keratinocytes, Langerhans cells and γδT cells; T and B cells; epithelial endothelial and stromal cells of the skin), each of which expresses pattern recognition receptors that respond to pathogens and cell damage itself. Many of these receptors, in particular toll-like receptors and NOD-like receptors play an important role in the pathogenesis of psoriasis. The associated innate receptors signaling cascades that activate in the skin cells may become potential targets for the treatment of this disease. To date, there are several approved drugs for biological therapy of psoriasis. The study of the role of the innate immune cells receptors in inflammatory skin pathologies requires further exploration and new developments.

In silico Designing of a Multi-epitope-based Subunit Vaccine against SARS-CoV-2 (Delta Variant) by Exploiting Its Structural Proteins: A Reverse Vaccinomics and Immunoinformatics Approach

Background: The continuously emerging novel strains of SARS-CoV-2 remain a menace to the global population. The vicious delta variant (originated in India) is considered one of the most infectious/contagious variants of SARS-CoV-2. The transmission frequency of this variant is 225% higher than other variants, extending its prevalence and causing a massive surge in the COVID-19 pandemic. It is also the most ravenous variant among others. Objective: Though the delta variant has already disappeared, it could re-emerge/come out at any time with a more powerful strike than earlier. Therefore, to tackle such ferocity, this research is undertaken with a next-generation vaccine development strategy to design a multi-epitope-based subunit vaccine against the delta variant of SARS-CoV-2, which might boost the body's immunity. Materials and Methods: In the present investigation, reverse vaccinomics and immunoinformatics approaches were adopted to create an immune-stimulating prospective vaccine candidate having B cell, helper T cell (Th)/helper T lymphocyte (HTL), cytotoxic T cell (Tc)/cytotoxic T lymphocyte (CTL), and interferon-gamma (IFN-γ) inducing epitopes by exploiting the SARS-CoV-2 (delta variant) (GenBank: MZ724536.1) structural proteins: envelope glycoprotein (E), nucleocapsid phosphoprotein (N), surface glycoprotein (S), and membrane glycoprotein (M). The established vaccine construct was then completed by combining antigenic epitopes with adjuvants and linkers. Subsequently, the 3D model of the suggested vaccine was created and docked with an immune receptor (Toll-Like Receptor-4). A molecular dynamics (MD) simulation study was performed to confirm the binding stability between the vaccine conjugate and TLR4. Later, an immune simulation study was carried out to predict the in silico immune response of the vaccine candidate. To effectively express the developed vaccine in a bacterial system (E. coli), in silico codon optimization and cloning were done in an expression vector to manufacture it on a large scale. Results: According to the computational analysis, the vaccine candidate was found to be highly antigenic while maintaining favorable properties for the human body. Molecular docking and dynamics simulation study between the suggested vaccine construct and TLR4 immune receptor depicted it as extremely efficient and stable, ensuring a proper immunological response within the host cell. Eventually, an in silico immune simulation study of the vaccine candidate demonstrated a robust immune response to vaccine administration. Conclusion: We have hypothesized that the constructed vaccine model is benign, stable, and immunogenic, making it a promising/potent candidate for immune system stimulation against SARSCOV- 2 (DV). Hereof, wet lab-based investigations are needed to justify the competence of the novel vaccine candidate towards the delta variant along with other variants of SARS-CoV-2.

Introducing Degradable Cationic Nanogels Carrying TLR9 Stimulating Oligonucleotides.

Cationic, core-crosslinked nanogel particles are prepared from synthetic biodegradable materials. These fully hydrophilic nanogels offer superior customizability compared to common lipid nanoparticles, thereby circumventing intrinsic immune stimulatory properties. Electrostatic loading allows for complexation of nucleic acids including the immune stimulatory Toll-like receptor 9 (TLR9) agonistCpG-ODN (cytidine-phosphate-guanosine oligodeoxynucleotide). Only when complexed inside nanogels, one can control CpG-ODN's biodistribution, prevent systemic toxicity, and increase bioavailability at target locations. Nanogels are prepared from cyclic aliphatic carbonate monomers with reactive pentafluorophenyl (PFP) esters. First, block copolymers are acquired via cationic ring opening polymerization (CROP) onto polyethylene glycol (PEG). Upon self-assembly in ethanol, the micelles' core is cationically core-crosslinked, and the resulting fully hydrophilic particles exhibit sizes of ≈20nm, also upon loading with CpG-ODN. In vitro, they promote intracellular delivery devoid of carrier-related toxicities, while retaining the immune stimulatory properties of the TLR agonist cargo. In vivo, the nanogels reduce systemic liver immune responses and remain near the injection site. Additionally, delivery into cDC1 (conventional dentritic cells type 1) antigen-presenting cells, which are highly relevant for antitumoral T-cell immune responses, is confirmed. Altogether, cationic, core-crosslinked polycarbonate nanogels show promise for nucleic acid delivery, showcasing controlled immunostimulatory cargo delivery and an enhanced hydrolytic biodegradability profile, highly valuable for cancer immunotherapy.

Cooperative tumor inhibition by CpG-oligodeoxynucleotide and cyclic dinucleotide in head and neck cancer involves T helper cytokine and macrophage phenotype reprogramming

Head and neck cancer ranks as the sixth most common cancer worldwide, highlighting the critical need for the development of new therapies to enhance treatment efficacy. The activation of innate immune receptors given their potent immune stimulatory properties aid in the eradication of cancer cells. In this study, we investigated the immune mechanism and anti-tumor function of a Toll-like receptor 9 (TLR9) agonist, CpG-oligodeoxynucleotide-2722 (CpG-2722), in combination with cyclic dinucleotides, which are agonists of stimulator of interferon genes (STING). Our results revealed that CpG-2722 stimulation increased the expression of Th1 pro-inflammatory cytokines. Stimulation by STING agonists exhibited lower expression of Th1 cytokines but higher expression of Th2 cytokines compared to CpG-2722. However, the combination of these two agonists significantly enhanced Th1 cytokines while reducing Th2 cytokines. Moreover, in vivo experiment showed that both CpG-2722 and 2'3'-c-di-AMP suppressed head and neck tumor growth, with their combination proving more effective than the use of these agonists alone. The combined treatment cooperatively promoted the production of Th1 cytokines and type I interferons, while suppressing Th2 cytokines in the tumors as observed in vitro. Additionally, it led to the accumulation of M1 macrophages, dendritic cells, and T cells, shaping a favorable tumor microenvironment for T cell-mediated tumor killing. The anti-tumor activity of the CpG-2722 and 2'3'-c-di-AMP combination depends on the macrophage presence but does not directly activate M1 macrophage polarization, instead working through a reprogrammed cytokine profile. Furthermore, this combination shows a cooperative anti-tumor activity with anti-PD-1 in treating head and neck tumors. Overall, these findings highlight a Th response and macrophage phenotype reprograming involved functional mechanism underlying the cooperative activity of the combination of TLR9 and STING agonists in the immunotherapy of head and neck cancer.

Prognostic significance of soluble forms of the PD-1 receptor and its ligand PD-L1 in gastric cancer

Introduction. Despite advances in the diagnosis and drug therapy of some cancers over the past decade, solid tumors, particularly gastric cancer, still have a poor prognosis and remain a leading cause of death worldwide. Therefore, the development of methods for timely diagnosis, identification of new targets for therapy and biochemical prognosis factors is an urgent problem in clinical oncology. In recent years, the focus of clinical attention has been on immune checkpoint receptors and ligands that can identify patients for immunotherapy. The clinical and prognostic significance of the levels of soluble forms of the programmed cell death receptor PD-1 and its ligand PD-L1 in the blood of patients with gastric cancer is currently not fully determined.Aim. Comparative study of the levels of sPD-1 and sPD-L1 in the blood plasma of healthy donors and patients with gastric cancer, taking into account the prevalence of the tumor process and the prognosis of overall survival.Materials and methods. The study included 100 patients with stomach cancer aged from 25 to 81 years (57 men, 43 women), who underwent examination and treatment at the N. N. Blokhin National Medical Research Center for Oncology. The concentration of sPD-L1 and sPD-1 was determined in blood plasma obtained according to standard methods before the start of specific treatment, using reagent kits for enzyme-linked immunosorbent assay “Human PD-L1 Platinum ELISA” and “Human PD-1 ELISA kit” (Affimetrix, eBioscience, USA) in accordance with the manufacturer’s instructions. The content of markers was expressed in picograms (pg) per 1 ml of blood plasma. To compare indicators and analyze their relationships, the nonparametric Mann–Whitney test was used. Overall survival analysis was performed using the Kaplan–Meier method. For all statistical tests, p values <0.05 were considered statistically significant.Results. The analysis did not reveal a connection at a threshold level of sPD-1 of 8.0 pg / ml in the blood plasma of patients with gastric cancer with overall survival rates (p = 0.59). However, an additional analysis conducted in a group of patients with gastric cancer with stages I–II demonstrated that a marker level ≥8.0 pg / ml is a favorable prognostic factor (p = 0.0039), while in advanced stages III–IV the disease it has no prognostic significance. There was no significant correlation between sPD-L1 concentrations in the blood plasma of patients with gastric cancer and overall survival rates (p = 0.35), however, the best long-term results were found at a threshold level of marker concentrations in blood plasma <35 pg / ml.Conclusion. An sPD-1 level ≥8.0 pg / ml can serve as a favorable prognostic factor in stages I–II of gastric cancer, while in advanced stages III–IV of the disease it has no prognostic significance. The prognostic role of sPD-L1 in patients with gastric cancer has not been identified. The study needs to be continued in combination with additional predictive biomarkers for gastric cancer.

The role of inhibitory immune checkpoint receptors in the pathogenesis of Alzheimer's disease.

There is mounting evidence that microglial cells have a key role in the pathogenesis of Alzheimer's disease (AD). In AD pathology, microglial cells not only are unable to remove β-amyloid (Aβ) plaques and invading pathogens but also are involved in synaptic pruning, chronic neuroinflammation, and neuronal degeneration. Microglial cells possess many different inhibitory immune checkpoint receptors, such as PD-1, LILRB2-4, Siglecs, and SIRPα receptors, which can be targeted by diverse cell membrane-bound and soluble ligand proteins to suppress the functions of microglia. Interestingly, in the brains of AD patients there are elevated levels of many of the inhibitory ligands acting via these inhibitory checkpoint receptors. For instance, Aβ oligomers, ApoE4, and fibronectin are able to stimulate the LILRB2-4 receptors. Increased deposition of sialoglycans, e.g., gangliosides, inhibits microglial function via Siglec receptors. AD pathology augments the accumulation of senescent cells, which are known to possess a high level of PD-L1 proteins, and thus, they can evade immune surveillance. A decrease in the expression of SIRPα receptor in microglia and its ligand CD47 in neurons enhances the phagocytic pruning of synapses in AD brains. Moreover, cerebral neurons contain inhibitory checkpoint receptors which can inhibit axonal growth, reduce synaptic plasticity, and impair learning and memory. It seems that inappropriate inhibitory immune checkpoint signaling impairs the functions of microglia and neurons thus promoting AD pathogenesis. KEY MESSAGES: Microglial cells have a major role in the pathogenesis of AD. A decline in immune activity of microglia promotes AD pathology. Microglial cells and neurons contain diverse inhibitory immune checkpoint receptors. The level of ligands for inhibitory checkpoint receptors is increased in AD pathology. Impaired signaling of inhibitory immune checkpoint receptors promotes AD pathology.

Immuno-Informatics Insight into the Relationship Between Cholesterol and Cytokines in Cutaneous Leishmaniasis: From clinics to computation.

The role of serum cholesterol and its interactions with cytokines in human cutaneous leishmaniasis (CL) pathophysiology is unknown. This study aimed to evaluate the correlation among serum total cholesterol (TC), very-low-density lipoprotein cholesterol (VLDL-C), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG) and cytokines (including interleukin [IL] 10), IL-12 and tumour necrosis factor-alpha [TNF-α]) in CL. The cholesterol-cytokine network was analysed to illuminate the pathogenesis of CL. This case-control study was conducted from December 2022 to March 2023 in hospitals within Baghdad and Wasit provinces, Iraq, and included CL and CL-free subjects ranging between 20-30 years of age. The serum samples were analysed via commercial kits to detect TC, IL-10, IL-12, TNF-α, VLDL-C, LDL-C, HDL-C and TG levels. Computational efforts to dissect cholesterol-protein interaction networks were employed using STITCH. A total of 50 CL and 25 control subjects were included. The TC, HDL-C and LDL-C levels in CL patients were markedly lower (P = 0.0001) than in control subjects, whereas the IL-10, IL-12, TNF-α, VLDL-C and TG levels were higher in CL patients. Serum cholesterol showed no correlation with cytokines; however, a significant correlation (r = 0.57; P = 0.026) was observed between IL-12 and TNF-α. Within the cholesterol-protein network, cholesterol potentially interacted with IL-10, connecting cholesterol to modules with immunological significance, including TRAF1, TRAF2 and TNF receptor superfamily member 1B, as well as IL-10, IL-10RA and IL-12RB1. This study showed the alteration of lipid and lipoprotein in CL and introduced 2 immunological modules in CL, highlighting the importance of the altered cholesterol-cytokine interaction network in CL.

Immuno-oncologic profiling by stage-dependent transcriptome and proteome analyses of spontaneously regressing canine cutaneous histiocytoma.

Canine cutaneous histiocytoma (CCH) is a tumor that originates from dermal Langerhans cells and affects particularly young dogs. The common spontaneous regression of CCH makes it an interesting model in comparative oncology research. Previous studies have indicated that anti-tumor immune responses may be involved, but details remain speculative to date. Here, we asked which specific immuno-oncological dynamics underlie spontaneous regression of CCH on mRNA and protein levels. QuantSeq 3' mRNA sequencing with functional over-representation analysis and an nCounter RNA hybridization assay were employed on 21 formalin-fixed, paraffin-embedded CCH samples representing three different tumor stages (dataset information: GSE261387-Immuno-Oncologic Profiling by Stage-Dependent Transcriptome and Proteome Analyses of Spontaneously Regressing Canine Cutaneous Histiocytoma-OmicsDI). Nine additional samples were subjected to matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). Surprisingly, only minor stage-specific differences were found. When we investigated expression of B7 family ligands and CD28 family receptors holding co-stimulatory and -inhibitory functions, respectively, we found a higher abundance of CD80, CD86, CTLA4 and CD28, which may trigger a balanced activation of lymphocyte-mediated immune responses. CD80 and CD86 expressing cells were further quantified by in situ hybridization and compared with data from three cases of canine histiocytic sarcoma (HS), a malignant tumor variant originating from antigen-presenting interstitial dendritic cells. A stage-specific increase of CD80 expressing cells was recorded in CCH from the tumor bottom to the top, while CD86 was continuously and homogenously expressed at high levels. Overall expression of CD80 in CCH was similar to that in HS (73.3 ± 37.4% vs 62.1 ± 46.4%), while significantly more CD86 expressing tumor cells were found in CCH (94.7 ± 10.3%) when compared to HS (57.6 ± 11.0%). Our data suggest that major immuno-oncological pathways are not regulated during regression of CCH on the mRNA or protein levels as detectable by the methods used. Instead, our data provide further evidence supporting previous hypotheses towards a role of immune stimulatory B7 family ligands and CD28 family receptors in the regression of CCH.

Effects of a protease inhibitor camostat mesilate on gut microbial function in patients with irritable bowel syndrome: A pilot randomized placebo-controlled study

Introduction: Increased fecal protease activity which may induce visceral hypersensitivity has been observed in patients with irritable bowel syndrome (IBS). Serine proteases modulate FK506 binding protein (FKBP)-type peptidylprolyl cis-trans isomerase (PPIase) activity associated with immune and glucocorticoid receptor functions. The aims were to investigate whether camostat mesilate (CM), a serine protease inhibitor, modifies fecal bacterial function associated with FKBP-type PPIases ameliorates in patients with IBS. Methods: Randomly assigned 16 patients with IBS received 200 mg po tid of CM and 16 patients received placebo for 14 days. Self-reported adequate relief (AR) as a primary endpoint, IBS Symptom Severity Scale (IBS-SSS) and colonic motor and pain thresholds to colorectal distention were assessed before and after treatment. The fecal bacterial content was inferred from 16S rRNA gene sequence data using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. Results: CM significantly increased the relative abundance of Streptococcus and the functional abundances of serine protease and FKBP-type PPIase FklB and SlyD more than placebo after treatment. CM treatment was not superior to placebo in proportion of AR although colonic motor response partially changed. Conclusion: CM modulated the fecal microbiome composition and functional potentials that are related to FKBP-type PPIase activity in IBS patients. These findings suggest that protease inhibitors may modify gut microbial function along with abnormal immunological and/or stress responses that underlie pathophysiology of IBS.

Computer-aided rational design of a mRNA vaccine against Guanarito mammarenavirus.

Guanarito mammarenavirus (GTOV) is a highly pathogenic virus that leads to Venezuelan hemorrhagic fever (VHF). Despite being a severe disease, there are currently no commercially available drugs or vaccines for its prevention. Here we computationally formulated a mRNA vaccine construct (VC) from the genome of GTOV to produce immunity against its infections. Two proteins, namely zinc-finger motif protein (NP_899220.1), and nucleocapsid protein (NP_899211.1) were screened as potential candidates for downstream analysis. We determined the T and B cell epitopes of the candidate proteins. The resulting epitopes were analyzed, and the best epitopes were utilized in the formation of the peptide vaccine construct. The secondary and tertiary structures of the peptide construct were predicted and validated. Docking was conducted to check the binding energy of the designed peptide vaccine with the human immune receptors, namely TLR2 and TLR4. Our designed vaccine showed stable interactions with the HLA molecules, as verified through normal mode and MD simulation analysis. The immune simulation results indicated a positive immune response against the construct. A potentially stable mRNA vaccine was formulated by adding of sequences such as the Kozak, Goblin 5' UTR, tPA-signal peptide, MITD, 3' UTRs, and a poly(A) tail to the peptide vaccine construct. Lastly, the expression probability of the mRNA vaccine was confirmed in the expression system of E. coli strain K12. The designed vaccine showed the potential to elicit an immune response against the GTOV infection; however, experimental validation is recommended to verify the in-silico findings of this study.

Buprenorphine Induces Human Fetal Membrane Sterile Inflammation.

Opioid-use disorder (OUD) during pregnancy has increased in the United States to critical levels and is a leading cause of maternal morbidity and mortality. Untreated OUD is associated with pregnancy complications in particular, preterm birth. Medications for OUD, such as buprenorphine, are recommended with the added benefit that treatment during pregnancy increases treatment post-partum. However, the rate of preterm birth in individuals using illicit opioids or being treated with opioid agonist therapeutics is double that of the general population. Since inflammation in the placenta and the associated fetal membranes (FM) is a common underlying cause of preterm birth, we sought to determine if the opioid, buprenorphine, induces sterile inflammation in human FMs and to examine the mechanisms involved. Using an established in vitro human FM explant system, we report that buprenorphine significantly increased FM secretion of the inflammatory cytokine IL-6; the neutrophilic chemokine IL-8; and the inflammasome-mediated cytokine IL-1β, mirroring the inflammatory profile commonly seen at the maternal-fetal interface in preterm birth. Other factors that were elevated in FMs exposed to buprenorphine included the mediators of membrane weakening, prostaglandin E2 (PGE2), and matrix metalloproteinases, MMP1 and MMP9. Furthermore, this sterile inflammatory and weakening FM response induced by buprenorphine was mediated in part by innate immune Toll-like receptor 4 (TLR4), the NLRP3 inflammasome, the μ-opioid receptor, and downstream NFκB and ERK/JNK/MAPK signaling. This may provide the mechanistic link between opioid use in pregnancy and the elevated risk for preterm birth. Since there are adverse consequences of not treating OUD, our findings may help identify ways to mitigate the impact opioids have on pregnancy outcomes while allowing the continuation of maintenance therapy.

Roles of cathepsin S expression levels on the prognosis and tumour microenvironment in clear cell renal cell carcinoma

BackgroundIncreasing evidence suggests a link between the enzyme cathepsin S (CTSS) and tumour development. However, the potential involvement and molecular functions of CTSS in clear cell renal cell carcinoma (ccRCC) remain unclear.MethodsWe downloaded original data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases and integrated them using R. Kaplan–Meier plots of integrated expression scores were used to analyse survival outcomes. Additionally, we investigated mRNA expression, clinicopathological features, immune infiltrates, and single-cell sequencing analysis of CTSS in ccRCC. In vitro experiments were conducted with qRT-PCR and IHC staining.ResultsCTSS transcriptomic and proteomic levels were higher in ccRCC than in para-cancerous tissues. Low CTSS expression was correlated with poor prognosis in patients with ccRCC. Our data demonstrated that the expression of CTSS was strongly correlated with immune cell infiltration levels and gene markers of immune cells, chemokines, and receptors. Single-cell sequencing analysis demonstrated that CTSS expression was detectable in monocytes/macrophages. Finally, certain chemicals were confirmed to affect CTSS expression.ConclusionOur findings indicate that CTSS offers promise as a prognostic biomarker and novel immune-related therapeutic target for ccRCC.

Forced MyD88 signaling in microglia impacts the production and survival of regenerated retinal neurons.

Inflammation and microglia appear to be key factors influencing the outcome of retinal regeneration following acute retinal damage. Despite such findings, direct connection of microglia-specific inflammatory factors as drivers of regenerative responses in the retina are still not defined, and intracellular pathways activated to stimulate such signals from microglia are currently unknown. We became interested in MyD88 regulation in microglia because transcriptomic datasets suggest myd88 could be regulated temporally in zebrafish microglia responding to damage in the central nervous system. MyD88 is an intracellular molecular adaptor that initiates signaling cascades downstream of several innate immune receptors, and probably most well-known for inducing gene expression of pro-inflammatory factors. Using zebrafish, which spontaneously regenerate retinal neurons after acute retinal damage, we studied the effects of overactivation of MyD88 signaling in microglia and macrophages on the Müller glia-mediated regenerative response. Our results indicate that increased MyD88 signaling in microglia/macrophages impacts the initial response of Müller glia entering a regenerative response after acute, neurotoxin-induced retinal damage to inner retinal neurons. In addition, increased MyD88 signaling in microglia/macrophages resulted in reduced survival of inner retinal neurons in regenerated retinas. This work supports the idea that temporal control of inflammatory signaling is a key component in the production of MG-derived progenitors yet further indicates that such control is important for differentiation and survival of regenerated neurons.

A preliminary investigation on the protective effects of β-glucan and mannan induced trained immunity in pufferfish Takifugu obscurus

Immune stimuli are able to trigger long-term protective effects through mechanisms of trained immunity, which has attracted increasing attention. Although the existence of trained immunity has evidenced in teleost fish, while there were no such reports in pufferfish (Takifugu obscurus) so far. Therefore, the present study aimed to evaluate the induction of β-glucan and mannan on the trained immunity and their protective efficacy against Vibrio harveyi re-stimulation in pufferfish. β-glucan and mannan induction of trained immunity in head-kidney primary leukocytes is accompanied by a strong increase in immediate ROS burst, cumulative NO production and lactate concentrations after V. harveyi re-stimulation. In addition, β-glucan and mannan-treated pufferfish exhibited reduced bacterial loads in multiple tissues, a rapid and long-term elevated inflammatory response in head kidney during secondary V. harveyi infection. Notably, immune receptors dectin-1 and dectin-2, and cytokines tnfsf14 and il-1β exhibited comparatively upregulation to the β-glucan training, while NK-lysin and faslg showed stronger response to the mannan training post V. harveyi stimulation, implying the different signaling pathway activated post β-glucan and mannan training. Subsequent markers for immune training including abundance of genes encoding glycolytic enzymes (hk1, pfkla, and ldha) and transcription factors (mtor and hif-1α), as well as increased acetylation levels were elevated in the β-glucan and mannan trained pufferfish, depicting heightened glycolysis following β-glucan and mannan training. These results collectively demonstrated that β-glucan and mannan both induced protective responses against V. harveyi infection probably through mediating distinct signaling pathway in pufferfish, and studies are underway to harness its potential applicability for prime and boost vaccination strategies.

The wheat CC-NBS-LRR protein TaRGA3 confers resistance to stripe rust by suppressing ascorbate peroxidase 6 activity

Abstract Nucleotide-binding leucine-rich repeat (NLR) proteins are intracellular immune receptors that activate innate immune responses upon sensing pathogen attack. However, the molecular mechanisms by which NLR proteins initiate downstream signal transduction pathways to counteract pathogen invasion remain poorly understood. In this study, we identified the wheat (Triticum aestivum) NLR protein Resistance Gene Analogs3 (TaRGA3), which was significantly upregulated during Puccinia striiformis f. sp. tritici (Pst) infection. TaRGA3 and its coiled-coil (CC) domain, localized to the cytoplasm and nucleus, can induce cell death in Nicotiana benthamiana. Virus-induced gene silencing and overexpression suggested that TaRGA3 contributed to wheat resistance to stripe rust by facilitating reactive oxygen species (ROS) accumulation. Yeast 2-hybrid, luciferase complementation imaging, and co-immunoprecipitation assays revealed that TaRGA3 interacted with wheat protein Ascorbate Peroxidase 6 (TaAPX6). Further analysis showed that TaAPX6 specifically targeted the CC domain of TaRGA3. The TaRGA3–TaAPX6 interplay led to reduced enzyme activity of TaAPX6. Notably, TaAPX6 negatively regulated wheat resistance to Pst by removing excessive ROS accompanying Pst-induced hypersensitive responses. Our findings reveal that TaRGA3 responding to Pst infection confers enhanced wheat resistance to stripe rust, possibly by suppressing TaAPX6-modulated ROS scavenging, and demonstrate that TaRGA3 can be used to engineer stripe rust resistance in wheat.

The blast pathogen effector AVR-Pik binds and stabilizes rice heavy metal-associated (HMA) proteins to co-opt their function in immunity.

Intracellular nucleotide-binding domain and leucine-rich repeat-containing (NLR) receptors play crucial roles in immunity across multiple domains of life. In plants, a subset of NLRs contain noncanonical integrated domains that are thought to have evolved from host targets of pathogen effectors to serve as pathogen baits. However, the functions of host proteins with similarity to NLR integrated domains and the extent to which they are targeted by pathogen effectors remain largely unknown. Here, we show that the blast fungus effector AVR-Pik binds a subset of related rice proteins containing a heavy metal-associated (HMA) domain, one of the domains that has repeatedly integrated into plant NLR immune receptors. We find that AVR-Pik binding stabilizes the rice small HMA (sHMA) proteins OsHIPP19 and OsHIPP20. Knockout of OsHIPP20 causes enhanced disease resistance towards the blast pathogen, indicating that OsHIPP20 is a susceptibility gene (S-gene). We propose that AVR-Pik has evolved to bind HMA domain proteins and co-opt their function to suppress immunity. Yet this binding carries a trade-off, it triggers immunity in plants carrying NLR receptors with integrated HMA domains.

Machine learning model based on SERPING1, C1QB, and C1QC: A novel diagnostic approach for latent tuberculosis infection

AbstractBackgroundLatent tuberculosis infection (LTBI) is a significant source of active tuberculosis (ATB), yet distinguishing between them is challenging because specific biomarkers are lacking.MethodsWe analyzed four microarray datasets (GSE19491, GSE37250, GSE54992, GSE28623) from the gene expression omnibus to identify differentially expressed genes (DEGs). Using protein–protein interaction (PPI) networks and LASSO‐SVM algorithms, we selected three candidate biomarkers and evaluated their diagnostic efficacy. The expression levels of core genes were validated by RNA sequencing of healthy, ATB, and LTBI groups in a real‐world cohort. We conducted Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, predicted shared upstream miRNAs, constructed miRNA–hub and transcription factor (TF)–hub gene networks, and performed immune infiltration analysis.ResultsThree hub genes (SERPING1, C1QC, C1QB) were identified from 45 DEGs by PPI networks and machine learning screening. The diagnostic model based on the three hub genes had an area under the curve (AUC) value of 0.843 in the training set GSE19491 and 0.865 in the validation set GSE28623. Real‐world transcriptome sequencing confirmed the expression trends of the hub genes across healthy, LTBI, and ATB groups. GO analysis showed that the 45 hub genes were primarily associated with immune inflammatory responses and pattern recognition receptors, whereas KEGG analysis indicated enrichment in complement and coagulation cascades. The miRNA–hub and TF–hub gene network analysis identified nine miRNAs and the zinc finger TF GATA2 as potential co‐regulators of SERPING1, C1QC, and C1QB. Immune cell infiltration analysis identified significant differences in the immune microenvironment between LTBI and ATB, with macrophages and natural killer cells showing significant correlations with tuberculosis infection.ConclusionThe diagnostic model with SERPING1, C1QC, and C1QB shows promise in distinguishing LTBI from ATB, indicating its potential as a diagnostic tool.

B cell adapter for PI 3-kinase (BCAP) coordinates antigen internalization and trafficking through the B cell receptor.

B cell adapter for PI 3-kinase (BCAP) is an adaptor molecule associated with signaling through multiple immune receptors, including the B cell receptor (BCR). However, B cell-intrinsic role of BCAP in antibody responses is unclear. We investigated the role of BCAP in B cell response to viral particles and found a previously unidentified mechanism by which BCAP regulates antigen-specific responses. B cell-specific deletion of BCAP in mice leads to decreases in antigen-specific responses through defects in BCR-antigen endocytosis. BCAP is necessary to orchestrate actin reorganization around the antigen for efficient endocytosis through BCR and intracellular processing of antigens. Therefore, loss of BCAP from B cells leads to defects in antigen endocytosis, hampering the propagation of antigen-derived signals and decreasing the ability of B cells to present antigens to T cells. Thus, our study clarifies how BCAP regulates B cell responses to complex antigens and elucidates that antigen positioning inside B cells determines different B cell activation outcomes.

Diversification of molecular pattern recognition in bacterial NLR-like proteins

Antiviral STANDs (Avs) are bacterial anti-phage proteins evolutionarily related to immune pattern recognition receptors of the NLR family. Type 2 Avs proteins (Avs2) were suggested to recognize the phage large terminase subunit as a signature of phage infection. Here, we show that Avs2 from Klebsiella pneumoniae (KpAvs2) can recognize several different phage proteins as signature for infection. While KpAvs2 recognizes the large terminase subunit of Seuratvirus phages, we find that to protect against Dhillonvirus phages, KpAvs2 recognizes a different phage protein named KpAvs2-stimulating protein 1 (Ksap1). KpAvs2 directly binds Ksap1 to become activated, and phages mutated in Ksap1 escape KpAvs2 defense despite encoding an intact terminase. We further show that KpAvs2 protects against a third group of phages by recognizing another protein, Ksap2. Our results exemplify the evolutionary diversification of molecular pattern recognition in bacterial Avs2, and show that a single pattern recognition receptor evolved to recognize different phage-encoded proteins.

Immunological face of megakaryocytes.

Megakaryocytes (MKs), which are traditionally known for their role in platelet production, are now emerging as unique immune cells with diverse capabilities. They express immune receptors, participate in pathogen recognition and response, phagocytose pathogens, contribute to antigen presentation, and interact with various immune cell types. When encountering inflammatory challenges, MKs exhibit intricate immune functions that can either promote or inhibit inflammation. These responses are mediated through mechanisms, such as the secretion of either anti-inflammatory or pro-inflammatory cytokines and release of immunomodulatory platelets according to specific conditions. This intricate array of responses necessitates a detailed exploration to determine whether the immune functions of MKs are carried out by the entire MK population or by a specific subpopulation. Breakthroughs in single-cell RNA sequencing have uncovered a unique "immune MK" subpopulation, revealing its distinct characteristics and immunoregulatory functions. This review provides latest insights into MKs' immune attributes and their roles in physiological and pathological contexts and emphasizes the discovery and functions of "immune MKs".