Pulmonary Antigen-presenting Cells Research Articles

Age-dependent changes in phagocytic activity: in vivo response of mouse pulmonary antigen presenting cells to direct lung delivery of charged PEGDA nanoparticles

BackgroundCurrent needle-based vaccination for respiratory viruses is ineffective at producing sufficient, long-lasting local immunity in the elderly. Direct pulmonary delivery to the resident local pulmonary immune cells can create long-term mucosal responses. However, criteria for drug vehicle design rules that can overcome age-specific changes in immune cell functions have yet to be established.ResultsHere, in vivo charge-based nanoparticle (NP) uptake was compared in mice of two age groups (2- and 16-months) within the four notable pulmonary antigen presenting cell (APC) populations: alveolar macrophages (AM), interstitial macrophages (IM), CD103+ dendritic cells (DCs), and CD11b+ DCs. Both macrophage populations exhibited preferential uptake of anionic nanoparticles but showed inverse rates of phagocytosis between the AM and IM populations across age. DC populations demonstrated preferential uptake of cationic nanoparticles, which remarkably did not significantly change in the aged group. Further characterization of cell phenotypes post-NP internalization demonstrated unique surface marker expression and activation levels for each APC population, showcasing heightened DC inflammatory response to NP delivery in the aged group.ConclusionThe age of mice demonstrated significant preferences in the charge-based NP uptake in APCs that differed greatly between macrophages and DCs. Carefully balance of the targeting and activation of specific types of pulmonary APCs will be critical to produce efficient, age-based vaccines for the growing elderly population.Graphical

γδ T Cells Mediate Pressure Overload-Induced Cardiac Inflammation, Hypertrophy, Heart Failure Development, and Heart Failure Progression

Gamma delta T cells (γδ T cells) are T cells that have a γδ T-cell receptor (TCR) on their surface. γδ T cells display broad functional plasticity following recognition of infected or injured cells by production of cytokines and chemokines, and cytolysis of the infected or injured cells. However, the role of γδ T cells in heart failure (HF) development and HF progression is unknown. To investigate the role of γδ T cells in HF development and progression, we studied the effect of transverse aortic constriction (TAC) on cardiac inflammation, hypertrophy, and dysfunction in both wild type and TCRδ gene deficient (TCRδ−/−) mice, as TCRδ−/− mice have no γδ T cells. Interestingly, TCRδ−/− significantly attenuated TAC-induced left ventricular (LV) hypertrophy as evidenced by less increase of LV weight and its ratio to bodyweight or tibial length. TCRδ−/− also significantly attenuated TAC-induced increase of lung weight, right ventricular weight, and their ratio to bodyweight or tibial length. TCRδ−/− also significantly reduced TAC-induced decease of LV ejection fraction and LV fractional shortening, and LV dilatation. Furthermore, TCRδ−/− significantly attenuated TAC-induced LV cardiomyocyte hypertrophy, fibrosis, and immune cell infiltration. Moreover, we found that TCRδ−/− significantly reduced TAC-induced infiltration and activation of pulmonary antigen presenting cells, CD4 T cells and CD8 T cells. Together, these data indicate that γδ T cells exert an important role in promoting systolic overload-induced cardiac inflammation, HF development, and HF progression. This work was supported by NIH research grants R01HL161085, R01HL139797, P20GM104357, and P30GM149404. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Paracoccidioides brasiliensis infection increases regulatory T cell counts in female C57BL/6 mice infected via two distinct routes.

Studies that show an overview of the peripheral immune response in a model of Paracoccidioides brasiliensis (Pb) infection in females are scarce in the literature. We sought to characterize the innate and adaptive immune responses in female C57BL/6 mice infected with Pb through two distinct routes of administration, intranasal and intravenous. In addition to the lung, P. brasiliensis yeast cells were observed in liver and brain tissues of females infected intravenously. To our knowledge, our study is the first to prove the presence of this pathogenic fungus in the cerebral cortex of female mice. During the initial stages of infection, augmented expression of both MHCII and CD86 was observed on the surface of CD11c+ pulmonary antigen-presenting cells (APCs) in intranasally and intravenously infected females. However, CD40 expression was downregulated in these cells. Concomitantly with increasing serum IL-10 levels, we noted that splenic dendritic cells (DCs) from both intravenously- and intranasally-infected female mice had acquired an immature phenotype. Further, increased T regulatory cell counts were observed in female mice infected via both routes, along with an increase in the infiltration of IL-10-producing CD8+ T cells into the lungs. Moreover, we noted that P. brasiliensis infection resulted in enhanced IL-10 production - by CD11c+ APCs in the lung tissue - and induction of Th17 polarization. Taken together, our results suggest that P. brasiliensis could modulates the immune response in female mice by influencing the balance between regulatory T cells (Tregs) and Th17 polarization.

An inhalable nanoparticulate STING agonist synergizes with radiotherapy to confer long-term control of lung metastases

Mounting evidence suggests that the tumor microenvironment is profoundly immunosuppressive. Thus, mitigating tumor immunosuppression is crucial for inducing sustained antitumor immunity. Whereas previous studies involved intratumoral injection, we report here an inhalable nanoparticle-immunotherapy system targeting pulmonary antigen presenting cells (APCs) to enhance anticancer immunity against lung metastases. Inhalation of phosphatidylserine coated liposome loaded with STING agonist cyclic guanosine monophosphate–adenosine monophosphate (NP-cGAMP) in mouse models of lung metastases enables rapid distribution of NP-cGAMP to both lungs and subsequent uptake by APCs without causing immunopathology. NP-cGAMP designed for enhanced cytosolic release of cGAMP stimulates STING signaling and type I interferons production in APCs, resulting in the pro-inflammatory tumor microenvironment in multifocal lung metastases. Furthermore, fractionated radiation delivered to one tumor-bearing lung synergizes with inhaled NP-cGAMP, eliciting systemic anticancer immunity, controlling metastases in both lungs, and conferring long-term survival in mice with lung metastases and with repeated tumor challenge.

Mucosal Immunization with a pH-Responsive Nanoparticle Vaccine Induces Protective CD8+ Lung-Resident Memory T Cells.

Tissue-resident memory T cells (TRM) patrol nonlymphoid organs and provide superior protection against pathogens that commonly infect mucosal and barrier tissues, such as the lungs, intestine, liver, and skin. Thus, there is a need for vaccine technologies that can induce a robust, protective TRM response in these tissues. Nanoparticle (NP) vaccines offer important advantages over conventional vaccines; however, there has been minimal investigation into the design of NP-based vaccines for eliciting TRM responses. Here, we describe a pH-responsive polymeric nanoparticle vaccine for generating antigen-specific CD8+ TRM cells in the lungs. With a single intranasal dose, the NP vaccine elicited airway- and lung-resident CD8+ TRM cells and protected against respiratory virus challenge in both sublethal (vaccinia) and lethal (influenza) infection models for up to 9 weeks after immunization. In elucidating the contribution of material properties to the resulting TRM response, we found that the pH-responsive activity of the carrier was important, as a structurally analogous non-pH-responsive control carrier elicited significantly fewer lung-resident CD8+ T cells. We also demonstrated that dual-delivery of protein antigen and nucleic acid adjuvant on the same NP substantially enhanced the magnitude, functionality, and longevity of the antigen-specific CD8+ TRM response in the lungs. Compared to administration of soluble antigen and adjuvant, the NP also mediated retention of vaccine cargo in pulmonary antigen-presenting cells (APCs), enhanced APC activation, and increased production of TRM-related cytokines. Overall, these data suggest a promising vaccine platform technology for rapid generation of protective CD8+ TRM cells in the lungs.

Tissue-resident monocytes promote the establishment of lung-resident CD8 T cell memory following influenza infection

Abstract Lung tissue resident memory CD8 T cells (TRM) have been shown to be critical in protecting against heterologous influenza virus challenge by limiting early viral replication and promoting more rapid viral clearance. Unlike other mucosal tissues, we have found that environmental signals are insufficient for the establishment of lung TRM, and that pulmonary antigen encounter is necessary for TRM to differentiate in the lung. This indicates a likely role for pulmonary antigen presenting cells (APC’s) in the process of lung TRM development, and thus we investigated the role of lung APC subsets on the establishment of lung CD8 TRM following influenza infection. Although many lung APC subsets contain flu nucleoprotein (FluNP) over the course of infection, most lung APC’s do not contain FluNP once virus has been cleared by day 10 post-infection. In contrast, lung monocytes continue to have high numbers of FluNP-bearing cells through day 15 post infection, the same time we observe the appearance of flu-specific CD8 T cells with a TRM phenotype. As these data suggest a potential role for monocytes as drivers of TRM differentiation, we tested mice deficient for the chemokine receptor CCR2 (CCR2−/−), which have a significant defect in the recruitment of monocytes to the lung. In our murine influenza model these CCR2−/− mice had significantly less flu-specific lung CD8 TRM than WT controls. Notably, this defect was not observed in the flu-specific CD8 memory T cells in the lung vasculature or mediastinal lymph node (MedLN), indicating this effect is specific for tissue-resident memory cells. Thus, these data show that antigen presentation by CCR2+ monocytes have a likely role in the lung in the establishment of lung CD8 TRM.

Nanoparticle surface charge impacts distribution, uptake and lymph node trafficking by pulmonary antigen-presenting cells

Nanoparticle surface charge impacts distribution, uptake and lymph node trafficking by pulmonary antigen-presenting cells

Nanoparticle surface charge impacts distribution, uptake and lymph node trafficking by pulmonary antigen-presenting cells

Engineered nanoparticles have the potential to expand the breadth of pulmonary therapeutics, especially as respiratory vaccines. Notably, cationic nanoparticles have been demonstrated to produce superior local immune responses following pulmonary delivery; however, the cellular mechanisms of this increased response remain unknown. To this end, we investigated the cellular response of lung APCs following pulmonary instillation of anionic and cationic charged nanoparticles. While nanoparticles of both surface charges were capable of trafficking to the draining lymph node and were readily internalized by alveolar macrophages, both CD11b and CD103 lung dendritic cell (DC) subtypes preferentially associated with cationic nanoparticles. Instillation of cationic nanoparticles resulted in the upregulation of Ccl2 and Cxc10, which likely contributes to the recruitment of CD11b DCs to the lung. In total, these cellular mechanisms explain the increased efficacy of cationic formulations as a pulmonary vaccine carrier and provide critical benchmarks in the design of pulmonary vaccine nanoparticles. From the Clinical EditorAdvance in nanotechnology has allowed the production of precise nanoparticles as vaccines. In this regard, pulmonary delivery has the most potential. In this article, the authors investigated the interaction of nanoparticles with various types of lung antigen presenting cells in an attempt to understand the cellular mechanisms. The findings would further help the future design of much improved vaccines for clinical use.

Distinct regulation of Th2 and Th17 responses to allergens by pulmonary antigen presenting cells in vivo

Accumulating evidence demonstrates that both Th2 and Th17 responses are involved in the pathogenesis of allergic airway inflammation in animals as well as in humans. The lung contains diverse types of antigen presenting cells. However, the mechanism by which these antigen presenting cells regulate Th2 versus Th17 responses in the lung remains incompletely understood. Here, we show that intranasal administration of fungal protease allergen induced both Th2 and Th17 responses in the lung with different kinetics. Notably, depletion of CD11c+ cells or macrophages greatly diminished the numbers of allergen-specific Th2 cells in the lung, the infiltration of eosinophils into the airway and airway hyperreactivity. In sharp contrast, depletion of the same antigen presenting cells significantly increased the numbers of allergen-specific Th17 cells in the lung and the infiltration of neutrophils into the airway. Moreover, although a subpopulation of lung epithelial cells express MHC II, lack of MHC II expression in parenchymal cells did not alter pulmonary Th2 and Th17 responses. Our results demonstrate that antigen presenting cells differentially regulate the generation of pulmonary Th2 and Th17 cells in response to intranasal protease allergens.

Age related pharmacokinetic and pharmacodynamic response of intranasal rGM-CSF (P4190)

Abstract Respiratory syncytial virus (RSV) is one of the leading causes of respiratory tract infections in children. Nearly every child will be infected by the age of two, yet there is currently no vaccine or effective treatment for RSV infection. Previous studies have shown that immunotherapy, such as recombinant GM-CSF (rGM-CSF), expedites viral clearance, likely due to increased activation and accumulation of pulmonary antigen-presenting cells (APCs). This study examines the pharmacokinetics and pharmacodynamics of a weight-based, inhaled rGM-CSF dose in infant compared to adult mice. Using a Luminex assay, the concentration of rGM-CSF in digested lung tissue and blood was analyzed over 24 hours. In lung digest, rGM-CSF was rapidly detected in both ages with levels peaking at 1 hour and decreasing to endogenous levels by 8 hours. rGM-CSF levels in the blood peaked at 0.5 hours and decreased by 4 hours in pups, while adult levels peaked at 1 hour and decreased by 8 hours. Whole lung was analyzed by flow cytometry for macrophage activation at 4, 8, 24, and 48 hours post dose. In pups and adults, CD11c+/CD11b+ expression increased, suggesting activation or infiltration of APCs. CD86 and MHC class II expression increased significantly in adults, with a more marked MHCII increase at 48 hours. Using a non-compartmental pharmacokinetic modeling approach, we predict that increasing the dose from 50 to 170ng/g will achieve similar biological outcomes in pup compared to adult mice.

Protective efficacy of CD4 memory T cells depends on route of administration of inactivated influenza vaccine (113.31)

Abstract Studies aimed at determining the impact route of influenza vaccination has on vaccine efficacy revealed reduced protection against influenza virus challenge afforded by intranasal delivery compared to subcutaneous delivery of inactivated H1N1 influenza A virus. Both vaccine routes induced similar anti-viral antibody titers, similar numbers of anti-viral CD4 T cells, and undetectable anti-viral CD8 T cell responses. Further analysis of vaccine-induced CD4 memory T cell responses revealed that CD4 memory T cells primed in the lung draining lymph nodes were defective in recruiting anti-viral CD8 effectors to the lungs during challenge infections compared to the recruitment of CD8 effectors to the lungs by peripherally primed CD4 memory T cells. Since the influx of anti-viral CD8 effector T cells to the airways during influenza virus infection is a key event for virus control and elimination, we assayed for the expression of type-1 chemoattractants in the respiratory tract of vaccinated mice following challenge infection and discovered reduced lung expression of chemoattractants in the presence of intranasally primed CD4 memory T cells. We also determined that the presence of intranasally primed CD4 memory T cells reduced the ability of pulmonary antigen presenting cells to stimulate CD8 effectors directly ex vivo. We are currently assessing whether route of influenza vaccination also impacts susceptibility to secondary bacterial pneumonia following influenza challenge.

Effect of BSA Antigen Sensitization during the Acute Phase of Influenza A Viral Infection on CD11c+ Pulmonary Antigen Presenting Cells

Influenza A viral infection is concerned with induction of asthma. CD11c+ pulmonary antigen presenting cells (APCs) play a central role in sensitization with inhaled antigens during the acute phase of influenza A viral infection and also reside on bronchial epithelium for the long term after sensitization. To investigate the role of CD11c+ pulmonary APCs in the inhaled antigen sensitization during the acute phase of influenza A viral infection, we analyzed their function. Mice were infected with influenza A virus and were sensitized intranasally with BSA/alum during the acute phase of influenza A viral infection. Expression of surface antigens on CD11c+ pulmonary APCs was analyzed by FACS. Cytokine production from CD11c+ pulmonary APCs, and interaction between CD11c+ pulmonary APCs and naïve CD4+ T cells was assessed by ELISA. Ability of antigen presentation by CD11c+ pulmonary APCs was measured by proliferation assay. BSA antigen sensitization during the acute phase of influenza A viral infection induced eosinophil recruitment into the lungs after BSA antigen challenge and moderately increased expression of MHC class II molecules on CD11c+ pulmonary APCs. The interaction between the CD11c+ pulmonary APCs and naïve CD4+ T cells secreted large amounts of IL-10. BSA antigen sensitization during the acute phase of influenza A viral infection enhanced IL-10 production from naïve CD4+ T cell interaction with CD11c+ pulmonary APCs. The IL-10 secretion evoked Th2 responses in the lungs with downregulation of Th1 responses and was important for the eosinophil recruitment into the lungs after BSA antigen challenge.

Inhaled CD86 Antisense Oligonucleotide Suppresses Pulmonary Inflammation and Airway Hyper-Responsiveness in Allergic Mice

The B7-family molecule CD86, expressed on the surface of pulmonary and thoracic lymph node antigen-presenting cells, delivers essential costimulatory signals for T-cell activation in response to inhaled allergens. CD86-CD28 signaling is involved in priming allergen-specific T cells, but it is unclear whether these interactions play a role in coordinating memory T-helper 2 cell responses. In the ovalbumin (OVA)-induced mouse model of asthma, administration of CD86-specific antibody before systemic sensitization suppresses inhaled OVA-induced pulmonary inflammation and airway hyper-responsiveness (AHR). In previously OVA-sensitized mice, systemic and intranasal coadministration of CD86 antibody is required to produce these effects. To directly assess the importance of pulmonary CD86 expression in secondary immune responses to inhaled allergens, mice were sensitized and locally challenged with nebulized OVA before treatment with an inhaled aerosolized CD86 antisense oligonucleotide (ASO). CD86 ASO treatment suppressed OVA-induced up-regulation of CD86 protein expression on pulmonary dendritic cells and macrophages as well as on recruited eosinophils. Suppression of CD86 protein expression correlated with decreased methacholine-induced AHR, airway inflammation, and mucus production following rechallenge with inhaled OVA. CD86 ASO treatment reduced BAL eotaxin levels, but it did not reduce CD86 protein on cells in the draining lymph nodes of the lung, and it had no effect on serum IgE levels, suggesting a local and not a systemic effect. These results demonstrate that CD86 expression on pulmonary antigen-presenting cells plays a vital role in regulating pulmonary secondary immune responses and suggest that treatment with an inhaled CD86 ASO may have utility in asthma and other chronic inflammatory lung conditions.

Granulocyte-macrophage colony-stimulating factor expressed by recombinant respiratory syncytial virus attenuates viral replication and increases the level of pulmonary antigen-presenting cells.

An obstacle to developing a vaccine against human respiratory syncytial virus (RSV) is that natural infection typically does not confer solid immunity to reinfection. To investigate methods to augment the immune response, recombinant RSV (rRSV) was constructed that expresses murine granulocyte-macrophage colony-stimulating factor (mGM-CSF) from a transcription cassette inserted into the G-F intergenic region. Replication of rRSV/mGM-CSF in the upper and lower respiratory tracts of BALB/c mice was reduced 23- to 74- and 5- to 588-fold, respectively, compared to that of the parental rRSV. Despite this strong attenuation of replication, the level of RSV-specific serum antibodies induced by rRSV/mGM-CSF was comparable to, or marginally higher than, that of the parental rRSV. The induction of RSV-specific CD8(+) cytotoxic T cells was moderately reduced during the initial infection, which might be a consequence of reduced antigen expression. Mice infected with rRSV/mGM-CSF had elevated levels of pulmonary mRNA for gamma interferon (IFN-gamma) and interleukin 12 (IL-12) p40 compared to animals infected by wild-type rRSV. Elevated synthesis of IFN-gamma could account for the restriction of RSV replication, as was observed previously with an IFN-gamma-expressing rRSV. The accumulation of total pulmonary mononuclear cells and total CD4(+) T lymphocytes was accelerated in animals infected with rRSV/mGM-CSF compared to that in animals infected with the control virus, and the level of IFN-gamma-positive or IL-4-positive pulmonary CD4(+) cells was elevated approximately twofold. The number of pulmonary lymphoid and myeloid dendritic cells and macrophages was increased up to fourfold in mice infected with rRSV/mGM-CSF compared to those infected with the parental rRSV, and the mean expression of major histocompatibility complex class II molecules, a marker of activation, was significantly increased in the two subsets of dendritic cells. Enhanced antigen presentation likely accounts for the maintenance of a strong antibody response despite reduced viral replication and would be a desirable property for a live attenuated rRSV vaccine.