Local Mucosal Immune Responses Research Articles

Double synergic chitosan-coated poly (lactic-co-glycolic) acid nanospheres loaded with nucleic acids as an intranasally administered vaccine delivery system to control the infection of foot-and-mouth disease virus

The spread of foot-and-mouth disease virus (FMDV) through aerosol droplets among cloven-hoofed ungulates in close contact is a major obstacle for successful animal husbandry. Therefore, the development of suitable mucosal vaccines, especially nasal vaccines, to block the virus at the initial site of infection is crucial. Here, we constructed eukaryotic expression plasmids containing the T and B-cell epitopes (pTB) of FMDV in tandem with the molecular mucosal adjuvant Fms-like tyrosine kinase receptor 3 ligand (Flt3 ligand, FL) (pTB-FL). Then, the constructed plasmid was electrostatically attached to mannose-modified chitosan-coated poly(lactic-co-glycolic) acid (PLGA) nanospheres (MCS-PLGA-NPs) to obtain an active nasal vaccine targeting the mannose-receptor on the surface of antigen-presenting cells (APCs). The MCS-PLGA-NPs loaded with pTB-FL not only induced a local mucosal immune response, but also induced a systemic immune response in mice. More importantly, the nasal vaccine afforded an 80% protection rate against a highly virulent FMDV strain (AF72) when it was subcutaneously injected into the soles of the feet of guinea pigs. The nasal vaccine prepared in this study can effectively induce a cross-protective immune response against the challenge with FMDV of same serotype in animals and is promising as a potential FMDV vaccine.

A universal recombinant adenovirus type 5 vector-based COVID-19 vaccine.

A universal recombinant adenovirus type-5 (Ad5) vaccine against COVID19 (Ad-US) was constructed, and immunogenicity and broad-spectrum of Ad5-US were evaluated with both intranasal and intramuscular immunization routes. The humoral immune response of Ad5-US in serum and bronchoalveolar lavage fluid were evaluated by the enzyme-linked immunosorbent assay (ELISA), recombinant vesicular stomatitis virus based pseudovirus neutralization assay, and angiotensin-converting enzyme-2 (ACE2) -binding inhibition assay. The cellular immune response and Th1/Th2 biased immune response of Ad5-US were evaluated by the IFN-γ ELISpot assay, intracellular cytokine staining, and Meso Scale Discovery (MSD) profiling of Th1/Th2 cytokines. Intramuscular priming followed by an intranasal booster with Ad5-US elicited the broad-spectrum and high levels of IgG, IgA, pseudovirus neutralizing antibody (PNAb), and Th1-skewing of the T-cell response. Overall, the adenovirus type-5 vectored universal SARS-CoV-2 vaccine Ad5-US was successfully constructed, and Ad5-US was highly immunogenic and broad spectrum. Intramuscular priming followed by an intranasal booster with Ad5-US induced the high and broad spectrum systemic immune responses and local mucosal immune responses.

Early mucosal events promote distinct mucosal and systemic antibody responses to live attenuated influenza vaccine

Compared to intramuscular vaccines, nasally administered vaccines have the advantage of inducing local mucosal immune responses that may block infection and interrupt transmission of respiratory pathogens. Live attenuated influenza vaccine (LAIV) is effective in preventing influenza in children, but a correlate of protection for LAIV remains unclear. Studying young adult volunteers, we observe that LAIV induces distinct, compartmentalized, antibody responses in the mucosa and blood. Seeking immunologic correlates of these distinct antibody responses we find associations with mucosal IL-33 release in the first 8 hours post-inoculation and divergent CD8+ and circulating T follicular helper (cTfh) T cell responses 7 days post-inoculation. Mucosal antibodies are induced separately from blood antibodies, are associated with distinct immune responses early post-inoculation, and may provide a correlate of protection for mucosal vaccination. This study was registered as NCT04110366 and reports primary (mucosal antibody) and secondary (blood antibody, and nasal viral load and cytokine) endpoint data.

Identification of a pharyngeal mucosal lymphoid organ in zebrafish and other teleosts: Tonsils in fish?

The constant exposure of the fish branchial cavity to aquatic pathogens causes local mucosal immune responses to be extremely important for their survival. Here, we used a marker for T lymphocytes/natural killer (NK) cells (ZAP70) and advanced imaging techniques to investigate the lymphoid architecture of the zebrafish branchial cavity. We identified a sub-pharyngeal lymphoid organ, which we tentatively named “Nemausean lymphoid organ” (NELO). NELO is enriched in T/NK cells, plasma/B cells, and antigen-presenting cells embedded in a network of reticulated epithelial cells. The presence of activated T cells and lymphocyte proliferation, but not V(D)J recombination or hematopoiesis, suggests that NELO is a secondary lymphoid organ. In response to infection, NELO displays structural changes including the formation of T/NK cell clusters. NELO and gill lymphoid tissues form a cohesive unit within a large mucosal lymphoid network. Collectively, we reveal an unreported mucosal lymphoid organ reminiscent of mammalian tonsils that evolved in multiple teleost fish families.

Protective immunity induced by an inhaled SARS-CoV-2 subunit vaccine

Targeting the site of infection is a promising strategy for improving vaccine effectivity. To date, licensed COVID-19 vaccines have been administered intramuscularly despite the fact that SARS-CoV-2 is a respiratory virus. Here, we aim to induce local protective mucosal immune responses with an inhaled subunit vaccine candidate, ISR52, based on the SARS-CoV-2 Spike S1 protein. When tested in a lethal challenge hACE2 transgenic SARS-CoV-2 mouse model, intranasal and intratracheal administration of ISR52 provided superior protection against severe infection, compared to the subcutaneous injection of the vaccine. Interestingly for a protein-based vaccine, inhaled ISR52 elicited both CD4 and CD8 T-cell Spike-specific responses that were maintained for at least 6 months in wild-type mice. Induced IgG and IgA responses cross-reacting with several SARS- CoV-2 variants of concern were detected in the lung and in serum and protected animals displayed neutralizing antibodies. Based on our results, we are developing ISR52 as a dry powder formulation for inhalation, that does not require cold-chain distribution or the use of needle administration, for evaluation in a Phase I/II clinical trial.

TLR2 in γδ T cells is required for metabolic support of their IL-17A response to a commensal bacterium on the ocular surface

Abstract The ocular surface is colonized by commensal microbiota, which tune the local mucosal immune response. We previously identified an ocular surface commensal, Corynebacterium mastitidis (C. mast), which induced IL-17A production from γδ T cells in the conjunctiva and eye-draining lymph nodes (DLN), and enhanced host resistance to fungal and bacterial pathogens. To elucidate how IL-17A producing γδ T cells (γδT17) are activated by C. mast, we associated WT and TLR2−/− mice with C. mast, and investigated the role of TLR2 in this process. This was based on the rationale that C. mastis a Gram-positive bacterium and that TLR2 expression on γδT cells increased after C. mast association. Mechanistic studies showed that TLR2 expression was required not only on DCs (for IL-1 production) but also on the γδT cells. RNA-Seq revealed that genes related to mitochondrial oxidative phosphorylation were dysregulated in TLR2−/− γδT17 cells, indicating that engagement of TLR2 may regulate metabolic processes in γδT17 cells. Seahorse assay confirmed that TLR2−/− γδ T17 cells displayed impaired oxygen consumption rates and lower ATP production. Interestingly, lysosomal activity, which plays a central role in cellular metabolism, was decreased in TLR2−/− γδ T17 cells. Enhancement of lysosomal activity by curcumin C1 restored ATP generation in TLR2−/− γδ T17 cells. We propose that intrinsic TLR2 signaling in γδ T cells is required for metabolic support of their IL-17A response.

Local and systemic immune responses induced by intranasal immunization with biomineralized foot-and-mouth disease virus-like particles.

Foot-and-mouth disease virus (FMDV) infects the host by invading mucosal epithelial cells of the respiratory or digestive tract. Therefore, establishing a specific antiviral mucosal immune barrier can effectively block viral invasion. We evaluated local mucosal and systemic immune responses elicited by intranasal immunization of mice with foot-and-mouth disease (FMD) calcium phosphate mineralized virus-like particles (CaP-VLPs) and tested whether three commercial mucosal adjuvants enhanced the immunogenicity of the antigen. The biosafety of the vaccine was verified through gross observation and pathological analysis of the lungs. CaP-VLPs effectively induced secretion of IgA (sIgA) from multiple sites in mouse mucosa and produced anti-FMD-specific IgG in the serum. Splenic lymphocytes specifically proliferated and secreted IFN-γ following antigen stimulation, indicating the vaccine can induce a certain level of cellular immune response. Finally, the pathological examination confirmed that CaP-VLPs did not cause substantial damage to the lungs of animals after immunization via mucosal administration. Notably, the vaccine mixed with S adjuvant increased the content of sIgA and serum IgG, and the high level of IgG in serum was maintained at least 7 weeks. Overall, this study reveals that FMD CaP-VLPs can induce good local mucosal immune and systemic immune response through intranasal immunization, and the immune response was specifically enhanced by S adjuvant. These data support that CaP-VLPs-S as a candidate mucosal vaccine for the prevention of FMD vaccine infection.

Research progress and prospect in mucosal B cells and immunoglobulins of teleost fish

<p indent="0mm">Fish live in a microbially rich and complex aquatic environment, which exposes their mucosal surfaces to a variety of attacks from external pathogens. Teleost fish have evolved unique mucosa-associated lymphoid tissues (MALTs) that serve as the first line of defense against pathogens. So far, seven MALTs in teleost fish have been described, including gut-associated lymphoid tissue (GALT), skin-associated lymphoid tissue (SALT), gill-associated lymphoid tissue (GIALT), nasal-associated lymphoid tissue (NALT), buccal-associated lymphoid tissues, pharyngeal-associated lymphoid tissues, and the newly discovered swim bladder-associated lymphoid tissues. Because teleost MALT lacks lymph nodes, it has only evolved as a network of diffuse leucocytes within the mucosal epithelia, which is known as diffuse MALT (D-MALT). Teleost fish, unlike invertebrates, have evolved the cardinal elements of adaptive immunity to protect themselves from pathogens in their aquatic environment. Mucosal B cells and immunoglobulins (Igs) in teleost MALTs, in particular, are important players in local mucosal adaptive immune responses. In teleost fish, the three bona fide immunoglobulin isotypes (i.e., IgM, IgD, and IgT) can be found in varying proportions in MALT secretions, and the IgT/IgM ratio in mucus is much higher than that in serum in the absence of antigenic stimulation. A couple of functional studies have recently revealed that IgM and IgT responses are specialized in systemic and mucosal compartments, respectively. The primary role of Igs in adaptive immune responses has been conserved throughout evolution, as they can neutralize pathogens or promote their elimination on mucosal surfaces, preventing further infection. Teleost fish lack organized lymphoid structures known as O-MALT (e.g., Peyer’s patches and tonsils), but B-cells could locally proliferate and generate pathogenic-specific Igs in the MALTs, indicating that MALT in teleosts may function as both an inductive and effector site. Mucosal surfaces in teleost MALT harbor an incredibly dense and diverse commensal microbiota, which is one of the conserved features. Notably, a significant portion of the commensal microbiota is coated with secreted Igs (sIgs), with IgT being the predominant isotype associated with those bacteria. Recent advances in bacterial flow cytometry combined with high-throughput sequencing have aided in the identification of IgT-coated bacteria and shed light on the biological implications of sIgs coating commensal microbiota. Teleost fish secretory IgT, like mammalian and bird IgA, may target mucosal pathogens for elimination, and coating on the surface of microbiota allows for commensal colonization and homeostasis. Therefore, studying and revealing the immunological mechanism of fish MALT in anti-infection and maintaining mucosal commensal homeostasis is extremely important in fish immunology and even vertebrate comparative immunology in general. We summarize the current research process on the composition of the fish mucosal immune system, the function of mucosal B cells and Igs against pathogen infections, and the interactions between sIgs and microbiota in this review. Finally, we outline the future prospects for fish mucosal immunity, with the goal of providing a reference from a mucosal vaccination standpoint for the prevention and control of fish diseases.

Oral immunization of mice with recombinant Lactobacillus plantarum expressing a Trichinella spiralis galectin induces an immune protection against larval challenge

BackgroundTrichinella spiralis is an important foodborne parasite that presents a severe threat to food safety. The development of an anti-Trichinella vaccine is an important step towards controlling Trichinella infection in food animals and thus ensure meat safety. Trichinella spiralis galectin (Tsgal) is a novel protein that has been identified on the surface of this nematode. Recombinant Tsgal (rTsgal) was found to participate in larval invasion of intestinal epithelium cells (IECs), whereas anti-rTsgal antibodies impeded the invasion.MethodsThe rTsgal/pSIP409- pgsA′ plasmid was constructed and transferred into Lactobacillus plantarum strain NC8, following which the in vitro biological properties of rTsgal/NC8 were determined. Five groups of mice were orally immunized three times, with a 2-week interval between immunizations, with recombinant NC8-Tsgal, recombinant NC8-Tsgal + α-lactose, empty NC8, α-lactose only or phosphate-buffered saline (PBS), respectively. The vaccinated mice were infected orally with T. spiralis larvae 2 weeks following the last vaccination. Systemic and intestinal local mucosal immune responses and protection were also assessed, as were pathological changes in murine intestine and skeletal muscle.ResultsrTsgal was expressed on the surface of NC8-Tsgal. Oral immunization of mice with rTsgal vaccine induced specific forms of serum immunoglobulin G (IgG), namely IgG1/IgG2a, as well as IgA and gut mucosal secretion IgA (sIgA). The levels of interferon gamma and interleukin-4 secreted by cells of the spleen, mesenteric lymph nodes, Peyer's patches and intestinal lamina propria were significantly elevated at 2–6 weeks after immunization, and continued to rise following challenge. Immunization of mice with the oral rTsgal vaccine produced a significant immune protection against T. spiralis challenge, as demonstrated by a 57.28% reduction in the intestinal adult worm burden and a 53.30% reduction in muscle larval burden, compared to the PBS control group. Immunization with oral rTsgal vaccine also ameliorated intestinal inflammation, as demonstrated by a distinct reduction in the number of gut epithelial goblet cells and mucin 2 expression level in T. spiralis-infected mice. Oral administration of lactose alone also reduced adult worm and larval burdens and relieved partially inflammation of intestine and muscles.ConclusionsImmunization with oral rTsgal vaccine triggered an obvious gut local mucosal sIgA response and specific systemic Th1/Th2 immune response, as well as an evident protective immunity against T. spiralis challenge. Oral rTsgal vaccine provided a prospective approach for control of T. spiralis infection.Graphical

Th1 and Th17 mucosal immune responses elicited by nasally inoculation in mice with virulence factors of Mycoplasma hyopneumoniae

Nicotinamide Adenine Dinucleotide-Dependent (NADH) flavin oxidoreductase and NADH oxidase (NOX) are important virulence factors of Mycoplasma hyopneumoniae (Mhp), which are devoted to the function of adhesion, oxidative stress damage and apoptosis to host cells in our previous studies. Here, immune responses of NADH flavin oxidoreductase (NFOR) and NOX in mice and immune efficacy inoculated with intramuscular (IM), intranasal (IN), intramuscular unite intranasal (IM + IN) approaches were evaluated and compared. Cellular immunity levels, systemic immune and local mucosal immune responses were investigated by indirect enzyme-linked immunosorbent assay (iELISA) and quantitative reverse transcription PCR (qRT-PCR). Mice inoculated with NFOR and NOX by IM and IN or IM + IN could induce obvious secretion of specific immunoglobulin G (IgG) and secretory immunoglobulin A antibodies (sIgA) compared to those in negative control group. IM + IN inoculation resulted in systemic and local mucosal immune responses that were strongly produced. Moreover, Mhp NFOR and NOX could activate local mucosal immune responses mediated by Th1 and Th17 cells by IN. Our finding supported the notion that IM + IN was an effective immunization route for Mhp, which lays a foundation for more effective prevention of Mhp, and provides theoretical basis for the development of new subunit vaccines of Mhp.

Phenotypic characteristics and protective efficacy of an attenuated Mycoplasma hyopneumoniae vaccine by aerosol administration

With the improvement of large-scale breeding in pig farms, conventional head-by-head immunization has disadvantages with low efficiency and high cost. Considering that most pathogens leading to pulmonary diseases circulate from the respiratory mucosa, immunization through the respiratory tract route has been a highly attractive vaccine delivery strategy. In this study, to develop an effective Mycoplasma hyopneumoniae (Mhp) aerosol vaccine, a customized ultrasonic atomizer was developed. The aerodynamic diameter, activity, and content of the Mhp aerosol vaccine were measured. In addition, piglets were immunized with the Mhp aerosol vaccine, and the immunity of the animal challenge protection test was evaluated. At the end of nebulization, the mass median aerodynamic diameters (MMAD) and geometric standard deviation (GSD) of the aerosol were 2.98 ± 0.02 μm and 1.51 ± 0.02, respectively. Moreover, 10 min after nebulization, the MMAD and GSD of the aerosol were 2.76 ± 0.02 μm and 1.51 ± 0.01, respectively, which were hardly changed. Compared with theoretical value, the actual titer of aerosol vaccines presented in 50% color changing unit (CCU50) after nebulization decreased 0.6. The shape, size, and uniformity of collected aerosols are relatively stable. The proportion of Mhp in aerosol produced by vaccine stock solution and 10 times diluted vaccine solution was 76.52% and 58.82%, respectively, and the average number of Mhp in a single aerosol was 3.06 and 1.51, respectively. In addition, the aerosol vaccine antigen particles could be transported to the lower respiratory tract, a local mucosal immune response was induced in piglets. The vaccine colonized the respiratory tract and significantly decline the lung lesion index after aerosol vaccination. In conclusion, an effective aerosol vaccine against Mhp infection was developed. And this is the first effective assessment for Mhp live vaccine with aerosolization against infection in piglets.

TLR2-mediated mucosal immune priming boosts anti-rhabdoviral immunity in early vertebrates

Most pathogens utilize mucosal surfaces to enter and propagate within the host. As one of the main pathogens of fatal and highly contagious diseases, rhabdoviruses are distributed widely in nature affecting both human and animals. Therefore, local mucosal immune responses, most effectively induced by mucosal vaccines, act as frontline immunity to block the pathogens at its initial replication sites. However, the underlying regulatory mechanisms of mucosal immunity triggered by mucosal vaccine remains unclear. Herein, a rhabdoviruses glycoprotein-based mucosal vaccine (G131c) was used to elucidate the regulatory mechanism of local mucosal immunity in zebrafish, a typical immunological model. Firstly, we verified the strong immunoprotection of G131c mucosal vaccine. Furthermore, the delivery kinetics of G131c was evaluated in vivo, indicating the effective uptake of vaccines by mucosal tissues through immersion vaccination. Importantly, we demonstrate immersion with G131c vaccine could activate antigen presenting cells (APCs) at the local mucosal sites, and then arose robust local mucosal and systemic immune responses. More critically, we found that G131c mediated these immune effects by interacting with Toll-like receptor 2 (TLR2) and activating downstream MAPK and NF-κB signaling pathways. Thus, our findings provide previously unappreciated evidence that rhabdovirus glycoprotein could interact with TLR2 and then activate the APCs in local mucosal sites. This study provides a comprehensive perspective on the mechanism of TLR2-mediated mucosal immunity in the early vertebrates.

Interaction between gut microbiota dysbiosis and lung infection as gut-lung axis caused by Streptococcus suis in mouse model

Streptococcus suis (S. suis) is an important zoonotic pathogen threatening the global pig farming industry. It causes respiratory and digestive tract infections simultaneously in pigs. The balanced gut microbiota not only affects the local mucosal immune response but also involves the regulation of the immune status of the distant lung tissues that is termed as "gut-lung" axis. Whether S. suis affects the gut during lung infection and how does the intestinal microbial disturbance play role in the development of lung infection during S. suis exposure is not clear yet. Therefore, in the current study, we constructed the animal model using six-week-old mice (N = 48) divided into four groups with S. suis serotype 2 (SS2)-induced lung infection and the antibiotic treated gut microbiota dysbiosis. By means of various techniques (like HE staining, RT-qPCR, Western Blot and ELISA and viability detection) we explored that S. suis can concurrently cause intestinal tissue damage and inflammation after lung infection. Moreover, gut microbiota dysbiosis changes the balance of Th1/Th2 cells that aggravates lung injury during the infection. Thus, "gut-lung" axis of the communication between the gut microbiota and lung infection was established through the spleen and blood. In addition, intestinal dysbacteriosis can affect alveolar macrophage activity for a long time and the balance of gut microbiota plays an important role in lung infection caused by S. suis. Hence, this study clarified the pulmonary infection caused by SS2 from the perspective of the intestinal microbiota providing novel theoretical basis for the treatment of related lung diseases.

Nasal vaccines for COVID-19: Current trends and future perspectives

Coronavirus disease (COVID-19), a highly contagious viral respiratory illness, has resulted in widespread human losses, as well as posing more newer difficulties to the global health infrastructure. Vaccination has been a powerful public health tool for preventing deadly diseases, and it is still the most effective weapon when dealing with pandemics. Intranasal vaccines form an important part of the next-generation vaccines being developed to bolster our arsenal against infectious diseases. Nasal delivery of vaccines induces both systemic and local mucosal immune responses to help scale up the war against the inhaled pathogens. Owing to its simplicity, ease, convenience, safety, and higher effectivity, intranasal vaccines are turning out to be a promising alternative to the parenteral and other mucosal routes of administration. Intranasal vaccines are considered more efficacious than conventional parenteral injectable vaccines for influenza virus. The vaccination rate can be increased as the intranasal vaccine is directly delivered into nasal cavity and involves less cumbersome and painless procedure than intravenous administration. Nasal mucosa is an easily accessible organ with rich vascular supply and large surface area available for absorption aiding in quick absorption of vaccine. Furthermore, the intranasal vaccines are more affordable than the conventional vaccines.

Bile Acid Diarrhea Is Associated With Increased Intestinal Permeability Compared With Irritable Bowel Syndrome-Diarrhea

Irritable bowel syndrome (IBS) is associated with diverse peripheral as well as central pathophysiologic mechanisms. 1 Camilleri M. N Engl J Med. 2012; 367: 1626-1635 Google Scholar About 25% of patients with IBS-diarrhea (IBS-D) have bile acid diarrhea (BAD). 2 Valentin N. et al. Gut. 2016; 65: 1951-1959 Google Scholar Intestinal barrier alterations with a subsequent local mucosal immune response to luminal microbial antigens may contribute to the development of IBS. 3 Dunlop S.P. et al. Am J Gastroenterol. 2006; 101: 1288-1294 Google Scholar A summary of intestinal permeability in IBS showed equivocal results in the comparison of permeability in IBS-D and health. 4 Camilleri M. et al. Am J Physiol Gastrointest Liver Physiol. 2019; 317: G17-G39 Google Scholar

Distinct systemic and mucosal immune responses during acute SARS-CoV-2 infection

Coordinated local mucosal and systemic immune responses following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection either protect against coronavirus disease 2019 (COVID-19) pathologies or fail, leading to severe clinical outcomes. To understand this process, we performed an integrated analysis of SARS-CoV-2 spike-specific antibodies, cytokines, viral load and bacterial communities in paired nasopharyngeal swabs and plasma samples from a cohort of clinically distinct patients with COVID-19 during acute infection. Plasma viral load was associated with systemic inflammatory cytokines that were elevated in severe COVID-19, and also with spike-specific neutralizing antibodies. By contrast, nasopharyngeal viral load correlated with SARS-CoV-2 humoral responses but inversely with interferon responses, the latter associating with protective microbial communities. Potential pathogenic microorganisms, often implicated in secondary respiratory infections, were associated with mucosal inflammation and elevated in severe COVID-19. Our results demonstrate distinct tissue compartmentalization of SARS-CoV-2 immune responses and highlight a role for the nasopharyngeal microbiome in regulating local and systemic immunity that determines COVID-19 clinical outcomes.

Bacillus subtilis Spore-Trained Dendritic Cells Enhance the Generation of Memory T Cells via ICAM1.

Immunological memory is a cardinal feature of the immune system. The intestinal mucosa is the primary exposure and entry site of infectious organisms. For an effective and long-lasting safeguard, a robust immune memory system is required, especially by the mucosal immunity. It is well known that tissue-resident memory T cells (Trms) provide a first response against infections reencountered at mucosal tissues surfaces, where they accelerate pathogen clearance. However, their function in intestinal immunization remains to be investigated. Here, we report enhanced local mucosal and systemic immune responses through oral administration of H9N2 influenza whole inactivated virus (H9N2 WIV) plus Bacillus subtilis spores. Subsequently, H9N2 WIV plus spores led to the generation of CD103+ CD69+ Trms, which were independent of circulating T cells during the immune period. Meanwhile, we also found that Bacillus subtilis spores could stimulate Acrp30 expression in 3T3-L1 adipocytes. Moreover, spore-stimulated adipocyte supernatant also upregulated the expression of intercellular adhesion molecule-1 (ICAM1) in dendritic cells (DCs). Furthermore, the proportion of HA-tetramer+ cells was severely curtailed upon suppressed ICAM1 expression, which also depended on HA-loaded DCs. Taken together, our data demonstrated that spore-promoted H9N2 WIV induced an immune response by enhancing Trms populations, which were associated with the activation of ICAM1 in DCs.

The Interplay between the Gut Microbiome and the Immune System in the Context of Infectious Diseases throughout Life and the Role of Nutrition in Optimizing Treatment Strategies.

Infectious diseases and infections remain a leading cause of death in low-income countries and a major risk to vulnerable groups, such as infants and the elderly. The immune system plays a crucial role in the susceptibility, persistence, and clearance of these infections. With 70–80% of immune cells being present in the gut, there is an intricate interplay between the intestinal microbiota, the intestinal epithelial layer, and the local mucosal immune system. In addition to the local mucosal immune responses in the gut, it is increasingly recognized that the gut microbiome also affects systemic immunity. Clinicians are more and more using the increased knowledge about these complex interactions between the immune system, the gut microbiome, and human pathogens. The now well-recognized impact of nutrition on the composition of the gut microbiota and the immune system elucidates the role nutrition can play in improving health. This review describes the mechanisms involved in maintaining the intricate balance between the microbiota, gut health, the local immune response, and systemic immunity, linking this to infectious diseases throughout life, and highlights the impact of nutrition in infectious disease prevention and treatment.

The storage stability of Bacillus subtilis spore displaying cysteine protease of Clonorchis sinensis and its effect on improving the gut microbiota of mice.

Bacillus subtilis (B. subtilis) spore can serve as an ideal vehicle for expressing heterologous antigens, and elicit specific immune responses by oral administration. In previous studies, we successfully constructed the recombinant B. subtilis spores expressing cysteine protease of Clonorchis sinensis (C. sinensis, B.s-CsCP), and confirmed that oral administration of B.s-CsCP could elicit good protective immune responses in mice. In this study, Gram staining was used to observe the morphology of B.s-CsCP in different form, and the storage of liquid spores and lyophilized spores at different temperatures was compared. The mice were orally immunized with three different doses of spores (2×108, 1×109, and 5×109 CFU/day) for three times in total at biweekly interval. Then, antibody levels of mice were measured, the safety of spores was evaluated, and the changes of gut microbiota after oral gavage of spores (1×109 dose) were investigated. Results showed that B. subtilis was a typical Gram-positive bacterium, and its spore had good resistance to chemical dye. Liquid B. subtilis spores resuspended in sterile water could be stored for a long time at 4 °C or below, while lyophilized spores could be well stored even at RT and better at lower temperatures. Oral administration of B. subtilis spores to mice could stimulate both local mucosal and systemic immune responses in a dose-dependent manner without toxic side effects. Besides, beneficial bacteria producing butyrate such as Odoribacter were increased, while potential pathogens such as Escherichia-Shigella were decreased in mice intestine. Therefore, our work further confirmed that B. subtilis spores expressing CsCP could be a promising oral vaccine against C. sinensis with the advantages of stability, safety, easy storage, and promotion of intestinal health.Key Points• Recombinant CsCP B. subtilis spores could be easily preserved in either liquid or freeze-dried state.• Oral immunization of recombinant spores in mice could increase both local and system immune levels in a dose-dependent manner.• Oral administration of recombinant spores increased the number of beneficial bacteria and reduced the number of harmful bacteria in the intestinal tract of mice.

Study on Immune Response of Organs of Epinephelus coioides and Carassius auratus After Immersion Vaccination With Inactivated Vibrio harveyi Vaccine.

Immersion vaccination relies on the response of fish mucosa-associated lymphoid tissues, the Crucian carp (Carassius auratus) and Grouper (Epinephelus coioides) were researched in this paper to examine local mucosal immune responses and associated humoral system responses following immersion vaccination. We administered 1.5 × 107 CFU/ml formalin-inactivated Vibrio harveyi cells and measured mucus and serum antibody titers as well as IgM, MHC II mRNA levels in immune organs. The mucosal antibody response preceded the serum response indicating a role for local mucosal immunity in immersion vaccination. IgM and MHC II mRNA levels were relatively greater for the spleen and head kidney indicating the importance and central position of systemic immunity. Expression levels were also high for the gills while skin levels were the lowest. IgM and MHC II mRNA levels were altered over time following vaccination and the hindgut, liver and spleen were similar indicating a close relationship, so the absolute value of r is used to analyze the correlation among different organs immunized. It can be inferred the existence of an internal immune molecular mechanism for Immune synergy hindgut-liver-spleen, from the peak time (14th day), the relative ratio of genes expression in the same tissues between the immunized grouper and the control group (26 times), and Pearson correlation coefficient (0.8<|r|<1). Injection challenges with live V. harveyi indicated that the relative protection rates for the crucian carp and Grouper was basically the same at 44.4% and 47.4%, respectively. It is believe that crucian carp may be used as a substitute for the valuable grouper in immunity experiment, just from aspect of the relative percent survival (RPS) and how it changes with time. But they were not consistent about the IgM mRNA expression between that of crucian carp and grouper after immersion the Vibrio vaccine.