Nasal-associated Lymphoid Tissue Research Articles

Anti-sulfated-glycan monoclonal antibody S2 inhibits lymphocyte recruitment to nasal-associated lymphoid tissues and attenuates allergic rhinitis

Abstract Nasal-associated lymphoid tissue (NALT) is a mucosal lymphoid tissue that functions as a border of defense against inhaled antigens. Lymphocyte recruitment to NALT is mediated by the interaction between L-selectin on lymphocytes and sulfated-glycans on high endothelial venules (HEV) in NALT. HEV are specialized post capillary venules regulating lymphocyte entry form blood into parenchyma of lymphoid organs. It has been previously reported that lymphocyte recruitment to NALT was markedly blocked in HEV-expressed N-acetylglucosamine-6-O-sulfotransferase (GlcNAc6ST) −1 and −2 double-deficient (DKO) mice. In the DKO mice, immune responses against nasally administered ovalbumin (OVA) including OVA-specific IgE, sneezes and nose scratches were significantly diminished. We previously generated an anti-sulfated-glycan monoclonal antibody S2 which recognizes 6-sulfo sialyl Lewis X (sLeX) and 6-sulfo sialyl N-acetyllactosamine expressed on HEV in NALT by immunizing GlcNAc6ST-1/2 DKO mice with CHO-K1 cells stably expressing 6-sulfo sLeX. S2 administration inhibited lymphocyte recruitment to NALT and allergic rhinitis induced by intranasal administration of OVA. S2 administration to OVA-immunized mice resulted in the reduction of OVA-specific serum IgE, and counts of sneezes and nose scratches after nasal immunization. Total cell numbers in NALT and expression of Th2-related cytokines such as IL-5 and IL-13 were also diminished after S2 administration. Taken together, these results suggest that S2 would serve as a novel therapeutic agent useful for the treatment of allergic rhinitis.

Colonization-induced protection against invasive pneumococcal disease in mice is independent of CD103 driven adaptive immune responses.

Nasopharyngeal colonization with Streptococcuspneumoniae (the pneumococcus) is known to mount protective adaptive immune responses in rodents and humans. However, the cellular response of the nasopharyngeal compartment to pneumococcal colonization and its importance for the ensuing adaptive immune response is only partially defined. Here we show that nasopharyngeal colonization with S.pneumoniae triggered substantial expansion of both integrin αE (CD103) positive dendritic cells (DC) and T lymphocytes in nasopharynx, nasal-associated lymphoid tissue (NALT) and cervical lymph nodes (CLN) of WT mice. However, nasopharyngeal de-colonization and pneumococcus-specific antibody responses were similar between WT and CD103 KO mice or Batf3 KO mice. Also, naïve WT mice passively immunized with antiserum from previously colonized WT and CD103KO mice were similarly protected against invasive pneumococcal disease (IPD). In summary, the data show that CD103 is dispensable for pneumococcal colonization-induced adaptive immune responses in mice.

Experimental Inoculation in Rats and Mice by the Giant Marseillevirus Leads to Long-Term Detection of Virus.

The presence of the giant virus of amoeba Marseillevirus has been identified at many different sites on the human body, including in the bloodstream of asymptomatic subjects, in the lymph nodes of a child with adenitis, in one adult with Hodgkin's disease, and in the pharynx of an adult. A high seroprevalence of the Marseillevirus has been recorded in the general population. Whether Marseillevirus can disseminate and persist within a mammal after entry remains unproven. We aimed to assess the ability of the virus to disseminate and persist into healthy organisms, especially in the lymphoid organs. Parenteral inoculations were performed by intraperitoneal injection (in rats and mice) or intravenous injection (in rats). Airway inoculation was performed by aerosolization (in mice). Dissemination and persistence were assessed by using PCR and amebal co-culture. Serologies were performed by immunofluorescent assay. Pathological examination was conducted after standard and immunohistochemistry staining. After intraperitoneal inoculation in mice and rats, Marseillevirus was detected in the bloodstream during the first 24 h. Persistence was noted until the end of the experiment, i.e., at 14 days in rats. After intravenous inoculation in rats, the virus was first detected in the blood until 48 h and then in deep organs with infectious virus detected until 14 and 21 days in the liver and the spleen, respectively. Its DNA was detected for up to 30 days in the liver and the spleen. After aerosolization in mice, infectious Marseillevirus was present in the lungs and nasal associated lymphoid tissue until 30 days post inoculation but less frequently and at a lower viral load in the lung than in the nasal associated lymphoid tissue. No other site of dissemination was found after aerosol exposure. Despite no evidence of disease being observed, the 30-day long persistence of Marseillevirus in rats and mice, regardless of the route of inoculation, supports the hypothesis of an infective potential of the virus in certain conditions. Its constant and long-term detection in nasal associated lymphoid tissue in mice after an aerosol exposure suggests the involvement of naso-pharyngeal associated lymphoid tissues in protecting the host against environmental Marseillevirus.

Seeding of the mucosal leukocytes in the HALT and trachea of White Leghorn chickens

ABSTRACTCharacterising the immune cells of the head-associated lymphoid tissues (HALT) and trachea during maturation in young birds is critical to understanding the immunological responses to avian respiratory diseases and vaccines. Selected mucosal leukocytes of the conjunctiva-associated lymphoid tissue (CALT), Harderian gland (HG), nasal-associated lymphoid tissue (NALT) and trachea from 4-, 6-, 8-, and 10-week-old chickens were enumerated and phenotyped. HG, NALT, and trachea cellularity increased as the birds aged with cell viability varying by tissue. The results showed that the T cell subset numbers, but not B cell numbers, increased in the mucosal tissues of chickens during aging.

CGAMP Promotes Germinal Center Formation and Production of IgA in Nasal-Associated Lymphoid Tissue.

Induction of immunoglobulin (Ig) A in the mucosa of the upper respiratory tract and the nasal cavity protects against influenza virus infection. Cyclic dinucleotides (CDNs) are used as mucosal adjuvants to enhance the immunogenicity of intranasal influenza hemagglutinin (HA) vaccines. The adjuvant activity of 2′3′ cyclic guanosine monophosphate–adenosine monophosphate (cGAMP) on Ig production was investigated in nasal-associated lymphoid tissue (NALT), serum of wild-type C57BL/6J, and stimulator of interferon genes (STING)-deficient mice, which do not recognize cGAMP. Mice were vaccinated intranasally with a HA vaccine with or without the cGAMP adjuvant. IgA and IgG production, T-cell responses, germinal center formation, and cytokine expression in NALT were assayed. cGAMP enhanced IgA and IgG production, and promoted T-cell responses. Intranasal administration of cGAMP activated both NALT and systemic immune cells, induced a favorable cytokine environment for IgA induction, and promoted germinal center formation. The cGAMP effect was STING-dependent. Taken together, cGAMP as an HA vaccine adjuvant promoted a STING-dependent NALT environment suitable for the enhancement of IgA production.

Immunotherapeutic efficacy of liposome-encapsulated refined allergen vaccines against Dermatophagoides pteronyssinus allergy.

Allergen specific immunotherapy (AIT) can modulate the allergic response causing a long-term symptom subsidence/abolishment which leads to reduced drug use and prevention of new sensitization. AIT of house dust mite allergy (HDM) using the mite crude extract (CE) as the therapeutic agent is not only less effective than the AIT for many other allergens, but also frequently causes adverse effects during the treatment course. In this study, mouse model of Dermatophagoides pteronyssinus (Dp) allergy was invented for testing therapeutic efficacies of intranasally administered liposome (L) encapsulated vaccines made of single Dp major allergens (L-Der p 1, L-Der p 2), combined allergens (L-Der p 1 and Der p 2), and crude Dp extract (L-CE). The allergen sparing intranasal route was chosen as it is known that the effective cells induced at the nasal-associated lymphoid tissue can exert their activities at the lower respiratory tissue due to the common mucosal traffic. Liposome was chosen as the vaccine delivery vehicle and adjuvant as the micelles could reduce toxicity of the entrapped cargo. The Dp-CE allergic mice received eight doses of individual vaccines/placebo on alternate days. All vaccine formulations caused reduction of the Th2 response of the Dp allergic mice. However, only the vaccines made of single refined allergens induced expressions of immunosuppressive cytokines (TGF-β, IL-35 and/or IL-10) which are the imperative signatures of successful AIT. The data emphasize the superior therapeutic efficacy of single refined major allergen vaccines than the crude allergenic extract vaccine.

Discriminating between Interstitial and Circulating Leukocytes in Tissues of the Murine Oral Mucosa Avoiding Nasal-Associated Lymphoid Tissue Contamination.

Periodontitis is a chronic inflammatory response to a microbial biofilm that destroys bone and soft tissues supporting the teeth. Murine models of periodontitis based on Porphyromonas gingivalis (Pg) colonization have shown that extravasation of leukocytes into oral tissue is critical to driving alveolar bone destruction. Identifying interstitial leukocytes is key to understanding the immunopathogenesis of periodontitis. Here, we describe a robust flow cytometry assay based on intravenous FITC-conjugated anti-mouse CD45 mAb that distinguishes interstitial leukocytes in the oral mucosa of mice from those circulating within the vasculature or in post-dissection contaminating blood. Unaccounted circulating leukocytes skewed the relative frequency of B cells and granulocytes and inflated the numbers of all leukocyte cell types. We also describe a dissection technique that avoids contamination of oral mucosal tissues with nasal-associated lymphoid tissues (NALT), a B cell rich organ that can inflate leukocyte numbers at least 10-fold and skew the assessment of interstitial CD4 T cell phenotypes. Unlike circulating CD4 T cells, interstitial CD4 T cells were almost exclusively antigen-experienced cells (CD44hi). We report for the first time the presence of antigen-experienced Pg-specific CD4 T cells in NALT following oral feeding of mice with Pg. This new combined flow cytometry and dissection approach allows identification of leukocytes infiltrating the connective tissues of the murine oral mucosa and avoids confounding analyses of leukocytes not recruited to inflamed oral mucosal tissues in disease conditions like periodontitis, candidiasis, or sialadenitis.

Nasal-associated lymphoid tissues (NALTs) support the recall but not priming of influenza virus-specific cytotoxic T cells

The lymphoid tissue that drains the upper respiratory tract represents an important induction site for cytotoxic T lymphocyte (CTL) immunity to airborne pathogens and intranasal vaccines. Here, we investigated the role of the nasal-associated lymphoid tissues (NALTs), which are mucosal-associated lymphoid organs embedded in the submucosa of the nasal passage, in the initial priming and recall expansion of CD8+ T cells following an upper respiratory tract infection with a pathogenic influenza virus and immunization with a live attenuated influenza virus vaccine. Whereas NALTs served as the induction site for the recall expansion of memory CD8+ T cells following influenza virus infection or vaccination, they failed to support activation of naïve CD8+ T cells. Strikingly, NALTs, unlike other lymphoid tissues, were not routinely surveyed during the steady state by circulating T cells. The selective recruitment of memory T cells into these lymphoid structures occurred in response to infection-induced elevation of the chemokine CXCL10, which attracted CXCR3+ memory CD8+ T cells. These results have significant implications for intranasal vaccines, which deliver antigen to mucosal-associated lymphoid tissue and aim to elicit protective CTL-mediated immunity.

THE LYMPH NODES IN RATS WITH EXPERIMENTAL TYPE 1 DIABETES MELLITUS (DM-1)

The aim is to study morphofunctional structure of NALT (nasal associated lymphoid tissue) and visceral lymph nodes of rats with experimental type 1 diabetes mellitus (DM-1) and to define the effectiveness of the treatment with herbal drug “Imupret”. Materials and methods: The experiment involved 20 animals, divided into 4 groups: the 1st group was the control group of healthy rats, the 2nd group was the control group subject to prophylactic treatment with “Imupret, the 3rd group included rats with experimental diabetes, and the 4th group included rats with experimental diabetes subject to treatment with “Imupret. Functional changes in immune organs were evaluated by the results of morphometric analysis; morphological pattern was evaluated by histostructural changes. Results. The research revealed that under conditions of diabetes mellitus type 1, the volume, area and density of the lymphoid tissue decreased, and only its "fine" cell was detected. The paper demonstrates the development of relative immune deficiency in immunocompetent organs in rats with diabetes mellitus type 1. The use of drug "Imupret" demonstrated its immunomodulatory function, which is especially important in terms of immunosuppression in patient with DM-1. Conclusion. The received results are of a great clinical significance, and show the necessity of early prevention and treatment of immunity disorders under conditions of diabetes mellitus type 1.

Nasopharyngeal colonization with Streptococcus pneumoniae triggers dendritic cell dependent antibody responses against invasive disease in mice.

Nasopharyngeal colonization with Streptococcus pneumoniae (Spn) is an important precondition for the development of pneumococcal pneumonia. At the same time, nasopharyngeal colonization with Spn has been shown to mount adaptive immune responses against Spn in mice and humans. Cellular responses of the nasopharyngeal compartment, including the nasal-associated lymphoid tissue, to pneumococcal colonization and their importance for developing adaptive immune responses are poorly defined. We show that nasopharyngeal colonization with S.pneumoniae led to substantial expansion of dendritic cells (DCs) both in nasopharyngeal tissue and nasal-associated lymphoid tissue of mice. Depletion of DCs achieved by either diphtheria toxin (DT) treatment of chimeric zDC+/DTR mice, or by use of FMS-like tyrosine kinase 3 ligand (Flt3L) KO mice exhibiting congenitally reduced DC pool sizes, significantly diminished antibody responses after colonization with Spn, along with impaired protective immunity against invasive pneumococcal disease. Collectively, the data show that classical DCs contribute to pneumococcal colonization induced adaptive immune responses against invasive pneumococcal disease in two different mouse models. These data may be useful for future nasopharyngeal vaccination strategies against pneumococcal diseases in humans.

IgD class switching is initiated by microbiota and limited to mucosa-associated lymphoid tissue in mice

Class-switch recombination (CSR) alters the Ig isotype to diversify antibody effector functions. IgD CSR is a rare event, and its regulation is poorly understood. We report that deficiency of 53BP1, a DNA damage-response protein, caused age-dependent overproduction of secreted IgD resulting from increased IgD CSR exclusively within B cells of mucosa-associated lymphoid tissues. IgD overproduction was dependent on activation-induced cytidine deaminase, hematopoietic MyD88 expression, and an intact microbiome, against which circulating IgD, but not IgM, was reactive. IgD CSR occurred via both alternative nonhomologous end-joining and homologous recombination pathways. Microbiota-dependent IgD CSR also was detected in nasal-associated lymphoid tissue of WT mice. These results identify a pathway, present in WT mice and hyperactivated in 53BP1-deficient mice, by which microbiota signal via Toll-like receptors to elicit IgD CSR.

Allergic inflammation is exacerbated by allergen-induced type 2 innate lymphoid cells in a murine model of allergic rhinitis.

Group 2 innate lymphoid cells (ILC2s) represent a new innate effector leukocyte population that mediates type-2 immune response. However, the contribution of ILC2s to allergic rhinitis (AR) is currently not well defined. To evaluate the potential existence and function of allergen-induced ILC2s in the experimental AR. We established a murine model of AR using ovalbumin (OVA) and aluminium hydroxide. The OVA-induced ILC2s were sorted and purified from the mouse nasal-associated lymphoid tissue (NALT). Then, we assessed ILC2s responses to mouse recombinant interleukin (rmIL)-25, anti-IL17RB antibody and CC chemokine ligand (CCL) 25 in the culture. After that, we adoptively transferred the NALT-derived ILC2s alone or plus rmIL-25 or anti-IL17RB antibody to the murine model of AR to investigate their role in the nasal allergic inflammation. We showed that ILC2s could be induced by OVA in the NALT of AR model. They were induced to secrete IL-5 and IL-13 by rmIL-25, and blocking of IL17RB contributed to the decreased production of these cytokines in the culture. We found that CCL25 induced the NALT-derived ILC2s migration through CC chemokine receptor 9 on ILC2s in vitro. Numbers of sneezing and nasal rubbing as well as counts of invasive eosinophils were all enhanced after the adoptive transfer of cultured ILC2s in vitro. The expressions of IL-5, IL-13, IL-25 and CCL25 in the NLF of allergic mice were also increased. These findings show that ILC2s play a proinflammatory role in the murine AR model, and also highlight ILC2s as a new target in the future AR therapy.

Toll-like Receptors 2 and 4-Mediated Reciprocal Th17 and Antibody Responses to Group A Streptococcus Infection.

The role of Toll-like receptors (TLRs) in adaptive immunity is incompletely understood. Recurrent human infections by group A streptococcus (GAS) and associated autoimmune conditions suggest that the immunity to GAS is intricately regulated and that TLRs may be involved in the regulation. This study investigated adaptive mucosal immune responses to GAS in TLR2-/- and TLR4-/- mice with an intranasal infection model. Flow cytometric analyses of nasal-associated lymphoid tissue (NALT) cells showed that robust T helper 17 (Th17) cell responses to GAS in wild-type (WT) mice were reduced in TLR2-/- mice by 50%. Conversely, antibody levels and follicular T and B cells in the germinal center of NALT were significantly higher in TLR2-/- than in WT mice. However, antibody response to soluble antigens coimmunized with GAS was similar in WT and TLR2-/- mice. Moreover, the adaptive clearance of GAS in TLR2-/- mice was as efficient as in WT mice, whereas it was significantly impaired in TLR4-/- mice in which antibody responses were significantly lower than in WT mice. Activation of TLR2 by GAS is responsible for massive Th17 activation and deficient antibody response, which may increase predisposition to GAS-related autoimmunity and reduce protection efficiency.

Burkholderia pseudomallei Capsule Exacerbates Respiratory Melioidosis but Does Not Afford Protection against Antimicrobial Signaling or Bacterial Killing in Human Olfactory Ensheathing Cells.

Melioidosis, caused by the bacterium Burkholderia pseudomallei, is an often severe infection that regularly involves respiratory disease following inhalation exposure. Intranasal (i.n.) inoculation of mice represents an experimental approach used to study the contributions of bacterial capsular polysaccharide I (CPS I) to virulence during acute disease. We used aerosol delivery of B. pseudomallei to establish respiratory infection in mice and studied CPS I in the context of innate immune responses. CPS I improved B. pseudomallei survival in vivo and triggered multiple cytokine responses, neutrophil infiltration, and acute inflammatory histopathology in the spleen, liver, nasal-associated lymphoid tissue, and olfactory mucosa (OM). To further explore the role of the OM response to B. pseudomallei infection, we infected human olfactory ensheathing cells (OECs) in vitro and measured bacterial invasion and the cytokine responses induced following infection. Human OECs killed >90% of the B. pseudomallei in a CPS I-independent manner and exhibited an antibacterial cytokine response comprising granulocyte colony-stimulating factor, tumor necrosis factor alpha, and several regulatory cytokines. In-depth genome-wide transcriptomic profiling of the OEC response by RNA-Seq revealed a network of signaling pathways activated in OECs following infection involving a novel group of 378 genes that encode biological pathways controlling cellular movement, inflammation, immunological disease, and molecular transport. This represents the first antimicrobial program to be described in human OECs and establishes the extensive transcriptional defense network accessible in these cells. Collectively, these findings show a role for CPS I in B. pseudomallei survival in vivo following inhalation infection and the antibacterial signaling network that exists in human OM and OECs.

Enhanced intranasal delivery of mRNA vaccine by overcoming the nasal epithelial barrier via intra- and paracellular pathways

Facing the threat of highly variable virus infection, versatile vaccination systems are urgently needed. Intranasal mRNA vaccination provides a flexible and convenient approach. However, the nasal epithelium remains a major biological barrier to deliver antigens to nasal associated lymphoid tissue (NALT). To address this issue, a potent polymer-based intranasal mRNA vaccination system for HIV-1 treatment was synthesized using cationic cyclodextrin-polyethylenimine 2k conjugate (CP 2k) complexed with anionic mRNA encoding HIV gp120. The delivery vehicle containing CP 2k and mRNA overcame the epithelial barrier by reversibly opening the tight junctions, enhanced the paracellular delivery of mRNA and consequently minimized absorption of toxins in the nasal cavity. Together with the excellent intracellular delivery and prolonged nasal residence time, strong system and mucosal anti-HIV immune responses as well as cytokine productions were achieved with a balanced Th1/Th2/Th17 type. Our study provided the first proof of evidence that cationic polymers can be used as safe and potent intranasal mRNA vaccine carriers to overcome the nasal epithelial barrier. The safe and versatile polymeric delivery system represents a promising vaccination platform for infectious diseases.

Adaptive immunity and protection generated by nanoparticle-based vaccination against influenza virus

Event Abstract Back to Event Adaptive immunity and protection generated by nanoparticle-based vaccination against influenza virus Jonathan Goodman1, Kathleen Ross1, Balaji Narasimhan1, Thomas J Waldschmidt2 and Kevin L Legge2 1 Iowa State University, Chemical and Biological Engineering, United States 2 University of Iowa, Pathology, United States Each year influenza A virus (IAV) causes significant seasonal illness. The high rate of severe seasonal illness and threat of a pandemic outbreak has renewed interest in developing novel influenza vaccines. Following primary IAV infection, the development of both neutralizing antibody and a cytotoxic specific T cell response is important in terminating the acute infection and long-term protective immunity. While current influenza vaccines lead to the production of influenza neutralizing antibodies, it remains unclear whether a robust CD8+ T cell response is generated following vaccination[1]-[4]. Our hypothesis is that immunizations that generate local (i.e., lung) in addition to systemic immunity will offer the greatest protection against future IAV encounters. Polyanhydride nanovaccines have been shown to be efficacious in inducing antibody and T cell responses[5]. Therefore, we tested an IAV nanovaccine for induction of both local neutralizing antibody and cytotoxic CD8+ T cell responses. Mice were vaccinated intranasally with 200 µg of polyanhydride nanoparticles containing 5 µg hemagglutinin (HA), 5 µg nucleoprotein (NP) and 2% CpG 1668 together with 2.5 µg of free HA and NP. At various times post-vaccination, the T cell and B cell responses in the lungs and draining lymph nodes (dLNs) were measured by flow cytometry[3],[6]-[8]. In addition, mice were challenged with infectious IAV, and morbidity and mortality were monitored[3]. On day 7 post nanovaccine immunization, we observed an increased frequency and number of IAV-reactive CD4+ and CD8+ T cells in the lungs and dLNs of mice vs. non-vaccinated control mice (Fig. 1 and not shown). Further, B cell germinal center (GC) responses were induced in the dLNs and nasal associated lymphoid tissue (NALT) by day 12 and persisted until day 30 (Fig. 2). Finally our initial challenge experiments suggest that the IAV nanovaccine may confer protection against lethal dose infection of homologous virus (not shown). The IAV nanovaccine induced antigen-experienced IAV-specific CD4+ and CD8+ T cell responses in the lungs and dLNs. The IAV nanovaccine also induced a strong GC response in the dLNs and NALT indicating potent ability to induce Th cell-driven B cell responses in the airway. Overall our results suggest that the nanovaccine may invoke long-lived humoral responses as well as potentially protective T cells against influenza infection. Importantly, this new vaccination strategy may induce these long-lived B cell and T cell responses both locally and systemically. Fig 1. Intranasal nanovaccine induces strong IAV-specific CD8+ (A) and CD4+ (B) T cell responses in the lungs at day 7 post-vaccination (n= 1 experiment with 4-5 mice per group). Fig 2. Intranasal IAV nanovaccine induces strong GC responses in the dLNs (A) and NALT (B) at days 12-30 post-vaccination. N= 3-4 mice per time point. NALT was pooled from 3-4 mice at each time given limited cell recoveries. Flow cytometry examples are from day 18.

Group A Streptococcus intranasal infection promotes CNS infiltration by streptococcal-specific Th17 cells.

Group A streptococcal (GAS) infection induces the production of Abs that cross-react with host neuronal proteins, and these anti-GAS mimetic Abs are associated with autoimmune diseases of the CNS. However, the mechanisms that allow these Abs to cross the blood-brain barrier (BBB) and induce neuropathology remain unresolved. We have previously shown that GAS infection in mouse models induces a robust Th17 response in nasal-associated lymphoid tissue (NALT). Here, we identified GAS-specific Th17 cells in tonsils of humans naturally exposed to GAS, prompting us to explore whether GAS-specific CD4+ T cells home to mouse brains following i.n. infection. Intranasal challenge of repeatedly GAS-inoculated mice promoted migration of GAS-specific Th17 cells from NALT into the brain, BBB breakdown, serum IgG deposition, microglial activation, and loss of excitatory synaptic proteins under conditions in which no viable bacteria were detected in CNS tissue. CD4+ T cells were predominantly located in the olfactory bulb (OB) and in other brain regions that receive direct input from the OB. Together, these findings provide insight into the immunopathology of neuropsychiatric complications that are associated with GAS infections and suggest that crosstalk between the CNS and cellular immunity may be a general mechanism by which infectious agents exacerbate symptoms associated with other CNS autoimmune disorders.

Intranasal Immunization with DOTAP Cationic Liposomes Combined with DC-Cholesterol Induces Potent Antigen-Specific Mucosal and Systemic Immune Responses in Mice.

Despite the progress made by modern medicine, infectious diseases remain one of the most important threats to human health. Vaccination against pathogens is one of the primary methods used to prevent and treat infectious diseases that cause illness and death. Vaccines administered by the mucosal route are potentially a promising strategy to combat infectious diseases since mucosal surfaces are a major route of entry for most pathogens. However, this route of vaccination is not widely used in the clinic due to the lack of a safe and effective mucosal adjuvant. Therefore, the development of safe and effective mucosal adjuvants is key to preventing infectious diseases by enabling the use of mucosal vaccines in the clinic. In this study, we show that intranasal administration of a cationic liposome composed of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and 3β-[N-(N',N'-dimethylaminoethane)-carbamoyl] (DC-chol) (DOTAP/DC-chol liposome) has a potent mucosal adjuvant effect in mice. Intranasal vaccination with ovalbumin (OVA) in combination with DOTAP/DC-chol liposomes induced the production of OVA-specific IgA in nasal tissues and increased serum IgG1 levels, suggesting that the cationic DOTAP/DC-chol liposome leads to the induction of a Th2 immune response. Additionally, nasal-associated lymphoid tissue and splenocytes from mice treated with OVA plus DOTAP/DC-chol liposome showed high levels of IL–4 expression. DOTAP/DC-chol liposomes also enhanced OVA uptake by CD11c+ dendritic cells in nasal-associated lymphoid tissue. These data demonstrate that DOTAP/DC-chol liposomes elicit immune responses via an antigen-specific Th2 reaction. These results suggest that cationic liposomes merit further development as a mucosal adjuvant for vaccination against infectious diseases.

Mannan-decorated thiolated Eudragit microspheres for targeting antigen presenting cells via nasal vaccination

Mucosal vaccination of protein as an antigen requires appropriate delivery or adjuvant systems to deliver antigen to mucosal immune cells efficiently and generate valid immune responses. For successful nasal immunization, the obstacles imposed by the normal process of mucociliary clearance which limits residence time of applied antigens and low antigen delivery to antigen presenting cells (APCs) in nasal associated lymphoid tissue (NALT) need to be overcome for the efficient vaccination. Here, we prepared mucoadhesive and mannan-decorated thiolated Eudragit microspheres (Man-TEM) as a nasal vaccine carrier to overcome the limitations. Mucoadhesive thiolated Eudragit (TE) were decorated with mannan for targeting mannose receptors (MR) in antigen presenting cells (APCs) to obtain efficient immune responses. The potential adjuvant ability of Man-TEM for intranasal immunization was confirmed by in vitro and in vivo experiments. In mechanistic study using APCs in vitro, we obtained that Man-TEM enhanced the receptor-mediated endocytosis by stimulating the MR receptors of APCs. The nasal vaccination of OVA-loaded Man-TEM in mice showed higher levels of serum IgG and mucosal sIgA than the soluble OVA group due to the specific recognition of MR of APCs by the mannan in the Man-TEM. These results suggest that mucoadhesive and Man-TEM may be a promising candidate for nasal vaccine delivery system to elicit systemic and mucosal immunity.

Delivery of antigen to nasal-associated lymphoid tissue microfold cells through secretory IgA targeting local dendritic cells confers protective immunity

Transmission of mucosal pathogens relies on their ability to bind to the surfaces of epithelial cells, to cross this thin barrier, and to gain access to target cells and tissues, leading to systemic infection. This implies that pathogen-specific immunity at mucosal sites is critical for the control of infectious agents using these routes to enter the body. Although mucosal delivery would ensure the best onset of protective immunity, most of the candidate vaccines are administered through the parenteral route. The present study evaluates the feasibility of delivering the chemically bound p24gag (referred to as p24 in the text) HIV antigen through secretory IgA (SIgA) in nasal mucosae in mice. We show that SIgA interacts specifically with mucosal microfold cells present in the nasal-associated lymphoid tissue. p24-SIgA complexes are quickly taken up in the nasal cavity and selectively engulfed by mucosal dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin-positive dendritic cells. Nasal immunization with p24-SIgA elicits both a strong humoral and cellular immune response against p24 at the systemic and mucosal levels. This ensures effective protection against intranasal challenge with recombinant vaccinia virus encoding p24. This study represents the first example that underscores the remarkable potential of SIgA to serve as a carrier for a protein antigen in a mucosal vaccine approach targeting the nasal environment.