Innate immune recognition: mechanisms and pathways

Modulation of peptidoglycan recognition protein expression alters begomovirus vectoring efficiency and fitness of Bemisia tabaci

Peptidoglycan recognition proteins (PGRPs) are evolutionarily conserved molecules. Their role in the immune response to invading pathogens makes them a natural target for viral defence study in a wide range of organisms. Silverleaf whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is one of the invasive insect pests and transmits begomoviruses in a circulative and persistent manner to vegetables, legumes, fibres and ornamentals. The virus entry, retention, circulation, and release process involve interactions with several proteins in B. tabaci and evade innate immunity to avoid the antiviral mechanisms. The present study investigated the role of BtPGRP in chilli leaf curl virus (ChiLCV, Begomovirus capsica) transmission by B. tabaci. Silencing of BtPGRP using double-stranded (ds) RNA led to the loss of innate immunity to ChiLCV resulting in increased virus titre in B. tabaci. DsBtPGRP was orally administered to adults of B. tabaci at a concentration of 1, 3, and 5 μg/mL. The expression of BtPGRP was downregulated up to 4.67-fold. The virus titre in B. tabaci increased 90.05 times post-exposure to dsBtPGRP at 5 μg/mL. The test plants inoculated with ChiLCV by dsBtPGRP-exposed B. tabaci expressed severe curling symptoms with a higher virus load and transmission ratio than the control. Besides, the silencing of BtPGRP also induced up to 56.67% mortality in treated B. tabaci. The active site pocket of BtPGRP was found to interact directly with the ChiLCV-CP in computational analyses. Key residues of BtPGRP, including Tyr45, Asp84, His86, Trp87, and Asn119 exhibited critical interactions with the ChiLCV-CP. To our knowledge, this is the first report on the effect of PGRP silencing on ChiLCV acquisition and transmission efficiency and fitness of B. tabaci Asia II I.

Unlocking the therapeutic potential of gut microbiota for preventing and treating aging-related neurological disorders

Billions of microorganisms inhabit the human gut and maintain overall health. Recent research has revealed the intricate interaction between the brain and gut microbiota through the microbiota-gut-brain axis (MGBA) and its effect on neurodegenerative disorders (NDDs). Alterations in the gut microbiota, known as gut dysbiosis, are linked to the development and progression of several NDDs. Studies suggest that the gut microbiota may be a viable target for improving cognitive health and reducing hallmarks of brain aging. Numerous pathways including hypothalamic-pituitary-adrenal axis stimulation, neurotransmitter release disruption, system-wide inflammation, and increased intestinal and blood-brain barrier permeability connect gut dysbiosis to neurological conditions. Metabolites produced by the gut microbiota influence neural processes that affect brain function. Clinical interventions depend on the capacity to understand the equilibrium between beneficial and detrimental gut microbiota, as it affects both neurodegeneration and neuroprotection. The importance of the gut microbiota and its metabolites during brain aging and the development of neurological disorders is summarized in this review. Moreover, we explored the possible therapeutic effects of the gut microbiota on age-related NDDs. Highlighting various pathways that connect the gut and the brain, this review identifies several important domains where gut microbiota-based interventions could offer possible solutions for age-related NDDs. Furthermore, prebiotics and probiotics are discussed as effective alternatives for mitigating indirect causes of gut dysbiosis. These therapeutic interventions are poised to play a significant role in improving dysbiosis and NDDs, paving the way for further research.

Novel immunomodulatory peptides from hydrolysates of the Rana spinosa (Quasipaa spinosa) meat and their immunomodulatory activity mechanism

In this study, hydrolysates of Rana spinosa meat were purified and characterized, and combined with molecular docking to screen potential immunomodulatory peptides and explore their activities and mechanisms of action. The results showed that 582 peptides were identified from the hydrolysates, and three novel immunomodulatory peptides, GIHETTYNS (1020.4512 Da), IADRMQKE (989.4964 Da), and IVRDIKEK (999.6077 Da), were obtained by molecular docking. These peptides significantly increased the proliferative activity of RAW264.7 cells and accelerated its cell cycle proceeding, promoted the production of NO, IL-6, and TNF-α, and enhanced ROS levels. The molecular docking analysis revealed that immunomodulatory peptides bound to the key regions of TLR4/MD-2 by hydrogen bonds and hydrophobic interactions, and the common sites of action were LYS A:458, ARG A:434, and ARG D: 90. Furthermore, these immunomodulatory peptides had favorable safety and stability properties in silico analysis. These novel peptides are expected to be new natural materials for immunomodulators.

Ubiquitination-dependent degradation of DHX36 mediated by porcine circovirus type 3 capsid protein

Porcine circovirus type 3 (PCV3) is an emerging pathogen that causes porcine dermatitis, and reproductive failure. PCV3 Cap interacts with DExD/H-box helicase 36 (DHX36), a protein that functions primarily through regulating interferon (IFN)-β production. However, how the interaction between DHX36 and PCV3 Cap regulates viral replication remains unknown. Herein, we observed impaired PCV3 proliferation after DHX36 overexpression as indicated by decreased Rep protein expression and virus production. In contrast, PCV3 replication increased upon small interfering RNA-mediated DHX36 depletion. Furthermore, DHX36 positively regulated IFN-β production and interferon-stimulated genes (ISGs) expression. Mechanistically, PCV3 Cap interacted with DHX36, and the PCV3 Cap-NLS and DHX36-NTD were essential for the interaction. Furthermore, DHX36 may get degraded because its binding cellular partners became ubiquitinated and then reduced, and PCV3 Cap-(35-100aa) also promoted the degradation of DHX36 through the K48-linked ubiquitination. Taken together, these results show that DHX36 antagonizes PCV3 replication by interacting with PCV3 Cap and activating IFN-β response, which provides important insight on the prevention and controlling of PCV3 infection. IMPORTANCE: Porcine circovirus type 3 (PCV3) is a newly discovered pathogen associated with multiple clinicopathological signs. Clarifying the mechanisms that host factors modulate PCV3 replication helps understanding of the viral pathogenesis. The PCV3 capsid (Cap) protein has been shown to interact with DExD/H-box helicase 36 (DHX36) (Zhou et al., 2022b), a crucial protein that regulates virus replication. Herein, we further demonstrated that DHX36 protein is degraded in PCV3-infected cells and antagonizes the replication of PCV3 and that DHX36 increases interferon-β and interferon-stimulated gene levels by binding to PCV3 Cap. In addition, PCV3 infection could decrease DHX36 expression levels to antagonize its antiviral activity. These results reveal a molecular mechanism by which DHX36 antagonizes PCV3 replication by binding to PCV3 Cap protein and activating IFN signals, thereby providing important targets for preventing and controlling PCV3 infection.

Immunometabolism in the Aging Heart

Structural, functional, and molecular-level changes in the aging heart are influenced by a dynamic interplay between immune signaling and cellular metabolism that is referred to as immunometabolism. This review explores the crosstalk between cellular metabolic pathways including glycolysis, oxidative phosphorylation, fatty acid metabolism, and the immune processes that govern cardiac aging. With a rapidly aging population that coincides with increased cardiovascular risk and cancer incidence rates, understanding the immunometabolic underpinnings of cardiac aging provides a foundation for identifying therapeutic targets to mitigate cardiac dysfunction. Aging alters the immune environment of the heart by concomitantly driving the changes in immune cell metabolism, mitochondrial dysfunction, and redox signaling. Shifts in these metabolic pathways exacerbate inflammation and impair tissue repair, creating a vicious cycle that accelerates cardiac functional decline. Treatment with cancer therapy further complicates this landscape, as aging-associated immunometabolic disruptions augment the susceptibility to cardiotoxicity. The current review highlights therapeutic strategies that target the immunometabolic axis to alleviate cardiac aging pathologies. Interventions include modulating metabolic intermediates, improving mitochondrial function, and leveraging immune signaling pathways to restore cardiac health. Advances in immunometabolism thus hold significant potential for translating preclinical findings into therapies that improve the quality of life for the aging population and underscore the need for approaches that address the immunometabolic mechanisms of cardiac aging, providing a framework for future research.

Mechanisms of intestinal DNA damage and inflammation induced by ammonia nitrogen exposure in Litopenaeus vannamei

Ammonia nitrogen, a common aquaculture pollutant, harms crustaceans by causing intestinal inflammation, though its exact mechanisms are unclear. Thus, we exposed shrimp to 0, 2, 10 and 20 mg/L NH4Cl exposure for 0, 3, 6, 12, 24, 48, 72 h, and explored the intestinal stress, apoptosis, proliferation, inflammation and its histopathological changes. This research indicated that ammonia nitrogen exposure heightens plasma dopamine (DA), 5-hydroxytryptamine (5-HT), norepinephrine (NE), and acetylcholine (ACh) levels, alters gene expression of neurotransmitter receptors in the intestine, triggering the PLCCa2+ pathway and induces endoplasmic reticulum stress. Additionally, mitochondrial fission-related genes (Drp1, FIS1) significantly increase, the level of reactive oxygen species (ROS) was significantly elevated in the intestine, which induced DNA damage effects and initiated the DNA repair function, mainly through the base excision repair pathway, but with a low repair efficiency. By determining the expression of key genes of caspase-dependent and non-caspase-dependent apoptotic pathways, it was found that ammonia nitrogen exposure induced apoptosis in intestinal cells, proliferation key signaling pathways such as Wnt, EGFR and FOXO signaling showed an overall decrease after ammonia nitrogen exposure, combined with the gene expression of cell cycle proteins and proliferation markers, indicated that the proliferation of intestinal cells was inhibited. Performing pearson correlation analysis of intestinal cell damage, proliferation, and inflammatory factors, we hypothesized that ammonia nitrogen exposure induces intestinal endoplasmic reticulum stress and mitochondrial fission, induces elevated ROS, leads to DNA damage, and causes inflammation and damage in intestinal tissues by the underlying mechanism of promoting apoptosis and inhibiting proliferation.

The concept of natural genome reconstruction.Part 1. Basic provisions of the "natural genome reconstruction" concept. Changing the genome of hematopoietic stem cells using several natural cellular mechanisms that are inherent in the hematopoietic cell and determine its biological status as "the source of the body's reparative potential"

We present a series of articles proving the existence of a previously unknown mechanism of interaction between hematopoietic stem cells and extracellular double-stranded DNA (and, in particular, double-stranded DNA of the peripheral bloodstream), which explains the possibility of emergence and fixation of genetic information contained in double-stranded DNA of extracellular origin in hematopoietic stem cells. The concept of the possibility of stochastic or targeted changes in the genome of hematopoietic stem cells is formulated based on the discovery of new, previously unknown biological properties of poorly differentiated hematopoietic precursors. The main provisions of the concept are as follows. The hematopoietic stem cell takes up and internalizes fragments of extracellular double-stranded DNA via a natural mechanism. Specific groups of glycocalyx factors, including glycoproteins/proteoglycans, glycosylphosphatidylinositol-anchored proteins and scavenger receptors, take part in the internalization event. The binding sites for DNA fragments are heparin-binding domains and clusters of positively charged amino acid residues that are parts of protein molecules of these factors. Extracellular fragments delivered to the internal compartments of hematopoietic stem cells initiate terminal differentiation, colony formation, and proliferation of hematopoietic precursors. The molecular manifestation of these processes is the emergence and repair of pangenomic single-strand breaks. The occurrence of pangenomic single-strand breaks and restoration of genome (genomic DNA) integrity are associated with activation of a "recombinogenic situation" in the cell; during its active phase, stochastic homologous recombination or other recombination events between extracellular fragments localized in the nucleus and chromosomal DNA are possible. As a result, genetic material of initially extracellular localization either integrates into the recipient genome with the replacement of homologous chromosomal segments, or is transitively present in the nucleus and can manifest itself as a new genetic trait. It is assumed that as a result of stochastic acts of homologous exchange, chromosome loci are corrected in hematopoietic stem cells that have acquired mutations during the existence of the organism, which are the cause of clonal hematopoiesis associated with old age. In this regard, there is a fundamental possibility of changing the hematopoietic status of hematopoietic stem cells in the direction of polyclonality and the original diversity of clones. Such events can form the basis for the rejuvenation of the blood-forming cell system. The results of the laboratory's work indicate that other stem cells in the body capture extracellular DNA fragments too. This fact creates a paradigm for the overall rejuvenation of the body.

Continuous Treatment with IncobotulinumtoxinA Despite Presence of BoNT/A Neutralizing Antibodies: Immunological Hypothesis and a Case Report

Botulinum Neurotoxin A (BoNT/A) is a bacterial protein that has proven to be a valuable pharmaceutical in therapeutic indications and aesthetic medicine. One major concern is the formation of neutralizing antibodies (nAbs) to the core BoNT/A protein. These can interfere with the therapy, resulting in partial or complete antibody (Ab)-mediated secondary non-response (SNR) or immunoresistance. If titers of nAbs reach a level high enough that all injected BoNT/A molecules are neutralized, immunoresistance occurs. Studies have shown that continuation of treatment of neurology patients who had developed Ab-mediated partial SNR against complexing protein-containing (CPC-) BoNT/A was in some cases successful if patients were switched to complexing protein-free (CPF-) incobotulinumtoxinA (INCO). This seems to contradict the layperson's basic immunological understanding that repeated injection with the same antigen BoNT/A should lead to an increase in antigen-specific antibody titers. As such, we strive to explain how immunological memory works in general, and based on this, we propose a working hypothesis for this paradoxical phenomenon observed in some, but not all, neurology patients with immunoresistance. A critical factor is the presence of potentially immune-stimulatory components in CPC-BoNT/A products that can act as immunologic adjuvants and activate not only naïve, but also memory B lymphocyte responses. Furthermore, we propose that continuous injection of a BoN/TA formulation with low immunogenicity, e.g., INCO, may be a viable option for aesthetic patients with existing nAbs. These concepts are supported by a real-world case example of a patient with immunoresistance whose nAb levels declined with corresponding resumption of clinical response despite regular INCO injections.

The influence of metabolic disorders on adaptive immunity

The immune system plays a crucial role in protecting the body from invading pathogens and maintaining tissue homoeostasis. Maintaining homoeostatic lipid metabolism is an important aspect of efficient immune cell function and when disrupted immune cell function is impaired. There are numerous metabolic diseases whereby systemic lipid metabolism and cellular function is impaired. In the context of metabolic disorders, chronic inflammation is suggested to be a major contributor to disease progression. A major contributor to tissue dysfunction in metabolic disease is ectopic lipid deposition, which is generally caused by diet and genetic factors. Thus, we propose the idea, that similar to tissue and organ damage in metabolic disorders, excessive accumulation of lipid in immune cells promotes a dysfunctional immune system (beyond the classical foam cell) and contributes to disease pathology. Herein, we review the evidence that lipid accumulation through diet can modulate the production and function of immune cells by altering cellular lipid content. This can impact immune cell signalling, activation, migration, and death, ultimately affecting key aspects of the immune system such as neutralising pathogens, antigen presentation, effector cell activation and resolving inflammation.

The Importance of Predictive Biomarkers and Their Correlation with the Response to Immunotherapy in Solid Tumors-Impact on Clinical Practice

Background/Objectives: Immunotherapy has changed the therapeutic approach for various solid tumors, especially lung tumors, malignant melanoma, renal and urogenital carcinomas, demonstrating significant antitumor activity, with tolerable safety profiles and durable responses. However, not all patients benefit from immunotherapy, underscoring the need for predictive biomarkers that can identify those most likely to respond to treatment. Methods: The integration of predictive biomarkers into clinical practice for immune checkpoint inhibitors (ICI) holds great promise for personalized cancer treatment. Programmed death ligand 1 (PD-L1) expression, tumor mutational burden (TMB), microsatellite instability (MSI), gene expression profiles and circulating tumor DNA (ctDNA) have shown potential in predicting ICI responses across various cancers. Results: Challenges such as standardization, validation, regulatory approval, and cost-effectiveness must be addressed to realize their full potential. Predictive biomarkers are crucial for optimizing the clinical use of ICIs in cancer therapy. Conclusions: While significant progress has been made, further research and collaboration among clinicians, researchers, and regulatory institutes are essential to overcome the challenges of clinical implementation. However, little is known about the relationship between local and systemic immune responses and the correlation with response to oncological therapies and patient survival.

Inflammatory Memory in Epidermal Stem Cells - A New Strategy for Recurrent Inflammatory Skin Diseases

The ability of the skin to "remember" has been a potential mechanism for studying recurrent skin diseases. While it has been thought that the ability to retain past encounters is the prerogative of immune cells, it has recently been discovered that skin tissue stem cells can also take on this task. Epithelial stem cells undergoing inflammation retain their "memory" through epigenetic reprogramming and exhibit rapid epithelialization and epidermal proliferation upon secondary stimulation. This is a non-specific memory modality independent of conventional immune memory, in which histone modifications (acetylation and methylation) and specific transcription factors (AP-1 and STAT3) are involved in the establishment of inflammatory memories, and AIM2/Caspase-1/IL-1β mainly performs the rapid effects of memory. This finding is intriguing for addressing recurrent inflammatory skin diseases, which may explain the fixed-site recurrence of inflammatory skin diseases and develop new therapeutic strategies in the future. However, more research is still needed to decipher the mysteries of memory.

Microcrystal electron diffraction structure of Toll-like receptor 2 TIR-domain-nucleated MyD88 TIR-domain higher-order assembly

Eukaryotic TIR (Toll/interleukin-1 receptor protein) domains signal via TIR-TIR interactions, either by self-association or by interaction with other TIR domains. In mammals, TIR domains are found in Toll-like receptors (TLRs) and cytoplasmic adaptor proteins involved in pro-inflammatory signaling. Previous work revealed that the MAL TIR domain (MALTIR) nucleates the assembly of MyD88TIR into crystalline arrays in vitro. A microcrystal electron diffraction (MicroED) structure of the MyD88TIR assembly has previously been solved, revealing a two-stranded higher-order assembly of TIR domains. In this work, it is demonstrated that the TIR domain of TLR2, which is reported to signal as a heterodimer with either TLR1 or TLR6, induces the formation of crystalline higher-order assemblies of MyD88TIR in vitro, whereas TLR1TIR and TLR6TIR do not. Using an improved data-collection protocol, the MicroED structure of TLR2TIR-induced MyD88TIR microcrystals was determined at a higher resolution (2.85 Å) and with higher completeness (89%) compared with the previous structure of the MALTIR-induced MyD88TIR assembly. Both assemblies exhibit conformational differences in several areas that are important for signaling (for example the BB loop and CD loop) compared with their monomeric structures. These data suggest that TLR2TIR and MALTIR interact with MyD88 in an analogous manner during signaling, nucleating MyD88TIR assemblies unidirectionally.

The role of bacterial size, shape and surface in macrophage engulfment of uropathogenic E. coli cells

Uropathogenic Escherichia coli (UPEC) can undergo extensive filamentation in the host during acute urinary tract infections (UTIs). It has been hypothesised that this morphological plasticity allows bacteria to avoid host immune responses such as macrophage engulfment. However, it is still unclear what properties of filaments are important in macrophage-bacteria interactions. The aim of this work was to investigate the contribution of bacterial biophysical parameters, such as cell size and shape, and physiological parameters, such as cell surface and the environment, to macrophage engulfment efficiency. Viable, reversible filaments of known lengths and volumes were produced in the UPEC strain UTI89 using a variety of methods, including exposure to cell-wall targeting antibiotics, genetic manipulation and isolation from an in vitro human bladder cell model. Quantification of the engulfment ability of macrophages using gentamicin-protection assays and fluorescence microscopy demonstrated that the ability of filaments to avoid macrophage engulfment is dependent on a combination of size (length and volume), shape, cell surface and external environmental factors. UTI89 filamentation and macrophage engulfment efficiency were also found to occur independently of the SOS-inducible filamentation genes, sulA and ymfM in both in vivo and in vitro models of infection. Compared to filaments formed via antibiotic inhibition of division, the infection-derived filaments were preferentially targeted by macrophages. With several strains of UPEC now resistant to current antibiotics, our work identifies the importance of bacterial physiological and morphological states during infection.

Monitoring lipopolysaccharide-induced macrophage polarization by surface-enhanced Raman scattering

Macrophages are among the most important components of the innate immune system where the interaction of pathogens and their phagocytosis occur as the first barrier of immunity. When nanomaterials interact with the human body, they have to face macrophages as well. Thus, understanding of nanomaterials-macrophage interactions and underlying mechanisms is crucial. For this purpose, various methods are used. In this study, surface-enhanced Raman scattering (SERS) is proposed by studying lipopolysaccharide (LPS) induced macrophage polarization using gold nanoparticles (AuNPs) as an alternative to the current approaches. For this purpose, the murine macrophage cell line, RAW 264.7 cells, was polarized by LPS, and polarization mechanisms were characterized by nitrite release and reactive oxygen species (ROS) formation and monitored using SERS. The spectral changes were interpreted based on the molecular pathways induced by LPS. Furthermore, polarized macrophages by LPS were exposed to the toxic AuNPs doses to monitor the enhanced phagocytosis and related spectral changes. It was observed that LPS induced macrophage polarization and enhanced AuNP phagocytosis by activated macrophages elucidated clearly from SERS spectra in a label-free non-destructive manner.

Mononuclear Phagocytes, Cellular Immunity, and Nobel Prizes: A Historic Perspective

The mononuclear phagocyte system includes monocytes, macrophages, some dendritic cells, and multinuclear giant cells. These cell populations display marked heterogeneity depending on their differentiation from embryonic and bone marrow hematopoietic progenitors, tissue location, and activation. They contribute to tissue homeostasis by interacting with local and systemic immune and non-immune cells through trophic, clearance, and cytocidal functions. During evolution, they contributed to the innate host defense before effector mechanisms of specific adaptive immunity emerged. Mouse macrophages appear at mid-gestation and are distributed throughout the embryo to facilitate organogenesis and clear cells undergoing programmed cell death. Yolk sac, AGM, and fetal liver-derived tissue-resident macrophages persist throughout postnatal and adult life, supplemented by bone marrow-derived blood monocytes, as required after injury and infection. Nobel awards to Elie Metchnikoff and Paul Ehrlich in 1908 drew attention to cellular phagocytic and humoral immunity, respectively. In 2011, prizes were awarded to Jules Hoffmann and Bruce Beutler for contributions to innate immunity and to Ralph Steinman for the discovery of dendritic cells and their role in antigen presentation to T lymphocytes. We trace milestones in the history of mononuclear phagocyte research from the perspective of Nobel awards bearing directly and indirectly on their role in cellular immunity.

Antibody-Mediated Serum Resistance Protects Pseudomonas aeruginosa During Bloodstream Infections

BACKGROUND

Pseudomonas aeruginosa is a frequent pathogen isolated from bacterial bloodstream infection (BSI) and is associated with high mortality. To survive in the blood, P aeruginosa must resist the bactericidal action of complement (ie, serum killing). Antibodies usually promote serum killing through the classical complement pathway; however, "cloaking antibodies" (cAbs) have been described, which paradoxically protect bacteria from serum killing. The relevance of cAbs in P aeruginosa BSI is unknown.

METHODS

Serum and P aeruginosa were collected from a cohort of 100 patients with BSI. Isolates were tested for sensitivity to healthy control serum (HCS). cAb prevalence was determined in sera. Patient sera were mixed with HCS to determine if killing of the matched isolate was inhibited.

RESULTS

Overall, 36 patients had elevated titers of cAbs, and 34 isolates were sensitive to HCS killing. Fifteen patients had cAbs and HCS-sensitive isolates; of these patients, 14 had serum that protected their matched bacteria from HCS killing. Patients with cAbs were less likely to be neutropenic or have comorbidities.

CONCLUSIONS

cAbs are prevalent in patients with P aeruginosa BSI and allow survival of otherwise serum-sensitive bacteria in the bloodstream. Generation of cAbs may be a risk factor for the development of BSI.

Mechanical control of antigen detection and discrimination by T and B cell receptors

The adaptive immune response is orchestrated by just two cell types, T cells and B cells. Both cells possess the remarkable ability to recognize virtually any antigen through their respective antigen receptors-the T cell receptor (TCR) and B cell receptor (BCR). Despite extensive investigations into the biochemical signaling events triggered by antigen recognition in these cells, our ability to predict or control the outcome of T and B cell activation remains elusive. This challenge is compounded by the sensitivity of T and B cells to the biophysical properties of antigens and the cells presenting them-a phenomenon we are just beginning to understand. Recent insights underscore the central role of mechanical forces in this process, governing the conformation, signaling activity, and spatial organization of TCRs and BCRs within the cell membrane, ultimately eliciting distinct cellular responses. Traditionally, T cells and B cells have been studied independently, with researchers working in parallel to decipher the mechanisms of activation. While these investigations have unveiled many overlaps in how these cell types sense and respond to antigens, notable differences exist. To fully grasp their biology and harness it for therapeutic purposes, these distinctions must be considered. This review compares and contrasts the TCR and BCR, placing emphasis on the role of mechanical force in regulating the activity of both receptors to shape cellular and humoral adaptive immune responses.

Anti‑inflammatory effects of methanol extract from Peperomia dindygulensis Miq. mediated by HO‑1 in LPS‑induced RAW 264.7 cells

Inflammation serves as a multifaceted defense mechanism activated by pathogens, cellular damage and irritants, aiming to eliminate primary causes of injury and promote tissue repair. Peperomia dindygulensis Miq. (P. dindygulensis), prevalent in Vietnam and southern China, has a history of traditional use for treating cough, fever and asthma. Previous studies on its phytochemicals have shown their potential as anti-inflammatory agents, yet underlying mechanisms remain to be elucidated. The present study investigated the regulatory effects of P. dindygulensis on the anti-inflammatory pathways. The methanol extracts of P. dindygulensis (PDME) were found to inhibit nitric oxide (NO) production and induce heme oxygenase-1 (HO-1) expression in murine macrophages. While MAPKs inhibitors, such as SP600125, SB203580 and U0126 did not regulate HO-1 expression, the treatment of cycloheximide, a translation inhibitor, reduced HO-1. Furthermore, PDME inhibited lipopolysaccharide (LPS)-induced inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and TNF-α expression at both the mRNA and protein levels. The activity of NOS and the expression of TNF-α, iNOS and COX-2 decreased in LPS-stimulated Raw 264.7 cells treated with PDME and this effect was regulated by inhibition of HO-1 activity. These findings suggested that PDME functions as an HO-1 inducer and serves as an effective natural anti-inflammatory agent in LPS-induced inflammation.

The first report of a C-type lectin contains a CLIP domain involved in antibacterial defense in Macrobrachium nipponense

We identified a novel C-type lectin (CTL) from Macrobrachium nipponense, designated as Mn-clip-Lec. It consists of 1315 bp with an open reading frame of 1098 bp, encoding a polypeptide of 365 amino acids. Mn-clip-Lec contains 6 exons and 5 introns. Mn-clip-Lec possessed a CLIP domain at the N-terminal and two carbohydrate recognition domains at the C-terminal. Interaction between Mn-clip-Lec and MnLec was found by Yeast two-hybrid analysis. The expressions of Mn-clip-Lec, MnLec, prophenoloxidase (proPO)-activating system-associated genes (MnPPAF, MnPPAE, and MnPO), and antimicrobial peptides (AMPs) (MnALF and MnCRU) were up-regulated after the challenge with Staphylococcus aureus. RNA interference (RNAi)-mediated suppression of the Mn-clip-Lec and MnLec genes in S. aureus-challenged prawns reduced the transcripts of MnPPAF, MnPPAE, MnPO, MnALF and MnCRU. Knockdown of Mn-clip-Lec and MnLec resulted in decrease in PO activity in M. nipponense infected with S. aureus. The recombinant Mn-clip-Lec (rMn-clip-Lec) protein bound all tested bacteria and agglutinated S. aureus. A sugar-binding assay revealed that rMn-clip-Lec could bind to LPS or PGN. rMn-clip-Lec accelerated the clearance of S. aureus in vivo. Our findings suggest that Mn-clip-Lec and its interacting MnLec play important roles in the induction of the proPO system and AMPs expression in M. nipponense during bacterial infection.

Immune function of a C-type lectin with long tandem repeats and abundant threonine in the ridgetail white prawn Exopalaemon carinicauda

C-type lectins (CTLs) are an important class of pattern recognition receptors (PRRs) that exhibit structural and functional diversity in invertebrates. Repetitive DNA sequences are ubiquitous in eukaryotic genomes, representing distinct modes of genome evolution and promoting new gene generation. Our study revealed a new CTL that is composed of two long tandem repeats, abundant threonine, and one carbohydrate recognition domain (CRD) in Exopalaemon carinicauda and has been designated EcTR-CTL. The full-length cDNA of EcTR-CTL was 1242 bp long and had an open reading frame (ORF) of 999 bp that encoded a protein of 332 amino acids. The genome structure of EcTR-CTL contains 4 exons and 3 introns. The length of each repeat unit in EcTR-CTL was 198 bp, which is different from the short tandem repeats reported previously in prawns and crayfish. EcTR-CTL was abundantly expressed in the intestine and hemocytes. After Vibrio parahaemolyticus and white spot syndrome virus (WSSV) challenge, the expression level of EcTR-CTL in the intestine was upregulated. Knockdown of EcTR-CTL downregulated the expression of anti-lipopolysaccharide factor, crustin, and lysozyme during Vibrio infection. The recombinant CRD of EcTR-CTL (rCRD) could bind to bacteria, lipopolysaccharides, and peptidoglycans. Additionally, rCRD can directly bind to WSSV. These findings indicate that 1) CTLs with tandem repeats may be ubiquitous in crustaceans, 2) EcTR-CTL may act as a PRR to participate in the innate immune defense against bacteria via nonself-recognition and antimicrobial peptide regulation, and 3) EcTR-CTL may play a positive or negative role in the process of WSSV infection by capturing virions.

Revisiting the role of hypoxia-inducible factors and nuclear factor erythroid 2-related factor 2 in regulating macrophage inflammation and metabolism

The recent birth of the immunometabolism field has comprehensively demonstrated how the rewiring of intracellular metabolism is critical for supporting the effector functions of many immune cell types, such as myeloid cells. Among all, the transcriptional regulation mediated by Hypoxia-Inducible Factors (HIFs) and Nuclear factor erythroid 2-related factor 2 (NRF2) have been consistently shown to play critical roles in regulating the glycolytic metabolism, redox homeostasis and inflammatory responses of macrophages (Mφs). Although both of these transcription factors were first discovered back in the 1990s, new advances in understanding their function and regulations have been continuously made in the context of immunometabolism. Therefore, this review attempts to summarize the traditionally and newly identified functions of these transcription factors, including their roles in orchestrating the key events that take place during glycolytic reprogramming in activated myeloid cells, as well as their roles in mediating Mφ inflammatory responses in various bacterial infection models.

Gut-brain axis: A cutting-edge approach to target neurological disorders and potential synbiotic application

The microbiota-gut-brain axis (MGBA) represents a sophisticated communication network between the brain and the gut, involving immunological, endocrinological, and neural mediators. This bidirectional interaction is facilitated through the vagus nerve, sympathetic and parasympathetic fibers, and is regulated by the hypothalamic-pituitary-adrenal (HPA) axis. Evidence shows that alterations in gut microbiota composition, or dysbiosis, significantly impact neurological disorders (NDs) like anxiety, depression, autism, Parkinson's disease (PD), and Alzheimer's disease (AD). Dysbiosis can affect the central nervous system (CNS) via neuroinflammation and microglial activation, highlighting the importance of the microbiota-gut-brain axis (MGBA) in disease pathogenesis. The microbiota influences the immune system by modulating chemokines and cytokines, impacting neuronal health. Synbiotics have shown promise in treating NDs by enhancing cognitive function and reducing inflammation. The gut microbiota's role in producing neurotransmitters and neuroactive compounds, such as short-chain fatty acids (SCFAs), is critical for CNS homeostasis. Therapeutic interventions targeting the MGBA, including dietary modulation and synbiotic supplementation, offer potential benefits for managing neurodegenerative disorders. However, more in-depth clinical studies are necessary to fully understand and harness the therapeutic potential of the MGBA in neurological health and disease.

Therapeutic potential of exosomes derived from mesenchymal stem cells for treatment of systemic lupus erythematosus

Autoimmune diseases are caused by an imbalance in the immune system, producing autoantibodies that cause inflammation leading to tissue damage and organ dysfunction. Systemic Lupus Erythematosus (SLE) is one of the most common autoimmune diseases and a major contributor to patient morbidity and mortality. Although many drugs manage the disease, curative therapy remains elusive, and current treatment regimens have substantial side effects. Recently, the therapeutic potential of exosomes has been extensively studied, and novel evidence has been demonstrated. A direct relationship between exosome contents and their ability to regulate the immune system, inflammation, and angiogenesis. The unique properties of extracellular vesicles, such as biomolecule transportation, biodegradability, and stability, make exosomes a promising treatment candidate for autoimmune diseases, particularly SLE. This review summarizes the structural features of exosomes, the isolation/purification/quantification method, their origin, effect, immune regulation, a critical consideration for selecting an appropriate source, and their therapeutic mechanisms in SLE.

Innate and germline immune memory: specificity and heritability of the ancient immune mechanisms for adaptation and survival

The immune memory is one of the defensive strategies developed by both unicellular and multicellular organisms for ensuring their integrity and functionality. While the immune memory of the vertebrate adaptive immune system (based on somatic recombination) is antigen-specific, encompassing the generation of memory T and B cells that only recognize/react to a specific antigen epitope, the capacity of vertebrate innate cells to remember past events is a mostly non-specific mechanism of adaptation. This "innate memory" can be considered as germline-encoded because its effector tools (such as innate receptors) do not need somatic recombination for being active. Also, in several organisms the memory-related information is integrated in the genome of germline cells and can be transmitted to the progeny for several generations, but it can also be erased depending on the environmental conditions. Overall, depending on the organism, its environment and its living habits, innate immune memory appears to be a mechanism for achieving better protection and survival against repeated exposure to microbes/stressful agents present in the same environment or occurring in the same anatomical district, able to adapt to changes in the environmental cues. The anatomical and functional complexity of the organism and its lifespan drive the generation of different immune memory mechanisms, for optimal adaptation to changes in the living/environmental conditions. The concept of innate immunity being non-specific needs to be revisited, as a wealth of evidence suggests a significant degree of specificity both in the primary immune reaction and in the ensuing memory-like responses. This is clearly evident in invertebrate metazoans, in which distinct scenarios can be observed, with both non-specific (immune enhancement) or specific (immune priming) memory-like responses. In the case of mammals, there is evidence that some degree of specificity can be attained in different situations, for instance as organ-specific protection rather than microorganism-specific reaction. Thus, depending on the challenges and conditions, innate memory can be non-specific or specific, can be integrated in the germline and transmitted to the progeny or be short-lived, thereby representing an exceptionally plastic mechanism of defensive adaptation for ensuring individual and species survival.

Experimental Infection Models and Their Usefulness for White Spot Syndrome Virus (WSSV) Research in Shrimp

White spot syndrome virus (WSSV) is marked as one of the most economically devastating pathogens in shrimp aquaculture worldwide. Infection of cultured shrimp can lead to mass mortality (up to 100%). Although progress has been made, our understanding of WSSV's infection process and the virus-host-environment interaction is far from complete. This in turn hinders the development of effective mitigation strategies against WSSV. Infection models occupy a crucial first step in the research flow that tries to elucidate the infectious disease process to develop new antiviral treatments. Moreover, since the establishment of continuous shrimp cell lines is a work in progress, the development and use of standardized in vivo infection models that reflect the host-pathogen interaction in shrimp is a necessity. This review critically examines key aspects of in vivo WSSV infection model development that are often overlooked, such as standardization, (post)larval quality, inoculum type and choice of inoculation procedure, housing conditions, and shrimp welfare considerations. Furthermore, the usefulness of experimental infection models for different lines of WSSV research will be discussed with the aim to aid researchers when choosing a suitable model for their research needs.

Porcine reproductive and respiratory syndrome virus infection induces microRNA novel-216 production to facilitate viral-replication by targeting MAVS 3´UTR

Porcine reproductive and respiratory syndrome virus (PRRSV) has caused significant economic losses in the swine industry. In this study, the high-throughput sequencing, microRNAs (miRNAs) mimic, and lentivirus were used to screen for potential miRNAs that can promote PRRSV infection in porcine alveolar macrophages or Marc-145 cells. It was observed that novel-216, a previously unidentified miRNA, was upregulated through the p38 signaling pathway during PRRSV infection, and its overexpression significantly increased PRRSV replication. Further analysis revealed that novel-216 regulated PRRSV replication by directly targeting mitochondrial antiviral signaling protein (MAVS), an upstream molecule of type Ⅰ IFN that mediates the production and response of type Ⅰ IFN. The proviral function of novel-216 on PRRSV replication was abolished by MAVS overexpression, and this effect was reversed by the 3'UTR of MAVS, which served as the target site of novel-216. In conclusion, this study demonstrated that PRRSV-induced upregulation of novel-216 served to inhibit the production and response of typeⅠ IFN and facilitate viral replication, providing new insights into viral immune evasion and persistent infection.

When Our Best Friend Becomes Our Worst Enemy: The Mitochondrion in Trauma, Surgery, and Critical Illness

Common for major surgery, multitrauma, sepsis, and critical illness, is a whole-body inflammation. Tissue injury is able to trigger a generalized inflammatory reaction. Cell death causes release of endogenous structures termed damage associated molecular patterns (DAMPs) that initiate a sterile inflammation. Mitochondria are evolutionary endosymbionts originating from bacteria, containing molecular patterns similar to bacteria. These molecular patterns are termed mitochondrial DAMPs (mDAMPs). Mitochondrial debris released into the extracellular space or into the circulation is immunogenic and damaging secondary to activation of the innate immune system. In the circulation, released mDAMPS are either free or exist in extracellular vesicles, being able to act on every organ and cell in the body. However, the role of mDAMPs in trauma and critical care is not fully clarified. There is a complete lack of knowledge how they may be counteracted in patients. Among mDAMPs are mitochondrial DNA, cardiolipin, N-formyl peptides, cytochrome C, adenosine triphosphate, reactive oxygen species, succinate, and mitochondrial transcription factor A. In this overview, we present the different mDAMPs, their function, release, targets, and inflammatory potential. In light of present knowledge, the role of mDAMPs in the pathophysiology of major surgery and trauma as well as sepsis, and critical care is discussed.

Complexing Protein-Free Botulinum Neurotoxin A Formulations: Implications of Excipients for Immunogenicity

The formation of neutralizing antibodies is a growing concern in the use of botulinum neurotoxin A (BoNT/A) as it may result in secondary treatment failure. Differences in the immunogenicity of BoNT/A formulations have been attributed to the presence of pharmacologically unnecessary bacterial components. Reportedly, the rate of antibody-mediated secondary non-response is lowest in complexing protein-free (CF) IncobotulinumtoxinA (INCO). Here, the published data and literature on the composition and properties of the three commercially available CF-BoNT/A formulations, namely, INCO, Coretox® (CORE), and DaxibotulinumtoxinA (DAXI), are reviewed to elucidate the implications for their potential immunogenicity. While all three BoNT/A formulations are free of complexing proteins and contain the core BoNT/A molecule as the active pharmaceutical ingredient, they differ in their production protocols and excipients, which may affect their immunogenicity. INCO contains only two immunologically inconspicuous excipients, namely, human serum albumin and sucrose, and has demonstrated low immunogenicity in daily practice and clinical studies for more than ten years. DAXI contains four excipients, namely, L-histidine, trehalosedihydrate, polysorbate 20, and the highly charged RTP004 peptide, of which the latter two may increase the immunogenicity of BoNT/A by introducing neo-epitopes. In early clinical studies with DAXI, antibodies against BoNT/A and RTP004 were found at low frequencies; however, the follow-up period was critically short, with a maximum of three injections. CORE contains four excipients: L-methionine, sucrose, NaCl, and polysorbate 20. Presently, no data are available on the immunogenicity of CORE in human beings. It remains to be seen whether all three CF BoNT/A formulations demonstrate the same low immunogenicity in patients over a long period of time.

DNA at the center of mammalian innate immune recognition of bacterial biofilms

Historically, the study of innate immune detection of bacterial infections has focused on the recognition of pathogen-associated molecular patterns (PAMPs) from bacteria growing as single cells in planktonic phase. However, over the past two decades, studies have highlighted an adaptive advantage of bacteria: the formation of biofilms. These structures are complex fortresses that stand against a hostile environment, including antibiotics and immune responses. Extracellular DNA (eDNA) is a crucial component of the matrix of most known biofilms. In this opinion article, I propose that eDNA is a universal PAMP that the immune system uses to recognize biofilms. Outstanding questions concern the discrimination between biofilm-associated eDNA and DNA from planktonic bacteria, the innate receptors involved, and the immune response to biofilms.

Immunomodulation in non-alcoholic fatty liver disease: exploring mechanisms and applications

Non-alcoholic fatty liver disease (NAFLD) exhibits increased lipid enrichment in hepatocytes. The spectrum of this disease includes stages such as nonalcoholic simple fatty liver (NAFL), nonalcoholic steatohepatitis (NASH), and liver fibrosis. Changes in lifestyle behaviors have been a major factor contributing to the increased cases of NAFLD patients globally. Therefore, it is imperative to explore the pathogenesis of NAFLD, identify therapeutic targets, and develop new strategies to improve the clinical management of the disease. Immunoregulation is a strategy through which the organism recognizes and eliminates antigenic foreign bodies to maintain physiological homeostasis. In this process, multiple factors, including immune cells, signaling molecules, and cytokines, play a role in governing the evolution of NAFLD. This review seeks to encapsulate the advancements in research regarding immune regulation in NAFLD, spanning from underlying mechanisms to practical applications.

Impact of maternal live yeast supplementation to sows on intestinal inflammatory cytokine expression and tight junction proteins in suckling and weanling piglets

Recent studies have highlighted the importance of maternal nutrition during gestation and lactation in modulating the gastrointestinal development and health of offspring. Therefore, the objective of this study was to determine the effects of live yeast (LY) supplementation to sows during late gestation and throughout lactation on markers of gut health of piglets prior to weaning and immediately postweaning. On day 77 of gestation, forty sows were allotted based on parity and expected farrowing dates to two dietary treatments: without (CON) or with (LY) supplementation at 0.05% and 0.1% of diet during gestation and lactation, respectively. On postnatal days (PND) 0, 10, 18, and postweaning days (PWD) 7 and 14, one piglet from each of 10 sows per treatment were selected for intestinal tissue collection (n = 10). Real-time PCR and western blotting analyses were used to determine the mucosal expression of immune and antioxidant-regulatory genes and tight junction markers of gut health in the duodenum, jejunum, and ileum. Inflammatory and tight junction markers on PND 0 were not affected by maternal dietary treatment. On PND 18, maternal LY supplementation increased (P < 0.05) mRNA expression of interleukin (IL)-6 and tended (P = 0.08) to increase expression of IL-10 in the ileal muocsa. Maternal LY supplementation also increased (P < 0.05) expression of IL-1β in the ileal mucosa on PWD 14. Likewise, expression of superoxide dismutase (SOD) 1 was increased (P < 0.05) by LY on PND 10, 18, and PWD 14, with a tendency (P = 0.09) for a greater mRNA abundance of catalase on PND 14 in the ileal mucosa. Compared to CON piglets, LY piglets had a higher (P < 0.05) protein abundance of E-cadherin in the jejunal mucosa on PND 0, PWD 7, and PWD 14. Levels of occludin and claudin-4 were also higher (P < 0.05) in the jejunum of LY piglets on PWD 14. No differences were found in jejunal histomorphological measurements between treatments. In conclusion, this study shows that maternal LY supplementation affects key markers of gut health and development in the offspring that may impact the future growth potential and health of newborn piglets.

Effect of functionalized titanium particles with dexamethasone-loaded nanospheres on macrophage polarization and activity

OBJECTIVE

The aim of this study was to determine the effect of titanium micro particles (TiP) previously functionalized with nanoparticles doped with dexamethasone (Dex) and doxycycline (Dox), on macrophage polarization and activity.

METHODS

Macrophages RAW264.7 were cultured in the presence TiP loaded with dexamethasone -NPs (Dex)- and doxycycline -NPs (Dox)-, and as control, TiP with or without doped NPs. Cells were tested with and without previous bacterial lipopolysaccharide endotoxin (LPS) stimulation. Their morphology, proliferation, cytotoxicity, phenotypic change, and cytokines release were assessed by LIVE/DEAD, DNA release, metabolic activity, brightfield and scanning electron microscopy. The test Kruskall-Wallis was used for comparisons, while the cytokine expression profiles were examined by hierarchical clustering (p < 0.05).

RESULTS

Upon exposure with TiP macrophages were activated and polarized to M1, but without depicting cytotoxic effects. The particles were phagocytised, and vacuolized. When exposed to functionalised TiP with NPs(Dex) and NPs(Dox), the ratio M1/M2 was up to forty times lower compared to TiP alone. When exposed to LPS, TiP reduced cell viability in half. Functionalised TiP with NPs(Dex) inhibited the cytokine release exerted by TiP on macrophages. When macrophages were exposed to functionalised TiPs with NPs(Dex) with and without LPS, the effect of TiP on cytokine secretion was inhibited.

SIGNIFICANCE

Functionalised TiPs with NPs(Dex) and NPs(Dox) may potentially have beneficial effects on modulating titanium and LPS-related inflammatory reactions.

Macrophage memory: Types, mechanisms, and its role in health and disease

On the basis of the mechanisms of action and characteristics of immune effects, immunity is commonly categorized into innate and adaptive immunity. Adaptive immunity is associated with the response to non-self-entities and is characterized by high specificity and memory properties. In contrast, innate immunity has traditionally been considered devoid of memory characteristics. However, an increasing number of studies have sought to challenge this conventional immunological dogma and shown that innate immune cells exhibit a more robust and rapid response to secondary stimulation, thus providing evidence of the immunological memory in innate immunity. Macrophages, which are among the most important innate immune cells, can also acquire memory phenotype that facilitates the mediation of recall responses. Macrophage memory is a relatively new concept that is revolutionizing our understanding of macrophage biology and immunological memory and could lead to a new class of vaccines and immunotherapies. In this review, we describe the characteristics and mechanisms of macrophage memory, as well as its essential roles in various diseases.

Decades Long Involvement of THP-1 Cells as a Model for Macrophage Research: A Comprehensive Review

Over the years, researchers have endeavored to identify dependable and reproducible in vitro models for examining macrophage behavior under controlled conditions. The THP-1 cell line has become a significant and widely employed tool in macrophage research within these models. Originating from the peripheral blood of individuals with acute monocytic leukemia, this human monocytic cell line can undergo transformation into macrophage-like cells, closely mirroring primary human macrophages when exposed to stimulants. Macrophages play a vital role in the innate immune system, actively regulating inflammation, responding to infections, and maintaining tissue homeostasis. A comprehensive understanding of macrophage biology and function is crucial for gaining insights into immunological responses, tissue healing, and the pathogenesis of diseases such as viral infections, autoimmune disorders, and neoplastic conditions. This review aims to thoroughly evaluate and emphasize the extensive history of THP-1 cells as a model for macrophage research. Additionally, it will delve into the significance of THP-1 cells in advancing our comprehension of macrophage biology and their invaluable contributions to diverse scientific domains.

Nanovaccines for Advancing Long-Lasting Immunity against Infectious Diseases

Infectious diseases, particularly life-threatening pathogens such as small pox and influenza, have substantial implications on public health and global economies. Vaccination is a key approach to combat existing and emerging pathogens. Immunological memory is an essential characteristic used to evaluate vaccine efficacy and durability and the basis for the long-term effects of vaccines in protecting against future infections; however, optimizing the potency, improving the quality, and enhancing the durability of immune responses remains challenging and a focus for research involving investigation of nanovaccine technologies. In this review, we describe how nanovaccines can address the challenges for conventional vaccines in stimulating adaptive immune memory responses to protect against reinfection. We discuss protein and nonprotein nanoparticles as useful antigen platforms, including those with highly ordered and repetitive antigen array presentation to enhance immunogenicity through cross-linking with multiple B cell receptors, and with a focus on antigen properties. In addition, we describe how nanoadjuvants can improve immune responses by providing enhanced access to lymph nodes, lymphnode targeting, germinal center retention, and long-lasting immune response generation. Nanotechnology has the advantage to facilitate vaccine induction of long-lasting immunity against infectious diseases, now and in the future.

Modulatory immune responses in fungal infection associated with organ transplant - advancements, management, and challenges

Organ transplantation stands as a pivotal achievement in modern medicine, offering hope to individuals with end-stage organ diseases. Advancements in immunology led to improved organ transplant survival through the development of immunosuppressants, but this heightened susceptibility to fungal infections with nonspecific symptoms in recipients. This review aims to establish an intricate balance between immune responses and fungal infections in organ transplant recipients. It explores the fundamental immune mechanisms, recent advances in immune response dynamics, and strategies for immune modulation, encompassing responses to fungal infections, immunomodulatory approaches, diagnostics, treatment challenges, and management. Early diagnosis of fungal infections in transplant patients is emphasized with the understanding that innate immune responses could potentially reduce immunosuppression and promise efficient and safe immuno-modulating treatments. Advances in fungal research and genetic influences on immune-fungal interactions are underscored, as well as the potential of single-cell technologies integrated with machine learning for biomarker discovery. This review provides a snapshot of the complex interplay between immune responses and fungal infections in organ transplantation and underscores key research directions.

MicroRNAs regulating macrophages infected with Leishmania L. (V.) Braziliensis isolated from different clinical forms of American tegumentary leishmaniasis

Background

Leishmaniasis is an infectious disease caused by protozoa of the genus Leishmania. There are still no vaccines, and therapeutic options are limited, indicating the constant need to understand the fine mechanisms of its pathophysiology. An approach that has been explored in leishmaniasis is the participation of microRNAs (miRNAs), a class of small non-coding RNAs that act, in most cases, to repress gene expression. miRNAs play a role in the complex and plastic interaction between the host and pathogens, either as part of the host's immune response to neutralize infection or as a molecular strategy employed by the pathogen to modulate host pathways to its own benefit.

Methods

Monocyte-derived macrophages from healthy subjects were infected with isolates of three clinical forms of L. braziliensis: cutaneous (CL), mucosal (ML), and disseminated (DL) leishmaniasis. We compared the expression of miRNAs that take part in the TLR/NFkB pathways. Correlations with parasite load as well as immune parameters were analyzed.

Results

miRNAs -103a-3p, -21-3p, 125a-3p -155-5p, -146a-5p, -132- 5p, and -147a were differentially expressed in the metastatic ML and DL forms, and there was a direct correlation between miRNAs -103a-3p, -21-3p, -155-5p, -146a-5p, -132-5p, and -9-3p and parasite load with ML and DL isolates. We also found a correlation between the expression of miR-21-3p and miR-146a-5p with the antiapoptotic gene BCL2 and the increase of viable cells, whereas miR-147a was indirectly correlated with CXCL-9 levels.

Conclusion

The expression of miRNAs is strongly correlated with the parasite load and the inflammatory response, suggesting the participation of these molecules in the pathogenesis of the different clinical forms of L. braziliensis.

Influences of Aged Bone Marrow Macrophages on Skeletal Health and Senescence

PURPOSE OF REVIEW

The purpose of this review is to discuss the role of macrophages in the regulation of skeletal health with age, particularly in regard to both established and unexplored mechanisms in driving inflammation and senescence.

RECENT FINDINGS

A multitude of research has uncovered mechanisms of intrinsic aging in macrophages, detrimental factors released by these immune cells, and crosstalk from senescent mesenchymal cell types, which altogether drive age-related bone loss. Furthermore, bone marrow macrophages were recently proposed to be responsible for the megakaryocytic shift during aging and overall maintenance of the hematopoietic niche. Studies on extra-skeletal macrophages have shed light on possible conserved mechanisms within bone and highlight the importance of these cells in systemic aging. Macrophages are a critically important cell type in maintaining skeletal homeostasis with age. New discoveries in this area are of utmost importance in fully understanding the pathogenesis of osteoporosis in aged individuals.

Microbial sensing in the intestine

The gut microbiota plays a key role in host health and disease, particularly through their interactions with the immune system. Intestinal homeostasis is dependent on the symbiotic relationships between the host and the diverse gut microbiota, which is influenced by the highly co-evolved immune-microbiota interactions. The first step of the interaction between the host and the gut microbiota is the sensing of the gut microbes by the host immune system. In this review, we describe the cells of the host immune system and the proteins that sense the components and metabolites of the gut microbes. We further highlight the essential roles of pattern recognition receptors (PRRs), the G protein-coupled receptors (GPCRs), aryl hydrocarbon receptor (AHR) and the nuclear receptors expressed in the intestinal epithelial cells (IECs) and the intestine-resident immune cells. We also discuss the mechanisms by which the disruption of microbial sensing because of genetic or environmental factors causes human diseases such as the inflammatory bowel disease (IBD).

Host Defense Proteins and Peptides with Lipopolysaccharide-Binding Activity from Marine Invertebrates and Their Therapeutic Potential in Gram-Negative Sepsis

Sepsis is a life-threatening complication of an infectious process that results from the excessive and uncontrolled activation of the host's pro-inflammatory immune response to a pathogen. Lipopolysaccharide (LPS), also known as endotoxin, which is a major component of Gram-negative bacteria's outer membrane, plays a key role in the development of Gram-negative sepsis and septic shock in humans. To date, no specific and effective drug against sepsis has been developed. This review summarizes data on LPS-binding proteins from marine invertebrates (ILBPs) that inhibit LPS toxic effects and are of interest as potential drugs for sepsis treatment. The structure, physicochemical properties, antimicrobial, and LPS-binding/neutralizing activity of these proteins and their synthetic analogs are considered in detail. Problems that arise during clinical trials of potential anti-endotoxic drugs are discussed.

Microbiota Metabolites and Immune Regulation Affect Ischemic Stroke Occurrence, Development, and Prognosis

The gut microbiota are not only related to the development and occurrence of digestive system disease, but also have a bidirectional relationship with nervous system diseases via the microbiota-gut-brain axis. At present, correlations between the gut microbiota and neurological diseases, including stroke, are one of the focuses of investigation and attention in the medical community. Ischemic stroke (IS) is a cerebrovascular disease accompanied by focal neurological deficit or central nervous system injury or death. In this review, we summarize the contemporary latest research on correlations between the gut microbiota and IS. Additionally, we discuss the mechanisms of gut microbiota implicated in IS and related to metabolite production and immune regulation. Moreover, the factors of gut microbiota that affecting IS occurrence, and research implicating the gut microbiota as potential therapeutic targets for IS, are highlighted. Our review highlights the evidential relationships and connections between the gut microbiota and IS pathogenesis and prognosis.

Understanding the Gut-Brain Axis and Its Therapeutic Implications for Neurodegenerative Disorders

The gut-brain axis (GBA) is a complex bidirectional communication network connecting the gut and brain. It involves neural, immune, and endocrine communication pathways between the gastrointestinal (GI) tract and the central nervous system (CNS). Perturbations of the GBA have been reported in many neurodegenerative disorders (NDDs), such as Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS), among others, suggesting a possible role in disease pathogenesis. The gut microbiota is a pivotal component of the GBA, and alterations in its composition, known as gut dysbiosis, have been associated with GBA dysfunction and neurodegeneration. The gut microbiota might influence the homeostasis of the CNS by modulating the immune system and, more directly, regulating the production of molecules and metabolites that influence the nervous and endocrine systems, making it a potential therapeutic target. Preclinical trials manipulating microbial composition through dietary intervention, probiotic and prebiotic supplementation, and fecal microbial transplantation (FMT) have provided promising outcomes. However, its clear mechanism is not well understood, and the results are not always consistent. Here, we provide an overview of the major components and communication pathways of the GBA, as well as therapeutic approaches targeting the GBA to ameliorate NDDs.

Material matters: exploring the interplay between natural biomaterials and host immune system

Biomaterials are widely used for various medical purposes, for instance, implants, tissue engineering, medical devices, and drug delivery systems. Natural biomaterials can be obtained from proteins, carbohydrates, and cell-specific sources. However, when these biomaterials are introduced into the body, they trigger an immune response which may lead to rejection and failure of the implanted device or tissue. The immune system recognizes natural biomaterials as foreign substances and triggers the activation of several immune cells, for instance, macrophages, dendritic cells, and T cells. These cells release pro-inflammatory cytokines and chemokines, which recruit other immune cells to the implantation site. The activation of the immune system can lead to an inflammatory response, which can be beneficial or detrimental, depending on the type of natural biomaterial and the extent of the immune response. These biomaterials can also influence the immune response by modulating the behavior of immune cells. For example, biomaterials with specific surface properties, such as charge and hydrophobicity, can affect the activation and differentiation of immune cells. Additionally, biomaterials can be engineered to release immunomodulatory factors, such as anti-inflammatory cytokines, to promote a tolerogenic immune response. In conclusion, the interaction between biomaterials and the body's immune system is an intricate procedure with potential consequences for the effectiveness of therapeutics and medical devices. A better understanding of this interplay can help to design biomaterials that promote favorable immune responses and minimize adverse reactions.

Immunogenicity of lipid nanoparticles and its impact on the efficacy of mRNA vaccines and therapeutics

Several studies have utilized a lipid nanoparticle delivery system to enhance the effectiveness of mRNA therapeutics and vaccines. However, these nanoparticles are recognized as foreign materials by the body and stimulate innate immunity, which in turn impacts adaptive immunity. Therefore, it is crucial to understand the specific type of innate immune response triggered by lipid nanoparticles. This article provides an overview of the immunological response in the body, explores how lipid nanoparticles activate the innate immune system, and examines the adverse effects and immunogenicity-related development pathways associated with these nanoparticles. Finally, we highlight and explore strategies for regulating the immunogenicity of lipid nanoparticles.

Research progress of pattern recognition receptors in red swamp crayfish (Procambarus clarkii)

Though Procambarus clarkii (red swamp crayfish) is a lower invertebrate, it has nonetheless developed a complex innate immune system. The crayfish farming industry has suffered considerable economic losses in recent years as a consequence of bacterial and viral diseases. Hence, perhaps the most effective ways to prevent microbial infections in P. clarkii are to examine and elucidate its innate immunity. The first step in the immune response is to recognize pathogen-associated molecular patterns (PAMPs) through pattern recognition receptors (PRRs). PRRs are expressed mainly on immune cell surfaces and recognize at least one PAMP. Thence, downstream immune responses are activated and pathogens are phagocytosed. To date, the PRRs identified in P. clarkii include Toll-like receptors (TLRs), lectins, fibrinogen-related proteins (FREPs), and β-1,3-glucan-binding proteins (BGRPs). The present review addresses recent progress in research on PRRs and aims to provide guidance for improving immunity and preventing and treating infectious diseases in P. clarkii.

Enterococcus faecium HDRsEf1 Promotes Systemic Th1 Responses and Enhances Resistance to SalmonellaTyphimurium Infection

The gut microbiota is known to regulate the immune system and thereby influence susceptibility to infection. In this study, we observed that the administration of Enterococcus faecium HDRsEf1 (HDRsEf1) led to an improvement in the development of the immune system. This was evidenced by an increase in both the spleen index and the area of spleen white pulp. Specifically, the proportion of T helper (Th) 1 cells and the production of IFN-γ and IL-12 were significantly increased in the spleens of mice treated with HDRsEf1. In agreement with the in vivo results, we found that Th1-related cytokines, including IFN-γ and IL-12p70, were strongly induced in splenocytes treated with HDRsEf1. In addition, Th1 cell activation and high-level secretion of IL-12p70 were also confirmed by coculture of CD4+ T cells with bone marrow-derived dendritic cells treated with HDRsEf1. Moreover, the employment of HDRsEf1 was identified to augment resilience against systemic infection provoked by S. Typhimurium and stimulate the expression of the genes for TNFα and iNOS in the initial stage of infection, signifying that reinforced Th1 cells and IL-12 might activate macrophages for antibacterial safeguards. In summary, our study suggests that HDRsEf1 could act as an effective immunobiotic functional agent, promoting systemic Th1 immunological responses and priming defenses against infection.

The TRAF gene family in turbot (Scophthalmus maximus): Identification, characterization, molecular evolution and expression patterns analysis

Tumor necrosis factor receptor-associated factor (TRAF) is an important structural protein, which can bind to TNF receptors and participate in the regulation of TNF signaling pathway. Nonetheless, few studies have been conducted to investigate the systematic identification of TRAF gene family in teleost and role in innate immunity of turbot (Scophthalmus maximus). In this study, eight TRAF genes, namely SmTRAF2aa, SmTRAF2ab, SmTRAF2b, SmTRAF3, SmTRAF4a, SmTRAF5, SmTRAF6 and SmTRAF7, were identified and annotated in turbot by using bioinformatics methods. Analysis of the phylogenetic, syntenic and molecular evolution demonstrated that all SmTRAF members were evolutionarily conserved in teleost. Domain analysis showed all SmTRAF proteins contained a typical conserved N-terminal RING finger domain. Most SmTRAF proteins contained a MATH domain at the C-terminal, while SmTRAF7 contains seven duplicate WD40 domains. In addition, quantitative real-time PCR was performed to detect the expression patterns of SmTRAFs in tissues from healthy and Vibrio anguillarum infected turbots. The results indicated SmTRAFs had diverse tissue expression patterns and the expression of TRAF gene changed significantly after V. anguillarum infection. This study provided a basis for understanding the roles of TRAFs in the innate immune response of turbot.

Inflammasome activation by viral infection: mechanisms of activation and regulation

Viral diseases are the most common problems threatening human health, livestock, and poultry industries worldwide. Viral infection is a complex and competitive dynamic biological process between a virus and a host/target cell. During viral infection, inflammasomes play important roles in the host and confer defense mechanisms against the virus. Inflammasomes are polymeric protein complexes and are considered important components of the innate immune system. These immune factors recognize the signals of cell damage or pathogenic microbial infection after activation by the canonical pathway or non-canonical pathway and transmit signals to the immune system to initiate the inflammatory responses. However, some viruses inhibit the activation of the inflammasomes in order to replicate and proliferate in the host. In recent years, the role of inflammasome activation and/or inhibition during viral infection has been increasingly recognized. Therefore, in this review, we describe the biological properties of the inflammasome associated with viral infection, discuss the potential mechanisms that activate and/or inhibit NLRP1, NLRP3, and AIM2 inflammasomes by different viruses, and summarize the reciprocal regulatory effects of viral infection on the NLRP3 inflammasome in order to explore the relationship between viral infection and inflammasomes. This review will pave the way for future studies on the activation mechanisms of inflammasomes and provide novel insights for the development of antiviral therapies.

Establishment and characterization of Yellow River carp (Cyprinus carpio haematopterus) muscle cell line and its application to fish virology and immunology

The Yellow River carp (Cyprinus carpio haematopterus) is a vital economically farmed fish of the Cyprinidae family. With the development of intensive aquaculture, carp production has increased dramatically, leading to the frequent occurrence of various diseases. Cell lines are considered the most cost-effective resource for in vitro studies and are widely used for physiological and pathological studies because of accessibility and convenience. This research established a novel immortal cell line CCM (Yellow River carp muscle cells) derived from the carp muscle. CCM has been passed over 71 generations for 1 year. The morphology of CCM and the adhesion and extension processes were captured by light and electron microscopy. CCM were passaged every 3 days with 20% FBS DMEM/F12 at 1:3. The optimum conditions for CCM growth were 28 °C and 20% FBS concentration. DNA sequencing of 16S rRNA and COI showed that CCM was derived from carp. CCM positively reacts to anti-PAX7 and anti-MyoD antibodies of carp. Analysis of chromosomes revealed that the chromosomal pattern number of CCM was 100. Transfection experiment demonstrated that CCM might be utilized to express foreign genes. Furthermore, cytotoxicity testing showed that CCM was susceptible to Aeromonas hydrophila, Aeromonas salmonicida, Aeromonas veronii, and Staphylococcus Aureus. The organophosphate pesticides (chlorpyrifos and glyphosate) or heavy metals (Hg, Cd, and Cu) exhibited dose-dependent cytotoxicity against CCM. After LPS treatment, the MyD88-IRAKs-NFκB pathway stimulates inflammatory-related factor il1β, il8, il10, and nfκb expression. LPS did not seem to cause oxidative stress in CCM, and the expression of cat and sod was not affected. Poly (I:C) through TLR3-TRIF-MyD88-TRAF6-NFκB and TRIF-TRAF3-TBK1-IRF3 activated the transcription of related factors, increased expression of anti-viral protein, but no changes in apoptosis-related genes. To our knowledge, this is the first muscle cell line in Yellow River carp and the first study on the immune response signal pathways of Yellow River carp based on the muscle cell line. CCM cell line provides a more rapid and efficient experimental material for fish immunology research, and this study preliminarily elucidated its immune response strategy to LPS and poly (I:C).