Pulmonary Vaccination Research Articles

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 48h, 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.

Predicting major clinical events among Canadian adults with laboratory-confirmed influenza infection using the influenza severity scale

We developed and validated the Influenza Severity Scale (ISS), a standardized risk assessment for influenza, to estimate and predict the probability of major clinical events in patients with laboratory-confirmed infection. Data from the Canadian Immunization Research Network’s Serious Outcomes Surveillance Network (2011/2012–2018/2019 influenza seasons) enabled the selecting of all laboratory-confirmed influenza patients. A machine learning-based approach then identified variables, generated weighted scores, and evaluated model performance. This study included 12,954 patients with laboratory-confirmed influenza infections. The optimal scale encompassed ten variables: demographic (age and sex), health history (smoking status, chronic pulmonary disease, diabetes mellitus, and influenza vaccination status), clinical presentation (cough, sputum production, and shortness of breath), and function (need for regular support for activities of daily living). As a continuous variable, the scale had an AU-ROC of 0.73 (95% CI, 0.71–0.74). Aggregated scores classified participants into three risk categories: low (ISS < 30; 79.9% sensitivity, 51% specificity), moderate (ISS ≥ 30 but < 50; 54.5% sensitivity, 55.9% specificity), and high (ISS ≥ 50; 51.4% sensitivity, 80.5% specificity). ISS demonstrated a solid ability to identify patients with hospitalized laboratory-confirmed influenza at increased risk for Major Clinical Events, potentially impacting clinical practice and research.

Lung IL-17A-Producing CD4+ T Cells Correlate with Protection after Intrapulmonary Vaccination with Differentially Adjuvanted Tuberculosis Vaccines.

Tuberculosis (TB), caused by Mycobacterium tuberculosis, results in approximately 1.6 million deaths annually. BCG is the only TB vaccine currently in use and offers only variable protection; however, the development of more effective vaccines is hindered by a lack of defined correlates of protection (CoP) against M. tuberculosis. Pulmonary vaccine delivery is a promising strategy since it may promote lung-resident immune memory that can respond rapidly to respiratory infection. In this study, CysVac2, a subunit protein previously shown to be protective against M. tuberculosis in mouse models, was combined with either Advax® adjuvant or a mixture of alum plus MPLA and administered intratracheally into mice. Peripheral immune responses were tracked longitudinally, and lung-local immune responses were measured after challenge. Both readouts were then correlated with protection after M. tuberculosis infection. Although considered essential for the control of mycobacteria, induction of IFN-γ-expressing CD4+ T cells in the blood or lungs did not correlate with protection. Instead, CD4+ T cells in the lungs expressing IL-17A correlated with reduced bacterial burden. This study identified pulmonary IL-17A-expressing CD4+ T cells as a CoP against M. tuberculosis and suggests that mucosal immune profiles should be explored for novel CoP.

Vaccination with mycobacterial lipid loaded nanoparticle leads to lipid antigen persistence and memory differentiation of antigen-specific T cells

Mycobacterium tuberculosis (Mtb) infection elicits both protein and lipid antigen-specific T cell responses. However, the incorporation of lipid antigens into subunit vaccine strategies and formulations has been underexplored, and the characteristics of vaccine-induced Mtb lipid-specific memory T cells have remained elusive. Mycolic acid (MA), a major lipid component of the Mtb cell wall, is presented by human CD1b molecules to unconventional T cell subsets. These MA-specific CD1b-restricted T cells have been detected in the blood and disease sites of Mtb-infected individuals, suggesting that MA is a promising lipid antigen for incorporation into multicomponent subunit vaccines. In this study, we utilized the enhanced stability of bicontinuous nanospheres (BCN) to efficiently encapsulate MA for in vivo delivery to MA-specific T cells, both alone and in combination with an immunodominant Mtb protein antigen (Ag85B). Pulmonary administration of MA-loaded BCN (MA-BCN) elicited MA-specific T cell responses in humanized CD1 transgenic mice. Simultaneous delivery of MA and Ag85B within BCN activated both MA- and Ag85B-specific T cells. Notably, pulmonary vaccination with MA-Ag85B-BCN resulted in the persistence of MA, but not Ag85B, within alveolar macrophages in the lung. Vaccination of MA-BCN through intravenous or subcutaneous route, or with attenuated Mtb likewise reproduced MA persistence. Moreover, MA-specific T cells in MA-BCN-vaccinated mice differentiated into a T follicular helper-like phenotype. Overall, the BCN platform allows for the dual encapsulation and in vivo activation of lipid and protein antigen-specific T cells and leads to persistent lipid depots that could offer long-lasting immune responses.

Vaccination with mycobacterial lipid loaded nanoparticle leads to lipid antigen persistence and memory differentiation of antigen-specific T cells.

Mycobacterium tuberculosis (Mtb) infection elicits both protein and lipid antigen-specific T cell responses. However, the incorporation of lipid antigens into subunit vaccine strategies and formulations has been underexplored, and the characteristics of vaccine-induced Mtb lipid-specific memory T cells have remained elusive. Mycolic acid (MA), a major lipid component of the Mtb cell wall, is presented by human CD1b molecules to unconventional T cell subsets. These MA-specific CD1b-restricted T cells have been detected in the blood and disease sites of Mtb-infected individuals, suggesting that MA is a promising lipid antigen for incorporation into multicomponent subunit vaccines. In this study, we utilized the enhanced stability of bicontinuous nanospheres (BCN) to efficiently encapsulate MA for in vivo delivery to MA-specific T cells, both alone and in combination with an immunodominant Mtb protein antigen (Ag85B). Pulmonary administration of MA-loaded BCN (MA-BCN) elicited MA-specific T cell responses in humanized CD1 transgenic mice. Simultaneous delivery of MA and Ag85B within BCN activated both MA- and Ag85B-specific T cells. Notably, pulmonary vaccination with MA-Ag85B-BCN resulted in the persistence of MA, but not Ag85B, within alveolar macrophages in the lung. Vaccination of MA-BCN through intravenous or subcutaneous route, or with attenuated Mtb likewise reproduced MA persistence. Moreover, MA-specific T cells in MA-BCN-vaccinated mice differentiated into a T follicular helper-like phenotype. Overall, the BCN platform allows for the dual encapsulation and in vivo activation of lipid and protein antigen-specific T cells and leads to persistent lipid depots that could offer long-lasting immune responses.

Immunity due to COVID-19 vaccination and its correlation with lung involvement severity as an indicator of disease severity

Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is a worldwide challenge; regarding the lack of an effective and efficient drug. It seems that the vaccine is the only modality to save the world from this pandemic. Objectives: This study was conducted to assess the effect of vaccination on preventing pulmonary involvement and the disease severity of COVID-19 patients. Patients and Methods: This descriptive-analytical study was conducted on 247 people with coronavirus disease 2019 infection. Demographic characteristics and vaccination status information were collected. Patients’ lung computed tomography scan findings were scored based on the pulmonary involvement percentage, and then according to this score, they were graded into severe, moderate, mild, and without lung involvement. The association between pulmonary involvement and vaccination status were evaluated by Fisher’s exact test and logistic regression. Results: Most participants were male, with a mean age of 53.74 ± 10.96 years. Most people (42.9%) were partial-vaccinated. Lungs in 53.3% were with lung involvement and in 46.6% were without. The correlation between pulmonary involvement and vaccination was significant (P&lt;0.001). Conclusion: Vaccination is an effective and efficient method in preventing coronavirus disease 2019 severity.

In silico EsxG EsxH rational epitope selection: Candidate epitopes for vaccine design against pulmonary tuberculosis.

Rational design of new vaccines against pulmonary tuberculosis is imperative. Early secreted antigens (Esx) G and H are involved in metal uptake, drug resistance, and immune response evasion. These characteristics make it an ideal target for rational vaccine development. The aim of this study is to show the rational design of epitope-based peptide vaccines by using bioinformatics and structural vaccinology tools. A total of 4.15 μs of Molecular Dynamics simulations were carried out to describe the behavior in solution of heterodimer, single epitopes, and epitopes loaded into MHC-II complexes. In order to predict T and B cell epitopes for antigenic activation, bioinformatic tools were used. Hence, we propose three epitopes with the potential to design pulmonary tuberculosis vaccines. The possible use of the proposed epitopes includes subunit vaccines, as a booster in BCG vaccination to improve its immune response, as well as the generation of antibodies that interfere with the Mycobacterium tuberculosis homeostasis, affecting its survival.

Aluminum-based metal–organic framework nanoparticles as pulmonary vaccine adjuvants

The adoption of pulmonary vaccines to advantageously provide superior local mucosal protection against aerosolized pathogens has been faced with numerous logistical and practical challenges. One of these persistent challenges is the lack of effective vaccine adjuvants that could be well tolerated through the inhaled route of administration. Despite its widespread use as a vaccine adjuvant, aluminum salts (alum) are not well tolerated in the lung. To address this issue, we evaluated the use of porous aluminum (Al)-based metal–organic framework (MOF) nanoparticles (NPs) as inhalable adjuvants. We evaluate a suite of Al-based MOF NPs alongside alum including DUT-4, DUT-5, MIL-53 (Al), and MIL-101-NH2 (Al). As synthesized, MOF NPs ranged between ~ 200 nm and 1 µm in diameter, with the larger diameter MOFs matching those of commercial alum. In vitro examination of co-stimulatory markers revealed that the Al-based MOF NPs activated antigen presenting cells more effectively than alum. Similar results were found during in vivo immunizations utilizing ovalbumin (OVA) as a model antigen, resulting in robust mucosal humoral responses for all Al MOFs tested. In particular, DUT-5 was able to elicit mucosal OVA-specific IgA antibodies that were significantly higher than the other MOFs or alum dosed at the same NP mass. DUT-5 also was uniquely able to generate detectable IgG2a titers, indicative of a cellular immune response and also had superior performance relative to alum at equivalent Al dosed in a reduced dosage vaccination study. All MOF NPs tested were generally well-tolerated in the lung, with only acute levels of cellular infiltrates detected and no Al accumulation; Al content was largely cleared from the lung and other organs at 28 days despite the two-dose regime. Furthermore, all MOF NPs exhibited mass median aerodynamic diameters (MMADs) of ~ 1.5–2.5 µm when dispersed from a generic dry powder inhaler, ideal for efficient lung deposition. While further work is needed, these results demonstrate the great potential for use of Al-based MOFs for pulmonary vaccination as novel inhalable adjuvants.Graphical

Cesarean section in Swyer-James-Macleod syndrome: Anesthesia implications.

Dear Editor, Swyer-James-MacLeod Syndrome (SJMS) is a rare, acquired postinfectious condition characterized by bronchiectasis or emphysematous changes.[1,2] These patients have a high risk of perioperative pulmonary complications. A 28-year-old primigravida, at 24 weeks of gestation, came with dyspnea on exertion (grade-3) for the 3 months with no history of recurrent infections. On examination, there was diminished breath sounds on the left side. Chest radiograph (done with abdominal shield) showed left hyperlucent lung with reduced vascular markings and slight mediastinal shift. Rest of the investigations were normal. The patient was referred to chest physician for optimization and a diagnosis of Swyer-James syndrome with left lung bulla/pneumothorax was made. The patient was managed with bronchodilators (Metered-Dose Inhaler levosalbutamol and Tiotropium bromide) and breathing exercises (pursed-lip breathing, diaphragmatic breathing). Spirometry was not done since the patient was in the second trimester of pregnancy. The patient got symptomatically better and an elective cesarean section was planned. Blood gas analysis performed a day before surgery showed PH: 7.441, PCO2:25.6, PO2 = 70.6, Bicarbonate = 17, Base excess = 7.21, Oxygen saturation = 94.4%. High-risk written consent was taken and expected complications were explained. On the day of surgery, the patient was taken in the operation theatre after giving inhalational bronchodilators. Ondansetron 4 mg and ranitidine hydrochloride 50 mg were given intravenously 30 min prior to surgery. A 20-G intravenous cannula was secured, Ringer lactate was started and vital parameters were monitored. Spinal anesthesia with 10 mg of heavy bupivacaine and 25 micrograms of fentanyl in the right lateral position was given. The intraoperative period was uneventful. SJMS was first described in 1953 by Swyer and James, and later explained in detail by MacLeod. A chest radiograph demonstrates lobar or unilateral hyperlucent lung and normal or reduced volume of the affected lung. Patients can present with a multitude of symptoms ranging from asymptomatic with incidental radiographical diagnosis to severe symptoms such as dyspnea and repeated pulmonary infections.[1,2] This syndrome is usually diagnosed in childhood after an evaluation for recurrent respiratory infections, but sometimes they are asymptomatic and may be diagnosed in adulthood.[3,4] In a case series by S. S. Hadice et al.,[3] three out of four patients had no history of airway infection in childhood and were diagnosed in adulthood. The clinical incidence of SJMS in pregnancy is 1:2500.[2] The management focuses on early diagnosis, prevention, and treatment of recurrent pulmonary infections and vaccine administration.[2–4] Severe cases of SJMS may require anesthetic care cautiously tailored to significant obstructive pulmonary physiology.[5] Regional anesthesia should be preferred whenever feasible. Chopra S et al.,[2] reported the successful delivery in a case of SJMS under spinal anesthesia in emergency. Labor epidural anesthesia can also be used in electively scheduled patients and supplemented with low-dose spinal anesthesia before surgery, if required. General anesthesia is associated with risk of bulla rupture, worsening of pneumothorax, and other pulmonary complications. Drugs that can cause histamine release and bronchoconstriction should be avoided. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient and her father have given their consent for his images and other clinical information to be reported in the journal. The patient and father understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Pulmonary Administration of the Liposome-Based Adjuvant CAF01: Effect of Surface Charge on Mucosal Adjuvant Function

Mucosal surfaces of the lungs represent a major site of entry for airborne pathogens, and pulmonary administration of vaccines is an attractive strategy to induce protective mucosal immunity in the airways. Recently, we demonstrated the potential of pulmonary vaccination with the tuberculosis subunit antigen H56 adjuvanted with the cationic liposomal adjuvant formulation CAF01, which consists of the cationic lipid dimethyldioctadecylammonium (DDA) bromide and the synthetic cord factor trehalose-6,6'-dibehenate. However, the cationic charge of DDA represents a major safety challenge. Hence, replacing DDA with a safer zwitterionic or anionic phospholipid is an attractive approach to improve vaccine safety, but the effect of liposomal surface charge on the induction of mucosal immunity after airway immunization is poorly understood. Here, we investigated the effect of surface charge by replacing the cationic DDA component of CAF01 with zwitterionic dipalmitoylphosphatidylcholine (DPPC) or anionic dipalmitoylphosphatidylglycerol (DPPG), and we show that charge modification enhances antigen-specific pulmonary T-cell responses against co-formulated H56. We systematically replaced DDA with either DPPC or DPPG and found that these modifications resulted in colloidally stable liposomes that have similar size and morphology to unmodified CAF01. DPPC- or DPPG-modified CAF01 displayed surface charge-dependent protein adsorption and induced slightly higher follicular helper T cells and germinal center B cells in the lung-draining lymph nodes than unmodified CAF01. In addition, modified CAF01 induced significantly higher levels of H56-specific Th17 cells and polyfunctional CD4+ T cells in the lungs, as compared to unmodified CAF01. However, the strong H56-specific humoral responses induced by CAF01 in the lungs and spleen were not influenced by surface charge. Hence, these results provide insights into the importance of surface charge for liposomal adjuvant function and can also guide the design of safe pulmonary subunit vaccines against other mucosal pathogens.

Eosinophils Recruited during Pulmonary Vaccination Regulate Mucosal Antibody Production.

Eosinophils have been previously shown to be able to regulate early humoral responses during systemic vaccination. Here we investigated the role of eosinophils during pulmonary vaccination, comparing vaccine-induced responses in eosinophil-deficient (ΔdblGATA) and wild-type mice using a Th2 adjuvant. We observed that eosinophils were needed to induce a complete vaccine response, thereby eliciting specific antibody-secreting plasma cells in the regional lymph nodes and antibody secretion in the BAL at the early stage of the immune response. Reintroduction of eosinophils in the lungs of ΔdblGATA mice during the priming stage enhanced both specific IgM and IgG plasma cells but not specific IgA plasma cells. Upon vaccination, eosinophils migrated to the lungs and secreted cytokines involved in B-cell activation, which might promote antibody production. Importantly, however, the absence of eosinophils did not impair late immune responses in a prime/boost protocol because, in that setup, we uncovered a compensating mechanism involving a Th17 pathway. In conclusion, our data demonstrate for the first time a new role for eosinophils during lung mucosal vaccination, whereby they accelerate early immune responses (IgM and IgG) while regulating IgA production at the late stages.

COVID-19 Variants in Critically Ill Patients: A Comparison of the Delta and Omicron Variant Profiles.

Background: Coronavirus disease is a pandemic that has disrupted many human lives, threatening people’s physical and mental health. Each pandemic wave struck in different ways, infectiveness-wise and mortality-wise. This investigation focuses on critically ill patients affected by the last two variants, Delta and Omicron, and aims to analyse if any difference exists between the two groups. Methods: intensive care unit (ICU) COVID-19 consecutive admissions between 1 October 2021 and 31 March 2022 were recorded daily, and data concerning the patients’ demographics, variants, main comorbidities, ICU parameters on admission, and the outcome were analysed by a univariate procedure and by a multivariate analysis. Results: 65 patients were enrolled, 31 (47.69%) belonging to the Omicron versus 34 (52.31%) to the Delta group. The mortality rate was 52.94% for the Omicron group versus 41.9% for the Delta group. A univariate analysis showed that the Omicron variant was associated with total comorbidities number, Charlson Comorbidity Index (CCI), pre-existing pulmonary disease, vaccination status, and acute kidney injury (AKI). In stepwise multivariate analysis, the total number of comorbidities was positively associated with the Omicron group, while pulmonary embolism was negatively correlated with the Omicron group. Conclusion: Omicron appears to have lost some of the hallmarks of the Delta variant, such as endothelialitis and more limited cellular tropism when it comes to the patients in the ICU. Further studies are encouraged to explore different therapeutic approaches to treat critical patients with COVID-19.

OP0178 COVID-19 BREAKTHROUGH INFECTIONS IN VACCINATED PATIENTS WITH IMMUNE-MEDIATED INFLAMMATORY DISEASES AND CONTROLS – DATA FROM TWO PROSPECTIVE COHORT STUDIES

BackgroundConcerns have been raised regarding risks of COVID-19 breakthrough infections in vaccinated patients with immune-mediated inflammatory diseases (IMIDs) treated with immunosuppressants, but data on COVID-19 breakthrough infections in these patients are still scarce.ObjectivesThe primary objective was to compare the incidence and severity of COVID-19 breakthrough infections with the SARS-CoV-2 delta variant between fully vaccinated IMID patients with immunosuppressants, and controls (IMID patients without immunosuppressants and healthy controls). The secondary objective was to explore determinants of breakthrough infections.MethodsIn this study we pooled data collected from two large ongoing prospective multi-center cohort studies (Target to-B! [T2B!] study and ARC study). Clinical data were collected between February and December 2021, using digital questionnaires, standardized electronic case record forms and medical files. Post-vaccination serum samples were analyzed for anti-RBD antibodies (T2B! study only) and anti-nucleocapsid antibodies to identify asymptomatic breakthrough infections (ARC study only). Logistic regression analyses were used to assess associations with the incidence of breakthrough infections. Multivariable models were adjusted for age, sex, cardiovascular disease, chronic pulmonary disease, obesity and vaccine type.ResultsWe included 3207 IMID patients with immunosuppressants and 1810 controls (985 IMID patients without immunosuppressants and 825 healthy controls). The incidence of COVID-19 breakthrough infections was comparable between patients with immunosuppressants (5%) and controls (5%). The absence of SARS-CoV-2 IgG antibodies after COVID-19 vaccination was independently associated with an increased incidence of breakthrough infections (P 0.044). The proportion of asymptomatic COVID-19 breakthrough cases that were additionally identified serologically in the ARC cohort was comparable between IMID patients with immunosuppressants and controls; 66 (10%) of 695 patients vs. 64 (10%) of 647 controls. Hospitalization was required in 8 (5%) of 149 IMID patients with immunosuppressants and 5 (6%) of 86 controls with a COVID-19 breakthrough infection. Hospitalized cases were generally older, and had more comorbidities compared with non-hospitalized cases (Table 1). Hospitalization rates were significantly higher among IMID patients treated with anti-CD20 therapy compared to IMID patients using any other immunosuppressant (3 [23%] of 13 patients vs. 5 [4%] of 128 patients, P 0.041; Table 1).Table 1.Determinants of the severity of COVID-19 breakthrough infections.Ambulatory care (n = 222)Hospitalized (n = 13)Group - no. (%)IMID patients with immunosuppressants141(64)8(62)IMID patients without immunosuppressants49(22)3(23)Healthy controls32(14)2(15)Patient characteristicsAge, years – mean (SD)51(14)60(11)Female sex – no. (%)143(64)4(31)Comorbidities – no. (%)Cardiovascular disease17(8)5(39)Chronic pulmonary disease17(8)4(31)Diabetes15(7)3(23)Obesity34(15)5(39)Immunosuppressants– no. (%)Methotrexate36(16)2(15)TNF inhibitor48(22)2(15)Anti-CD20 therapy13(6)3(23)Mycophenolate mofetil3(1)0(0)S1P modulator5(2)0(0)Other immunosuppressants70(32)3(23)ConclusionThe incidence of COVID-19 breakthrough infections in IMID patients with immunosuppressants was comparable to controls, and infections were mostly mild. Anti-CD20 therapy might increase patients’ susceptibility to severe COVID-19 breakthrough infections, but traditional risk factors also continue to have a critical contribution to the disease course of COVID-19. Therefore, we argue that most patients with IMIDs should not necessarily be seen as a risk group for severe COVID-19, and that integrating other risk factors should become standard practice when discussing treatment options, COVID-19 vaccination, and adherence to infection prevention measures with patients.Disclosure of InterestsNone declared

Chronic obstructive pulmonary disease and influenza vaccination effect in preventing outpatient and inpatient influenza cases

Evidence of influenza vaccine effectiveness in preventing confirmed influenza among persons diagnosed with chronic obstructive pulmonary disease (COPD) is scarce. We assessed the average effect of influenza vaccination in the current and prior seasons in preventing laboratory-confirmed influenza in COPD patients. We carried out a pooled test-negative case–control design in COPD patients hospitalized or presented to primary healthcare centres with influenza-like illness who were tested for influenza in 2015/2016 to 2019/2020 seasons in Navarre, Spain. Influenza vaccination status in the current and 5 prior seasons was compared between confirmed-influenza cases and test-negative controls. Vaccination effect was compared between target patients for vaccination with and without COPD. Out of 1761 COPD patients tested, 542 (31%) were confirmed for influenza and 1219 were test-negative controls. Average effect for current-season vaccination in preventing influenza was 40% (95% CI 20–54%), and for vaccination in prior seasons only was 24% (95% CI –10 to 47%). Point estimates seemed higher in preventing outpatient cases (60% and 58%, respectively) than inpatient cases (37% and 19%, respectively), but differences were no statistically significant. Influenza vaccination effect was similar in target population with and without COPD (p = 0.339). Influenza vaccination coverage in control patients with COPD was 68.3%. A 13.7% of the influenza cases in patients with COPD could be prevented by extending the influenza vaccine coverage. Average effect of current-season influenza vaccination was moderate to prevent influenza in COPD persons. The increase of influenza vaccination coverage can still prevent COPD exacerbations.

Development and Testing of a Spray-Dried Tuberculosis Vaccine Candidate in a Mouse Model.

Converting a vaccine into a thermostable dry powder is advantageous as it reduces the resource burden linked with the cold chain and provides flexibility in dosage and administration through different routes. Such a dry powder presentation may be especially useful in the development of a vaccine towards the respiratory infectious disease tuberculosis (TB). This study assesses the immunogenicity and protective efficacy of spray-dried ID93+GLA-SE, a promising TB vaccine candidate, against Mycobacterium tuberculosis (Mtb) in a murine model when administered via different routes. Four administration routes for the spray-dried ID93+GLA-SE were evaluated along with relevant controls—1) reconstitution and intramuscular injection, 2) reconstitution and intranasal delivery, 3) nasal dry powder delivery via inhalation, and 4) pulmonary dry powder delivery via inhalation. Dry powder intranasal and pulmonary delivery was achieved using a custom nose-only inhalation device, and optimization using representative vaccine-free powder demonstrated that approximately 10 and 44% of the maximum possible delivered dose would be delivered for intranasal delivery and pulmonary delivery, respectively. Spray-dried powder was engineered according to the different administration routes including maintaining approximately equivalent delivered doses of ID93 and GLA. Vaccine properties of the different spray-dried lots were assessed for quality control in terms of nanoemulsion droplet diameter, polydispersity index, adjuvant content, and antigen content. Our results using the Mtb mouse challenge model show that both intranasal reconstituted vaccine delivery as well as pulmonary dry powder vaccine delivery resulted in Mtb control in infected mice comparable to traditional intramuscular delivery. Improved protection in these two vaccinated groups over their respective control groups coincided with the presence of cytokine-producing T cell responses. In summary, our results provide novel vaccine formulations and delivery routes that can be harnessed to provide protection against Mtb infection.

Immunological Assessment of Lung Responses to Inhalational Lipoprotein Vaccines Against Bacterial Pathogens.

Lipopeptides or lipoproteins show potential as safe and effective subunit vaccines for protection against bacterial pathogens. Provided suitable adjuvants are selected, such as the TLR2-stimulating molecules Pam2Cys and Pam3Cys, these may be formulated as inhalational vaccines to optimize localized pulmonary immune responses. Here, we present methods to assess antigen-specific memory lymphocyte responses to novel vaccines, with a focus on immune responses in the lung tissue and bronchoalveolar space. We describe detection of T-cell responses via leukocyte restimulation, followed by intracellular cytokine staining and flow cytometry, enzyme-linked immunosorbent spot assay (ELISpot), and sustained leukocyte restimulation for detection of antigen-specific memory responses. We also detail assessment of antibody responses to vaccine antigens, via enzyme-linked immunosorbent assay (ELISA)-based detection. These methods are suitable for testing a wide range of pulmonary vaccines.

Pulmonary BCG induces lung-resident macrophage activation and confers long-term protection against tuberculosis.

Bacillus Calmette-Guerin (BCG) is an attenuated bacterial vaccine used to protect against Mycobacterium tuberculosis (Mtb) in regions where infections are highly prevalent. BCG is currently delivered by the intradermal route, but alternative routes of administration are of great interest, including intrapulmonary delivery to more closely mimic respiratory Mtb infection. In this study, mice subjected to pulmonary delivery of green fluorescent protein–tagged strains of virulent (Mtb) and attenuated (BCG) mycobacteria were studied to better characterize infected lung cell subsets. Profound differences in dissemination patterns were detected between Mtb and BCG, with a strong tendency of Mtb to disseminate from alveolar macrophages (AMs) to other myeloid subsets, mainly neutrophils and recruited macrophages. BCG mostly remained in AMs, which promoted their activation. These preactivated macrophages were highly efficient in containing Mtb bacilli upon challenge and disrupting early bacterial dissemination, which suggests a potential mechanism of protection associated with pulmonary BCG vaccination. Respiratory BCG also protected mice against a lethal Streptococcus pneumoniae challenge, suggesting that BCG-induced innate activation could confer heterologous protection against respiratory pathogens different from Mtb. BCG drove long-term activation of AMs, even after vaccine clearance, and these AMs reacted efficiently upon subsequent challenge. These results suggest the generation of a trained innate memory-like response in AMs induced by pulmonary BCG vaccination.

Intrapulmonary vaccination with delta-inulin adjuvant stimulates non-polarised chemotactic signalling and diverse cellular interaction

There is an urgent need for novel vaccination strategies to combat respiratory pathogens. Mucosal vaccine delivery is an attractive option as it directly targets the site of infection; however, preclinical development has been hindered by a lack of suitable mucosal adjuvants and a limited understanding of their immune effects in the lung environment. Herein, we define the early immune events following the intrapulmonary delivery of a vaccine incorporating the adjuvant delta-inulin. Analysis of the early inflammatory response showed vaccine-induced innate cell recruitment to lungs and local lymph nodes (LN) was transient and non-polarised, correlating with an increase in pulmonary chemotactic factors. Use of fluorescently labelled adjuvant revealed widespread tissue dissemination of adjuvant particles, coupled with broad cellular uptake and transit to the lung-draining LN by a range of innate immune cells. Mass cytometric analysis revealed extensive phenotypic changes in innate and adaptive cell subsets induced by vaccination; this included identification of unconventional lymphocytes such as γδ-T cells and MAIT cells that increased following vaccination and displayed an activated phenotype. This study details a comprehensive view of the immune response to intrapulmonary adjuvant administration and provides pre-clinical evidence to support delta-inulin as a suitable adjuvant for pulmonary vaccines.

Strategy to enhance dendritic cell-mediated DNA vaccination in the lung.

We here introduce a new paradigm to promote pulmonary DNA vaccination. Specifically, we demonstrate that nanoparticles designed to rapidly penetrate airway mucus (mucus-penetrating particle or MPP) enhance the delivery of inhaled model DNA vaccine (i.e. ovalbumin-expressing plasmids) to pulmonary dendritic cells (DC), leading to robust and durable local and trans-mucosal immunity. In contrast, mucus-impermeable particles were poorly taken up by pulmonary DC following inhalation, despite their superior ability to mediate DC uptake in vitro compared to MPP. In addition to the enhanced immunity achieved in mucosal surfaces, inhaled MPP unexpectedly provided significantly greater systemic immune responses compared to gold-standard approaches applied in the clinic for systemic vaccination, including intradermal injection and intramuscular electroporation. We also showed here that inhaled MPP significantly enhanced the survival of an orthotopic mouse model of aggressive lung cancer compared to the gold-standard approaches. Importantly, we discovered that MPP-mediated pulmonary DNA vaccination induced memory T-cell immunity, particularly the ready-to-act effector memory-biased phenotype, both locally and systemically. The findings here underscore the importance of breaching the airway mucus barrier to facilitate DNA vaccine uptake by pulmonary DC and thus to initiate full-blown immune responses.

Therapeutic efficacy of pulmonary live tuberculosis vaccines against established asthma by subverting local immune environment.

BackgroundSubstantial recent advances in the comprehension of the molecular and cellular mechanisms behind asthma have evidenced the importance of the lung immune environment for disease outcome, making modulation of local immune responses an attractive therapeutic target against this pathology. Live attenuated mycobacteria, such as the tuberculosis vaccine BCG, have been classically linked with a type 1 response, and proposed as possible modulators of the type 2 response usually associated with asthma.MethodsIn this study we used different acute and chronic murine models of asthma to investigate the therapeutic efficacy of intranasal delivery of the live tuberculosis vaccines BCG and MTBVAC by regulating the lung immune environment associated with airway hyperresponsiveness (AHR).FindingsIntranasal administration of BCG, or the novel tuberculosis vaccine candidate MTBVAC, abrogated AHR-associated hallmarks, including eosinophilia and lung remodeling. This correlated with the re-polarization of allergen-induced M2 macrophages towards an M1 phenotype, as well as with the induction of a strong allergen-specific Th1 response. Importantly, vaccine treatment was effective in a scenario of established chronic asthma where a strong eosinophil infiltration was already present prior to immunization. We finally compared the nebulization efficiency of clinical formulations of MTBVAC and BCG using a standard commercial nebulizer for potential aerosol application.InterpretationOur results demonstrate that pulmonary live tuberculosis vaccines efficiently revert established asthma in mice. These data support the further exploration of this approach as potential therapy against asthma.FundingSpanish Ministry of Science [grant numbers: BIO2014-5258P, RTI2018-097625-B-I00], Instituto de Salud Carlos III, Gobierno de Aragón/Fondo Social Europeo, University of Zaragoza [grant number: JIUZ-2018-BIO-01].