Nasopharynx-associated Lymphoid Tissue Research Articles

Immunohistochemistry of the nasal cavity-associated lymphoid tissue in the dolphin (Stenella coeruleoalba, Meyen 1833).

The striped dolphin (Stenella coeruleoalba) is a medium-sized pelagic dolphin with a single external nasal opening (blowhole) located in the rostral and dorsal regions of the skull. The nasal cavity is divided into three sections: the olfactory, respiratory, and vestibular areas. The surface epithelium lining the regio vestibularis is the first tissue in the nose to be directly affected by environmental antigens. Cetaceans have a significant amount of mucosa-associated lymphoid tissue (MALT) located throughout their bodies. The lymphoid tissue found in the nasal mucosa is known as nose- or nasopharynx-associated lymphoid tissue (NALT). NALT has not yet been studied in dolphins, but it has been identified and documented in humans and laboratory rodents. This study utilized toll-like receptor 2 (TLR2), CD4, Langerin/CD207, and inducible nitric oxide synthase to characterize, for the first time, immune cells in the mucosal regio vestibularis of the S. coeruleoalba nasal cavity using confocal microscopy immunofluorescence techniques. The findings revealed scattered immune cells immunoreactive to the tested antibodies, present in both the epithelial tissue lining the nasal cavity vestibulum and the underlying connective tissue. This study enhances our comprehension of the immune system of cetaceans. RESEARCH HIGHLIGHTS: This study provides new insights into NALT in S. coeruleoalba. This research deepens the knowledge of the skin of cetaceans.

A rat model of adenoid hypertrophy constructed by using ovalbumin and lipopolysaccharides to induce allergy, chronic inflammation, and chronic intermittent hypoxia.

Adenoid hypertrophy (AH) is a common pediatric disease that significantly impacts the growth and quality of life of children. However, there is no replicable and valid model for AH. An AH rat model was developed via comprehensive allergic sensitization, chronic inflammation induction, and chronic intermittent hypoxia (CIH). The modeling process involved three steps: female Sprague-Dawley rats (aged 4-5 weeks) were used for modeling. Allergen sensitization was induced via intraperitoneal administration and intranasal provocation using ovalbumin (OVA); chronic nasal inflammation was induced through intranasal lipopolysaccharide (LPS) administration for sustained nasal irritation; CIH akin to obstructive sleep apnea/hypopnea syndrome was induced using an animal hypoxia chamber. Postmodel establishment, behaviors, and histological changes in nasopharynx-associated lymphoid tissue (NALT) and nasal mucosa were assessed. Arterial blood gas analysis and quantification of serum and tissue levels of (interleukin) IL-4 and IL-13, OVA-specific immunoglobulin E (sIgE), eosinophil cationic protein (ECP), tumor necrosis factor (TNF-α), IL-17, and transforming growth factor (TGF)-β were conducted for assessment. The treatment group received a combination of mometasone furoate and montelukast sodium for a week and then was evaluated. Rats exhibited notable nasal symptoms and hypoxia after modeling. Histopathological analysis revealed NALT follicle hypertrophy and nasal mucosa inflammatory cell infiltration. Elevated IL-4, IL-13, IL-17, OVA-sIgE, ECP, and TNF-α levels and reduced TGF-β levels were observed in the serum and tissue of model-group rats. After a week of treatment, the treatment group exhibited symptom and inflammatory factor improvement. The model effectively simulates AH symptoms and pathological changes. But it should be further validated for genetic, immunological, and hormonal backgrounds in the currently used and other strains and species.

Intranasal trans-sialidase-based vaccine against Trypanosoma cruzi triggers a mixed cytokine profile in the nasopharynx-associated lymphoid tissue and confers local and systemic immunogenicity

Trypanosoma cruzi, the agent of Chagas disease, can infect through conjunctive or oral mucosas. Therefore, the induction of mucosal immunity by vaccination is relevant not only to trigger local protection but also to stimulate both humoral and cell-mediated responses in systemic sites to control parasite dissemination. In a previous study, we demonstrated that a nasal vaccine based on a Trans-sialidase (TS) fragment plus the mucosal STING agonist c-di-AMP, was highly immunogenic and elicited prophylactic capacity. However, the immune profile induced by TS-based nasal vaccines at the nasopharyngeal-associated lymphoid tissue (NALT), the target site of nasal immunization, remains unknown. Hence, we analyzed the NALT cytokine expression generated by a TS-based vaccine plus c-di-AMP (TSdA+c-di-AMP) and their association with mucosal and systemic immunogenicity. The vaccine was administered intranasally, in 3 doses separated by 15 days each other. Control groups received TSdA, c-di-AMP, or the vehicle in a similar schedule. We demonstrated that female BALB/c mice immunized intranasally with TSdA+c-di-AMP boosted NALT expression of IFN-γ and IL-6, as well as IFN-β and TGF-β. TSdA+c-di-AMP increased TSdA-specific IgA secretion in the nasal passages and also in the distal intestinal mucosa. Moreover, T and B-lymphocytes from NALT-draining cervical lymph nodes and spleen showed an intense proliferation after ex-vivo stimulation with TSdA. Intranasal administration of TSdA+c-di-AMP provokes an enhancement of TSdA-specific IgG2a and IgG1 plasma antibodies, accompanied by an increase IgG2a/IgG1 ratio, indicative of a Th1-biased profile. In addition, immune plasma derived from TSdA+c-di-AMP vaccinated mice exhibit in-vivo and ex-vivo protective capacity. Lastly, TSdA+c-di-AMP nasal vaccine also promotes intense footpad swelling after local TSdA challenge. Our data support that TSdA+c-di-AMP nasal vaccine triggers a NALT mixed pattern of cytokines that were clearly associated with an evident mucosal and systemic immunogenicity. These data are useful for further understanding the immune responses elicited by the NALT following intranasal immunization and the rational design of TS-based vaccination strategies for prophylaxis against T. cruzi.

A Novel Organized Nasopharynx-Associated Lymphoid Tissue in Teleosts That Expresses Molecular Markers Characteristic of Mammalian Germinal Centers.

Nasal immunity is an ancient and conserved arm of the mucosal immune system in vertebrates. In teleost fish, we previously reported the presence of a nasopharynx-associated lymphoid tissue (NALT) characterized by scattered immune cells located in the trout olfactory lamellae. This diffuse NALT mounts innate and adaptive immune responses to nasal infection or vaccination. In mammals, lymphoid structures such as adenoids and tonsils support affinity maturation of the adaptive immune response in the nasopharyngeal cavity. These structures, known as organized NALT (O-NALT), have not been identified in teleost fish to date, but their evolutionary forerunners exist in sarcopterygian fish. In this study, we report that the rainbow trout nasal cavity is lined with a lymphoepithelium that extends from the most dorsal opening of the nares to the ventral nasal cavity. Within the nasal lymphoepithelium we found lymphocyte aggregates called O-NALT in this study that are composed of ∼ 56% CD4+, 24% IgM+, 16% CD8α+, and 4% IgT+ lymphocytes and that have high constitutive aicda mRNA expression. Intranasal (i.n.) vaccination with live attenuated infectious hematopoietic necrosis virus triggers expansions of B and T cells and aicda expression in response to primary i.n. vaccination. IgM+ B cells undergo proliferation and apoptosis within O-NALT upon prime but not boost i.n. vaccination. Our results suggest that novel mucosal microenvironments such as O-NALT may be involved in the affinity maturation of the adaptive immune response in early vertebrates.

Detection of Swine Influenza A and Porcine Reproductive and Respiratory Syndrome Viruses in Nasopharynx-Associated Lymphoid Tissue

Porcine respiratory disease complex, which is caused by a combination of pathogens, including swine influenza A virus (SIV) and porcine reproductive respiratory syndrome virus (PRRSV), results in significant economic losses in pig production systems. Nasopharynx-associated lymphoid tissue (NALT) plays an important role in the uptake of pathogens and defence of the nasal mucosa in rodents and humans. We characterized NALT M cells in pigs and detected SIV antigen and PRRSV nucleic acid in NALT using histopathological, immunohistochemical and in-situ hybridization analyses. All SIV- and PRRSV-positive cases examined had suppurative nasopharyngitis and pneumonia. M cells were detected by immunohistochemistry and the distribution of M cells showed an increase in the middle section of NALT. SIV antigen was detected in M cells and PRRSV nucleic acid was demonstrated in the cytoplasm of macrophages in NALT. We believe that SIV and PRRSV infection in the upper respiratory tract induces local immunosuppression and these results confirm that swine NALT is a location for virus replication and may be strongly associated with the development of pneumonia in pigs.

Discovery of an organized nasopharynx-associated lymphoid tissue in the nasal cavity of rainbow trout and its role in secondary adaptive immune responses to nasal vaccines

Abstract The olfactory organ of all vertebrates is constantly exposed to pathogens. The nasal mucosa is therefore equipped with a local immune system that protects the host from infection. In teleost fish, we previously described the presence of a diffuse nasopharynx-associated lymphoid tissue (NALT) found in the olfactory lamellae. This diffuse NALT (d-NALT) consists of myeloid and lymphoid cells but lacks an organized structure. Rainbow trout d-NALT mounts quick innate immune responses as well as adaptive immune responses to nasal vaccines. Here we report the discovery of a novel lymphoid structure located in the inner epithelial lining of the nasal cavity, opposite to the tips of the olfactory lamellae, in rainbow trout. This lymphoid structure represents the first description of an organized NALT (O-NALT) in teleost fish. Rainbow trout O-NALT is rich in B and T lymphocytes at the steady state with a proportion of approximately 8:3:1 IgM+ B cells, CD8+ T cells and IgT+ cells, respectively. Using laser capture microdissection we show that compared to d-NALT, O-NALT is highly enriched in expression of CD4, CD8 and IgM but not IgT. Strikingly, O-NALT expresses 8-fold higher levels of activation-induced cytidine deaminase aidc mRNA compared to d-NALT. Following primary and secondary intranasal vaccination with a live attenuated viral vaccine against infectious hematopoietic necrosis (IHN), trout O-NALT was expanded with increased numbers of B and T cell lymphocytes. Our results indicate that teleost fish posses organized lymphoid structures in the nasal cavity that participate in the maturation of the adaptive immune response and that need to be considered as important players in the response to mucosal vaccines. This work was supported by USDA NIFA award # 2020-67015-31457

Development of allergic rhinitis immunotherapy using antigen-loaded small extracellular vesicles.

Allergic rhinitis is caused by a breakdown of the Th1/Th2 balance, in which the allergen-induced Th2 immune response predominates over the Th1 immune response, culminating in IgE-mediated anaphylaxis. In this study, we used small extracellular vesicles (sEVs), cell-derived membrane vesicles with a particle size of 100nm, as simultaneous delivery carriers for allergens (ovalbumin, OVA) and CpG DNA, an adjuvant that can induce a Th1 immune response, for the treatment of allergic rhinitis. sEVs loaded with CpG DNA and OVA(CpG-OVA-sEVs) were successfully prepared. CpG-OVA-sEVs possessed an average particle size of 90nm and average zeta potential of -30mV. CpG DNA modification did not influence the uptake of sEVs by dendritic cells and CpG-OVA-sEV can activate dendritic cells. The CpG-OVA-sEVs were delivered to the nasopharynx-associated lymphoid tissue (NALT) of mice and were primarily taken up by the CD11c positive cells after intranasal administration. Intranasally administering CpG-OVA-sEVs significantly enhanced OVA-specific IgG antibody titers in mice models of allergic rhinitis, suggesting a transformed Th1/2 balance. Moreover, The CpG-OVA-sEV administration alleviated allergic symptoms compared to the control group. Further, the amount of IgE secreted in mouse serum decreased. Thus, CpG-OVA-sEVs could be a useful therapeutic method for treating allergic rhinitis.

Title IgA Nephropathy and Oral Bacterial Species Related to Dental Caries and Periodontitis.

A relationship between IgA nephropathy (IgAN) and bacterial infection has been suspected. As IgAN is a chronic disease, bacteria that could cause chronic infection in oral areas might be pathogenetic bacteria candidates. Oral bacterial species related to dental caries and periodontitis should be candidates because these bacteria are well known to be pathogenic in chronic dental disease. Recently, several reports have indicated that collagen-binding protein (cnm)-(+) Streptococcs mutans is relate to the incidence of IgAN and the progression of IgAN. Among periodontal bacteria, Treponema denticola, Porphyromonas gingivalis and Campylobacte rectus were found to be related to the incidence of IgAN. These bacteria can cause IgAN-like histological findings in animal models. While the connection between oral bacterial infection, such as infection with S. mutans and periodontal bacteria, and the incidence of IgAN remains unclear, these bacterial infections might cause aberrantly glycosylated IgA1 in nasopharynx-associated lymphoid tissue, which has been reported to cause IgA deposition in mesangial areas in glomeruli, probably through the alteration of microRNAs related to the expression of glycosylation enzymes. The roles of other factors related to the incidence and progression of IgA, such as genes and cigarette smoking, can also be explained from the perspective of the relationship between these factors and oral bacteria. This review summarizes the relationship between IgAN and oral bacteria, such as cnm-(+) S. mutans and periodontal bacteria.

Histopathological findings of the nasopharynx-associated lymphoid tissue of pigs co-infected with porcine circovirus 2 and porcine reproductive and respiratory syndrome virus.

Porcine circovirus 2 (PCV2) causes porcine circovirus-associated disease, and co-infection with porcine reproductive and respiratory syndrome virus (PRRSV) severely affects the pig breeding industry. Both viruses target the macrophages in lymphoid tissues. Various porcine pathogens enter via the nasal cavity, and the nasopharynx-associated lymphoid tissue (NALT) acts as the mucosal immune system. However, the pathological analysis has not progressed. This study aimed to histologically examine the NALT of pigs with suspected PCV2 and PRRSV infections. Six pigs were subjected to necropsy, and their NALT, tonsils, and mesenteric lymph nodes were collected. Macrophages, lymphocytic depletion, multinucleated giant cells, intracytoplasmic inclusion bodies, and neutrophil infiltration increased in the NALT. In situ hybridization revealed positive signals for PCV2 in the NALT of all pigs and PRRSV in the NALT of three pigs. PCV2-positive macrophages were mainly identified in the follicles, whereas PRRSV-positive tissues were found primarily around the crypt and directly below the epithelium. Quantitative PCR revealed 108-1010 copies of PCV2 DNA/µL and 102-104 copies of PRRSV DNA/µL in the NALT. Therefore, both PCV2 and PRRSV were detected in the NALT of pigs. In conclusion, the infection and replication of both viruses in the NALT and tonsils may suppress host immunity and promote co-infection with other pathogens.

Activation of mucosal immunity and novel prophylactic and therapeutic strategy in combating COVID-19

Coronavirus disease 2019 (COVID-19) emerges as an expeditiously growing pandemic, in the human population caused by the highly transmissible RNA virus severe acute respiratory syndrome of coronavirus 2 (SARS-CoV-2). Prognosis of SARS-CoV-2 infection predominantly occurs at the angiotensin-converting enzyme 2 receptor and transmembrane protease serine type 2 positive (ACE2 + TMPRSS2)+ epithelial cells of the mucosal surface like nasal, oral mucosae, and/or the conjunctival surface of the eye where it has interacted along with the immune system. The primary host response towards the pathogen starts from an immune microenvironment of nasopharynx-associated lymphoid tissue (NALT) and mucosa-associated lymphoid tissue (MALT). The presence of exhausted lymphocytes, lymphopenia, pneumonia and cytokine storm is the hallmark of COVID-19. The multifaceted nature of co-morbidity factors like obesity and type 2 diabetes and its effects on immunity can alter the pathogenesis of SARS-CoV-2 infection. Adipose tissue is a crucial endocrine organ that secretes a plethora of factors like adipokines, cytokines, and chemokines that have a profound impact on metabolism and augments the expression of mucosal pro-inflammatory cytokines, like tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), and the interleukin-12 (IL-12)/IL-23. Mucosal immunization could be a superior approach to activate mucosal and systemic immune responses against pathogenic invasion at mucosal surface entry ports. Mucosal vaccines are also able to generate strong systemic humoral immunity—required to neutralize any virus particle that dodges the primary immune response. To develop an efficient vaccine against mucosal pathogens, considering the designing of the delivery route, immunomodulatory features, and adjuvants are very important. In this article, we further provide evidence to understand the significant role of mucosal immunity, along with secretory and circulating immunoglobulin A (IgA) antibodies in generating a novel mucosal vaccine against COVID-19. Moreover, along with mucosal vaccines, we should look for combination treatment strategies with plant bioactive molecules. Glycan-binding lectins against viral proteins for targeted activation of mucosal immune response are one of such examples. This might play a promising role to halt this emerging virus.

Review: The Nose as a Route for Therapy. Part 2 Immunotherapy.

The nose provides a route of access to the body for inhalants and fluids. Unsurprisingly it has a strong immune defense system, with involvement of innate (e.g., epithelial barrier, muco- ciliary clearance, nasal secretions with interferons, lysozyme, nitric oxide) and acquired (e.g., secreted immunoglobulins, lymphocytes) arms. The lattice network of dendritic cells surrounding the nostrils allows rapid uptake and sampling of molecules able to negotiate the epithelial barrier. Despite this many respiratory infections, including SARS-CoV2, are initiated through nasal mucosal contact, and the nasal mucosa is a significant “reservoir” for microbes including Streptococcus pneumoniae, Neisseria meningitidis and SARS -CoV-2. This review includes consideration of the augmentation of immune defense by the nasal application of interferons, then the reduction of unnecessary inflammation and infection by alteration of the nasal microbiome. The nasal mucosa and associated lymphoid tissue (nasopharynx-associated lymphoid tissue, NALT) provides an important site for vaccine delivery, with cold-adapted live influenza strains (LAIV), which replicate intranasally, resulting in an immune response without significant clinical symptoms, being the most successful thus far. Finally, the clever intranasal application of antibodies bispecific for allergens and Intercellular Adhesion Molecule 1 (ICAM-1) as a topical treatment for allergic and RV-induced rhinitis is explained.

Lipopolysaccharide Derived From the Lymphoid-Resident Commensal Bacteria Alcaligenes faecalis Functions as an Effective Nasal Adjuvant to Augment IgA Antibody and Th17 Cell Responses

Alcaligenes spp., including A. faecalis, is a gram-negative facultative bacterium uniquely residing inside the Peyer’s patches. We previously showed that A. faecalis-derived lipopolysaccharides (Alcaligenes LPS) acts as a weak agonist of toll-like receptor 4 to activate dendritic cells and shows adjuvant activity by enhancing IgG and Th17 responses to systemic vaccination. Here, we examined the efficacy of Alcaligenes LPS as a nasal vaccine adjuvant. Nasal immunization with ovalbumin (OVA) plus Alcaligenes LPS induced follicular T helper cells and germinal center formation in the nasopharynx-associated lymphoid tissue (NALT) and cervical lymph nodes (CLNs), and consequently enhanced OVA-specific IgA and IgG responses in the respiratory tract and serum. In addition, nasal immunization with OVA plus Alcaligenes LPS induced OVA-specific T cells producing IL-17 and/or IL-10, whereas nasal immunization with OVA plus cholera toxin (CT) induced OVA-specific T cells producing IFN-γ and IL-17, which are recognized as pathogenic type of Th17 cells. In addition, CT, but not Alcaligenes LPS, promoted the production of TNF-α and IL-5 by T cells. Nasal immunization with OVA plus CT, but not Alcaligenes LPS, led to increased numbers of neutrophils and eosinophils in the nasal cavity. Together, these findings indicate that the benign nature of Alcaligenes LPS is an effective nasal vaccine adjuvant that induces antigen-specific mucosal and systemic immune responses without activation of inflammatory cascade after nasal administration.

The central role of the nasal microenvironment in the transmission, modulation, and clinical progression of SARS-CoV-2 infection.

The novel coronavirus SARS-CoV-2 enters into the human body mainly through the ACE2 + TMPRSS2+ nasal epithelial cells. The initial host response to this pathogen occurs in a peculiar immune microenvironment that, starting from the Nasopharynx-Associated Lymphoid Tissue (NALT) system, is the product of a long evolutionary process that is aimed to first recognize exogenous airborne agents. In the present work, we want to critically review the latest molecular and cellular findings on the mucosal response to SARS-CoV-2 in the nasal cavity and in NALT, and to analyze its impact in the subsequent course of COVID-19. Finally, we want to explore the possibility that the regulation of the systemic inflammatory network against the virus can be modulated starting from the initial phases of the nasal and nasopharyngeal response and this may have several clinical and epidemiological implications starting from a mucosal vaccine development.

IgT Plays a Predominant Role in the Antibacterial Immunity of Rainbow Trout Olfactory Organs.

The olfactory organs (OOs) of vertebrates play important roles in their extraordinary chemosensory capacity, a process during which they are continuously exposed to environmental pathogens. Nasopharynx-associated lymphoid tissue (NALT) contains B cells and immunoglobulins (Igs), which function as the first defense line against antigens in mammals and also exist in teleosts. However, the immune responses of teleost NALT B cells and Igs during bacterial infection remain largely uncharacterized. In this study, rainbow trout were infected with Flavobacterium columnare via continuous immersion, after which the adaptive immune responses within NALT were evaluated. F. columnare could invade trout nasal mucosa and cause histopathological changes in trout OO. Moreover, the accumulation of IgT+ B cells in trout nasal mucosa was induced by bacterial challenge, which was accompanied by strong bacteria-specific IgT responses in the nasal mucus. Importantly, our study is the first to report local nasal-specific immune responses in teleosts during bacterial challenge by characterizing the local proliferation of IgT+ B cells and generation of bacteria-specific IgT in trout OOs after F. columnare infection. In addition to the strong IgT and IgT+ B cells responses in OO, bacteria-specific IgT and IgM were also detected in serum following bacterial challenge. Taken together, our findings suggest that IgT functions as an important mucosal Ig in teleost NALT and mediates local adaptive immunity during bacterial infection, which is similar to their protective role during parasitic infection.

Vaccination Route Determines the Kinetics and Magnitude of Nasal Innate Immune Responses in Rainbow Trout (Oncorhynchus mykiss).

Simple SummaryMany pathogens exploit the olfactory route to reach critical organs in the body such as the brain or lungs. Thus, effective onset of an early innate immune response in the nasal epithelium is key to stopping pathogen progression. The stimulation of nasal immunity by vaccines may depend on the type of vaccine and vaccination route. The goal of this study was to evaluate the ability of a live attenuated viral vaccine to stimulate innate immunity in the olfactory organ of rainbow trout, a teleost fish of commercial aquaculture value. The kinetics and magnitude of the innate immune response depended on the route of vaccination, with the strongest and fastest responses recorded in intranasally vaccinated fish. Injection vaccination had an intermediate effect, whereas immersion vaccination resulted in delayed and weak nasal innate immunity. Injection vaccination, even with the vehicle control, induced mortality in fingerlings, whereas nasal and immersion vaccines were safe. Challenge experiments with the live virus revealed that nasal and injected vaccines conferred very high and comparable levels of protection, but immersion vaccination only induced transient protection. In conclusion, the route of vaccination determines the type, magnitude and velocity of the innate immune response in the nasal epithelium of animals.Many pathogens infect animal hosts via the nasal route. Thus, understanding how vaccination stimulates early nasal immune responses is critical for animal and human health. Vaccination is the most effective method to prevent disease outbreaks in farmed fish. Nasal vaccination induces strong innate and adaptive immune responses in rainbow trout and was shown to be highly effective against infectious hematopoietic necrosis (IHN). However, direct comparisons between intranasal, injection and immersion vaccination routes have not been conducted in any fish species. Moreover, whether injection or immersion routes induce nasal innate immune responses is unknown. The goal of this study is to compare the effects of three different vaccine delivery routes, including intranasal (IN), intramuscular (i.m.) injection and immersion (imm) routes on the trout nasal innate immune response. Expression analyses of 13 immune-related genes in trout nasopharynx-associated lymphoid tissue (NALT), detected significant changes in immune expression in all genes analyzed in response to the three vaccination routes. However, nasal vaccination induced the strongest and fastest changes in innate immune gene expression compared to the other two routes. Challenge experiments 7 days post-vaccination (dpv) show the highest survival rates in the IN- and imm-vaccinated groups. However, survival rates in the imm group were significantly lower than the IN- and i.m.-vaccinated groups 28 dpv. Our results confirm that nasal vaccination of rainbow trout with live attenuated IHNV is highly effective and that the protection conferred by immersion vaccination is transient. These results also demonstrate for the first time that immersion vaccines stimulate NALT immune responses in salmonids.

10-Hydroxydecanoic Acid Potentially Elicits Antigen-Specific IgA Responses.

The effective antigen (Ag) uptake by microfold cells (M-cells) is important for the induction of an efficient mucosal immune responses. Here, we show that 10-hydroxydecanoic acid (10-HDAA) from royal jelly (RJ) potentially supports M-cell differentiation and induces effective antigen-specific mucosal immune responses in cynomolgus macaques. 10-HDAA increases the expression level of receptor activator of nuclear factor-kappaB (NF-κB) (RANK) in Caco-2 cells, which suggests that 10-HDAA potentially prompts the differentiation of Caco-2 cells into M-cells and increased transcytosis efficiency. This idea is supported by the following observations. Intranasal administration of 10-HDAA increased the number of M-cells in the epithelium overlying nasopharynx-associated lymphoid tissue (NALT) in macaques. Oral administration of 10-HDAA increased the number of M-cells in the follicle-associated epithelium (FAE) covering Peyer's patches (PPs) and significantly increased the antigen-specific immunoglobulin A (IgA) level in macaques. These findings suggest that the exogenous honeybee-derived medium-chain fatty acid 10-HDAA may effectively enhance antigen-specific immune responses.

Chemically Synthesized Alcaligenes Lipid A Shows a Potent and Safe Nasal Vaccine Adjuvant Activity for the Induction of Streptococcus pneumoniae-Specific IgA and Th17 Mediated Protective Immunity.

Effective and safe vaccine adjuvants are needed to appropriately augment mucosal vaccine effects. Our previous study demonstrated that lipopolysaccharide (LPS) from Peyer’s patch resident Alcaligenes stimulated dendritic cells to promote the production of mucosal immunity-enhancing cytokines (e.g., IL-6 and BAFF), thus enhancing antigen-specific immune responses (including IgA production and Th17 responses) without excessive inflammation. Here, we chemically synthesized Alcaligenes lipid A, the biologically active part of LPS, and examined its efficacy as a nasal vaccine adjuvant for the induction of protectively immunity against Streptococcus pneumoniae infection. Mice were nasally immunized with pneumococcal surface protein A (PspA) as a vaccine antigen for S. pneumoniae, together with Alcaligenes lipid A. Alcaligenes lipid A supported the generation of high levels of PspA-specific IgA and IgG responses through the augmentation of germinal center formation in the nasopharynx-associated lymphoid tissue and cervical lymph nodes (CLNs). Moreover, Alcaligenes lipid A promoted PspA-specific CD4+ Th17 responses in the CLNs and spleen. Furthermore, neutrophils were recruited to infection sites upon nasal infection and synchronized with the antigen-specific T and B cell responses, resulting in the protection against S. pneumoniae infection. Taken together, Alcaligenes lipid A could be applied to the prospective adjuvant to enhance nasal vaccine efficacy by means of augmenting both the innate and acquired arms of mucosal immunity against respiratory bacterial infection.

Fish nasal immunity: From mucosal vaccines to neuroimmunology

Like terrestrial vertebrates, bony fishes have a nasopharynx-associated lymphoid tissue (NALT) that protects the host against invading pathogens. Despite nasal immunity being a relatively new field in fish immunology, the investigation of nasal immune systems has already illuminated fundamental aspects of teleost mucosal immune systems as well as neuroimmunology. In this review, we highlight the importance of nasal infections in bony fish and the progress that has been made towards understanding how fish respond locally and systemically to nasal infection or vaccination. We also want to highlight the complex interactions between neurons and immune cells that occur in the olfactory organ during the course of an immune response. We predict that similar neuroimmune interactions govern immune responses at all mucosal tissues in bony fish. Understanding the principles of mucosal immune responses in teleost NALT has therefore revealed important aspects of fish mucosal immunity that are critical for mucosal vaccination in aquaculture.

Airway mucociliary dysfunction enhances antigen-specific nasal IgA immune responses to cholera toxin-based nasal vaccine

Abstract Nasal mucosal tissues are equipped with physical barriers, mucus and cilia, on their surface. The mucus captures inhaled materials, and the cilia remove the captured materials from the epithelial layer by asymmetrical beating. Effect of nasal physical barriers on the vaccine efficacy remains to be investigated. Tubulin tyrosine ligase-like family member 1 (Ttll1) is an essential enzyme for appropriate movement of the cilia on respiratory epithelium, and its deficiency (Ttll1-KO) leads to the impaired asymmetrical beating of cilia and consequent mucus accumulation in the nasal cavity. Here, when mice were intranasally immunized with pneumococcal surface protein A (PspA) together with cholera toxin, Ttll1-KO mice showed higher levels of PspA-specific IgA in the nasal wash and increased numbers of PspA-specific IgA-producing plasma cells in the nasal passages when compared with Ttll1 hetero (He) mice. Mucus removal by N-acetylcysteine did not affect the enhanced immune responses in Ttll1-KO mice. We further found that retention time of PspA in the nasal cavity in Ttll1-KO mice was longer than that in Ttll1-He mice. Consistently, uptake of PspA by dendritic cells was higher in the nasopharynx-associated lymphoid tissue (NALT) of Ttll1-KO mice than that of Ttll1-He mice. These results indicate that the ciliary function of removing vaccine antigen from the NALT epithelial layer is a critical determinant of the efficacy of nasal vaccine.

Impaired mucociliary motility enhances antigen-specific nasal IgA immune responses to a cholera toxin-based nasal vaccine.

Nasal mucosal tissues are equipped with physical barriers, mucus and cilia, on their surface. The mucus layer captures inhaled materials, and the cilia remove the inhaled materials from the epithelial layer by asymmetrical beating. The effect of nasal physical barriers on the vaccine efficacy remains to be investigated. Tubulin tyrosine ligase-like family, member 1 (Ttll1) is an essential enzyme for appropriate movement of the cilia on respiratory epithelium, and its deficiency (Ttll1-KO) leads to mucus accumulation in the nasal cavity. Here, when mice were intra-nasally immunized with pneumococcal surface protein A (PspA, as vaccine antigen) together with cholera toxin (CT, as mucosal adjuvant), Ttll1-KO mice showed higher levels of PspA-specific IgA in the nasal wash and increased numbers of PspA-specific IgA-producing plasma cells in the nasal passages when compared with Ttll1 hetero (He) mice. Mucus removal by N-acetylcysteine did not affect the enhanced immune responses in Ttll1-KO mice versus Ttll1-He mice. Immunohistological and flow cytometry analyses revealed that retention time of PspA in the nasal cavity in Ttll1-KO mice was longer than that in Ttll1-He mice. Consistently, uptake of PspA by dendritic cells was higher in the nasopharynx-associated lymphoid tissue (NALT) of Ttll1-KO mice than that of Ttll1-He mice. These results indicate that the ciliary function of removing vaccine antigen from the NALT epithelial layer is a critical determinant of the efficacy of nasal vaccine.