hnRNPs in antiviral innate immunity.

During virus infection, many host proteins are redirected from their normal cellular roles to restrict and terminate infection. Heterogeneous nuclear ribonucleoproteins (hnRNPs) are cellular RNA-binding proteins critical to host nucleic acid homeostasis, but can also be involved in the viral infection process, affecting virus replication, assembly and propagation. It has become evident that hnRNPs play important roles in modulation of host innate immunity, which provides critical initial protection against infection. These novel findings can potentially lead to the leveraging of hnRNPs in antiviral therapies. We review hnRNP involvement in antiviral innate immunity, in humans, mice and other animals, and discuss hnRNP targeting as a potential novel antiviral therapeutic.

Macrophages directly kill bladder cancer cells through TNF signaling as an early response to BCG therapy.

The Bacillus Calmette-Guérin (BCG) vaccine is the oldest cancer immunotherapeutic agent in use. Despite its effectiveness, its initial mechanisms of action remain largely unknown. Here, we elucidate the earliest cellular mechanisms involved in BCG-induced tumor clearance. We developed a fast preclinical in vivo assay to visualize in real time and at single-cell resolution the initial interactions among bladder cancer cells, BCG and innate immunity using the zebrafish xenograft model. We show that BCG induced the recruitment and polarization of macrophages towards a pro-inflammatory phenotype, accompanied by induction of the inflammatory cytokines tnfa, il1b and il6 in the tumor microenvironment. Macrophages directly induced apoptosis of human cancer cells through zebrafish TNF signaling. Macrophages were crucial for this response as their depletion completely abrogated the BCG-induced phenotype. Contrary to the general concept that macrophage anti-tumoral activities mostly rely on stimulating an effective adaptive response, we demonstrate that macrophages alone can induce tumor apoptosis and clearance. Thus, our results revealed an additional step to the BCG-induced tumor immunity model, while providing proof-of-concept experiments demonstrating the potential of this unique model to test innate immunomodulators.

Tissue distribution and expression dynamics of trefoil factor genes in the hydroid Hydractinia symbiolongicarpus.

Proteins of the trefoil factor family (TFF) participate in mucosal repair and are formed by single or tandemly repeated trefoil domains. TFFs have been extensively studied in mammals and amphibians, but they have not been functionally characterized in other animals. Here we report the identification of two genes expressed in the hydroid Hydractinia symbiolongicarpus, predicted to encode trefoil domain-containing peptides, one with four trefoil domains in tandem and the other one with a trefoil domain flanked by two ShKT domains. Differential expression analyses by qPCR after an immune challenge and an induced mechanical damage, reveal that the former gene (hysyTFF) had no significant changes in expression after the inductions. However, the latter (hysyTFF-like) was overexpressed after three hours post immune challenge and was downregulated after the first hour post epithelial damage. Immunoblot analyses using specific IgY antibodies revealed that hysyTFF is secreted as a high molecular weight complex. Finally, whole mount immunofluorescence assays showed that hysyTFF was predominantly expressed in the endoderm of stolons and polyps, and sparsely in the ectoderm of both polyps and larvae. Thus, the tissue distribution and expression dynamics of trefoil factor genes in H. symbiolongicarpus suggest that hysyTFF is part of an ancient mechanism of epithelial restitution, and the newly reported hysyTFF-like might act as an immune effector gene, perhaps encoding an antibacterial peptide.

Baseline and stress-induced changes in plasma bacterial killing ability against gram-negative bacteria are partially mediated by the complement system in Rhinella diptycha toads.

The plasma bacterial killing ability (BKA) is modulated by the stress response in vertebrates, including amphibians. The complement system is an effector mechanism comprised of a set of proteins present in the plasma that once activated can promote bacterial lysis. Herein, we investigated whether changes in plasma BKA as a result of the acute stress response and an immune challenge are mediated by the complement system in Rhinella diptycha toads. Additionally, we investigated whether the observed changes in plasma BKA are associated with changes in plasma corticosterone levels (CORT). We subjected adult male toads to a restraint or an immune challenge (with three concentrations of Aeromonas hydrophila heat inactivated), and then evaluated the plasma BKA against A. hydrophila, in vitro. We determined the complement system activity on plasma BKA, by treating the plasma (baseline, 1 h and 24 h post-restraint, and after the immune challenge) with ethylenediaminetetraacetic acid, heat, or protease. Our results showed increased CORT 1 h and 24 h after restraint and decreased plasma BKA 24 h post-restraint. The inhibitors of the complement system decreased the plasma BKA compared with untreated plasma at all times (baseline, 1 h, and 24 h after restraint), demonstrating that the plasma BKA activity is partially mediated by the complement system. The immune challenge increased CORT, with the highest values being observed in the highest bacterial concentration, compared with control. The plasma BKA was not affected by the immune challenge but was demonstrated to be partially mediated by the complement system. Our results demonstrated that restraint and the immune challenge activated the hypothalamus-pituitary-interrenal axis, by increasing plasma CORT levels in R. diptycha. Also, our results demonstrated the complement system is participative in the plasma BKA for baseline and post-stress situations in these toads.

Autoimmunity in patients with inborn errors of immunity: A case series.

OBJECTIVE: To assess the prevalence of systemic and organ-specific autoimmunity among individuals with human inborn errors of immunity (IEI). METHODS: Retrospective study. We recorded demographic variables, type of immunodeficiency, and systemic and organ specific autoimmunity. RESULTS: We included 48 patients (54.1% men) with mean age of 32.1 years. The most common IEIs included combined immunodeficiency with syndromic features (31.2%) and predominantly antibody deficiency (20.1%). We observed autoimmunity in 15 patients (31.2%): 12 organ-specific autoimmunity and 5 systemic autoimmunity, not mutually exclusive groups. Organ-specific autoimmunity preceded the onset of IEI in 5 patients, was concurrent in one patient, and developed after the diagnosis of IEI in 6 cases. From the systemic autoimmunity group, we observed polyarteritis nodosa (n = 2), antiphospholipid syndrome (APS) (n = 2), and overlap of limited systemic sclerosis/APS/Sjögren's syndrome (n = 1), and in all cases, this occurred after the IEI diagnosis. CONCLUSION: Our findings confirm the coexistence of autoimmunity and IEI. This overlap may be attributed to B and T cell disorders, as well as potential alterations in the microbiota in these patients.

The Expression of Toll-like Receptors (TLR7 and TLR9) in Class III and Class IV of Recently Diagnosed Lupus Nephritis with 12-Month Follow-Up.

Renal involvement is an important cause of morbidity and mortality in systemic lupus erythematosus (SLE). The present study included patients with recently diagnosed Class III and Class IV lupus nephritis (LN) treated by Rheumatology who, upon the detection of alterations in their kidney function, were referred to Nephrology for the joint management of both medical specialties. The purpose of this study was to compare the plasma expression of Toll-Like Receptor 7 (TLR7) and TLR9 in healthy control (HC) subjects and newly diagnosed Class III and Class IV LN patients with 12-month follow-ups. The plasma expression of TLR7 and TLR9 proteins was determined by the ELISA method. A significant increase in the expression of TLR7 protein was found in Class III LN in the basal determination compared to the expression in the HC (p = 0.002) and at 12 months of follow-up (p = 0.03) vs. HC. The expression of TLR9 showed a behavior opposite to that of TLR7. TLR9 showed decreased protein expression in LN Class III patients' baseline and final measurements. The result was similar in the basal and final determinations of LN Class IV compared to the expression in HC. A significant decrease in SLEDAI -2K was observed at 12 months of follow-up in patients in Class III (p = 0.01) and Class IV (p = 0.0001) of LN. Complement C3 levels improved significantly at 12-month follow-up in Class IV patients (p = 0.0001). Complement C4 levels decreased significantly at 12-month follow-up in LN Class III compared to baseline (p = 0.01). Anti-DNA antibodies decreased significantly at 12 months of follow-up in Class IV LN (p = 0.01). A significant increase in proteinuria was found at 12 months of follow-up in Class III LN, compared to the baseline determination (p = 0.02). In LN Class IV, proteinuria decreased at 12 months of follow-up compared to baseline (p = 0.0001). Albuminuria decreased at 12 months of follow-up in LN Class IV (p = 0.006). Class IV LN, albuminuria also decreased at 12 months of follow-up (p = 0.009). Hematuria persisted in all patients and the glomerular filtration rate did not change. Three Class IV patients died before 12 months of follow-up from various causes. In conclusion, although the rheumatologic data appeared to improve, the renal function data remained inconsistent. Decreased expression of TLR9 and increased expression of TLR7 could be useful in the early diagnosis of Class III and Class IV LN is correct.

Diminazene aceturate inhibits the SARS-CoV-2 spike protein-induced inflammation involving leukocyte migration and DNA extracellular traps formation.

AIMS: To investigate the SARS-CoV-2 Spike protein (Spk)-induced inflammatory response and its downmodulation by diminazene aceturate (DIZE). MATERIALS AND METHODS: Through inducing Spk inflammation in murine models, leukocyte migration to the peritoneum, levels of myeloperoxidase (MPO), malondialdehyde (MDA), rolling and adhesion of mesenteric leukocytes, and vascular permeability were investigated. Extracellular DNA traps (DETs) induced by Spk and the production of IL-6 and TNF-α were analyzed using human neutrophils, monocytes, and macrophages. In silico assays assessed the molecular interaction between DIZE and molecules related to leukocyte migration and DETs induction. KEY FINDINGS: Spk triggered acute inflammation, demonstrated by increasing leukocyte migration. Oxidative stress was evidenced by elevated levels of MPO and MDA in the peritoneal liquid. DIZE attenuated cell migration, rolling, and leukocyte adhesion, improved vascular barrier function, mitigated DETs, and reduced the production of Spk-induced pro-inflammatory cytokines. Computational studies supported our findings, showing the molecular interaction of DIZE with targets such as ß2 integrin, PI3K, and PAD2 due to its intermolecular coupling. SIGNIFICANCE: Our results outline a novel role of DIZE as a potential therapeutic agent for mitigating Spk-induced inflammation.

PARP14 is regulated by the PARP9/DTX3L complex and promotes interferon γ-induced ADP-ribosylation.

Protein ADP-ribosylation plays important but ill-defined roles in antiviral signalling cascades such as the interferon response. Several viruses of clinical interest, including coronaviruses, express hydrolases that reverse ADP-ribosylation catalysed by host enzymes, suggesting an important role for this modification in host-pathogen interactions. However, which ADP-ribosyltransferases mediate host ADP-ribosylation, what proteins and pathways they target and how these modifications affect viral infection and pathogenesis is currently unclear. Here we show that host ADP-ribosyltransferase activity induced by IFNγ signalling depends on PARP14 catalytic activity and that the PARP9/DTX3L complex is required to uphold PARP14 protein levels via post-translational mechanisms. Both the PARP9/DTX3L complex and PARP14 localise to IFNγ-induced cytoplasmic inclusions containing ADP-ribosylated proteins, and both PARP14 itself and DTX3L are likely targets of PARP14 ADP-ribosylation. We provide evidence that these modifications are hydrolysed by the SARS-CoV-2 Nsp3 macrodomain, shedding light on the intricate cross-regulation between IFN-induced ADP-ribosyltransferases and the potential roles of the coronavirus macrodomain in counteracting their activity.

Potential Involvement of the South American Lungfish Intelectin-2 in Innate-Associated Immune Modulation.

Intelectins belong to a family of lectins with specific and transitory carbohydrate interaction capabilities. These interactions are related to the activity of agglutinating pathogens, as intelectins play a significant role in immunity. Despite the prominent immune defense function of intelectins, limited information about its structural characteristics and carbohydrate interaction properties is available. This study investigated an intelectin transcript identified in RNA-seq data obtained from the South American lungfish (Lepidosiren paradoxa), namely LpITLN2-B. The structural analyses predicted LpITLN2-B to be a homo-trimeric globular protein with the fibrinogen-like functional domain (FReD), exhibiting a molecular mass of 57 kDa. The quaternary structure is subdivided into three monomers, A, B, and C, and each domain comprises 11 ß-sheets: an anti-parallel ß-sheet, a ß-hairpin, and a disordered ß-sheet structure. Molecular docking demonstrates a significant interaction with disaccharides rather than monosaccharides. The preferential interaction with disaccharides highlights the potential interaction with pathogen molecules, such as LPS and Poly(I:C). The hemagglutination assay inhibited lectins activity, especially maltose and sucrose, highlighting lectin activity in L. paradoxa samples. Overall, our results show the potential relevance of LpITLN2-B in L. paradoxa immune defense against pathogens.

STINGing Defenses: Unmasking the Mechanisms of DNA Oncovirus-Mediated Immune Escape.

DNA oncoviruses represent an intriguing subject due to their involvement in oncogenesis. These viruses have evolved mechanisms to manipulate the host immune response, facilitating their persistence and actively contributing to carcinogenic processes. This paper describes the complex interactions between DNA oncoviruses and the innate immune system, with a particular emphasis on the cGAS-STING pathway. Exploring these interactions highlights that DNA oncoviruses strategically target and subvert this pathway, exploiting its vulnerabilities for their own survival and proliferation within the host. Understanding these interactions lays the foundation for identifying potential therapeutic interventions. Herein, we sought to contribute to the ongoing efforts in advancing our understanding of the innate immune system in oncoviral pathogenesis.

Evolution of innate immunity: lessons from mammalian models shaping our current view of insect immunity.

The innate immune system, a cornerstone for organismal resilience against environmental and microbial insults, is highly conserved across the evolutionary spectrum, underpinning its pivotal role in maintaining homeostasis and ensuring survival. This review explores the evolutionary parallels between mammalian and insect innate immune systems, illuminating how investigations into these disparate immune landscapes have been reciprocally enlightening. We further delve into how advancements in mammalian immunology have enriched our understanding of insect immune responses, highlighting the intertwined evolutionary narratives and the shared molecular lexicon of immunity across these organisms. Therefore, this review posits a holistic understanding of innate immune mechanisms, including immunometabolism, autophagy and cell death. The examination of how emerging insights into mammalian and vertebrate immunity inform our understanding of insect immune responses and their implications for vector-borne disease transmission showcases the imperative for a nuanced comprehension of innate immunity's evolutionary tale. This understanding is quintessential for harnessing innate immune mechanisms' potential in devising innovative disease mitigation strategies and promoting organismal health across the animal kingdom.

MASTer cell: chief immune modulator and inductor of antimicrobial immune response.

Mast cells have long been recognized for their involvement in allergic pathology through the immunoglobulin E (IgE)-mediated degranulation mechanism. However, there is growing evidence of other "non-canonical" degranulation mechanisms activated by certain pathogen recognition receptors. Mast cells release several mediators, including histamine, cytokines, chemokines, prostaglandins, and leukotrienes, to initiate and enhance inflammation. The chemical nature of activating stimuli influences receptors, triggering mechanisms for the secretion of formed and new synthesized mediators. Mast cells have more than 30 known surface receptors that activate different pathways for direct and indirect activation by microbes. Different bacterial strains stimulate mast cells through various ligands, initiating the innate immune response, which aids in clearing the bacterial burden. Mast cell interactions with adaptative immune cells also play a crucial role in infections. Recent publications revealed another "non-canonical" degranulation mechanism present in tryptase and chymase mast cells in humans and connective tissue mast cells in mice, occurring through the activation of the Mas-related G protein-coupled receptor (MRGPRX2/b2). This receptor represents a new therapeutic target alongside antibiotic therapy. There is an urgent need to reconsider and redefine the biological role of these MASTer cells of innate immunity, extending beyond their involvement in allergic pathology.

Immunosuppressive effects of the mycotoxin patulin in macrophages.

Patulin (PAT) is a fungi-derived secondary metabolite produced by numerous fungal species, especially within Aspergillus, Byssochlamys, and Penicillium genera, amongst which P. expansum is the foremost producer. Similar to other fungi-derived metabolites, PAT has been shown to have diverse biological features. Initially, PAT was used as an effective antimicrobial agent against Gram-negative and Gram-positive bacteria. Then, PAT has been shown to possess immunosuppressive properties encompassing humoral and cellular immune response, immune cell function and activation, phagocytosis, nitric oxide and reactive oxygen species production, cytokine release, and nuclear factor-κB and mitogen-activated protein kinases activation. Macrophages are a heterogeneous population of immune cells widely distributed throughout organs and connective tissue. The chief function of macrophages is to engulf and destroy foreign bodies through phagocytosis; this ability was fundamental to his discovery. However, macrophages play other well-established roles in immunity. Thus, considering the central role of macrophages in the immune response, we review the immunosuppressive effects of PAT in macrophages and provide the possible mechanisms of action.

Impact of Toll-Like Receptors (TLRs) and TLR Signaling Proteins in Trigeminal Ganglia Impairing Herpes Simplex Virus 1 (HSV-1) Progression to Encephalitis: Insights from Mouse Models.

Herpes simplex virus 1 (HSV-1) or simplexvirus humanalpha 1 is a neurotropic virus that is responsible for orofacial infections in humans. More than 70% of the world's population may have seropositivity for HSV-1, and this virus is a leading cause of sporadic lethal encephalitis in humans. The role of toll-like receptors (TLRs) in defending against HSV-1 infection has been explored, including the consequences of lacking these receptors or other proteins in the TLR pathway. Cell and mouse models have been used to study the importance of these receptors in combating HSV-1, how they relate to the innate immune response, and how they participate in the orchestration of the adaptive immune response. Myeloid differentiation factor 88 (MyD88) is a protein involved in the downstream activation of TLRs and plays a crucial role in this signaling. Mice with functional MyD88 or TLR2 and TLR9 can survive HSV-1 infection. However, they can develop encephalitis and face a 100% mortality rate in a dose-dependent manner when MyD88 or TLR2 plus TLR9 proteins are non-functional. In TLR2/9 knockout mice, an increase in chemokines and decreases in nitric oxide (NO), interferon (IFN) gamma, and interleukin 1 (IL-1) levels in the trigeminal ganglia (TG) have been correlated with mortality.

Crosstalk between vault RNAs and innate immunity.

PURPOSE: Vault (vt) RNAs are noncoding (nc) RNAs transcribed by RNA polymerase III (RNA Pol III) with 5'-triphosphate (5'-PPP) termini that play significant roles and are recognized by innate immune sensors, including retinoic acid-inducible protein 1 (RIG-I). In addition, vtRNAs adopt secondary structures that can be targets of interferon-inducible protein kinase R (PKR) and the oligoadenylate synthetase (OAS)/RNase L system, both of which are important for activating antiviral defenses. However, changes in the expression of vtRNAs have been associated with pathological processes that activate proinflammatory pathways, which influence cellular events such as differentiation, aging, autophagy, apoptosis, and drug resistance in cancer cells. RESULTS: In this review, we summarized the biology of vtRNAs and focused on their interactions with the innate immune system. These findings provide insights into the diverse roles of vtRNAs and their correlation with various cellular processes to improve our understanding of their biological functions.

Antimicrobial peptides and other potential biomarkers of critical illness in SARS-CoV-2 patients with acute kidney injury. AMPAKI-CoV study.

Antimicrobial peptides (AMPs) constitute a complex network of 10-100 amino acid sequence molecules widely distributed in nature. While over 300 AMPs have been described in mammals, cathelicidins and defensins remain the most extensively studied. Some publications have explored the role of AMPs in COVID-19, but these findings are preliminary, and in vivo studies are still lacking. In this study, we report the plasma levels of five AMPs (LL-37, α-defensin 1, α-defensin 3, ß-defensin 1, and ß-defensin 3), using the ELISA technique (MyBioSource, San Diego, CA, United States, kits MBS2601339 (beta-defensin 1), MBS2602513 (beta-defensin 3), MBS703879 (alpha-defensin 1), MBS706289 (alpha-defensin 3), MBS7234921 (LL37)), and the measurement of six cytokines (tumor necrosis factor-α, interleukin-1ß, interleukin-6, interleukin-10, interferon-γ, and monocyte chemoattractant protein-1), through the magnetic bead immunoassay Milliplex® and the MAGPIX® System (MilliporeSigma, Darmstadt, Germany, kit HCYTOMAG-60 K (cytokines)), in 15 healthy volunteers, 36 COVID-19 patients without Acute Kidney Injury (AKI) and 17 COVID-19 patients with AKI. We found increased levels of α-defensin 1, α-defensin 3 and ß-defensin 3, in our COVID-19 population, when compared to healthy controls, along with higher levels of interleukin-6, interleukin-10, interferon-γ, and monocyte chemoattractant protein-1. These findings suggest that these AMPs and cytokines may play a crucial role in the systemic inflammatory response and tissue damage characterizing severe COVID-19. The levels of α-defensin 1 and α-defensin 3 were significantly higher in COVID-19 AKI group in comparison to the non-AKI group. Furthermore, IL-10 and the product IL-10 × IL-1B showed excellent performance in discriminating AKI, with AUCs of 0.86 and 0.88, respectively. Among patients with COVID-19, AMPs may play a key role in the inflammation process and disease progression. Additionally, α-defensin 1 and α-defensin 3 may mediate the AKI process in these patients, representing an opportunity for further research and potential therapeutic alternatives in the future.

Epstein-Barr virus: the mastermind of immune chaos.

The Epstein-Barr virus (EBV) is a ubiquitous human pathogen linked to various diseases, including infectious mononucleosis and multiple types of cancer. To control and eliminate EBV, the host's immune system deploys its most potent defenses, including pattern recognition receptors, Natural Killer cells, CD8+ and CD4+ T cells, among others. The interaction between EBV and the human immune system is complex and multifaceted. EBV employs a variety of strategies to evade detection and elimination by both the innate and adaptive immune systems. This demonstrates EBV's mastery of navigating the complexities of the immunological landscape. Further investigation into these complex mechanisms is imperative to advance the development of enhanced therapeutic approaches with heightened efficacy. This review provides a comprehensive overview of various mechanisms known to date, employed by the EBV to elude the immune response, while establishing enduring latent infections or instigate its lytic replication.

Positive selection has shaped the evolution of Argentine ant immune genes both in native and introduced supercolonies.

The highly invasive Argentine ant (Linepithema humile) started its colonisation from the species' native range in South America approximately 150 years ago and has since become one of the major pests in the world. We investigated how the shifts into new ranges have affected the evolution of Argentine ants' immune genes. To the best of our knowledge, this is the first broadscale population genetic study focusing on ants' immune genes. We analysed comprehensive targeted-seq data of immune and non-immune genes containing 174 genes from 18 Argentine ant supercolonies covering the species' native and introduced ranges. We predicted that the immune gene evolution of introduced supercolonies differs from that of the native supercolonies and proposed two different, non-mutually exclusive hypotheses for this: 1) the enemy release hypothesis and 2) the higher pathogen pressure hypothesis - both of which seem to explain the observed evolutionary patterns on their behalf. Our results show that the introduced supercolonies were targeted by weaker selection than natives, but positive selection was evident among supercolonies of both ranges. Moreover, in some cases, such as the antiviral RNAi genes, introduced range supercolonies harboured a higher proportion of positively selected genes than natives. This observation was striking, knowing the recent demographic history and the detected generally lower selection efficacy of introduced supercolonies. In conclusion, it is evident that pathogen pressure is ubiquitous and strongly affects the immune gene evolution in Argentine ants.

High production MBL2 polymorphisms protect against COVID-19 complications in critically ill patients: A retrospective cohort study.

Mannose-binding lectin (MBL) binds to SARS-CoV-2, inhibits infection of susceptible cells, and activates the complement system via the lectin pathway. In this study, we investigated the association of MBL2 polymorphisms with the risk of hospitalization and clinical worsening in patients with COVID-19. A total of 550 patients with COVID-19 were included (94 non-hospitalized and 456 hospitalized). Polymorphisms in MBL2 exon 1 (codons 52, 54 and 57) and promoter region (-550, -221, and +4) were determined by real-time PCR. MBL and complement proteins were measured by Luminex. A higher frequency of the H/H genotype and the HYPA haplotype was observed in non-hospitalized patients when compared to hospitalized. In addition, critically ill patients carrying haplotypes associated with high MBL levels (HYPA/HYPA + HYPA/LYPA + HYPA/LYQA + LYPA/LYQA + LYPA/LYPA + LYQA/LYQA + LXPA/HYPA + LXPA/LYQA + LXPA/LYPA) were protected against lower oxygen saturation levels (P = 0.02), use of invasive ventilation use (P = 0.02, OR 0.38), and shock (P = 0.01, OR 0.40), independent of other potential confounders adjusted by multivariate analysis. Our results suggest that variants in MBL2 associated with high MBL levels may play a protective role in the clinical course of COVID-19.