Mucosal immune responses to infection and vaccination in the respiratory tract

Exploring the standardization of human nasal antibody measurements

Mucosal immunity is crucial for preventing the infection and transmission of respiratory viruses. Nasal antibody is inversely correlated with a lower risk of infection with respiratory viruses. However, the current reference standard for nasal antibody assessment is serum-based, mainly consisting of monomeric IgG and IgA. The applicability of serum-derived standards for assessing nasal antibodies, consisting mostly of dimeric or polymeric secretory IgA (sIgA), remains unvalidated. Herein, we first proved that the sera-derived standard was not applicable for assessing nasal antibodies. Using a non-homologous standard as a calibrator introduced systematic error up to 10 times, which did not benefit the understanding of mucosal antibody response. Therefore, we attempted to develop two candidate standards (CS1, CS2) using nasal mucosal lining fluids (NMLFs) collected from SARS-CoV-2 Omicron convalescents or intranasal vaccine recipients, and CS3 using a sIgA monoclonal antibody. CS2 exhibited broad-spectrum binding activity against 12 SARS-CoV-2 strains, including all tested Omicron subvariants. A collaborative study conducted by seven laboratories demonstrated that CS2 improved the harmonization of inter-laboratory variability (pre-standardization geometric coefficients of variance, 14-314%; post-standardization, 3-35%). Using CS2 ensured an accurate assessment of nasal antibodies. Thus, CS2 was established as a national standard for evaluating nasal SARS-CoV-2-specific antibodies (Lot: 300052-202401, 1000 U/mL). Our work provides a benchmark for evaluating mucosal vaccines for SARS-CoV-2 and inspires new avenues for developing new reference standards for other mucosal vaccines.

Activation and maturation of antigen-specific B cells in nonectopic lung infiltrates are independent of germinal center reactions in the draining lymph node

Pulmonary T and B cells are important for protection of this mucosal barrier site. While viral infections lead to the development of ectopic lymphoid structures highly similar to those in germinal centers in secondary lymphoid organs, little is known about how T/B cooperation occurs in the unstructured, diffuse tissue infiltrates characteristic of autoimmune diseases and nonviral infections. Using a mouse model of interstitial lung inflammation, we found that naive B cells are directly activated in lung tissue. Despite the absence of any germinal center-like structures, the interaction of B cells with peripheral T helper cells results in efficient somatic hypermutation and class switching. As antigen-presenting cells, macrophages are critical for this process. Unique B-cell repertoires indicated that the lung response was autonomous from the lung-draining lymph node. Only lung GC-like B cells were switched to IgA and had a broader repertoire, making them ideal candidates for producing broadly neutralizing immunoglobulins against respiratory pathogens.

Lipid nanoparticles encapsulating both adjuvant and antigen mRNA improve influenza immune cross-protection in mice

The rapid approval of SARS-CoV-2 mRNA lipid nanoparticle (LNP) vaccines indicates the versatility of mRNA LNPs in an urgent vaccine need. However, the mRNA vaccines do not induce mucosal cellular responses or broad protection against recent variants. To improve cross-protection of mRNA vaccines, here we engineered a pioneered mRNA LNP encapsulating with mRNA constructs encoding cytokine adjuvant and influenza A hemagglutinin (HA) antigen for intradermal vaccination. The adjuvant mRNA encodes a novel fusion cytokine GIFT4 comprising GM-CSF and IL-4. We found that the adjuvanted mRNA LNP vaccine induced high levels of humoral antibodies and systemic T cell responses against heterologous influenza antigens and protected immunized mice against influenza A viral infections. Also, the adjuvanted mRNA LNP vaccine elicited early germinal center reactions in draining lymph nodes and promoted antibody-secreting B cell responses. In addition, we generated another adjuvant mRNA encoding CCL27, which enhanced systemic immune responses. We found the two adjuvant mRNAs both showed effective adjuvanticity in enhancing humoral and cellular responses in mice. Interestingly, intradermal immunizations of GIFT4 or CCL27 mRNA adjuvanted mRNA LNP vaccines induced significant lung tissue-resident T cells. Our findings demonstrate that the cytokine mRNA can be a promising adjuvant flexibly formulated into mRNA LNP vaccines to provoke strong immunity against viral variants.

Overview of the Q fever vaccine development: current status and future prospects

Coxiella burnetii, the causative agent of Q fever, is responsible for a globally significant zoonotic disease, characterized by flu-like symptoms. The primary reservoirs of C. burnetii are ruminant livestock, particularly goats, sheep, and cattle, which shed the bacterium through birth products, such as the placenta, amniotic fluid, and other secretions. Human infections typically occur via the inhalation of contaminated aerosols during direct or indirect contact with infected animals or their birthing materials. Consequently, individuals living in or working near livestock environments are at elevated risk, making Q fever both a location- and occupation-related disease. Owing to its remarkable environmental resilience and extremely low infectious dose, C. burnetii is classified as a Category B bioterrorism agent by the U.S. Centers for Disease Control and Prevention (CDC). These characteristics significantly complicate efforts to eradicate the bacterium and position vaccination as a key strategy for preventing human transmission. Although whole-cell vaccines (WCVs) are currently licensed for use in Australia, their widespread implementation has been hindered by their strong reactogenic responses in individuals with prior exposure to C. burnetii. This review provides an overview of past and current efforts to develop non-reactogenic C. burnetii vaccines and discusses possible approaches to enhance the efficiency and safety of these vaccines.

Recurrent respiratory papillomatosis: Immunological mechanisms involved in recurrence

Recurrent respiratory papillomatosis is a benign neoplastic pathology in children, young people, and adults. It causes a significant deterioration in the quality of life, with symptoms typically referred to as dysphonia and hoarseness. This disease, with variable clinical courses ranging from spontaneous resolution to dissemination of the lower airway or airway obstruction that puts the individual's life at risk, characteristically requires multiple surgical interventions. Therapy with adjuvant drugs does not yet prove the effectiveness necessary to limit the recurrence and need for surgical reoperation in this condition. The review aimed to synthesize the immunopathogenic mechanisms of relapse in recurrent respiratory papillomatosis published in the current literature and the immunological implication of risk factors and treatment.

ZBP1-driven cell death in severe influenza

Influenza A virus (IAV) infections can cause life-threatening illness in humans. The severity of disease is directly linked to virus replication in the alveoli of the lower respiratory tract. In particular, the lytic death of infected alveolar epithelial cells (AECs) is a major driver of influenza severity. Recent studies have begun to define the molecular mechanisms by which IAV triggers lytic cell death. Z-form nucleic-acid-binding protein 1 (ZBP1) senses replicating IAV and drives programmed cell death (PCD) in infected cells, including apoptosis and necroptosis in AECs and pyroptosis in myeloid cells. Necroptosis and pyroptosis, both lytic forms of death, contribute to pathogenesis during severe infections. Pharmacological blockade of necroptosis shows strong therapeutic potential in mouse models of lethal influenza. We suggest that targeting ZBP1-initiated necroinflammatory cell lysis, either alone or in combination antiviral drugs, will provide clinical benefit in severe influenza.

The intricate interplay among microbiota, mucosal immunity, and viral infection in the respiratory tract

The mucosal system serves as the primary barrier against respiratory diseases and plays a crucial role in combating viral infections through mucosal immunity. The resident microbial community constitutes the main component of the mucosal system and exerts a significant inhibitory impact on the invasion of exogenous agents. However, the precise relationship between resident microbiota, mucosal immunity, and viral infections remains incomplete. This review aims to summarize the regulatory interactions between the resident microbiota of the mucosal system and innate immune components such as mucosal immunity and trained immunity. By clarifying these complex relationships, this review seeks to identify potential targets for augmenting respiratory disease prevention strategies and developing novel vaccine formulations. Furthermore, we propose the possibility of integrating the fields of microbiome-based therapeutics and vaccine development to create multifunctional vaccine formulations capable of targeting mucosal immunity induction. Such an approach holds great potential in offering novel pathways and strategies for the prevention and treatment of respiratory diseases.

Enteroviruses Activate Cellular Innate Immune Responses Prior to Adaptive Immunity and Tropism Contributes to Severe Viral Pathogenesis

Numerous innate immune mechanisms have been shown to be activated during viral infections, including pattern recognition receptors (PRRs) functioning outside and inside the cell along with other sensors promoting the production of interferon and other cytokines. Innate cells, including NK cells, NKT cells, γδ T cells, dendritic cells, macrophages, and even neutrophils, have been shown to respond to viral infections. Several innate humoral responses to viral infections have also been identified. Adaptive immunity includes common cell-mediated immunity (CMI) and humoral responses. Th1, Th2, and Tfh CD4+ T cell responses have been shown to help activate cytotoxic T lymphocytes (CTLs) and to help promote the class switching of antiviral antibodies. Enteroviruses were shown to induce innate immune responses and the tropism of the virus that was mediated through viral attachment proteins (VAPs) and cellular receptors was directly related to the risk of severe disease in a primary infection. Adaptive immune responses include cellular and humoral immunity, and its delay in primary infections underscores the importance of vaccination in ameliorating or preventing severe viral pathogenesis.

Intranasal replicon SARS-CoV-2 vaccine produces protective respiratory and systemic immunity and prevents viral transmission

While mRNA vaccines have been effective in combating SARS-CoV-2, the waning of vaccine-induced antibody responses and lack of vaccine-induced respiratory tract immunity contribute to ongoing infection and transmission. In this work, we compare and contrast intranasal (i.n.) and intramuscular (i.m.) administration of a SARS-CoV-2 replicon vaccine delivered by a nanostructured lipid carrier (NLC). Both i.m. and i.n. vaccines induce potent systemic serum neutralizing antibodies, bone marrow-resident immunoglobulin G-secreting cells, and splenic T cell responses. The i.n. vaccine additionally induces robust respiratory mucosal immune responses, including SARS-CoV-2-reactive lung-resident memory T cell populations. As a booster following previous i.m. vaccination, the i.n. vaccine also elicits the development of mucosal virus-specific T cells. Both the i.m.- and i.n.-administered vaccines durably protect hamsters from infection-associated morbidity upon viral challenge, significantly reducing viral loads and preventing challenged hamsters from transmitting virus to naive cagemates. This replicon-NLC vaccine's potent systemic immunogenicity, and additional mucosal immunogenicity when delivered i.n., may be key for combating SARS-CoV-2 and other respiratory pathogens.

Immunocyte phenotypes and childhood disease susceptibility: insights from bidirectional Mendelian randomization and implications for immunomodulatory therapies

Immune cells are essential for maintaining immune homeostasis during childhood and influence both growth and disease susceptibility. However, the causal relationships between immunocyte phenotypes and childhood diseases remain unclear. This study employed a two-sample Mendelian Randomization (MR) analysis to assess causal associations between 731 immunocyte phenotypes and four major childhood diseases: childhood obesity, childhood absence epilepsy, childhood asthma, and childhood allergies. Genome-wide association study (GWAS) data were used, and stringent instrumental variable (IV) selection and multiple sensitivity analyses, including MR-Egger, weighted median, and leave-one-out tests, were applied to validate the robustness of the results. Significant associations were identified between specific T cell, monocyte, and B cell phenotypes and childhood diseases. Notably, CD8bright T cells and CD19 + B cells were positively correlated with childhood obesity, while monocyte subtypes were strongly associated with asthma pathophysiology. Reverse MR analysis indicated no significant causal effects of childhood diseases on immune phenotypes, except for negative associations between childhood asthma and TCRgd AC, and childhood allergy and CD28 + CD45RA + CD4 + cells. These findings highlight the critical role of immune dysregulation in childhood disease etiology and suggest potential targets for immunomodulatory therapies. Understanding these immune-disease interactions may inform novel pharmacological interventions, particularly in immune-mediated disorders such as asthma and obesity. Further research into immune-targeted therapies could enhance treatment strategies for pediatric conditions associated with chronic inflammation and immune dysfunction.

The Integrated Pulmonary Immune Response to Pneumonia

Pneumonia is an acute respiratory infection of the lower respiratory tract. The effectiveness of the host immune response determines the severity of infection, or whether pneumonia occurs at all. The lungs house both innate and adaptive immune systems, which integrate their activities to provide host defense that eliminates microbes and prevents lower respiratory infection from becoming severe. Professional immune cells in the lung, like macrophages and lymphocytes, work with lung constituents, like epithelial cells and fibroblasts, to optimize antimicrobial defense. The dynamics of the immune response during infection and the immune components contributing to defense are influenced by prior experiences with respiratory pathogens, remodeling lung immunity in ways that improve responses against subsequent infections. This review covers how innate and adaptive immune activities coordinate inside the lung to provide integrated and effective immune resistance against respiratory pathogens.

Transmucosal drug delivery: prospects, challenges, advances, and future directions

INTRODUCTION

Traditional administration routes have limitations including first-pass metabolism and gastrointestinal degradation for sensitive drugs (oral) and pain associated with parenteral injections, which also require trained personnel and refrigeration, making them expensive. This has increased interest in alternative routes, with mucosal surfaces being of high priority.

AREAS COVERED

Mucosal routes include ocular, oral (buccal/sublingual), nasal and vaginal mucosae which avoid the limitations of the oral and parenteral routes. Though mucosal routes show great potential, they are still hindered by several barriers, especially for systemic absorption, resulting in the development of more advanced novel drug delivery systems to overcome these limitations and achieve therapeutic actions both locally and systemically, similar to or exceeding the oral route. This paper systematically reviews and compares the different mucosal routes, challenges, and recent advances in advanced novel drug delivery system design for emerging clinical challenges including the advent of large biological macromolecules (proteins, peptides, and RNA) for treatment and prevention of diseases. The review also focuses on current challenges and future perspectives.

EXPERT OPINION

Among the various transmucosal routes discussed, nose-to-brain drug delivery has the greatest translational potential to go beyond the current state of the art and achieve significant clinical impact for neurological diseases.

Ozone-induced lung injury and inflammation: Pathways and therapeutic targets for pulmonary diseases caused by air pollutants

Exposure to ambient Ozone (O3) air pollution directly causes by its oxidative properties, respiratory epithelial cell injury, and cell death, which promote inflammation and hyperreactivity, posing a significant public health concern. Recent clinical and experimental studies have made strides in elucidating the mechanisms underlying O3-induced epithelial cell injury, inflammation, and airway hyperreactivity, which are discussed herein. The current data suggest that O3-induced oxidative stress is a central event-inducing oxeiptotic cell death pathway. O3-induced epithelial barrier damage and cell death, triggering the release of alarmins and damage-associated molecular patterns (DAMPs), with subsequent endogenous activation of Toll-like receptors (TLRs), DNA sensing pathways, and inflammasomes, activating interleukin-1-Myd88 inflammatory pathway with the production of a range of chemokines and cytokines. This cascade orchestrates lung tissue-resident cell activation in response to O3 in leukocyte and non-leukocyte populations, driving sterile innate immune response. Chronic inflammatory response to O3, by repeated exposures, supports a mixed phenotype combining asthma and emphysema, in which their exacerbation by other particulate pollutants potentially culminates in respiratory failure. We use data from lung single-cell transcriptomics to map genes of O3-damage sensing and signaling pathways to lung cells and thereby highlight potential hotspots of O3 responses. Deeper insights into these pathological pathways might be helpful for the identification of novel therapeutic targets and strategies.

Overview of mucosal immunity and respiratory infections in children: a focus on Africa

PURPOSE OF REVIEW

Given the substantial burden of respiratory tract infections (RTIs) on global paediatric health, enhancing our understanding of mucosal immunity can help us advance mucosal biomarkers for diagnosis, prognosis and possible interventions in order to improve health outcomes. This review highlights the critical role of mucosal immunity in paediatric RTIs and recent advances in mucosal interventions, which offer promising strategies to improve outcomes.

RECENT FINDINGS

The significant burden of paediatric RTIs and growing interest in mucosal immunity advanced our understanding of the role of the respiratory mucosal immune system in protective immunity against RTIs. Studies show that sub-Saharan Africa is disproportionately affected by paediatric RTIs with poverty-associated factors such as human immunodeficiency virus (HIV) and malnutrition as risk factors. Emerging evidence highlights the important role of the respiratory microbiome and mucosal innate and adaptive immune responses in protective immunity against RTIs.

SUMMARY

The growing interest in mucosal immunity in RTIs has not only advanced our understanding of the overall immune responses in RTIs but also created opportunities to improve RTI care through translation of knowledge from these studies into diagnostics, therapeutics, and vaccines.

Impact of QazVac vaccination on clinical manifestations and immune responses in post-COVID syndrome: a cross-sectional study

Introduction

Post-COVID syndrome, also known as long COVID, has emerged as a major public health concern, affecting a substantial proportion of individuals recovering from SARS-CoV-2 infection. This condition is characterized by persistent symptoms lasting at least 2 months after acute infection, significantly impacting quality of life and increasing healthcare burdens. In Kazakhstan, the recognition of post- COVID syndrome in national clinical protocols highlights the need for effective prevention and management strategies. Vaccination has been suggested as a key intervention to reduce the severity and prevalence of long COVID symptoms, yet data on its effectiveness, particularly for the domestic QazVac vaccine, remain limited. The aim of this study is to investigate the impact of vaccination with the domestic QazVac vaccine on the features of humoral and cellular immunity in patients with post-COVID conditions and to identify the leading clinical variants of the course.

Methods

We analyzed data from 90 vaccinated and 217 non-vaccinated patients, examining sex, age, smoking status, BMI, comorbidities, and clinical manifestations.

Results

There were no significant differences between the groups with regard to sex, age, and smoking status. However, the characteristics of the subjects indicated that vaccination was correlated with a lower prevalence of diabetes mellitus (2.2% vs. 11.1%, p = 0.011) and cardiovascular diseases (0.0% vs. 10.1%, p = 0.047), and a higher prevalence of hypertension among non-vaccinated subjects. With regard to clinical symptoms, vaccinated individuals presented a significantly decreased frequency of neurological (51.1% vs. 74.2%, p = 0.001), gastrointestinal (4.4% vs. 15.2%, p = 0.008), respiratory (21.1% vs. 36.4%, p = 0.009), rheumatological symptoms (26.7% vs. 38.7%, p = 0.044), and kidney symptoms (2.2% vs. 9.7%, p = 0.024). In contrast, unvaccinated participants had more memory loss (49.8% vs. 22.2%, p < 0.001), depression (31.3% vs. 6.7%, p < 0.001), joint pain (33.2% vs. 14.4%, p = 0.001), and other psychopathological symptoms.

Discussion

A sharp decrease in the frequency of neurological, gastrointestinal, respiratory, and rheumatological symptoms was recorded in vaccinated patients, advocating for the protective role of vaccination against long COVID-19 sequelae. These findings highlight the potential for vaccination to mitigate the burden of post-COVID complications across various organ systems.

Intranasal AAV Vaccination of SARS-CoV-2 Induce Strong and Sustained Neutralizing Antibodies in Mice

The COVID-19 pandemic continues to pose significant health challenges, despite existing vaccines. This study evaluates the immunogenicity of recombinant adeno-associated viruses (AAV) expressing SARS-CoV-2 spike proteins, administered intramuscularly and intranasally in mice. Both delivery methods of AAV5-spike, AAV5-spike stabilized trimer as well as AAV44.9-spike elicited robust serum anti-spike antibodies within 8-12 weeks, with high levels of anti-spike antibodies sustained for over a year. Comparison of mouse serum antibodies 16 weeks post intramuscular or intranasal AAV5 administration demonstrated similar SARS-CoV-2 spike binding neutralizing activity in vitro. Analysis of changes in cellular immunity by ELISpot at 12 weeks post-AAV spike transduction revealed interferon-γ induction in response to peptide challenge. Despite a decline in AAV vector DNA at the injection site, the persistence of anti-spike antibodies demonstrated that AAV-vectors can elicit lasting immune responses, highlighting nasal AAV administration as a potential strategy to block respiratory virus infections.

Oral probiotic extracellular vesicle therapy mitigates Influenza A Virus infection via blunting IL-17 signaling

The influenza A virus (IAV) damages intestinal mucosal tissues beyond the respiratory tract. Probiotics play a crucial role in maintaining the balance and stability of the intestinal microecosystem. Extracellular vesicles (EVs) derived from probiotics have emerged as potential mediators of host immune response and anti-inflammatory effect. However, the specific anti-inflammatory effects and underlying mechanisms of probiotics-derived EVs on IAV remain unclear. In the present study, we investigated the therapeutic efficacy of Lactobacillus reuteri EHA2-derived EVs (LrEVs) in a mouse model of IAV infection. Oral LrEVs were distributed in the liver, lungs, and gastrointestinal tract. In mice infected with IAV, oral LrEVs administration alleviated IAV-induced damages in the lungs and intestines, modified the microbiota compositions, and increased the levels of short-chain fatty acids in those organs. Mechanistically, LrEVs exerted their protective effects against IAV infection by blunting the pro-inflammatory IL-17 signaling. Furthermore, FISH analysis detected miR-4239, one of the most abundant miRNAs in LrEVs, in both lung and intestinal tissues. We confirmed that miR-4239 directly targets IL-17a. Our findings paved the ground for future application of LrEVs in influenza treatment and offered new mechanistic insights regarding the anti-inflammatory role of miR-4239.

Mucosal immunity elicited by a human-Fcγ receptor-I targeted intranasal vaccine platform enhances resistance against nasopharyngeal colonization of Streptococcus pneumoniae and induces broadly protective immunity against respiratory pathogens

The development of safe and effective mucosal vaccines are hampered by safety concerns associated with adjuvants or live attenuated microbes. We previously demonstrated that targeting antigens to the human-Fc-gamma-receptor-I (hFcγRI) eliminates the need for adjuvants, thereby mitigating safety concerns associated with the mucosal delivery of adjuvant formulated vaccines. Here we evaluated the role of the route of immunization in the mucosal immunity elicited by the hFcγRI-targeted vaccine approach. To enable Ag targeting, PspA from Streptococcus pneumoniae (Sp) was genetically fused with the hFcγRI-targeting antibody (α-hFcγRI) to generate PspA-FP. Intranasal (IN) immunization with the PspA-FP induced significantly higher IgA, IgG, and memory T cell response in the lung mucosa compared to that of the intramuscular (IM) route, while both routes exhibited similar increase in the systemic IgG response. The IN immunization elicited better resistance against nasal colonization (NC) of Sp compared to the IM immunization. Additionally, the resistance to NC with the IN administered PspA-FP was higher than the PspA-Alum formulation administered by the IM route. While the protection form lethal pulmonary Sp infection correlated with the systemic Ab response, the resistance from NC (of Sp) correlated with the mucosal immune response. Similar to the pneumococcal pneumoniae model, the hFcγRI-targeted vaccine (based on HA as Ag) was equally protective against pulmonary Influenza virus infection via both routes. However, the IN route promoted better protection compared to the IM route against a lethal pulmonary infection with Francisella tularensis (Ft). The enhanced protection against Ft correlated with the superior mucosal immune response elicited by the IN route compared to the IM route. These observations showed a differential requirement for mucosal delivery for protection depending on the type of pathogen. Moreover, this study revealed that the hFcγRI-targeted vaccine platform is broadly-effective as an adjuvant-free mucosal vaccine platform against respiratory pathogens.

Gamma-irradiated fowl cholera vaccines formulated with different adjuvants induced antibody response and cytokine expression in chickens

Fowl cholera is one of the most serious and economically important infectious diseases of poultry caused by Pasteurella multocida. Formalin-inactivated vaccine, administered intramuscularly, is widely used in Ethiopia with a low success rate. Gamma irradiation is an effective approach to inactivate pathogens for vaccine development. In a previous study, we reported the feasibility of developing gamma-irradiated vaccines that induced both systemic and mucosal antibody responses with complete protection against homologous lethal challenge. In the present study, we aimed to broaden our understanding of the immunogenicity of the gamma-irradiated vaccines by including peripheral blood mononuclear cells (PBMC) response analysis. A total of 156 eight-week-old fowl cholera-specific antibody negative Bovans Brown chickens were utilized in this experiment. The performances of gamma-irradiated P. multocida vaccines formulated with different adjuvants, Montanide Gel 01 PR (G-1), Carbigen® (G-2), Emulsigen-D®+aluminum hydroxide gel (G-3), and Emulsigen-p® (G-4) were evaluated in comparison with the formalin-inactivated vaccine (G-5) and unvaccinated control (G-6). Chickens received two doses of the vaccines at days 0 and 21. Sera, tracheal, and crop lavage were collected at days 0, 21, 35, and 56 to assess IgG and IgA levels using indirect and sandwich ELISA, respectively. PBMC proliferation was compared between vaccinated and unvaccinated controls. In addition, vaccination-induced expression of cytokine genes was analyzed in PBMC using qPCR. Chickens were challenged with 2.5x107 CFU/ml of P. multocida biotype A intramuscularly one day after day-56 sampling. Significant serum IgG titers were detected three weeks after primary vaccination in G1, G3, and G5. IgG titer substantially increased in all vaccinated groups two weeks post-booster dose. IgA response was induced by gamma-irradiated vaccines but not formalin-inactivated vaccines. Only PBMC from vaccinated chickens proliferated in response to re-stimulation with P. multocida antigen, indicating vaccine-specific priming. Interestingly, gamma-irradiated vaccines resulted in a higher fold change in mRNA transcripts of IFN-γ (>1000-fold change) IL-6 (>500-fold change), and IL-12p40 (>200-fold change), which are hallmarks of a Th1 dominant response, which is essential to combat intracellular infection. Lastly, the candidate vaccines demonstrated various levels of protection, with Emulsigen-D® containing vaccine rendering complete protection against homologous lethal challenge. In conclusion, gamma-irradiated vaccines can induce broad immune responses, humoral and cellular, and protect against severe outcome of fowl cholera. Therefore, this study has contributed to growing knowledge on the immunogenicity and efficacy of gamma-irradiated vaccines and has shown the potential of such a vaccine platform for field application in extensive as well as intensive farm settings.

Tissue-resident memory T cells in urinary tract diseases

Tissue-resident memory T (TRM) cells are a specialized subset of memory T cells that permanently reside in non-lymphoid tissues, providing localized and long-lasting immune protection. In the urinary tract, TRM cells play critical roles in defending against infections, mediating tumor immunity, and influencing the pathogenesis of chronic inflammatory diseases. Their therapeutic potential is immense, with promising avenues for vaccine development, enhanced cancer immunotherapy, and targeted treatments for chronic inflammation. However, challenges remain in harnessing their protective roles while minimizing their pathological effects, particularly in immunosuppressive or inflammatory microenvironments. This review explores the diverse roles of TRM cells in urinary tract diseases, including infections, cancer, and chronic inflammation, and discusses therapeutic strategies and future directions for leveraging TRM cells to improve clinical outcomes. By advancing our understanding of TRM cell biology, we can develop innovative interventions that balance their immune-protective and regulatory functions.

BEV 2C protein inhibits the NF-κB signalling pathway to promote viral replication by targeting IKBKB and p65

Bovine enterovirus, a member of the Enterovirus genus in the Picornaviridae family, causes severe digestive and respiratory illnesses in cattle. These illnesses threaten the healthy development of the cattle industry. Innate immunity plays a critical role in resisting viral infections, but viruses also use various strategies to evade or counteract the host's immune system. The mechanisms by which bovine enteroviruses evade the host immune response and promote their replication remain unclear. This study used the HY12 strain of enterovirus as a model to investigate its interaction with both bovine enterovirus and its host. Our findings indicate that bovine enterovirus promotes the replication of HY12 by disrupting the NF-κB pathway. Here, one strategy was to down-regulate the IΚBΚB expression to inhibit the activation of NF-κB. Another approach was to directly interact with p65 to reduce the dimerisation of p65/p50 and inhibit the phosphorylation and nuclear translocation of p65. Our study's results show that 2C's N-terminal 1-121 aa is essential for 2C-mediated inhibition of the NF-κB signalling pathway, and four amino acids (position 118-121 aa) are the interaction site of 2C with p65. This report is the first on BEV 2C protein promoting virus replication through new strategies, which provides novel insights into the understanding of enterovirus pathobiology and the development of drugs against BEV.

Calboxyvinyl polymer adjuvant enhances respiratory iga responses through mucosal and systemic administration

Adjuvants play a crucial role in enhancing vaccine efficacy. Although several adjuvants have been approved, there remains a demand for safer and more effective adjuvants for nasal vaccines. Here, we identified calboxyvinyl polymer (CVP) as a superior mucosal vaccine adjuvant from pharmaceutical base materials using our screening systems; single nasal vaccination of the CVP-combined influenza split vaccine-induced antigen-specific IgA and IgG antibodies and provided protection against lethal influenza virus infection. Furthermore, nasal vaccination with CVP-combined severe acute respiratory syndrome coronavirus 2 antigen protected against the virus and stimulated the production of highly cross-reactive IgG antibodies against variants XBB1.5 and JN.1. Intriguingly, intramuscular vaccination of the CVP-combined vaccine also elicited the production of IgA antibodies in both nasal wash and bronchoalveolar lavage fluid in mice and cynomolgus monkeys. CVP therefore offers superior adjuvanticity to existing adjuvants and is anticipated to be a safe and effective adjuvant for mucosal vaccines.

Molecular determinants of cross-strain influenza A virus recognition by αβ T cell receptors

Cross-reactive αβ T cell receptors (TCRs) recognizing multiple peptide variants can provide effective control of rapidly evolving viruses yet remain understudied. By screening 12 naturally occurring influenza-derived HLA-B*35:01-restricted nucleoprotein (NP)418-426 epitopes (B*35:01-NP418) that emerged since 1918 within influenza A viruses, including 2024 A/H5N1 viruses, we identified functional broadly cross-reactive T cells universally recognizing NP418 variants. Binding studies demonstrated that TCR cross-reactivity was concomitant with diminished antigen sensitivity. Primary human B*35:01/NP418+CD8+ T cell lines displayed reduced cross-reactivity in the absence of CD8 coreceptor binding, validating the low avidity of cross-reactive B*35:01-NP418+CD8+ T cell responses. Six TCR-HLA-B*35:01/NP418 crystal structures showed how cross-reactive TCRs recognized multiple B*35:01/NP418 epitope variants. Specific TCR interactions were formed with invariant and conserved peptide-HLA features, thus remaining distal from highly varied positions of the NP418 epitope. Our study defines molecular mechanisms associated with extensive TCR cross-reactivity toward naturally occurring viral variants highly relevant to universal protective immunity against influenza.

Early, Robust Mucosal Secretory Immunoglobulin A but not Immunoglobulin G Response to Severe Acute Respiratory Syndrome Coronavirus 2 Spike in Oral Fluid Is Associated With Faster Viral Clearance and Coronavirus Disease 2019 Symptom Resolution

BACKGROUND

Efforts are underway to support the development of novel mucosal coronavirus disease 2019 (COVID-19) vaccines. However, there is limited consensus about the complementary role of mucosal immunity in disease progression and how to evaluate immunogenicity of mucosal vaccines. This study investigated the role of oral mucosal antibody responses in viral clearance and COVID-19 symptom duration.

METHODS

Participants with polymerase chain reaction (PCR)-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection provided oral fluid for testing with SARS-CoV-2 antibody multiplex assays, nasal swabs for reverse-transcription PCR, and symptom information at up to 8 follow-ups from April 2020 to February 2022.

RESULTS

High and moderate oral fluid anti-spike (S) secretory IgA (SIgA) postinfection was associated with significantly faster viral clearance and symptom resolution across age groups with effect sizes equivalent to prior COVID-19 vaccine immunity at the time of infection. Those with high and moderate anti-S SIgA cleared the virus 14 (95% confidence interval [CI], 10-18) days and recovered 9-10 (95% CI, 6-14) days earlier. Delayed and higher anti-S IgG was associated with significantly longer time to clearance and recovery. Experiencing symptoms >4 weeks was associated with lower anti-receptor-binding domain SIgA 15-30 days after infection onset (P < .001).

CONCLUSIONS

Robust mucosal SIgA early postinfection appears to support faster clearance of SARS-CoV-2 and recovery from COVID-19 symptoms. This research underscores the importance of harmonizing mucosal immune response assays to evaluate new mucosal vaccines.

Pathogenesis of influenza and SARS-CoV-2 co-infection at the extremes of age: decipher the ominous tales of immune vulnerability

The co-circulation of influenza and SARS-CoV-2 has led to co-infection events, primarily affecting children and older adults, who are at higher risk for severe disease. Although co-infection prevalence is relatively low, it is associated with worse outcomes compared to mono-infections. Previous studies have shown that the outcomes of co-infection depend on multiple factors, including viral interference, virus-host interaction and host response. Children and the elderly exhibit distinct patterns of antiviral response, which involve airway epithelium, mucociliary clearance, innate and adaptive immune cells, and inflammatory mediators. This review explores the pathogeneses of SARS-CoV-2 and influenza co-infection, focusing on the antiviral responses in children and the elderly. By comparing immature immunity in children and immune senescence in older adults, we aim to provide insights for the clinical management of severe co-infection cases.

Endarachne binghamiae Extract Ameliorates Inflammatory Responses in Macrophages Through Regulation of MAPK, NF-kB and PI3K/AKT Pathways, and Prevents Acute Lung Injury in Mice

In this study, the anti-inflammatory effect of the hot water extract of Endarachne binghamiae (EB-WE), a type of marine brown algae, was investigated in LPS-stimulated RAW 264.7 cells and an acute lung injury (ALI) mouse model induced by intranasal LPS administration. Treatment with EB-WE significantly inhibited NO and pro-inflammatory cytokine (TNF-a and IL-6) production in LPS-stimulated RAW 264.7 cells. In mRNA analysis, the expression of pro-inflammatory cytokines, COX-2, and iNOS mRNAs, was down-regulated by EB-WE treatment. The phosphorylation of MAPK, IkB, and PI3K/AKT molecules responsible for signal pathways during inflammation in LPS-stimulated macrophages was also significantly inhibited by EB-WE. In an in vivo model for ALI, oral administration of EB-WE significantly reduced the level of pro-inflammatory cytokines (TNF-a, IL-1b, and IL-6) and chemokines (MCP-1, CXC-16, CXCL1, and TARC) in serum or bronchoalveolar lavage fluid (BALF) of mice. Similarly to the results in LPS-stimulated RAW 264.7 cells, treatment with EB-WE significantly inhibited intracellular signal pathways mediated by MAPK, IkB, and PI3K/AKT in lung tissues of mice with ALI, and also decreased the expression of mRNAs of inflammatory mediators such as TNF-a, IL-6, iNOS, and COX-2. Furthermore, the inhibitory effect of EB-WE on ALI was apparently confirmed in histological examination through lung tissue staining. Taken together, it is clear that EB-WE has potential activity to effectively ameliorate the inflammatory responses in macrophages through down-regulation of MAPK, NF-kB, and PI3K/AKT activation, and suppress acute lung injury induced by LPS. These findings strongly suggest that EB-WE is a promising natural product beneficial for developing preventive treatments and cures of inflammation-related diseases.

Mucosal immune response in biology, disease prevention and treatment

The mucosal immune system, as the most extensive peripheral immune network, serves as the frontline defense against a myriad of microbial and dietary antigens. It is crucial in preventing pathogen invasion and establishing immune tolerance. A comprehensive understanding of mucosal immunity is essential for developing treatments that can effectively target diseases at their entry points, thereby minimizing the overall impact on the body. Despite its importance, our knowledge of mucosal immunity remains incomplete, necessitating further research. The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has underscored the critical role of mucosal immunity in disease prevention and treatment. This systematic review focuses on the dynamic interactions between mucosa-associated lymphoid structures and related diseases. We delve into the basic structures and functions of these lymphoid tissues during disease processes and explore the intricate regulatory networks and mechanisms involved. Additionally, we summarize novel therapies and clinical research advances in the prevention of mucosal immunity-related diseases. The review also addresses the challenges in developing mucosal vaccines, which aim to induce specific immune responses while maintaining tolerance to non-pathogenic microbes. Innovative therapies, such as nanoparticle vaccines and inhalable antibodies, show promise in enhancing mucosal immunity and offer potential for improved disease prevention and treatment.

Antibodies directed against bacterial antigens in sera of Polish patients with primary biliary cholangitis

Background

Primary biliary cholangitis (PBC) is a cholestatic, autoimmune liver disease with the presence of characteristic autoantibodies. The aim of the work was to determine the level of antibodies directed against bacterial antigens: Chlamydia pneumoniae (anti-Cpn), Yersinia enterolitica (anti-Y.e), Helicobacter pylori (anti-Hp), Mycoplasma pneumoniae (anti- Mp.) and Escherichia coli (E.coli) in sera of PBC patients. We also performed in vitro studies on the impact of the bacterial peptides on the specific antigen-antibody binding.

Method

We screened 92 Polish PBC patients and sera samples from healthy donors and pathological controls. Autoantibodies and anti-bacterial antibodies were determined by commercially available ELISA kits. Specific inhibition of antibody binding was also detected by the in house ELISA method.

Results

Anti-Cpn, anti-Y. enterolitica, anti-Hp, anti-M. pneumoniae and anti-E. coli antibodies were significantly more common in the group of PBC patients than in the pathological and healthy control groups: 74%, 40%, 84%, 39% and 69% respectively. The mean level of anti-Cpn, anti- Y.e, anti-Hp and anti- M.p in the PBC group was significantly higher than those in the healthy group (p < 0.001). and in patients with other liver diseases. In sera of patients with the presence of positive anti-mitochondrial antibodies (AMA), specific for PBC, anti-bacterial antibodies have been found in 80% vs. 50% in sera with AMA negative. We observed inhibition of specific antigen-antibody binding by the bacterial peptide: EClpP (E. coli caseinolytic protease) and adenine glycosylase from E. coli caseinolytic protease P, ClpP Y.e from peptide of Y. enterolitica, Mp PDC from M. pneumonia peptide and adenine glycosylase of E. coli. Bacterial factors influence the specific binding of antibodies to pyruvate dehydrogenase (PDC-E2), gp210 and KLHL12 (kelch-like peptide 12) antigens.

Conclusion

Microbial mimics may be the major targets of cross-reactivity with human pyruvate dehydrogenase, gp210, and KLHL12 in PBC.

Pulmonary delivery of silver nanoparticles prevents influenza infection by recruiting and activating lymphoid cells

Silver nanoparticles (AgNPs) are a potential antiviral agent due to their ability to disrupt the viral particle or alter the virus metabolism inside the host cell. In vitro, AgNPs exhibit antiviral activity against the most common human respiratory viruses. However, their capacity to modulate immune responses during respiratory viral infections has yet to be explored. This study demonstrates that administering AgNPs directly into the lungs prior to infection can reduce viral loads and therefore virus-induced cytokines in mice infected with influenza virus or murine pneumonia virus. The prophylactic effect was diminished in mice with depleted lymphoid cells. We showed that AgNPs-treatment resulted in the recruitment and activation of lymphocytes in the lungs, particularly natural killer (NK) cells. Mechanistically, AgNPs enhanced the ability of alveolar macrophages to promote both NK cell migration and IFN-γ production. By contrast, following infection, in mice treated with AgNPs, NK cells exhibited decreased activation, indicating that these nanoparticles can regulate the potentially deleterious activation of these cells. Overall, the data suggest that AgNPs may possess prophylactic antiviral properties by recruiting and controlling the activation of lymphoid cells through interaction with alveolar macrophages.

Induction of protective immune responses at respiratory mucosal sites

Many pathogens enter the host through mucosal sites. Thus, interfering with pathogen entry through local neutralization at mucosal sites therefore is an effective strategy for preventing disease. Mucosally administered vaccines have the potential to induce protective immune responses at mucosal sites. This manuscript delves into some of the latest developments in mucosal vaccination, particularly focusing on advancements in adjuvant technologies and the role of these adjuvants in enhancing vaccine efficacy against respiratory pathogens. It highlights the anatomical and immunological complexities of the respiratory mucosal immune system, emphasizing the significance of mucosal secretory IgA and tissue-resident memory T cells in local immune responses. We further discuss the differences between immune responses induced through traditional parenteral vaccination approaches vs. mucosal administration strategies, and explore the protective advantages offered by immunization through mucosal routes.

Intranasal Immunization with DNA Vaccine HA-CCL19/Polyethylenimine/Chitosan Composite Provides Immune Protection Against H7N9 Infection

BACKGROUND/OBJECTIVES

The H7N9 avian influenza virus (AIV) constitutes a novel subtype of influenza virus that has emerged within the past decade. Empirical studies have demonstrated that H7N9 AIV holds the potential to trigger a human pandemic. Vaccines constitute the sole armament available to humanity in combating influenza epidemics. DNA vaccines present numerous merits; however, substantial conundrums persist regarding how to augment their immunogenicity and implement their delivery through mucosal immunization.

METHODS

In this study; BALB/c mice were utilized as a model to investigate the effect of CCL19 as a molecular adjuvant and to determine the immune response elicited by polyethylene imine (PEI) and chitosan (CS) as adjuvants during the delivery of a DNA vaccine through the nasal mucosal route.

RESULTS

Our results revealed that the CCL19 molecular adjuvant exerts a substantial immunomodulatory enhancement effect on the H7N9-HA DNA vaccine, inducing more pronounced cellular and humoral immunity. Additionally, our results indicated that the composite formed by the HA-CCL19 DNA in combination with PEI and CS effectively activates local mucosal immunity as well as systemic humoral and cellular immunity, offering 100% protection against lethal doses of homologous virus challenges.

CONCLUSIONS

CCL19 conspicuously augments the immunogenicity of the influenza virus HA DNA and conserves the integrity of the vaccine antigen. Simultaneously, CS and PEI proficiently facilitate the mucosal delivery of DNA, thereby eliciting mucosal immunity related to DNA vaccines. This study investigated the feasibility of utilizing nasal mucosa for DNA vaccine immunization, which holds significant implications for the advancement and application of DNA vaccines in public health.

COVID-19 mRNA Vaccines Induce Robust Levels of IgG but Limited Amounts of IgA Within the Oronasopharynx of Young Children

BACKGROUND

Understanding antibody responses to SARS-CoV-2 vaccination is crucial for refining COVID-19 immunization strategies. Generation of mucosal immune responses, including mucosal IgA, could be of potential benefit to vaccine efficacy; however, limited evidence exists regarding the production of mucosal antibodies following the administration of current mRNA vaccines to young children.

METHODS

We measured the levels of antibodies against SARS-CoV-2 from a cohort of children under 5 years of age (n = 24) undergoing SARS-CoV-2 mRNA vaccination (serially collected, matched serum and saliva samples) or in a convenience sample of children under 5 years of age presenting to pediatric emergency department (nasal swabs, n = 103). Furthermore, we assessed salivary and nasal samples for the ability to induce SARS-CoV-2 spike-mediated neutrophil extracellular traps (NET) formation.

RESULTS

Longitudinal analysis of post-vaccine responses in saliva revealed the induction of SARS-CoV-2-specific IgG but not IgA. Similarly, SARS-CoV-2-specific IgA was only observed in nasal samples obtained from previously infected children with or without vaccination, but not in vaccinated children without a history of infection. In addition, oronasopharyngeal samples obtained from children with prior infection were able to trigger enhanced spike-mediated NET formation, and IgA played a key role in driving this process.

CONCLUSIONS

Despite the induction of specific IgG in the oronasal mucosa, current intramuscular vaccines have limited ability to generate mucosal IgA in young children. These results confirm the independence of mucosal IgA responses from systemic humoral responses following mRNA vaccination and suggest potential future vaccination strategies for enhancing mucosal protection in this young age group.

Long-term trends and comparison of the burden of lower respiratory tract infections in China and globally from 1990 to 2021: an analysis based on the Global Burden of Disease study 2021

Background

This study aimed to describe the temporal trends in the age and sex burdens of lower respiratory infections (LRIs) in China and globally from 1990 to 2021 and to analyze their epidemiological characteristics to formulate corresponding strategies to control LRIs.

Methods

This study utilized open data from the Global Burden of Disease (GBD) database from 1990 to 2021 to assess the burden of disease based on the prevalence, incidence, mortality, years lost (YLLs), years lived with disability (YLDs), and disability-adjusted life-years (DALYs) of LRIs in China and globally. Moreover, a comprehensive comparative analysis of the epidemiological characteristics of LRIs in China and globally was conducted via the Joinpoint regression model, age-period-cohort model (APC model), and stratified analysis of the study method from multiple dimensions, such as age, sex, and period. Finally, we used an autoregressive integrated moving average (ARIMA) model to predict the disease burden in LRIs over the next 15 years.

Results

From 1990 to 2021, China's age-standardized incidence, deaths, and disability-adjusted life year (DALY) rates per 100,000 people decreased from 5,481.13 (95% CI: 5,149.05, 5,836.35) to 2,853.81 (95% CI: 2,663.94, 3,067.55), from 60.65 (95% CI. 52.96, 66.66) to 14.03 (95% CI: 11.68, 17) and from 3,128.39 (95% CI: 2,724.11, 3,579.57) to 347.67 (95% CI: 301.28, 402.94). The global age-standardized incidence, deaths, and DALY rates per 100,000 people, on the other hand, decreased from 6,373.17 (95% CI: 5,993.51, 6,746.04) to 4,283.61 (95% CI: 4,057.03, 4,524.89) and from 61.81 (95% CI: 56.66, 66.74) to 28.67 (95% CI: 25.92, 31.07) and from 3,472.9 (95% CI: 3,090.71, 3,872.11) to 1,168.8 (95% CI: 1,016.96, 1,336.95). The decline in the aforementioned indicators is greater in the female population than in the male population, and the decrease in China is more pronounced than the global trend. In China, the age-standardized incidence and mortality rates of LRIs showed an annual average percentage change (AAPC) of -2.12 (95% CI: -2.20, -2.03) and -4.77 (95% CI: -5.14, -4.39), respectively. Globally, the age-standardized incidence and mortality rates for LRIs decreased by -1.28 (95% CI: -1.37, -1.18) and -2.47 (95% CI: -2.61, -2.32). By 2036, the incidence of lower respiratory infections (LRI) among men and women in China is projected to decrease by 36.55 and 46.87%, respectively, while the mortality rates are expected to decline to 12.67% for men and increase by 71.85% for women. In comparison, the global decline in LRI incidence is lower than that observed in China, yet the reduction in mortality rates is greater globally than in China.

Conclusions

Age-standardized incidence, mortality and disability-adjusted life years (DALYs) decreased more in China than at the global level between 1990 and 2021. Compared with the previous period, the COVID-19 pandemic has led to a significant decrease in the disease burden of LRIs. As the population continues to age, the disease burden of LRIs in the old adult population will become a major new public health challenge.

Human airway epithelium controls Pseudomonas aeruginosa infection via inducible nitric oxide synthase

Introduction

Airway epithelial cells play a central role in the innate immune response to invading bacteria, yet adequate human infection models are lacking.

Methods

We utilized mucociliary-differentiated human airway organoids with direct access to the apical side of epithelial cells to model the initial phase of Pseudomonas aeruginosa respiratory tract infection.

Results

Immunofluorescence of infected organoids revealed that Pseudomonas aeruginosa invades the epithelial barrier and subsequently proliferates within the epithelial space. RNA sequencing analysis demonstrated that Pseudomonas infection stimulated innate antimicrobial immune responses, but specifically enhanced the expression of genes of the nitric oxide metabolic pathway. We demonstrated that activation of inducible nitric oxide synthase (iNOS) in airway organoids exposed bacteria to nitrosative stress, effectively inhibiting intra-epithelial pathogen proliferation. Pharmacological inhibition of iNOS resulted in expansion of bacterial proliferation whereas a NO producing drug reduced bacterial numbers. iNOS expression was mainly localized to ciliated epithelial cells of infected airway organoids, which was confirmed in primary human lung tissue during Pseudomonas pneumonia.

Discussion

Our findings highlight the critical role of epithelial-derived iNOS in host defence against Pseudomonas aeruginosa infection. Furthermore, we describe a human tissue model that accurately mimics the airway epithelium, providing a valuable framework for systemically studying host-pathogen interactions in respiratory infections.

Constructing the cGAMP-Aluminum Nanoparticles as a Vaccine Adjuvant-Delivery System (VADS) for Developing the Efficient Pulmonary COVID-19 Subunit Vaccines

The cGAMP-aluminum nanoparticles (CAN) are engineered as a vaccine adjuvant-delivery system to carry mixed RBD (receptor-binding domain) of the original severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its new variant for developing bivalent pulmonary coronavirus disease 2019 (COVID-19) vaccines (biRBD-CAN). High phosphophilicity/adsorptivity made intrapulmonary CAN instantly form the pulmonary ingredient-coated CAN (piCAN) to possess biomimetic features enhancing biocompatibility. In vitro biRBD-CAN sparked APCs (antigen-presenting cells) to mature and make extra reactive oxygen species, engendered lysosome escape effects and enhanced proteasome activities. Through activating the intracellular stimulator of interferon genes (STING) and nucleotide-binding domain and leucine-rich repeat and pyrin domain containing proteins 3 (NALP3) inflammasome pathways to exert synergy between cGAMP and AN, biRBD-CAN stimulated APCs to secret cytokines favoring mixed Th1/Th2 immunoresponses. Mice bearing twice intrapulmonary biRBD-CAN produced high levels of mucosal antibodies, the long-lasting systemic antibodies, and potent cytotoxic T lymphocytes which efficiently erased cells displaying cognate epitopes. Notably, biRBD-CAN existed in mouse lungs and different lymph nodes for at least 48 h, unveiling their sustained immunostimulatory activity as the main mechanism underlying the long-lasting immunity and memory. Hamsters bearing twice intrapulmonary biRBD-CAN developed high resistance to pseudoviral challenges performed using different recombinant strains including the ones with distinct SARS-CoV-2-spike mutations. Thus, biRBD-CAN as a broad-spectrum pulmonary COVID-19 vaccine candidate may provide a tool for controlling the emerging SARS-CoV-2 variants.

Preliminary Study on Type I Interferon as a Mucosal Adjuvant for Human Respiratory Syncytial Virus F Protein

Background: Human respiratory syncytial virus (HRSV) imposes a significant disease burden on infants and the elderly. Intranasal immunization using attenuated live vaccines and certain vector vaccines against HRSV has completed phase II clinical trials with good safety and efficacy.Recombinant protein vaccines for mucosal immunization require potent mucosal adjuvants. Type I interferon (IFN), as a natural mucosal adjuvant, significantly enhances antigen-presenting cell processing and antigen presentation, promoting the production of T and B cells. Methods: This study utilized human α2b interferon (IFN-human) and mouse α2 interferon (IFN-mouse) as nasal mucosal adjuvants in combination with fusion protein (F). Intranasal immunization was performed on BALB/c mice to evaluate the immunogenicity of the formulation in vivo. Results: Compared to the F protein immunization group, mice in the F + IFN-Human and F + IFN-Mouse experimental groups exhibited significantly increased neutralizing antibody titers and augmented secretion of IFN-γ and IL-4 by lymphocytes, and both of them could induce the production of high-titer specific IgA antibodies in mice (p < 0.001).The F + IFN-Human immunization induced the highest IgG and IgG1 antibody titers in mice; however, the F + IFN-Mouse immunization group elicited the highest neutralizing antibody titers (598), lowest viral loads in the lungs (Ct value of 31), and fastest weight recovery in mice. Moreover, mice in the F + IFN-Mouse immunization group displayed the mildest lung pathological damage (Total score of pathological injury was 2). Conclusions: In conclusion, IFN-Mouse, as a mucosal adjuvant for HRSV recombinant protein vaccines, demonstrated superior protective effects in mice compared to IFN-Human adjuvants.

Neisseria gonorrhoeae induces local secretion of IL-10 at the human cervix to promote colonization

Gonorrhea, caused by the human-restricted pathogen Neisseria gonorrhoeae, is a commonly reported sexually transmitted infection. Since most infections in women are asymptomatic, the true number of infections is likely much higher than reported. How gonococci (GC) colonize women's cervixes without triggering symptoms remains elusive. Using a human cervical tissue explant model, we found that GC inoculation increased the local secretion of both proinflammatory (IL-1β and TNF-α) and antiinflammatory (IL-10) cytokines during the first 24 hours of infection. Cytokine induction required GC expression of Opa isoforms that bind the host receptors carcinoembryonic antigen-related cell adhesion molecules (CEACAMs). GC inoculation induced NF-κB activation in both cervical epithelial and subepithelial cells. However, inhibition of NF-κB activation, which reduced GC-induced IL-1β and TNF-α, did not affect GC colonization. Neutralizing IL-10 or blocking IL-10 receptors by antibodies reduced GC colonization by increasing epithelial shedding and epithelial cell-cell junction disassembly. Inhibition of the CEACAM downstream signaling molecule SHP1/2, which reduced GC colonization and increased epithelial shedding, decreased GC-induced IL-10 secretion. These results show that GC induce local secretion of IL-10, a potent antiinflammatory cytokine, at the cervix by engaging the host CEACAMs to prevent GC-colonizing epithelial cells from shedding, providing a potential mechanism for GC asymptomatic colonization in women.

Time to Rethink Bronchiolitis Obliterans Syndrome Following Lung or Hematopoietic Cell Transplantation in Pediatric Patients

Background: Similar in histological characteristics and clinical manifestations, bronchiolitis obliterans syndrome (BOS) can develop following lung transplantation (LTx) or hematopoietic cell transplantation (HCT). In contrast to lung transplantation, where BOS is restricted to the lung allograft, HCT-related systemic graft-versus-host disease (GVHD) is the root cause of BOS. Because lung function declines following HCT, diagnosis becomes more difficult. Given the lack of proven effective medicines, treatment is based on empirical evidence. Methods: Cross-disciplinary learning is crucial, and novel therapies are under investigation to improve survival and avoid LTx. Recent advances have focused on updating the understanding of the etiology, clinical features, and pathobiology of BOS. It emphasizes the significance of learning from experts in other transplant modalities, promoting cross-disciplinary knowledge. Results: Our treatment algorithms are derived from extensive research and expert clinical input. It is important to ensure that immunosuppression is optimized and that any other conditions or contributing factors are addressed, if possible. Clear treatment algorithms are provided for each condition, drawing from the published literature and consensus clinical opinion. There are several novel therapies currently being investigated, such as aerosolized liposomal cyclosporine, Janus kinase inhibitors, antifibrotic therapies, and B-cell-directed therapies. Conclusions: We urgently need innovative treatments that can greatly increase survival rates and eliminate the need for LTx or re-transplantation.

Safety, efficacy and immunogenicity of aerosolized Ad5-nCoV COVID-19 vaccine in a non-inferiority randomized controlled trial

This phase 3, observer-blinded, non-inferiority randomized trial (ClinicalTrials.gov: NCT05517642), conducted from September 2022 to May 2023 at three Malaysian sites, involved 540 adults previously vaccinated with three COVID-19 doses. Participants were randomized 1:1 to receive either one dose of inhaled Recombinant COVID-19 Vaccine (Ad5-nCoV-IH) or intramuscular tozinameran (BNT-IM). The study assessed safety, vaccine efficacy (VE) and immunogenicity against SARS-CoV-2 variants. The primary outcome was the non-inferiority of anti-spike protein receptor-binding domain (S-RBD IgG) antibodies, with a 97.5% confidence interval lower limit for the geometric mean concentration (GMC) ratio >0.67. Ad5-nCoV-IH showed lower immunogenicity than BNT-IM, with a GMC ratio of 0.22 and a seroconversion rate difference of -71.91%. Adverse drug reactions (ADRs) were less frequent with Ad5-nCoV-IH (39.26%) compared to BNT-IM (64.68%). No serious vaccine-related adverse events were reported. Both vaccines had comparable efficacy against COVID-19 variants. This study was funded by Tianjin Biomedical Science and Technology Major Project.

Role of IgA1 protease-producing bacteria in SARS-CoV-2 infection and transmission: a hypothesis

Secretory (S) IgA antibodies against severe acute respiratory syndrome (SARS)-CoV-2 are induced in saliva and upper respiratory tract (URT) secretions by natural infection and may be critical in determining the outcome of initial infection. Secretory IgA1 (SIgA1) is the predominant isotype of antibodies in these secretions. Neutralization of SARS-CoV-2 is most effectively accomplished by polymeric antibodies such as SIgA. We hypothesize that cleavage of SIgA1 antibodies against SARS-CoV-2 by unique bacterial IgA1 proteases to univalent Fabα antibody fragments with diminished virus neutralizing activity would facilitate the descent of the virus into the lungs to cause serious disease and also enhance its airborne transmission to others. Recent studies of the nasopharyngeal microbiota of patients with SARS-CoV-2 infection have revealed significant increases in the proportions of IgA1 protease-producing bacteria in comparison with healthy subjects. Similar considerations might apply also to other respiratory viral infections including influenza, possibly explaining the original attribution of influenza to Haemophilus influenzae, which produces IgA1 protease.

Harnessing Variability Signatures and Biological Noise May Enhance Immunotherapies' Efficacy and Act as Novel Biomarkers for Diagnosing and Monitoring Immune-Associated Disorders

Lack of response to immunotherapies poses a significant challenge in treating immune-mediated disorders and cancers. While the mechanisms associated with poor responsiveness are not well defined and change between and among subjects, the current methods for overcoming the loss of response are insufficient. The Constrained Disorder Principle (CDP) explains biological systems based on their inherent variability, bounded by dynamic boundaries that change in response to internal and external perturbations. Inter and intra-subject variability characterize the immune system, making it difficult to provide a single therapeutic regimen to all patients and even the same patients over time. The dynamicity of the immune variability is also a significant challenge for personalizing immunotherapies. The CDP-based second-generation artificial intelligence system is an outcome-based dynamic platform that incorporates personalized variability signatures into the therapeutic regimen and may provide methods for improving the response and overcoming the loss of response to treatments. The signatures of immune variability may also offer a method for identifying new biomarkers for early diagnosis, monitoring immune-related disorders, and evaluating the response to treatments.

Biosafety and immunology: An interdisciplinary field for health priority

Biosafety hazards can trigger a host immune response after infection, invasion, or contact with the host. Whether infection with a microorganism results in disease or biosafety concerns depends to a large extent on the immune status of the population. Therefore, it is essential to investigate the immunological characteristics of the host and the mechanisms of biological threats and agents to protect the host more effectively. Emerging and re-emerging infectious diseases, such as the current coronavirus disease 2019 (COVID-19) pandemic, have raised concerns regarding both biosafety and immunology worldwide. Interdisciplinary studies involved in biosafety and immunology are relevant in many fields, including the development of vaccines and other immune interventions such as monoclonal antibodies and T-cells, herd immunity (or population-level barrier immunity), immunopathology, and multispecies immunity, i.e., animals and even plants. Meanwhile, advances in immunological science and technology are occurring rapidly, resulting in important research achievements that may contribute to the recognition of emerging biosafety hazards, as well as early warning, prevention, and defense systems. This review provides an overview of the interdisciplinary field of biosafety and immunology. Close collaboration and innovative application of immunology in the field of biosafety is becoming essential for human health.

In vivo spatiotemporal characterizing diverse body transportation of optical labeled high immunity aluminium adjuvants with photoacoustic tomography

Vaccine development requires high-resolution, in situ, and visual adjuvant technology. To address this need, this work proposed a novel adjuvant labeling that involved indocyanine green (ICG) and bovine serum albumin (BSA) with self-assembled aluminium adjuvant (Alum), which was called BSA@ICG@Alum. This compound exhibited excellent photoacoustic properties and has been confirmed its safety, biocompatibility, high antigen binding efficiency, and superior induction of immune response. Photoacoustic tomography (PAT) tracked the distribution of Alum in lymph nodes (LNs) and lymphatic vessels in real time after diverse injection modalities. The non-invasive imaging approach revealed that BSA@ICG@Alum was transported to the draining LNs 60 min after intramuscular injection and to distal LNs within 30 min after lymph node injection. In conclusion, PAT enabled real-time three-dimensional and quantitative visualization, thus offering a powerful tool for advancing vaccine design by providing critical insights into adjuvant transport and immune system activation.

Mucosal delivery of a prefusogenic-F, glycoprotein, and matrix proteins-based virus-like particle respiratory syncytial virus vaccine induces protective immunity as evidenced by challenge studies in mice

RSV infection remains a serious threat to the children all over the world, especially, in the low-middle income countries. Vaccine delivery via the mucosa holds great potential for inducing local immune responses in the respiratory tract. Previously, we reported the development of highly immunogenic RSV virus-like-particles (RSV-VLPs) based on the conformationally stable prefusogenic-F protein (preFg), glycoprotein and matrix protein. Here, to explore whether mucosal delivery of RSV-VLPs is an effective strategy to induce RSV-specific mucosal and systemic immunity, RSV-VLPs were administered via the nasal, sublingual and pulmonary routes to BALB/c mice. The results demonstrate that immunization with the VLPs via the mucosal routes induced minimal mucosal response and yet facilitated modest levels of serum IgG antibodies, enhanced T cell responses and the expression of the lung-homing marker CXCR3 on splenocytes. Immunization with VLPs via all three mucosal routes provided protection against RSV challenge with no signs of RSV induced pathology.

Inflammatory and Immune Mechanisms in COPD: Current Status and Therapeutic Prospects

Background

Chronic obstructive pulmonary disease (COPD) currently ranks among the top three causes of mortality worldwide, presenting as a prevalent and complex respiratory ailment. Ongoing research has underscored the pivotal role of immune function in the onset and progression of COPD. The immune response in COPD patients exhibits abnormalities, characterized by diminished anti-infection capacity due to immune senescence, heightened activation of neutrophils and macrophages, T cell infiltration, and aberrant B cell activity, collectively contributing to airway inflammation and lung injury in COPD.

Objective

This review aimed to explore the pivotal role of the immune system in COPD and its therapeutic potential.

Methods

We conducted a review of immunity and COPD published within the past decade in the Web of Science and PubMed databases, sorting through and summarizing relevant literature.

Results

This article examines the pivotal roles of the immune system in COPD. Understanding the specific functions and interactions of these immune cells could facilitate the development of novel therapeutic strategies and interventions aimed at controlling inflammation, enhancing immune function, and mitigating the impact of respiratory infections in COPD patients.

Escherichia coli LTB26 mutant enhances immune responses to rotavirus antigen VP8 in a mouse model

Adjuvant is a major supplementary component of vaccines to boost adaptive immune responses. To select an efficient adjuvant from the heat-labile toxin B subunit (LTB) of E. coli, four LTB mutants (numbered LTB26, LTB34, LTB57, and LTB85) were generated by multi-amino acid random replacement. Mice have been intranasally vaccinated with human rotavirus VP8 admixed. Among the four mutants, enzyme-linked immunosorbent assay (ELISA) revealed that LTB26 had enhanced mucosal immune adjuvanticity compared to LTB, showing significantly enhanced immune responses in both serum IgG and mucosal sIgA levels. The 3D modeling analysis suggested that the enhanced immune adjuvanticity of LTB26 might be due to the change of the first LTB α-helix to a β-sheet. The molecular mechanism was studied using transcriptomic and flow cytometric (FCM) analysis. The transcriptomic data demonstrated that LTB26 enhanced immune response by enhancing B cell receptor (BCR) and major histocompatibility complex (MHC) II+-related pathways. Furthermore, LTB26 promoted Th1 and Th2-type immune responses which were confirmed by detecting IFN-γ and IL-4 expression levels. Immunohistochemical analysis demonstrated that LTB26 enhanced both Th1 and Th2 type immunity. Therefore, LTB26 was a potent mucosal immune adjuvant meeting the requirement for use in human clinics in the future.

Novel Administration Routes, Delivery Vectors, and Application of Vaccines Based on Biotechnologies: A Review

Traditional vaccines can be classified into inactivated vaccines, live attenuated vaccines, and subunit vaccines given orally or via intramuscular (IM) injection or subcutaneous (SC) injection for the prevention of infectious diseases. Recently, recombinant protein vaccines, DNA vaccines, mRNA vaccines, and multiple/alternative administering route vaccines (e.g., microneedle or inhalation) have been developed to make vaccines more secure, effective, tolerable, and universal for the public. In addition to preventing infectious diseases, novel vaccines have currently been developed or are being developed to prevent or cure noninfectious diseases, including cancer. These vaccine platforms have been developed using various biotechnologies such as viral vectors, nanoparticles, mRNA, recombination DNA, subunit, novel adjuvants, and other vaccine delivery systems. In this review, we will explore the development of novel vaccines applying biotechnologies, such as vaccines based on novel administration routes, vaccines based on novel vectors, including viruses and nanoparticles, vaccines applied for cancer prevention, and therapeutic vaccines.