Mucosal Immunity Research Articles

Study on the physicochemical properties and immune regulatory mechanism of polysaccharide fraction from Aronia Melanocarpa fruit.

Aronia Melanocarpa (Michx.) Elliott fruit has been extensively used in the food and medicinal fields. This study aimed to analyze the physicochemical properties of a polysaccharide fraction (AMP2) isolated from this fruit for the first time and investigated its immune regulatory mechanism. The physicochemical properties of AMP2 were determined using high-performance gel permeation chromatography, PMP derivatization-high performance liquid chromatography, Ultraviolet spectroscopy, and infrared spectroscopy. The metagenomic technology was applied to investigate the regulatory effects and mechanisms of AMP2 on the gut microbiota of immunosuppressed mice. The results showed that molecular weight of AMP2 was 83,444Da, which was mainly composed of D-arabinose, D-xylose, D-mannose, D-rhamnose and D-glucose, and both β-type and α-type glycosidic bonds contained in its structure. AMP2 changed the composition of gut microbiota by increasing the number of beneficial and probiotic bacteria, thereby regulated the intestinal mucosal immune system of host. AMP2 improved intestinal immune system response and antimicrobial capacity through positive regulation of the NOD-like receptor signaling pathway and neutrophil extracellular trap formation. The results demonstrate the potential of AMP2 in immune regulation, providing a new perspective for its subsequent development and contributing to the development and application of related health foods.

Regionalization of intestinal microbiota and metabolites in the small intestine of the Bactrian camel

IntroductionPeyer's patches (PPs) are crucial antigen-inductive sites of intestinal mucosal immunity. Prior research indicated that, in contrast to other ruminants, PPs in the small intestine of Bactrian camels are found in the duodenum, jejunum, and ileum and display polymorphism. Using this information, we analyzed the microbial and metabolic characteristics in various segments of the Bactrian camel's small intestine to further elucidate how the immune system varies across different regions. MethodsIn this study, the microbiota and metabolite of 36 intestinal mucosal samples, including duodenal (D-PPs), jejunal (J-PPs), and ileal PPs (I-PPs), were profiled for six Bactrian camels using 16S rRNA gene sequencing and liquid chromatography with tandem mass spectrometry (LC-MS/MS). To confirm meaningful associations, we conducted connection analyses on the significantly different objects identified in each group's results. ELISA was used to analyze the levels of IgA, IgG, and IgM in the same tissues. ResultsThe microbiota and metabolite profiles of J-PPs and I-PPs were found to be similar, whereas those of D-PPs were more distinct. In J-PPs and I-PPs, the dominant bacterial genera included Clostridium, Turicibacter, and Shigella. In contrast, D-PPs had a significant increase in the abundance of Prevotella, Fibrobacter, and Succinobacter. Regarding the metabolomics, D-PPs exhibited high levels of polypeptides, acetylcholine, and histamine. On the other hand, J-PPs and I-PPs were characterized by an enrichment of free amino acids, such as L-arginine, L-glutamic acid, and L-serine. These metabolic differences mainly involve amino acid production and metabolic processes. Furthermore, the distribution of intestinal immunoglobulins highlighted the specificity of D-PPs. Our results indicated that proinflammatory microbes and metabolites were significantly enriched in D-PPs. In contrast, J-PPs and I-PPs contained substances that more effectively enhance immune responses, as evidenced by the differential distribution of IgA, IgG, and IgM.DiscussionThe intestinal microenvironment of Bactrian camels displays distinct regional disparities, which we propose are associated with variations in immunological function throughout different segments of the small intestine. This study highlights the specific traits of the intestinal microbiota and metabolites in Bactrian camels, offering a valuable reference for understanding the relationship between regional intestinal immunity and the general health and disease of the host.

The Crystal Structure of Human IgD-Fc Reveals Unexpected Differences With Other Antibody Isotypes.

Of the five human antibody isotypes, the function of IgD is the least well-understood, although various studies point to a role for IgD in mucosal immunity. IgD is also the least well structurally characterized isotype. Until recently, when crystal structures were reported for the IgD Fab, the only structural information available was a model for intact IgD based on solution scattering data. We now report the crystal structure of human IgD-Fc solved at 3.0 Å resolution. Although similar in overall architecture to other human isotypes, IgD-Fc displays markedly different orientations of the Cδ3 domains in the Cδ3 domain dimer and the lowest interface area of all the human isotypes. The nature of the residues that form the dimer interface also differs from those conserved in the other isotypes. By contrast, the interface between the Cδ2 and Cδ3 domains in each chain is the largest among the human isotypes. This interface is characterized by two binding pockets, not seen in other isotypes, and points to a potential role for the Cδ2/Cδ3 interface in stabilizing the IgD-Fc homodimer. We investigated the thermal stability of IgD-Fc, alone and in the context of an intact IgD antibody, and found that IgD-Fc unfolds in a single transition. Human IgD-Fc clearly has unique structural features not seen in the other human isotypes, and comparison with other mammalian IgD sequences suggests that these unique features might be widely conserved.

Limosilactobacillus reuteri B1/1 modulated the intestinal immune response in preventing Salmonella Enteritidis PT4 infection in a chicken ileal explant model

In this study, we observed the effect of the newly isolated probiotic strain Limosilactobacillus reuteri B1/1 on the relative gene expression of selected cytokines (interleukin-15, transforming growth factor-β4), tight junction proteins (E-cadherin, occludin), biomarker active intestinal stem cells - LGR5 (leucine-rich repeat containing G protein-coupled receptor), markers of mucosal intestinal immunity (mucin-2, immunoglobulin A), as well as the creation of a new biomarker of inflammation in the intestine - calprotectin on an ex vivo model of chicken ileal explant in the prevention of Salmonella Enteritidis PT4 infection. The ability of L. reuteri B1/1 to effectively modulate the mucosal immune response under pretreatment conditions in S. Enteritidis PT4 infection in a chicken ileal explant model was confirmed. In addition, our obtained results point to the fact that the new chicken ileum explant model could be a suitable model to investigate or test the influence of natural substances such as probiotic bacteria in the interaction with the intestine as well as pathogenic microorganisms. In addition, the results of our study may contribute to a deeper understanding of the action of newly isolated probiotic bacteria at the intestinal level using ex vivo models such as chicken ileum explant, which are able to mimic in vivo conditions sufficiently.

Intranasal delivery of a subunit protein vaccine provides protective immunity against JN.1 and XBB-lineage variants.

The mucosal immune response plays a crucial role in the prevention of respiratory viruses. Given the risk of recurrent SARS-CoV-2 infections in the population, the rapid development of next-generation intranasal COVID-19 vaccines with high safety and efficacy is paramount. In the current study, we developed a protein-based intranasal vaccine comprising the XBB.1.5 receptor binding domain (RBD)-derived trimeric recombinant protein (RBDXBB.1.5-HR) and an MF59-like oil-in-water adjuvant. Intranasal administration of RBDXBB.1.5-HR vaccine elicited robust and sustained humoral immune responses in mice and rats, resulting in high levels of neutralizing antibodies against XBB-lineage subvariants, with protection lasting for at least six months. The intranasal RBDXBB.1.5-HR vaccine generated potent mucosal immune responses, characterized by the inductions of tissue-resident T (TRM) cells, local cellular immunity, germinal center, and memory B cell responses in the respiratory tract. The combination of intramuscular and intranasal delivery of the RBDXBB.1.5-HR vaccine demonstrated exceptional systemic and mucosal protective immunity. Furthermore, intranasal delivery of RBDXBB.1.5-HR vaccine as a heterologous booster shot showed more effective boosting effects after mRNA administration compared to homologous vaccination, as evidenced by the induction of superior systemic and extra mucosal immune response. Importantly, the intranasal RBDXBB.1.5-HR vaccine conferred efficient protection against the challenge with authentic EG.5.1 viruses in vivo. These findings identify the intranasal RBDXBB.1.5-HR vaccine as a potential mucosal vaccine candidate for the prevention of SARS-CoV-2 infection.

Preliminary Study on Type I Interferon as a Mucosal Adjuvant for Human Respiratory Syncytial Virus F Protein.

Background: Human respiratory syncytial virus (HRSV) imposes a significant disease burden on infants and the elderly. Intranasal immunization using attenuated live vaccines and certain vector vaccines against HRSV has completed phase II clinical trials with good safety and efficacy.Recombinant protein vaccines for mucosal immunization require potent mucosal adjuvants. Type I interferon (IFN), as a natural mucosal adjuvant, significantly enhances antigen-presenting cell processing and antigen presentation, promoting the production of T and B cells. Methods: This study utilized human α2b interferon (IFN-human) and mouse α2 interferon (IFN-mouse) as nasal mucosal adjuvants in combination with fusion protein (F). Intranasal immunization was performed on BALB/c mice to evaluate the immunogenicity of the formulation in vivo. Results: Compared to the F protein immunization group, mice in the F + IFN-Human and F + IFN-Mouse experimental groups exhibited significantly increased neutralizing antibody titers and augmented secretion of IFN-γ and IL-4 by lymphocytes, and both of them could induce the production of high-titer specific IgA antibodies in mice (p < 0.001).The F + IFN-Human immunization induced the highest IgG and IgG1 antibody titers in mice; however, the F + IFN-Mouse immunization group elicited the highest neutralizing antibody titers (598), lowest viral loads in the lungs (Ct value of 31), and fastest weight recovery in mice. Moreover, mice in the F + IFN-Mouse immunization group displayed the mildest lung pathological damage (Total score of pathological injury was 2). Conclusions: In conclusion, IFN-Mouse, as a mucosal adjuvant for HRSV recombinant protein vaccines, demonstrated superior protective effects in mice compared to IFN-Human adjuvants.

A Passion for Small Things and Staying Primed: My Career in Virology and Immunology.

A love of science and animals, perseverance, and happenstance propelled my career in veterinary virology and immunology. I have focused on deadly enteric and respiratory viral infections in neonatal livestock and humans with an aim to understand their prevalence, pathogenesis, interspecies transmission, and immunity and develop vaccines. Research on animal coronaviruses (CoVs), including their broad interspecies transmission, provided a foundation to understand emerging zoonotic fatal human respiratory CoVs [severe acute respiratory syndrome, Middle East respiratory syndrome, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)] and reverse zoonosis of SARS-CoV-2 to animals. A highlight of my early research was the discovery of the gut-mammary gland-sIgA axis, documenting a common mucosal immune system. The latter remains pivotal to designing maternal vaccines for passive immunity in neonates. Our discovery and innovative cell propagation of fastidious human and animal rotaviruses and caliciviruses and their infectivity in germ-free animals has provided cell-adapted and animal disease models for ongoing virologic and immunologic investigations and vaccines. Nevertheless, besides the research discoveries, my lasting legacy remains the outstanding mentees who have enriched my science and my life.

Astragalus polysaccharide enhances maternal mucosal immunity against PEDV.

This study highlights the limitations of current porcine epidemic diarrhea virus (PEDV) vaccines in inducing sufficient maternal milk IgA, which is crucial for protecting neonatal piglets. By supplementing Astragalus polysaccharide (APS) into the vaccination regimen, we demonstrated a significant enhancement in milk PEDV-specific IgA levels, as well as improved cellular immune responses. APS also bolstered intestinal immune function and homeostasis in piglets. These findings suggest that APS supplementation could serve as an immune booster to enhance maternal immunity, offering a promising approach to better protect piglets against PEDV.

2'-Fucosyllactose and 3'-Sialyllactose Reduce Mortality in Neonatal Enteroaggregative Escherichia coli Infection by Improving the Construction of Intestinal Mucosal Immunity.

Human milk oligosaccharides could prevent pathogenic bacterial infections in neonates; however, direct in vivo anti-infection evidence was still lacking. Here, we systematically evaluated the effects of 2'-fucosyllactose (2'-FL) and 3'-sialyllactose (3'-SL) on the structural development and functional maturation in neonates and their defense against enteroaggregative Escherichia coli infection. It was found that supplementation with 2'-FL and 3'-SL improved the resistance of weaned mice to enteroaggregative E. coli. The mechanism related to the promotion of 2'-FL and 3'-SL in the maturation of intestinal mucosal immunity by promoting stem cell differentiation, mucus layer integrity, and tight junction formation. 2'-FL and 3'-SL significantly increased the ratio of Th1 and Treg cells in the lamina propria, contents of short-chain fatty acids, as well as the serum content of IgA. This study lays a theoretical basis for the application of 2'-FL and 3'-SL in infant formula, as well as the development of intestinal health products.

Influence of breastfeeding on the ontogenesis of mucosal immunity in children

The role of breastfeeding in the development of the cellular immune system, antimicrobial strategies of neutrophils, and local cytokine levels was evaluated in a single-center, prospective, open-label, uncontrolled study of healthy infants who were either naturally or artificially breastfed. The main group included practically healthy children who were exclusively breastfed for the first year of life. Thirty-six children were examined during the first stage and 25 from this group during the second stage. The comparison group included children who received an adapted cow’s milk formula during the first half-year of their lives and a different formula during the second half-year. Thirty-one children were examined during stage one and 27 from this group were examined during stage two. A comprehensive study of mucosal immunity was conducted, assessing the cytokine profile and cellular components using the method of smear prints from the nasal mucosa. The results showed that the nature of feeding during the first year of life influences the formation of mucosal immunity and programming the postnatal development of the child’s immunological reactivity. In the absence of the immunomodulatory effects of breast milk, there is an imbalance in the cytokine profile, with a physiological deviation of the immune response linked to the predominance of Th2 profiles. In contrast, breastfeeding promotes the optimal cellular composition of the upper respiratory mucosa and a cytomorphological neutrophil profile with minimal destructive changes. Breastfeeding programs the optimal functional profile of neutrophils, including the level of receptor activity, intracellular biocidal activity, cytotoxicity, ability to complete phagocytosis. This natural infant feeding method has a long-term protective effect, preventing neutrophil destruction under the influence of environmental factors and respiratory viral agents, and ensuring optimal mucosal immunity development in the respiratory tract.

Assessment of Single-Cycle M-Protein Mutated Vesicular Stomatitis Virus as a Safe and Immunogenic Mucosal Vaccine Platform for SARS-CoV-2 Immunogen Delivery.

The goal of the next-generation COVID-19 vaccine is to provide rapid respiratory tract protection with a single dose. Circulating antibodies do not protect the olfactory mucosa from viral infection, necessitating localized mucosal immunization. Live attenuated vesicular stomatitis virus (VSVMT)-based COVID-19 vaccines effectively stimulate mucosal immunity in animals, though safety concerns remain, particularly in immunocompromised populations. A viral vector capable of single-cycle replication may face less stringent regulatory requirements. A replication-defective VSVMT is developed with its G protein replaced by a SARS-CoV-2 spike protein (S) mutant, where residues K986 and V987 are substituted by prolines (S2P). This studies show that single-cycle VSVMT encoding Omicron subvariant S2P (VSVMT-S2P) is safe in both healthy and immunocompromised animals treated with cyclophosphamide (CP). Significant antibody and T-cell responses against the spike protein are observed in VSVMT-S2P vaccinated healthy animals. Intramuscular VSVMT-S2P administration induces neutralizing antibody responses comparable to those from replication-competent VSVMT-S. In immunocompromised animals, lower and delayed immune responses are observed. Thus, single-cycle M-protein mutated VSV offers a safe and effective platform for SARS-CoV-2 immunogen delivery. Remarkably, replication-competent VSVMT-S caused no pathogenicity and elicited potent mucosal immunity via intranasal administration, highlighting its potential as a mucosal COVID-19 vaccine.

Dissecting immunological mechanisms underlying influenza viral nucleoprotein-induced mucosal immunity against diverse viral strains

ABSTRACT The nucleoprotein (NP) of type A influenza virus (IAV) is highly conserved across all virus strains, making it an attractive candidate antigen for universal vaccines. While various studies have explored NP-induced mucosal immunity, here we interrogated the mechanistic differences between intramuscular (IM) and intranasal (IN) delivery of a recombinant adenovirus carrying NP fused with a bifunctional CD40 ligand. Despite being less effective than IM delivery in inducing systemic cellular immune responses and antibody-dependent cellular cytotoxicity (ADCC), IN immunization elicited superior antigen-specific recall humoral and cellular response in the nasal associated lymphoid tissue (NALT) of the upper respiratory tract, the initial site of immune recognition and elimination of inhaled pathogens. IN vaccination also induced significantly stronger pulmonary T cell responses in the lower respiratory tract than IM vaccination, in particular the CD8 T cells. Moreover, blocking lymphocyte circulation abrogated IM but not IN immunization induced protection, illustrating the critical role of local memory immune response upon viral infection. Notably, the CD40-targeted nasal delivery not only improved the magnitude but also the breadth of protection, including against lethal challenge with a newly isolated highly pathogenic avian H5N1 strain. These findings are informative for the design of universal mucosal vaccines, where the predominant mode of protection is independent of neutralizing antibodies.

Wide possibilities of topical therapy in the treatment of patients with infectious and inflammatory diseases of the pharynx

Despite medical advances, infectious and inflammatory upper respiratory diseases are the most common groups of diseases among outpatients. Viruses induce acute respiratory diseases in most patients; however, bacterial and “atypical” pathogens can cause exacerbations of chronic diseases such as adenoiditis, tonsillitis, pharyngitis and others. Prescribing etiotropic drugs to patients with infectious and inflammatory diseases of the pharynx can reduce the effectiveness of the therapy due to the growth of antimicrobial resistance. Increasing etiotropic drug resistance of some pathogens requires the selection of alternative agents for patients with infectious and inflammatory diseases of the pharynx. The non-specific prophylaxis of the latter is aimed to activate inner defense mechanisms using bacterial lysates (BL). Based on a review of the literature, the article discusses the features of the use and clinical effectiveness of topical BL in infectious and inflammatory diseases of the pharynx. BL are an important supplementation to the standard therapy regimen for inflammatory upper respiratory diseases, which contributes to the restoration of the immune response autoregulation, a reliable decrease in the frequency and duration of acute forms and exacerbations of chronic upper respiratory diseases, and reduced use of antibiotics and antipyretics. Evidence of possible mechanisms to correct immunity in infectious and inflammatory diseases of the pharynx, as well as a review of the clinical effectiveness of the medicine was demonstrated by example of Imudon. Its beneficial use to treat disease in the acute period is associated with its focal action on the infectious and inflammatory lesions. The drug is effective at any stage of the disease and can be used for prophylactic purposes due to activation of mucosal immunity in the respiratory tract. The high efficiency of Imudon is determined by its ability to activate phagocytosis and production of specific immunoglobulins by plasma cells, which reduces the risk of relapses and chronicity of the disease.

Harnessing Bacillus subtilis Spore Surface Display (BSSD) Technology for Mucosal Vaccines and Drug Delivery: Innovations in Respiratory Virus Immunization

Respiratory viruses present significant global health challenges due to their rapid evolution, efficient transmission, and zoonotic potential. These viruses primarily spread through aerosols and droplets, infecting respiratory epithelial cells and causing diseases of varying severity. While traditional intramuscular vaccines are effective in reducing severe illness and mortality, they often fail to induce sufficient mucosal immunity, thereby limiting their capacity to prevent viral transmission. Mucosal vaccines, which specifically target the respiratory tract’s mucosal surfaces, enhance the production of secretory IgA (sIgA) antibodies, neutralize pathogens, and promote the activation of tissue-resident memory B cells (BrMs) and local T cell responses, leading to more effective pathogen clearance and reduced disease severity. Bacillus subtilis spore surface display (BSSD) technology is emerging as a promising platform for the development of mucosal vaccines. By harnessing the stability and robustness of Bacillus subtilis spores to present antigens on their surface, BSSD technology offers several advantages, including enhanced stability, cost-effectiveness, and the ability to induce strong local immune responses. Furthermore, the application of BSSD technology in drug delivery systems opens new avenues for improving patient compliance and therapeutic efficacy in treating respiratory infections by directly targeting mucosal sites. This review examines the potential of BSSD technology in advancing mucosal vaccine development and explores its applications as a versatile drug delivery platform for combating respiratory viral infections.

Oral Administration of Zinc Sulfate with Intramuscular Foot-and-Mouth Disease Vaccine Enhances Mucosal and Systemic Immunity.

Background/Objectives: Foot-and-mouth disease (FMD) remains a significant global threat to livestock farming. Current commercial FMD vaccines present several challenges, including the risk of infection and adverse injection site reactions due to oil-based adjuvants. The complex immune environment of the gut-associated lymphoid tissue has the potential to induce broad and diverse immune responses. Therefore, we aimed to explore the potential of zinc sulfate as an oral adjuvant to enhance intestinal mucosal immunity and complement the effects of intramuscular (IM) FMD vaccination. Methods: We conducted serological analyses on mice and pigs, measuring secretory IgA (sIgA) levels and evaluating the expression of mucosal immunity-related genes in pigs. These assessments were used to investigate the systemic and mucosal immune responses induced by oral zinc sulfate administration in combination with an IM FMD vaccine. Results: This combination strategy significantly increased structural protein antibody titers and virus neutralization titers in experimental animals (mice) and target animals (pigs) across early, mid-, and long-term periods. Additionally, this approach enhanced the expression of key cytokines associated with mucosal immunity and increased sIgA levels, which are critical markers of mucosal immunity. Conclusions: Oral zinc sulfate administration may synergize with inactivated FMD vaccines, leading to sustained and enhanced long-term immune responses. This novel strategy could reduce the frequency of required vaccinations or allow for a lower antigen dose in vaccines, effectively stimulating the mucosal immune system and boosting systemic immunity. This approach has the potential to improve the overall efficacy of commercial FMD vaccines.

Exploring the mediating role of immune cells in the pathogenesis of IgA nephropathy through the inflammatory axis of gut microbiota from a genomic perspective.

IgA nephropathy (IgAN) is a chronic glomerular disease characterized by the deposition of IgA antibodies in the kidney's mesangium. Its pathogenesis involves genetic, immune, and environmental factors, particularly within the mucosal immune system and gut microbiota. Immune cells play a central role in mediating these processes, which this study investigates using Mendelian Randomization (MR) to explore causal relationships among gut microbiota, inflammatory markers, blood cells, and immune cells in IgAN pathogenesis. We conducted a two-sample MR analysis using Genome-Wide Association Study (GWAS) summary data to assess the causal effects of gut microbiota, inflammatory markers, and blood cell traits on IgAN. Data sources included the FinnGen dataset for IgAN and relevant GWAS datasets for immune traits, blood cells, and inflammatory markers. Inverse variance weighting (IVW) was the primary MR method, supported by sensitivity analyses. We particularly examined the mediation effect of immune cells on these exposures' influence on IgAN. Significant associations were found between several factors and IgAN. Gut microbiota traits, such as Firmicutes E and Sporomusales, increased IgAN risk, while Citrobacter A and Herbinix reduced it. Inflammatory markers, including Interleukin-10 and Fibroblast Growth Factor 23, promoted IgAN onset. Blood cell traits like red blood cell perturbation response increased risk, while monocyte perturbation response was protective. Immune traits played a key mediating role, with Transitional %B cells reducing IgAN risk and CD28- CD25 + + CD8br %T cells increasing it. This study highlights the pivotal mediating role of immune cells in the interactions between gut microbiota, inflammatory markers, and IgAN risk. These findings identify potential biomarkers and therapeutic targets, providing new insights into the immune mechanisms underlying IgAN and opportunities for intervention.

The immune responses elicited by six recombinant antigens of Mycoplasma hyopneumoniae in mice

Mycoplasma hyopneumoniae (M. hyopneumoniae) is the causative agent of swine enzootic pneumonia, resulting in substantial economic losses in global pig farming. Although vaccination is the primary strategy for controlling M. hyopneumoniae infection, current vaccines fall short in preventing transmission of this pathogen or protecting the body from secondary infection. This study aimed to assess the immunogenicity of six recombinant antigens (P97R1, P46, GAPDH, PdhA, DnaK, and EF-Tu) of M. hyopneumoniae through intramuscular immunization in mice. The results showed that the six antigens elicited high levels of serum IgG. Among them, P97R1, P46, PdhA, and DnaK stimulated robust antigen-specific IgA mucosal immune responses. CCK-8 assays revealed that both P97R1 and DnaK significantly increased the proliferation of mononuclear cells from spleen and lung, and DnaK also promoted the proliferation of blood mononuclear cells. Additionally, PdhA induced Th17-type immune response with a high level of IL-17 level in serum. Flow cytometry analysis indicated that P97R1 and PdhA increased the ratio of CD8+/CD4+ T lymphocyte, favoring cytotoxic T lymphocyte (CTL) immune responses. Notably, P97R1 immunization significantly decreased the percentages of CD4+ T cells while increased the percentages of CD8+ T cells. The present findings demonstrate that the candidate antigens P97R1, PdhA, and DnaK of M. hyopneumoniae induce specific humoral and mucosal immunity; P97R1 and DnaK also stimulated intense cellular immunity, and PdhA induced CTL and Th17-type immune responses. In conclusion, P97R1, PdhA, and DnaK emerge as potential candidate antigens for the future development of a more effective subunit vaccine against M. hyopneumoniae.

Modified PEG-Lipids Enhance the Nasal Mucosal Immune Capacity of Lipid Nanoparticle mRNA Vaccines.

Omicron, the predominant variant of SARS-CoV-2, exhibits strong immune-evasive properties, leading to the reduced efficacy of existing vaccines. Consequently, the development of versatile vaccines is imperative. Intranasal mRNA vaccines offer convenient administration and have the potential to enhance mucosal immunity. However, delivering vaccines via the nasal mucosa requires overcoming complex physiological barriers. The aim of this study is to modify PEGylated lipids to enhance the mucosal immune efficacy of the vaccine. The PEGylated lipid component of lipid nanoparticle (LNP) delivery vectors was modified with chitosan or mannose to generate novel LNPs that enhance vaccine adhesion or targeting on mucosal surfaces. The impact of the mRNA encoding the receptor-binding domain of Omicron BA.4/BA.5 on the immune response was examined. Compared to the unmodified LNP group, the IgG and IgA titers in the chitosan or mannose-modified LNP groups showed an increasing trend. The chitosan-modified group showed better effects. Notably, the PEGylated lipid with 1.5 mol% of chitosan modification produced high levels of IgG1 and IgG2a antibodies, promoting Th1/Th2 responses while also generating high levels of IgA, which can induce stronger cellular immunity, humoral immunity, and mucosal immunity. The 1.5 mol% of chitosan-modified LNPs (mRNA-LNP-1.5CS) can serve as a safe and effective carrier for intranasal mRNA vaccines, offering a promising strategy for combating the Omicron variant.

Immunologic Effects of a Novel Bovine Lactoferrin-Derived Peptide on the Gut and Clinical Perspectives.

Bovine lactoferrin is a natural iron-binding glycoprotein known for its antimicrobial, antiviral, antitumor, anti-inflammatory, and immunomodulatory properties. In this study, we artificially recombined a fragment of bovine lactoferrin with immunomodulatory and antimicrobial properties to create a novel peptide named LF-MQL. The primary objective was to investigate the effects of LF-MQL on the intestinal tract and immune cells in animals. First, we assessed the in vitro activation effects of LF-MQL on mouse peritoneal macrophages. The results indicated that LF-MQL enhanced the macrophage phagocytic activity and increased IL-1β mRNA expression without significantly affecting IL-6 mRNA levels. Next, we examined the effects of LF-MQL on mucosal immunity by administering LF-MQL orally at doses of 300 mg/kg, 30 mg/kg, and 3 mg/kg to mice. The results demonstrated that different doses of LF-MQL modulated IL-6 and IL-10 mRNA levels in the small intestine. Low doses enhanced the intestinal immune response, while higher doses reduced the inflammatory response. In conclusion, LF-MQL exerts immunomodulatory effects rather than simply boosting immune activity in animal models.

Tight junction regulation, intestinal permeability, and mucosal immunity in gastrointestinal health and disease.

The contributions of intestinal barrier loss, that is, increased permeability, to multiple disorders, including inflammatory bowel disease (IBD), have been a topic of speculation for many years, and the literature is replete with conclusions based on correlation and speculation. The goal of this article is to critically review recent advances in mechanistic understanding of barrier regulation and the evidence for and against contributions of intestinal barrier loss to disease pathogenesis. It is now recognized that intestinal permeability reflects the combined effects of two distinct routes across tight junctions, which form selectively permeable seals between adjacent epithelial cells, and mucosal damage that leads to nonselective barrier loss. These are referred to as pore and leak pathways across the tight junction and an unrestricted pathway at sites of damage. Despite advances in phenotypic and mechanistic characterization of three distinct permeability pathways, development of experimental agents that specifically target these pathways, and remarkable efficacy in preclinical models, pathway-targeted therapies have not been tested in human subjects. After decades of speculation, therapeutic interventions that target the intestinal barrier are nearly within reach. More widespread use of available tools and development of new tools that discriminate between pore, leak, and unrestricted pathway permeabilities and underlying regulatory mechanisms will be essential to understanding the local and systemic consequences of intestinal barrier loss.