NALT

Porcine circovirus-associated disease (PCVAD) and porcine respiratory disease complex (PRDC) significantly impact the pig industry worldwide. Porcine circovirus type 2 (PCV2) is the primary pathogen associated with PCVAD, whereas PRDC is caused by a combination of pathogens including porcine reproductive and respiratory syndrome virus (PRRSV) and pathogenic bacteria. Despite the availability of a PCV2 vaccine that effectively controls and prevents PCVAD, subclinical PCV2 infection (PCV2-SI) still occurs under field conditions. Various porcine pathogens enter via the nasal cavity, where nasopharynx-associated lymphoid tissue (NALT) plays an important role in nasal mucosal immunity. This study examined the pathogenesis of PRDC in pigs with PCV2-SI and the distribution of PCV2 and PRRSV in NALT using in-situ hybridization (ISH) analyses in PCV2-SI pigs. All six pigs had suppurative nasopharyngitis and suppurative pneumonia. Lymphoid tissue contained no cytoplasmic inclusions or giant cells. ISH showed positive signals for PCV2 in the NALT and lungs of all six pigs and PRRSV in the NALT of three pigs and lungs of five. PCV2-positive macrophages were primarily identified in the follicles of NALT, whereas PRRSV-positive macrophages were found primarily around crypts. This is the first study to suggest that replication of both viruses in NALT may cause suppression of local immunity and activate important risk factors of PRDC in pigs with PCV2-SI.

Antibody-mediated immune responses in mucosal tissues are critical for defending against pathogens while maintaining homeostasis with commensals. Nasal vaccination aims to induce local protection in the upper airway mucosa. Although B cell-driven immunity is well characterized in gut-associated lymphoid tissues such as Peyer's patches and mesenteric LNs, much less is known about analogous processes in the upper airways. Here, we show that B cell receptor (BCR) affinity and CCR6 regulate germinal center (GC) seeding and class-switch recombination (CSR) to IgA in nasal-associated lymphoid tissue (NALT) following nasal vaccination. B cells bearing low-affinity BCRs failed to upregulate CCR6 and did not support T follicular helper cell differentiation or seed GCs in the NALT. CCR6-deficient B cells were unable to migrate to the NALT subepithelial dome or undergo IgA CSR and seed GC effectively in response to nasal vaccination or commensal bacteria signals. Thus, effective targeting of B cell clones to induce CCR6 expression is essential for nasal vaccine design. © 2026 Liu et al.

Mucosal mRNA vaccines are promising for establishing immune barriers at pathogen entry points to prevent its infection and transmission. Nevertheless, these vaccines encounter challenges including rapid clearance, low reactivity to antigens, and suboptimal mRNA transfection efficiency. Addressing these limitations, we engineered an acid-responsive mRNA vaccine (PQOm) based on the Schiff-base polymers composed of quaternized chitosan (QCS), low molecular weight polyethyleneimine, and aldehyde functionalized polyethylene glycol, to stimulate potent mucosal and systemic immune responses. During the construction of PQOm, we not only revealed the significant impact of steric hindrance on mRNA transfection efficiency, but also demonstrated its ability to realize acid-responsive mRNA release and efficient mRNA transfection. Owing to the synergistic effect of its components, PQOm provided continuous stimulation to the nasal-associated lymphoid tissue (NALT) by adhering to the nasal mucosa for extended periods of up to 6 days. The continuous NALT stimulation, efficient transfection, and adjuvant effect of QCS collectively allowed PQOm to address the low reactivity of NALT to antigen, triggering robust mucosal and systemic immune responses without significant toxicity. In conclusion, PQOm represents a promising mucosal mRNA vaccine with high clinical potential for preventing viral infections.

BACKGROUND: Naegleria fowleri is a free-living amoeba that inhabits warm freshwater and causes primary amoebic meningoencephalitis (PAM), a rapidly fatal infection with >95% mortality. Due to the lack of early diagnosis and effective therapy, preventive vaccination represents a promising strategy. METHODS: This study evaluated short- and long-term immune protection in BALB/c mice (20 mice per group) immunized intranasally with total N. fowleri extract co-administered with cholera toxin (CT). Mice were challenged with a lethal dose of trophozoites either 24 h (short-term) or three months (long-term) after the fourth immunization; the latter group received a booster 24 h before challenge. Serum and nasal washes were analyzed for IgA and IgG antibodies by immunoblot, and lymphocyte subsets from nasal-associated lymphoid tissue (NALT) and nasal passages (NPs) were characterized by flow cytometry. RESULTS: Immunization conferred complete (100%) survival in the 24 h group and 60% protection in the 3-month group, whereas all control mice died. Immunoblotting showed that IgA and IgG antibodies recognized major N. fowleri antigens of 37, 45, 48 and 19, 37, and 100 kDa, respectively. Flow cytometry revealed increased activated and memory B lymphocytes, dendritic cells, and expression of CCR10, integrin α4β1, and FcγRIIB receptors, particularly in the 24 h group. CONCLUSIONS: Intranasal immunization with N. fowleri extract plus CT elicited both systemic and mucosal immune responses capable of short- and long-term protection. These findings highlight the potential of this immunization strategy as a foundation for developing effective vaccines against PAM.

INTRODUCTION: Estradiol has been shown to enhance anti-viral immunity and protect against HSV-2 infection. Previously, we reported that intranasal immunization with attenuated HSV-2 (TK-) in the presence of estradiol (E2) showed enhanced Th17 responses that led to increased anti-viral Th1 immunity in HSV-2 post-challenge. Whether enhanced Th17 cells also lead to improved B cell antibody responses against HSV-2 challenge in immunized mice in the presence of E2 was not examined and is the focus of the current study. METHODS: Ovariectomized (OVX) C57BL/6 or IL-17 knockout (IL-17-/-) mice were implanted with 17β-estradiol (E2) or placebo pellets subcutaneously. Two weeks later, mice were immunized intranasally with a single dose of 104 pfu of TK- HSV-2 and 4- or 6-weeks later, blood sera and vaginal washes were collected to measure IgG total and subtypes by ELISA. Mice were challenged intravaginally with 104 pfu of WT HSV-2 4-6 weeks post-immunization, and vaginal washes were collected daily until euthanized at day 5 post-challenge to determine viral titers and protection. Mononuclear cells isolated from vaginal tract, spleen, nasal associated lymphoid tissue (NALT), cervical lymph nodes (cLN) and iliac lymph nodes (iLN) tissues were analyzed by flow cytometry for plasma and memory B cell phenotypes. RESULTS: E2-treated WT OVX immunized mice after intravaginal HSV-2 challenge showed significantly increased HSV-2-specific IgG2b and IgG2c antibodies in serum and vaginal secretions compared to placebo mice and enhanced B220-CD138+ IgG2c+ plasma cells within the nasal mucosa and vaginal tract 6-weeks after immunization. Furthermore, E2 treatment enhanced the subsets of CD19+ IgD- memory B cells 4-weeks post immunization within the iLN and spleen. Notably, E2-induced increased B cell antibody responses conferred greater protection from HSV-2 challenge compared to placebo mice as evidenced by 2-3 logs decreased viral titers in the vaginal tract and 20% mice with genital pathology compared to 80% in placebo group, indicating better protection in E2-treated mice. Importantly, E2-mediated enhanced plasma and B cell antibody responses observed in WT mice were abrogated in IL-

BACKGROUND: Nasopharyngeal carriage of Streptococcus pneumoniae (Sp) in children is common and considered a prerequisite of invasive disease. Group 3 innate lymphoid cells (ILC3) are considered critical in mucosal homeostasis. It is not known if ILC3 play a role in Sp carriage and how ILC3 interact with Sp in the nasopharynx. METHODS: We characterized ILC3 in the nasopharynx-associated lymphoid tissue of children and adults and examined the relationship of ILC3 with Th17 cells and Sp carriage. We also analyzed the effects of Sp and Staphylococcus aureus on ILC3. RESULTS: We show that the frequencies of natural cytotoxicity receptor (NCR)+ ILC3 and IL-22-producing ILC3 in the adenotonsillar cells of children were markedly higher than in adults. By contrast, the frequency of Th17 was considerably lower in children than adults. Interestingly, the frequency of NCR+ILC3 in children who were Sp carriage+ve was higher than that of children who were Sp carriage-ve. Furthermore, stimulation of adenotonsillar cells with Sp culture supernatant induced a prominent ILC3 proliferative response and an increase in ILC3 number and level of HLA-DR expression, which correlated with a modest Th17 response. On the contrary, stimulation by S aureus culture supernatant reduced the ILC3 number and was accompanied by a strong Th17 response. CONCLUSIONS: The abundance of NCR+ILC3 in the nasopharynx of children is positively associated with Sp carriage. The positive relationship between ILC3 and Sp may suggest an important role of ILC3 in the nasopharyngeal carriage of Sp, and further investigation is warranted. Understanding local interactions between ILC3 and ILC3-promoting Sp or ILC3-repressing S aureus may lead to novel therapeutics against nasopharyngeal carriage and disease. © The Author(s) 2025. Published by Oxford University Press on behalf of Infectious Diseases Society of America.

Allergic rhinitis (AR) affects the quality of life of 400 million patients worldwide, and while the pharmacological treatment options are extensive, more effective and safer treatments continue to be developed. The immunomodulator Transferon Oral® (TO) improves the clinical presentation of patients with AR; however, the immunological mechanisms by which it exerts its therapeutic effect are under investigation. This study aimed to develop an ovalbumin (OVA)-induced AR murine model. AR was established in female BALB/c mice (5-8 weeks old) by intraperitoneal inoculation of 200 μL of OVA (1 mg/mL)/Al(OH)3 (1.3%) on days 0, 1, 2, 7, 8, 14 and 21, and subsequently stimulated daily intranasally (RIN) with 20 μL of OVA (1 mg/mL) until day 42. The establishment of RA was evidenced by the increase in serum IgE against OVA by ELISA (OD > 0.5) and clinical signs. Subsequently, the effect of TO (0.75 μg) orally and dexamethasone (Dexa; 125 μg) intraperitoneally was evaluated in RA mice (n=6) for 21 days with daily RIN. TO significantly decreased specific IgE levels (p < 0.0001) at 7 and 14 days of treatment, while Dexa did so until day 14 (p < 0.0001) compared to the RA control group. Additionally, an analysis showed that TO reduced basal lamina thickness and decreased eosinophil and mast cell infiltration in NALT compared with RA controls. This work demonstrates that TO modulates the core RA molecule, IgE, and cell migration in NALT, and is the first step toward understanding its mechanism of action in this disease. Publisher: La Rinitis Alérgica (RA) afecta la calidad de vida de 400 millones de pacientes en el mundo y aun cuando la oferta farmacológica para su tratamiento es amplia, se siguen desarrollando tratamientos más eficaces y seguros. El inmunomodulador Transferon Oral® (TO) mejora el cuadro clínico de pacientes con RA, no obstante, los mecanismos inmunológicos mediante los cuales ejerce su efecto terapéutico están en investigación. El objetivo de este estudio fue desarrollar un modelo murino de RA inducido por Ovoalbúmina (OVA). La RA se estableció en ratones hembra BALB/c (5-8 semanas de edad) mediante la inoculacion intraperitoneal de 200 μL de OVA (1 mg/mL)/Al

Influenza A viruses are categorized into two phylogenetic groups (group 1 and group 2) based on the structure of their hemagglutinin (HA) protein. Within group 2, H3N2 poses a particular challenge due to its rapid evolution, limited vaccine efficacy, and association with more severe influenza seasons. Although T cell responses have been extensively studied in the context of vaccine-induced protection, HA stem (HA2)-specific T cell responses have been relatively understudied, especially those related to nasal immunity. To address this, we engineered an adenoviral vector vaccine (Ad-HA2) expressing a consensus hemagglutinin stem sequence, derived through bioinformatic analysis of all H3 strains. The vaccine conferred heterosubtypic protection against lethal challenges with either H3N2 or H7N9, both belonging to group 2 influenza A viruses, with protection lasting at least six months post-vaccination. Notably, the vaccine induced robust HA2-specific humoral and cell-mediated responses in the nasal-associated lymphoid tissue (NALT) of the upper respiratory tract, the first line of immune defense against inhaled pathogens. The vaccine also elicited significant levels of antibodies and T cell responses in the lower respiratory tract and pulmonary immune sites. Furthermore, circulating antibodies in the serum demonstrated effective antibody-dependent cellular cytotoxicity (ADCC) activity. Finally, using a peptide pool matrix screening approach combined with in silico verification, we identified an immunogenic C-terminus region of the HA2 consensus sequence that activated CD4+ and CD8+ T cells, which warrants further investigation. Collectively, these findings are informative for the design and evaluation of mucosal influenza vaccines targeting the hemagglutinin stem. Crown Copyright © 2025. Published by Elsevier B.V. All rights reserved.

Lactoferrin is known to exhibit broad spectrum activity against a multitude of bacteria, fungi, and viruses due to its multi-functional mode of action. Recently, Lactea Therapeutics and its affiliates have developed a novel, patent-pending technology to purify naturally derived bovine lactoferrin (Lactea Lf) for use as a medical countermeasure that was not previously available. To assess the efficacy of Lactea Lf against biothreat pathogens, we performed biofilm inhibition assays and generated dose-response curves against Burkholderia pseudomallei, Burkholderia mallei, and Francisella tularensis for proof-of-principle studies. Here, we show that Lactea Lf can significantly inhibit biofilm and decrease the overall growth in a dose dependent manner for all Burkholderia species tested. Of note, Lactea Lf was found to completely inhibit biofilm formation by virulent B. pseudomallei without observing complete growth inhibition. The growth of F. tularensis was also significantly inhibited when cultured in the presence of Lactea Lf and appeared more sensitive to treatment when compared to B. pseudomallei. Based on these results, a pneumonic infection model using the F. tularensis LVS strain was performed prophylactically administering Lactea Lf and continuing treatment post challenge. No protection was observed in this model which prompted biodistribution studies using fluorescent tagged Lactea Lf. These experiments revealed that therapeutic material was mainly confined to the NALT region following intranasal delivery and then quickly dispersed or inactivated suggesting that future formulation and delivery method could be addressed to increase in vivo treatment efficacy. Taken together, these data support that Lactea Lf is a potentially new candidate for further studies as a broad-spectrum antimicrobial medical countermeasure with efficacy against several high priority biodefense-related bacterial pathogens.

Human alphaherpesvirus 1 (HSV-1) acute infection causes conjunctivitis, encephalitis, genital lesions, and herpes esophagitis. Following acute infection, HSV-1 and other alpha-herpesvirinae subfamily members establish life-long latency in neurons within the trigeminal ganglia and central nervous system. Notably, certain animal alpha-herpesvirinae subfamily members, including bovine alphaherpesvirus 1 (BoHV-1), canine herpesvirus 1, equine herpesvirus 4, and pseudorabies virus, establish a quiescent/latent infection in tonsils. BoHV-1 viral gene expression and virus shedding from tonsils also occur during reactivation from latency in calves. Consequently, we tested whether nasopharyngeal lymphoid tissue (NALT) harbors HSV-1 DNA in latently infected mice because it is structurally and functionally comparable with tonsils. NALT prepared from latently infected mice consistently contained viral DNA, but infectious virus was not detected. In contrast to latently infected TG neurons, the HSV-1 latency-associated transcript was not detected in NALT of latently infected mice. HSV-1 DNA levels, immediate early RNA expression, and virus shedding were readily detected when NALT explants were cultured with a medium containing the synthetic corticosteroid dexamethasone for 48 h. Increased viral DNA and virus production were not detected in NALT explants when incubated with a medium lacking dexamethasone. Sorting cells from NALT of HSV-1 latently infected mice revealed that dendritic cells, microfold cells, and natural killer cells, but not B or T cells, harbor HSV-1 DNA, and infectious virus was readily detected when cultured in medium containing dexamethasone. In summary, certain NALT cells consistently contain viral DNA in latently infected mice, and dexamethasone triggers viral gene expression and virus production. IMPORTANCE: Human alphaherpesvirus 1 (HSV-1) acute infection causes various diseases, including herpes esophagitis. HSV-1 subsequently establishes lifelong latency in neurons within the trigeminal ganglia and central nervous system. Viral DNA, but not infectious virus, was consistently detected in nasopharyngeal lymphoid tissue (NALT) of latently infected mice.

PURPOSE: Nasal associated lymphoid tissue (NALT) consisting of intraepithelial lymphocytes (IELs) and subepithelial lymphoid tissue has been scarcely studied. We aimed to compare the distribution of NALT in sinonasal polyps (cases) and normal nasal mucosa (controls). METHODS: We performed a preliminary, observational study of the distribution of subepithelial lymphoid follicles in 10 cases of sinonasal polyps and 10 normal controls. We also performed a count of CD4+, CD8 + and CD20 + IELs and CD34 + high endothelial venules (HEVs) using hemotoxylin and eosin staining and immunohistochemistry in both groups. RESULTS: The total area of both lymphatic follicle aggregates and organized lymphatic follicles in the lamina propria were significantly higher in cases than in controls (p < 0.001). CD4 + helper and CD8 + T cytotoxic IELs were identified in the epithelium of both controls and cases. The overall number of CD8 + IELs was significantly higher than the number of CD4 + IELs among both cases (p < 0.002) and controls (p < 0.002). CD4 + IEL count was significantly higher among cases than controls (p < 0.001), however. CD20 + IELs were absent in normal nasal mucosa but were seen in 3 cases of sinonasal polyp. The number of CD4 + follicular lymphocytes was also significantly higher in cases than controls (p = 0.005). Abundant HEVs were noted within the organized follicles and in the parafollicular region in both controls and cases. CONCLUSION: NALT, specifically lamina propria lymphatic follicles, and CD4+, CD8 + and CD20 + IELs, play an important role in mounting an inflammatory response in sinonasal polyposis. © 2026. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

INTRODUCTION: Well-organized nasal-associated lymphoid tissue (NALT) has been identified in the pharyngeal and tubal tonsils of both adults and children, and diffuse NALT has been identified in the superior, middle and inferior turbinate regions of children. However, it is not clear how to target these NALT sites with aerosolized vaccines. We explored whether head position and/or angle and distance of device insertion could be used to target fluorescein aerosol to NALT sites in three-dimensional printed models of the intranasal airways of an 18- and a 5-year-old (yo). METHODS: Three head positions (upright [Up], tilted back 45° [45] and supine [Su]), two angles of insertion (30° and 45°) and two distances of insertion (6 mm and 9 mm) were tested. Fluorescein aerosol was generated by an Aptar Pharma BiVax 200 µL intranasal atomizer. Percent fluorescein deposition was quantified in the anterior nose, the upper horizontal third of the model (superior turbinate region), middle third (middle turbinate), lower third (inferior turbinate and nasopharynx combined) and exit filter. RESULTS: Mean percent deposition in both models was <0.5% in the upper third and on the exit filter for all test conditions. A multivariate analysis showed that deposition in either model was unaffected by the angles of insertion and distances of insertion. However, middle third deposition was significantly higher in the 5-yo than in the 18-yo (p = 0.01) and anterior nose deposition was higher in the 18-yo than in the 5-yo (p < 0.01). When data from both models were combined, middle third deposition was highest in the supine position with Up < 45 < Su (p < 0.01) and lower third deposition was highest in the upright position with Up > 45 > Su (p = 0.03). DISCUSSION: These results suggest that, in individuals with similar nasal airway dimensions as our models: 1) supine and upright head positions might be used to target delivery of aerosolized vaccines generated by the BiVax intranasal atomizer to NALT sites in the middle turbinate and the inferior turbinate and nasopharynx combined, respectively; 2) delivery to the middle turbinate may be higher in children ≤5-yo; and 3) deposition in the anteri

Background/Objectives: The ongoing evolution of SARS-CoV-2 has highlighted the limitations of parenteral vaccines in preventing viral transmission, largely due to their failure to elicit robust mucosal immunity. Methods: Here, we evaluated an intranasal (IN) vaccine formulation consisting of recombinant receptor-binding domain (RBD) adsorbed onto human probiotic Bacillus subtilis DG101 spores. Results: In BALB/c mice, IN spore-RBD immunization induced strong systemic and mucosal humoral responses, including elevated specific IgG, IgM, and IgA levels in serum, bronchoalveolar lavage fluid (BALF), nasal-associated lymphoid tissue (NALT), and saliva. It further promoted mucosal B cell and T cell memory, along with a Th1/Tc1-skewed T cell response, characterized by increased IFN-γ-expressing CD4+ and CD8+ T cells in the lungs. Conclusions: All in all, these findings highlight the potential of intranasal vaccines adjuvanted with probiotic B. subtilis spores in inducing sterilizing immunity and limiting SARS-CoV-2 transmission.

INTRODUCTION: Middle East respiratory syndrome coronavirus (MERS-CoV) has emerged as a deadly pathogen with a mortality rate of up to 36.2%. MERS-CoV can cause severe respiratory tract disease and multiorgan failure. Therefore, therapeutic vaccines are urgently needed. This intensive review explores the human immune responses and their immunological mechanisms during MERS-CoV infection in the mucosa of the upper and lower respiratory tracts (URT and LRT, respectively). OBJECTIVE: The aim of this study is to provide a valuable, informative, and critical summary of the protective immune mechanisms against MERS-CoV infection in the URT/LRT for the purpose of preventing and controlling MERS-CoV disease and designing effective therapeutic vaccines. METHODS: In this review, we focus on the immune potential of the respiratory tract following MERS-CoV infection. We searched PubMed, Embase, Web of Science, Cochrane, Scopus, and Google Scholar using the following terms: "MERS-CoV", "B cells", "T cells", "cytokines", "chemokines", "cytotoxic", and "upper and lower respiratory tracts". RESULTS: We found and included 152 studies in this review. We report that the cellular innate immune response, including macrophages, dendritic cells, and natural killer cells, produces antiviral substances such as interferons and interleukins to prevent the virus from spreading. In the adaptive and humoral immune responses, CD4+ helper T cells, CD8+ cytotoxic T cells, B cells, and plasma cells protect against MERS-CoV infection in URT and LRT. CONCLUSION: The human nasopharynx-associated lymphoid tissue (NALT) and bronchus-associated lymphoid tissue (BALT) could successfully limit the spread of several respiratory pathogens. However, in the case of MERS-CoV infection, limited research has been conducted in humans with regard to immunopathogenesis and mucosal immune responses due to the lack of relevant tissues. A better understanding of the immune mechanisms of the URT and LRT is vital for the design and development of effective MERS-CoV vaccines. Study protocol for a randomised, phase II, double-blind, experimental medicine study of obinutuzumab versus rituximab in ANCA-associated vasculit

15. BMJ Open. 2024 Jul 17;14(7):e083277. doi: 10.1136/bmjopen-2023-083277. Study protocol for a randomised, phase II, double-blind, experimental medicine study of obinutuzumab versus rituximab in ANCA-associated vasculitis: ObiVas. McGovern DP(1)(2), McClure ME(3)(2), Coates M(3)(2), Bond S(4), M

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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. © 2024 The Authors. Animal Models and Experimental Medicine published by John Wiley & Sons Australia, Ltd on behalf of The Chinese Association for Laboratory Animal Sciences.

INTRODUCTION: Adenoid hypertrophy (AH) is a common upper respiratory disorder in children. Disturbances of gut microbiota have been implicated in AH. However, the interplay of alteration of gut microbiome and enlarged adenoids remains elusive. METHODS: 119 AH children and 100 healthy controls were recruited, and microbiome profiling of fecal samples in participants was performed using 16S rRNA gene sequencing. Fecal microbiome transplantation (FMT) was conducted to verify the effects of gut microbiota on immune response in mice. RESULTS: In AH individuals, only a slight decrease of diversity in bacterial community was found, while significant changes of microbial composition were observed between these two groups. Compared with HCs, decreased abundances of Akkermansia, Oscillospiraceae and Eubacterium coprostanoligenes genera and increased abundances of Bacteroides, Faecalibacterium, Ruminococcus gnavus genera were revealed in AH patients. The abundance of Bacteroides remained stable with age in AH children. Notably, a microbial marker panel of 8 OTUs were identified, which discriminated AH from HC individuals with an area under the curve (AUC) of 0.9851 in the discovery set, and verified in the geographically different validation set, achieving an AUC of 0.9782. Furthermore, transfer of mice with fecal microbiota from AH patients dramatically reduced the proportion of Treg subsets within peripheral blood and nasal-associated lymphoid tissue (NALT) and promoted the expansion of Th2 cells in NALT. CONCLUSION: These findings highlight the effect of the altered gut microbiota in the AH pathogenesis.