Objective The prevalence of drug-resistant Mycobacterium tuberculosis (Mtb) strains is exacerbating the global burden of tuberculosis (TB), highlighting the urgent need for new treatment strategies for TB. Methods The recombinant adenovirus vaccine expressing cyclic di-adenosine monophosphate (c-di-AMP) phosphodiesterase B (CnpB) (rAd-CnpB), was administered to normal mice via mucosal immunization, either alone or in combination with drug therapy, to treat Mtb respiratory infections in mice.Enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of antibodies in serum and bronchoalveolar lavage fluid (BALF). Real-time quantitative PCR was performed to assess the transcription levels of cytokines interferon γ(IFN-γ) and interleukin 10(IL-10) in mouse lungs. Flow cytometry was used to determine the proportions of CD4⁺ and CD8⁺ T cell subsets in the lungs and spleens. ELISA was employed to measure the levels of cytokines IFN-γ, IL-2, IL-10, inflammatory factors IL-6, and tumor necrosis factor α (TNF-α) secreted by spleen cells following antigen stimulation. The bacteria loads in the lungs and spleens of Mtb-infected mice were enumerated by plate counting methods. Resluts Intranasal immunization with rAd-CnpB induced high titers of IgG in mouse serum and the production of IgG and IgA in BALF, along with alterations in T lymphocyte subsets in the lungs and spleens. Administration of rAd-CnpB, either alone or in combination with drugs, to Mtb-infected mice significantly increased serum IgG levels as well as IgA and IgG levels in BALF. rAd-CnpB immunization promoted the secretion of CnpB-specific cytokines and inflammatory factors by splenocytes in Mtb-infected mice. However, rAd-CnpB immunotherapy, either alone or combined with drugs, did not significantly affect the bacterial loads in the lungs and spleens of mice with Mtb respiratory infections. Conclusion Mucosal immunization with rAd-CnpB induced significant mucosal, humoral and cellular immune responses in mice, and significantly enhanced CnpB-specific cellular immune responses in Mtb-infected mice.
Animals ; Adenoviridae/immunology* ; Mycobacterium tuberculosis/genetics* ; Mice ; Female ; Phosphoric Diester Hydrolases/genetics* ; Tuberculosis Vaccines/administration & dosage* ; Tuberculosis/prevention & control* ; Mice, Inbred BALB C ; Cytokines ; Lung/microbiology* ; Immunization ; Bronchoalveolar Lavage Fluid/immunology* ; Immunity, Mucosal

The mucosae represent the first line of defense against the invasion of most pathogens, and the mucosal immune system plays a crucial role in the control of infection. Mucosal vaccination can trigger both humoral and cell-mediated immune responses mucosally as well as systemically. Hence, protective immune responses can be elicited effectively by mucosal vaccination. Microfold (M) cells being unique to the mucosal immune system can take up luminal antigens and initiating antigen-specific immune responses. The number of antigen uptake by M cells is directly related to the immune efficacy of mucosal vaccines. Utilizing M cell ligands, M cells-targeting antigen delivery can achieve highly effective mucosal immune responses. The strategy of targeted delivery of antigens to M cells and its applications can be used for the improvement of mucosal immune responses and the development of mucosal vaccines. Despite these efforts, successful development of safe and effective mucosal vaccines remains a big challenge and needs a long way to go, and provably still resort to further researches on cellular properties and functions as well as mucosal immune mechanisms.
Immunity, Mucosal ; Ligands ; Mucous Membrane ; Vaccination ; Vaccines ; immunology

Opportunistic bacteria in apical periodontitis (AP) may pose a risk for systemic dissemination. Mucosal-associated invariant T (MAIT) cells are innate-like T cells with a broad and potent antimicrobial activity important for gut mucosal integrity. It was recently shown that MAIT cells are present in the oral mucosal tissue, but the involvement of MAIT cells in AP is unknown. Here, comparison of surgically resected AP and gingival tissues demonstrated that AP tissues express significantly higher levels of Vα7.2-Jα33, Vα7.2-Jα20, Vα7.2-Jα12, Cα and tumour necrosis factor (TNF), interferon (IFN)-γ and interleukin (IL)-17A transcripts, resembling a MAIT cell signature. Moreover, in AP tissues the MR1-restricted MAIT cells positive for MR1-5-OP-RU tetramer staining appeared to be of similar levels as in peripheral blood but consisted mainly of CD4 subset. Unlike gingival tissues, the AP microbiome was quantitatively impacted by factors like fistula and high patient age and had a prominent riboflavin-expressing bacterial feature. When merged in an integrated view, the examined immune and microbiome data in the sparse partial least squares discriminant analysis could identify bacterial relative abundances that negatively correlated with Vα7.2-Jα33, Cα, and IL-17A transcript expressions in AP, implying that MAIT cells could play a role in the local defence at the oral tissue barrier. In conclusion, we describe the presence of MAIT cells at the oral site where translocation of oral microbiota could take place. These findings have implications for understanding the immune sensing of polymicrobial-related oral diseases.
Adult ; Aged ; Female ; Humans ; Immunity, Mucosal ; immunology ; Male ; Microbiota ; Middle Aged ; Mucosal-Associated Invariant T Cells ; Natural Killer T-Cells ; immunology ; Periapical Periodontitis ; microbiology ; surgery

The gut microbiota is mainly composed of a diverse population of commensal bacterial species and plays a pivotal role in the maintenance of intestinal homeostasis, immune modulation and metabolism. The influence of the gut microbiota on solid organ transplantation has recently been recognized. In fact, several studies indicated that acute and chronic allograft rejection in small bowel transplantation (SBT) is closely associated with the alterations in microbial patterns in the gut. In this review, we focused on the recent findings regarding alterations in the microbiota following SBTand the potential roles of these alterations in the development of acute and chronic allograft rejection. We also reviewed important advances with respect to the interplays between the microbiota and host immune systems in SBT. Furthermore, we explored the potential of the gut microbiota as a microbial marker and/or therapeutic target for the predication and intervention of allograft rejection and chronic dysfunction. Given that current research on the gut microbiota has become increasingly sophisticated and comprehensive, large cohort studies employing metagenomic analysis and multivariate linkage should be designed for the characterization of host-microbe interaction and causality between microbiota alterations and clinical outcomes in SBT. The findings are expected to provide valuable insights into the role of gut microbiota in the development of allograft rejection and other transplant-related complications and introduce novel therapeutic targets and treatment approaches in clinical practice.
Biomarkers ; Gastrointestinal Microbiome ; Graft Rejection ; immunology ; Humans ; Immunity, Mucosal ; Intestine, Small ; microbiology ; transplantation ; Metagenomics ; Transplantation Tolerance ; immunology

OBJECTIVETo observe the effects of astragalus polysaccharide (AP) on the intestinal mucosal morphology, level of secretory IgA (s-IgA) in intestinal mucus, and distribution of T lymphocyte subsets in Peyer's patch in rats with severe scald injury.

METHODSOne hundred and thirty SD rats were divided into sham injury group (SI, sham injured, n = 10), scald group (S, n = 30), low dosage group (LD, n = 30), moderate dosage group (MD, n = 30), and high dosage group (HD, n = 30) according to the random number table. Rats in the latter 4 groups were inflicted with 30% TBSA full-thickness scald on the back. From post injury hour 2, rats in groups LD, MD, and HD were intraperitoneally injected with 0.5 mL AP solution with the dosage of 100, 200, and 300 mg/kg each day respectively, and rats in group S were injected with 0.5 mL normal saline instead. Ten rats from group SI immediately after injury and 10 rats from each of the latter 4 groups on post injury day (PID) 3, 7, 14 were sacrificed, and their intestines were harvested. The morphology of ileal mucosa was examined after HE staining; the level of s-IgA in ileal mucus was determined with double-antibody sandwich ELISA method; the proportions of CD3⁺, CD4⁺, CD8⁺ T lymphocytes in Peyer's patches of intestine were determined with flow cytometer, and the proportion of CD4⁺ to CD8⁺ was calculated. Data were processed with one-way analysis of variance, analysis of variance of factorial design, and SNK test.

RESULTS(1) Villi in normal form and intact villus epithelial cells were observed in rats of group SI immediately after injury, while edema of villi and necrosis and desquamation of an enormous amount of villi were observed in groups with scalded rats on PID 3, with significant infiltration of inflammatory cells. On PID 7, no obvious improvement in intestinal mucosal lesion was observed in groups with scalded rats. On PID 14, the pathology in intestinal mucosa of rats remained nearly the same in group S, and it was alleviated obviously in groups LD and MD, and the morphology of intestinal mucosa of rats in group HD was recovered to that of group SI. (2) On PID 3, 7, and 14, the level of s-IgA in intestinal mucus significantly decreased in groups S, LD, MD, and HD [(43 ± 5), (45 ± 5), (46 ± 5) µg/mL; (47 ± 5), (48 ± 5), (49 ± 6) µg/mL; (50 ± 6), (51 ± 5), (52 ± 5) µg/mL; (53 ± 6), (54 ± 5), (55 ± 5) µg/mL] as compared with that of rats in group SI immediately after injury [(69 ± 4) µg/mL, with P values below 0.05]. The level of s-IgA in intestinal mucus of rats in group MD was significantly higher than that in group S at each time point (with P values below 0.05), and that of group HD was significantly higher than that in groups S and LD at each time point (with P values below 0.05). (3) Compared with those of rats in group SI immediately after injury, the proportions of CD3⁺ T lymphocytes and CD4⁺ T lymphocytes significantly decreased in groups with scalded rats at each time point (with P values below 0.05), except for those in group HD on PID 14. The proportion of CD4⁺ T lymphocytes of rats in group LD was significantly higher than that in group S on PID 3 (P < 0.05). The proportions of CD3⁺ T lymphocytes and CD4⁺ T lymphocytes were significantly higher in groups MD and HD than in groups S and LD (except for the proportion of CD4⁺ T lymphocytes in group MD on PID 3 and 14) at each time point (with P values below 0.05). The proportion of CD3⁺ T lymphocytes on PID 7 and 14 and that of CD4⁺ T lymphocytes on PID 3 were significantly higher in group HD than in group MD (with P values below 0.05). Compared with that of rats in group SI immediately after injury, the proportion of CD8⁺ T lymphocytes significantly increased in the other 4 groups at each time point (with P values below 0.05). The proportion of CD8⁺ T lymphocytes was significantly lower in rats of group LD on PID 7 and 14 and groups MD and HD at each time point than in group S (with P values below 0.05). The proportion of CD8⁺ T lymphocytes was significantly lower in rats of group MD on PID 7 and 14 and group HD at each time point than in group LD (with P values below 0.05). The proportion of CD8⁺ T lymphocytes was significantly lower in rats of group HD on PID 7 and 14 than in group MD (with P values below 0.05). On PID 3, 7, and 14, the proportion of CD4⁺ to CD8⁺ was significantly lower in groups S, LD, MD, and HD (0.65 ± 0.11, 0.68 ± 0.13, 0.73 ± 0.22; 0.76 ± 0.15, 0.78 ± 0.14, 0.90 ± 0.10; 0.85 ± 0.21, 0.89 ± 0.18, 1.08 ± 0.19; 0.99 ± 0.20, 1.05 ± 0.21, 1.25 ± 0.23) as compared with that of rats in group SI immediately after injury (1.74 ± 0.20, with P values below 0.05). The proportion of CD4⁺ to CD8⁺ was significantly higher in rats of group HD than in group MD on PID 7 (P < 0.05), and the proportion was significantly higher in these two groups than in group S at each time point (with P values below 0.05). The proportion of CD4⁺ to CD8⁺ was significantly higher in rats of group MD on PID 14 and group HD at each time point than in group LD (with P values below 0.05). Compared within each group, the proportions of CD3⁺, CD4⁺, CD8⁺ T lymphocytes and the proportion of CD4⁺ to CD8⁺ of rats in groups LD, MD, and HD showed a trend of gradual elevation along with passage of time.

CONCLUSIONSAP can improve the injury to intestinal mucosa and modulate the balance of T lymphocyte subsets in Peyer's patch in a time- and dose-dependent manner, and it can promote s-IgA secretion of intestinal mucosa in a dose-dependent manner.

Animals ; Astragalus Plant ; adverse effects ; Burns ; immunology ; pathology ; physiopathology ; Dose-Response Relationship, Drug ; Immunity, Mucosal ; Immunoglobulin A ; metabolism ; Intestinal Mucosa ; metabolism ; physiology ; Intestine, Small ; metabolism ; Peyer's Patches ; immunology ; physiopathology ; Polysaccharides ; Rats ; Rats, Sprague-Dawley ; Soft Tissue Injuries ; T-Lymphocyte Subsets ; immunology

Vaccination is an effective strategy to prevent infectious or immune related diseases, which has made remarkable contribution in human history. Recently increasing attentions have been paid to mucosal vaccination due to its multiple advantages over conventional ways. Subunit or peptide antigens are more reasonable immunogens for mucosal vaccination than live or attenuated pathogens, however adjuvants are required to augment the immune responses. Many mucosal adjuvants have been developed to prime desirable immune responses to different etiologies. Compared with pathogen derived adjuvants, innate endogenous molecules incorporated into mucosal vaccines demonstrate prominent adjuvanticity and safety. Nowadays, cytokines are broadly used as mucosal adjuvants for participation of signal transduction of immune responses, activation of innate immunity and polarization of adaptive immunity. Desired immune responses are promptly and efficaciously primed on basis of specific interactions between cytokines and corresponding receptors. In addition, some other innate molecules are also identified as potent mucosal adjuvants. This review focuses on innate endogenous mucosal adjuvants, hoping to shed light on the development of mucosal vaccines.
Adjuvants, Immunologic ; Animals ; Humans ; Immunity, Innate ; immunology ; Immunity, Mucosal ; immunology ; Vaccines ; administration & dosage ; immunology

The patients in gastrointestinal surgery are always accompanied with malnutrition. Parenteral nutrition is the main support method for patients with intestinal dysfunction. The normal intestinal mucosal immune system can protect against bacteria in the gut. Parenteral nutrition without enteral stimulation injures of the intestinal mucosal immunity and increases the risk of infection. It is very important to protect intestinal mucosal barrier by nutrition support therapy.
Digestive System Surgical Procedures ; Humans ; Immunity, Mucosal ; Intestinal Mucosa ; immunology ; surgery ; Nutritional Support ; Wound Healing

The mucosal immune system defends against a vast array of pathogens, yet it exhibits limited responses to commensal microorganisms under healthy conditions. The oral-pharyngeal cavity, the gateway for both the gastrointestinal and respiratory tracts, is composed of complex anatomical structures and is constantly challenged by antigens from air and food. The mucosal immune system of the oral-pharyngeal cavity must prevent pathogen entry while maintaining immune homeostasis, which is achieved via a range of mechanisms that are similar or different to those utilized by the gastrointestinal immune system. In this review, we summarize the features of the mucosal immune system, focusing on T cell subsets and their functions. We also discuss our current understanding of the oral-pharyngeal mucosal immune system.
Epithelium ; immunology ; Humans ; Immunity, Cellular ; Immunity, Mucosal ; immunology ; Mouth Diseases ; immunology ; Mouth Mucosa ; immunology ; Pharynx ; immunology ; T-Lymphocyte Subsets ; classification ; immunology

Dendritic cells (DCs) are key modulators that shape the immune system. In mucosal tissues, DCs act as surveillance systems to sense infection and also function as professional antigen-presenting cells that stimulate the differentiation of naive T and B cells. On the basis of their molecular expression, DCs can be divided into several subsets with unique functions. In this review, we focus on intestinal DC subsets and their function in bridging the innate signaling and adaptive immune systems to maintain the homeostasis of the intestinal immune environment. We also review the current strategies for manipulating mucosal DCs for the development of efficient mucosal vaccines to protect against infectious diseases.
Animals ; Dendritic Cells/*immunology/metabolism ; Humans ; Immunity, Mucosal ; Intestinal Mucosa/cytology/*immunology ; T-Lymphocytes, Helper-Inducer/immunology

Vaccination is one of the most successful applications of immunology and for a long time has depended on parenteral administration protocols. However, recent studies have pointed to the promise of mucosal vaccination because of its ease, economy and efficiency in inducing an immune response not only systemically, but also in the mucosal compartment where many pathogenic infections are initiated. However, successful mucosal vaccination requires the help of an adjuvant for the efficient delivery of vaccine material into the mucosa and the breaking of the tolerogenic environment, especially in oral mucosal immunization. Given that M cells are the main gateway to take up luminal antigens and initiate antigen-specific immune responses, understanding the role and characteristics of M cells is crucial for the development of successful mucosal vaccines. Especially, particular interest has been focused on the regulation of the tolerogenic mucosal microenvironment and the introduction of the luminal antigen into the lymphoid organ by exploiting the molecules of M cells. Here, we review the characteristics of M cells and the immune regulatory factors in mucosa that can be exploited for mucosal vaccine delivery and mucosal immune regulation.
Administration, Oral ; Animals ; Antigens, Bacterial/*immunology ; Antigens, Viral/*immunology ; Bacterial Vaccines/administration & dosage/*immunology ; Humans ; Immunity, Mucosal ; Intestinal Mucosa/cytology/*immunology ; Peyer's Patches/cytology/*immunology ; Viral Vaccines/administration & dosage/*immunology