CpG in Combination with an Inhibitor of Notch Signaling Suppresses Formalin-Inactivated Respiratory Syncytial Virus-Enhanced Airway Hyperresponsiveness and Inflammation by Inhibiting Th17 Memory Responses and Promoting Tissue-Resident Memory Cells in Lungs

The potential role of CD8+ cytotoxic T lymphocytes and one branch connected with tissue-resident memory in non-luminal breast cancer

Advances in understanding the pathological mechanisms of breast cancer have resulted in the emergence of novel therapeutic strategies. However, triple-negative breast cancer (TNBC), a molecular subtype of breast cancer with a poor prognosis, lacks classical and general therapeutic targets, hindering the clinical application of several therapies to breast cancer. As insights into the unique immunity and molecular mechanisms of TNBC have become more extensive, immunotherapy has gradually become a valuable complementary approach to classical radiotherapy and chemotherapy. CD8+ cells are significant actors in the tumor immunity cycle; thus, research on TNBC immunotherapy is increasingly focused in this direction. Recently, CD8+ tissue-resident memory (TRM) cells, a subpopulation of CD8+ cells, have been explored in relation to breast cancer and found to seemingly play an undeniably important role in tumor surveillance and lymphocytic infiltration. In this review, we summarize the recent advances in the mechanisms and relative targets of CD8+ T cells, and discuss the features and potential applications of CD8+ TRM cells in non-luminal breast cancer immunotherapy.

Network analysis reveals age- and virus-specific circuits in nasal epithelial cells of extremely premature infants

BACKGROUND AND OBJECTIVES

Viral respiratory infections significantly affect young children, particularly extremely premature infants, resulting in high hospitalization rates and increased health-care burdens. Nasal epithelial cells, the primary defense against respiratory infections, are vital for understanding nasal immune responses and serve as a promising target for uncovering underlying molecular and cellular mechanisms.

METHODS

Using a trans-well pseudostratified nasal epithelial cell system, we examined age-dependent developmental differences and antiviral responses to influenza A and respiratory syncytial virus through systems biology approaches.

RESULTS

Our studies revealed differences in innate-receptor repertoires, distinct developmental pathways, and differentially connected antiviral network circuits between neonatal and adult nasal epithelial cells. Consensus network analysis identified unique and shared cellular-viral networks, emphasizing highly relevant virus-specific pathways, independent of viral replication kinetics.

CONCLUSION

This research highlights the importance of nasal epithelial cells in innate antiviral immune responses and offers crucial insights that allow for a deeper understanding of age-related differences in nasal epithelial cell immunity following respiratory virus infections.

Mycobacterium bovis BCG Given at Birth Followed by Inactivated Respiratory Syncytial Virus Vaccine Prevents Vaccine-Enhanced Disease by Promoting Trained Macrophages and Resident Memory T Cells

Respiratory syncytial virus (RSV) infects more than 60% of infants in their first year of life. Since an experimental formalin-inactivated (FI) RSV vaccine tested in the 1960s caused enhanced respiratory disease (ERD), few attempts have been made to vaccinate infants. ERD is characterized by Th2-biased responses, lung inflammation, and poor protective immune memory. Innate immune memory displays an increased nonspecific effector function upon restimulation, a process called trained immunity, or a repressed effector function upon restimulation, a process called tolerance, which participates in host defense and inflammatory disease. Mycobacterium bovis bacillus Calmette-Guérin (BCG) given at birth can induce trained immunity as well as heterologous Th1 responses. We speculate that BCG given at birth followed by FI-RSV may alleviate ERD and enhance protection through promoting trained immunity and balanced Th immune memory. Neonatal mice were given BCG at birth and then vaccinated with FI-RSV+Al(OH)3. BCG/FI-RSV+Al(OH)3 induced trained macrophages, tissue-resident memory T cells (TRM), and specific cytotoxic T lymphocytes (CTL) in lungs and inhibited Th2 and Th17 cell immune memory, all of which contributed to inhibition of ERD and increased protection. Notably, FI-RSV+Al(OH)3 induced tolerant macrophages, while BCG/FI-RSV+Al(OH)3 prevented the innate tolerance through promoting trained macrophages. Moreover, inhibition of ERD was attributed to trained macrophages or TRM in lungs but not memory T cells in spleens. Therefore, BCG given at birth to regulate trained immunity and TRM may be a new strategy for developing safe and effective RSV killed vaccines for young infants. IMPORTANCE RSV is the leading cause of severe lower respiratory tract infection of infants. ERD, characterized by Th2-biased responses, inflammation, and poor immune memory, has been an obstacle to the development of safe and effective killed RSV vaccines. Innate immune memory participates in host defense and inflammatory disease. BCG given at birth can induce trained immunity as well as heterologous Th1 responses. Our results showed that BCG/FI-RSV+Al(OH)3 induced trained macrophages, TRM, specific CTL, and balanced Th cell immune memory, which contributed to inhibition of ERD and increased protection. Notably, FI-RSV+Al(OH)3 induced tolerant macrophages, while BCG/FI-RSV+Al(OH)3 prevented tolerance through promoting trained macrophages. Moreover, inhibition of ERD was attributed to trained macrophages or TRM in lungs but not memory T cells in spleens. BCG at birth as an adjuvant to regulate trained immunity and TRM may be a new strategy for developing safe and effective RSV killed vaccines for young infants.

PLZF promotes the development of asthma tolerance via affecting memory phenotypes of immune cells

Clarifying the pathogenesis of asthma and/or identifying the specific pathway underlying oral asthma tolerance (OT) would be of great significance. In our previous study, promyelocytic leukemia zinc finger (PLZF), which reportedly regulates memory phenotypes, was found to promote ovalbumin (OVA)-induced OT. Therefore, this study aimed to explore the regulatory effects of PLZF on memory phenotypes in asthma and OT mouse models. We found that Zbtb16 (encoding PLZF) and PLZF⁺ cells were highly increased in OT lungs compared with asthmatic lungs. PLZF was co-expressed with GATA3, and IL-4⁺PLZF⁺ cells were significantly lower in OT lungs than in asthmatic lungs. Notably, memory cells were decreased in OT mice, and these mice had PLZF⁺ cells that expressed lower levels of CD44 than those of asthmatic mice. When Zbtb16 was overexpressed in splenic lymphocytes, the number of CD44⁺ cells decreased. There were increased memory cells in splenic lymphocytes after treatment with the supernatant of OVA-treated airway epithelial cells; however, this was reversed by Zbtb16 overexpression. Early respiratory syncytial virus infection increased memory cells and reduced PLZF⁺ cells in the OT mice. Collectively, these results indicate that PLZF may reduce the proportion of memory cells, thereby, promoting the establishment of OT.

Pulmonary resident memory T cells in respiratory virus infection and their inspiration on therapeutic strategies

The immune system generates memory cells on infection with a virus for the first time. These memory cells play an essential role in protection against reinfection. Tissue-resident memory T (TRM) cells can be generated in situ once attacked by pathogens. TRM cells dominate the defense mechanism during early stages of reinfection and have gradually become one of the most popular focuses in recent years. Here, we mainly reviewed the development and regulation of various TRM cell signaling pathways in the respiratory tract. Moreover, we explored the protective roles of TRM cells in immune response against various respiratory viruses, such as Respiratory Syncytial Virus (RSV) and influenza. The complex roles of TRM cells against SARS-CoV-2 infection are also discussed. Current evidence supports the therapeutic strategies targeting TRM cells, providing more possibilities for treatment. Rational utilization of TRM cells for therapeutics is vital for defense against respiratory viruses.

A recombinant bovine adenoviral mucosal vaccine expressing mycobacterial antigen-85B generates robust protection against tuberculosis in mice

Although the BCG vaccine offers partial protection, tuberculosis remains a leading cause of infectious disease death, killing ∼1.5 million people annually. We developed mucosal vaccines expressing the autophagy-inducing peptide C5 and mycobacterial Ag85B-p25 epitope using replication-defective human adenovirus (HAdv85C5) and bovine adenovirus (BAdv85C5) vectors. BAdv85C5-infected dendritic cells (DCs) expressed a robust transcriptome of genes regulating antigen processing compared to HAdv85C5-infected DCs. BAdv85C5-infected DCs showed enhanced galectin-3/8 and autophagy-dependent in vitro Ag85B-p25 epitope presentation to CD4 T cells. BCG-vaccinated mice were intranasally boosted using HAdv85C5 or BAdv85C5 followed by infection using aerosolized Mycobacterium tuberculosis (Mtb). BAdv85C5 protected mice against tuberculosis both as a booster after BCG vaccine (>1.4-log10 reduction in Mtb lung burden) and as a single intranasal dose (>0.5-log10 reduction). Protection was associated with robust CD4 and CD8 effector (TEM), central memory (TCM), and CD103+/CD69+ lung-resident memory (TRM) T cell expansion, revealing BAdv85C5 as a promising mucosal vaccine for tuberculosis.

The Notch Pathway: A Link Between COVID-19 Pathophysiology and Its Cardiovascular Complications

COVID-19 is associated with a large number of cardiovascular sequelae, including dysrhythmias, myocardial injury, myocarditis and thrombosis. The Notch pathway is one likely culprit leading to these complications due to its direct role in viral entry, inflammation and coagulation processes, all shown to be key parts of COVID-19 pathogenesis. This review highlights links between the pathophysiology of SARS-CoV2 and the Notch signaling pathway that serve as primary drivers of the cardiovascular complications seen in COVID-19 patients.

Engineering Vaccines for Tissue-Resident Memory T Cells

In recent years, tissue-resident memory T cells (TRM) have attracted significant attention in the field of vaccine development. Distinct from central and effector memory T cells, TRM cells take up residence in home tissues such as the lung or urogenital tract and are ideally positioned to respond quickly to pathogen encounter. TRM have been found to play a role in the immune response against many globally important infectious diseases for which new or improved vaccines are needed, including influenza and tuberculosis. It is also increasingly clear that TRM play a pivotal role in cancer immunity. Thus, vaccines that can generate this memory T cell population are highly desirable. The field of immunoengineering-that is, the application of engineering principles to study the immune system and design new and improved therapies that harness or modulate immune responses-is ideally poised to provide solutions to this need for next-generation TRM vaccines. This review covers recent developments in vaccine technologies for generating TRM and protecting against infection and cancer, including viral vectors, virus-like particles, and synthetic and natural biomaterials. In addition, it offers critical insights on the future of engineering vaccines for tissue-resident memory T cells.

Prefusion RSV F Immunization Elicits Th2-Mediated Lung Pathology in Mice When Formulated With a Th2 (but Not a Th1/Th2-Balanced) Adjuvant Despite Complete Viral Protection

Respiratory syncytial virus (RSV) remains the most common cause of lower respiratory tract infections in children worldwide. Development of a vaccine has been hindered by the risk of developing enhanced respiratory disease (ERD) upon natural exposure to the virus. Generation of higher quality neutralizing antibodies with stabilized pre-fusion F protein antigens has been proposed as a strategy to prevent ERD. We sought to test whether there was evidence of ERD in naïve BALB/c mice immunized with an unadjuvanted, stabilized pre-fusion F protein, and challenged with RSV line 19. We further sought to determine the extent to which formulation with a Th2-biased (alum) or a more Th1/Th2-balanced (Advax-SM) adjuvant influenced cellular responses and lung pathology. When exposed to RSV, mice immunized with pre-fusion F protein alone (PreF) exhibited increased airway eosinophilia and mucus accumulation. This was further exacerbated by formulation of PreF with Alum (aluminum hydroxide). Conversely, formulation of PreF with a Th1/Th2-balanced adjuvant, Advax-SM, not only suppressed RSV viral replication, but also inhibited airway eosinophilia and mucus accumulation. This was associated with lower numbers of lung innate lymphocyte cells (ILC2s) and CD4+ T cells producing IL-5+ or IL-13+ and increased IFNγ+ CD4+ and CD8+ T cells, in addition to RSV F-specific CD8+ T cells. These data suggest that in the absence of preimmunity, stabilized PreF antigens may still be associated with aberrant Th2 responses that induce lung pathology in response to RSV infection, and can be prevented by formulation with more Th1/Th2-balanced adjuvants that enhance CD4+ and CD8+ IFNγ+ T cell responses. This may support the use of stabilized PreF antigens with Th1/Th2-balanced adjuvants like, Advax-SM, as safer alternatives to alum in RSV vaccine candidates.

In vitro Notch-mediated adjuvant immunogenic potency is induced by combining QS-21 and MPL in a co-culture model of PBMC and HUVEC cells

Few vaccine adjuvants have been approved for human use although several are currently being studied in preclinical and clinical trial. MPL is a toll-like receptor agonist able to trigger a high and persistent antibody response via-TLR-4 while QS-21 activates the NLRP3 inflammasome. Data suggest that there is a cross-talk between Notch and TLR signaling pathways modulating the polarization of the immune response in a MyD88-dependent manner. However, the role of Notch on the mechanism action of immunogenic adjuvants has not been addressed yet. This study aims to evaluate the in vitro toxicity and inflammatory response triggered by MPL and QS-21 using an in vitro human cell co-culture model and to determine whether NFκB or Notch signaling pathways are involved in their mechanism of immunotoxicity. In order to do this, we evaluated the effect of QS- 21/MPL alone or in combination using a co-culture of PBMC and HUVEC using cytotoxicity, surface expression of ECAMs, cell adhesion and cytokine release, NF-κB activation and NOTCH1 expression as observation endpoints. We found that both MPL and QS-21 were cytotoxic at concentrations over 5 μg/mL. Both adjuvants were able to trigger the expression of ECAMs and induce firm adhesion of PBMC to the endothelium. QS-21 and MPL combination demonstrated a synergistic effect on cellular recruitment and cytokine release generating a switch from Th2 to Th1 cytokine profile. Both MPL and QS-21 by themselves were able to generate significant NF-κB activation. However, this effect was not observed when both adjuvants were combined. On the contrary, the adjuvants alone and combined induced an overexpression of NOTCH-1. This is an important finding, as it provides new evidence that these adjuvants could modulate reactogenicity of vaccines through Notch signaling.

Synonymous genome recoding: a tool to explore microbial biology and new therapeutic strategies

Synthetic genome recoding is a new means of generating designed organisms with altered phenotypes. Synonymous mutations introduced into the protein coding region tolerate modifications in DNA or mRNA without modifying the encoded proteins. Synonymous genome-wide recoding has allowed the synthetic generation of different small-genome viruses with modified phenotypes and biological properties. Recently, a decreased cost of chemically synthesizing DNA and improved methods for assembling DNA fragments (e.g. lambda red recombination and CRISPR-based editing) have enabled the construction of an Escherichia coli variant with a 4-Mb synthetic synonymously recoded genome with a reduced number of sense codons (n = 59) encoding the 20 canonical amino acids. Synonymous genome recoding is increasing our knowledge of microbial interactions with innate immune responses, identifying functional genome structures, and strategically ameliorating cis-inhibitory signaling sequences related to splicing, replication (in eukaryotes), and complex microbe functions, unraveling the relevance of codon usage for the temporal regulation of gene expression and the microbe mutant spectrum and adaptability. New biotechnological and therapeutic applications of this methodology can easily be envisaged. In this review, we discuss how synonymous genome recoding may impact our knowledge of microbial biology and the development of new and better therapeutic methodologies.

Local heroes or villains: tissue-resident memory T cells in human health and disease

Tissue-resident memory T (T_RM) cells are increasingly associated with the outcomes of health and disease. T_RM cells can mediate local immune protection against infections and cancer, which has led to interest in T_RM cells as targets for vaccination and immunotherapies. However, these cells have also been implicated in mediating detrimental pro-inflammatory responses in autoimmune skin diseases such as psoriasis, alopecia areata, and vitiligo. Here, we summarize the biology of T_RM cells established in animal models and in translational human studies. We review the beneficial effects of T_RM cells in mediating protective responses against infection and cancer and the adverse role of T_RM cells in driving pathology in autoimmunity. A further understanding of the breadth and mechanisms of T_RM cell activity is essential for the safe design of strategies that manipulate T_RM cells, such that protective responses can be enhanced without unwanted tissue damage, and pathogenic T_RM cells can be eliminated without losing local immunity.

Contribution of Resident Memory CD8+ T Cells to Protective Immunity Against Respiratory Syncytial Virus and Their Impact on Vaccine Design

Worldwide, human respiratory syncytial virus (RSV) is the most common etiological agent for acute lower respiratory tract infections (ALRI). RSV-ALRI is the major cause of hospital admissions in young children, and it can cause in-hospital deaths in children younger than six months old. Therefore, RSV remains one of the pathogens deemed most important for the generation of a vaccine. On the other hand, the effectiveness of a vaccine depends on the development of immunological memory against the pathogenic agent of interest. This memory is achieved by long-lived memory T cells, based on the establishment of an effective immune response to viral infections when subsequent exposures to the pathogen take place. Memory T cells can be classified into three subsets according to their expression of lymphoid homing receptors: central memory cells (T_CM), effector memory cells (T_EM) and resident memory T cells (T_RM). The latter subset consists of cells that are permanently found in non-lymphoid tissues and are capable of recognizing antigens and mounting an effective immune response at those sites. T_RM cells activate both innate and adaptive immune responses, thus establishing a robust and rapid response characterized by the production of large amounts of effector molecules. T_RM cells can also recognize antigenically unrelated pathogens and trigger an innate-like alarm with the recruitment of other immune cells. It is noteworthy that this rapid and effective immune response induced by T_RM cells make these cells an interesting aim in the design of vaccination strategies in order to establish T_RM cell populations to prevent respiratory infectious diseases. Here, we discuss the biogenesis of T_RM cells, their contribution to the resolution of respiratory viral infections and the induction of T_RM cells, which should be considered for the rational design of new vaccines against RSV.

CD4+ T Cells Drive Lung Disease Enhancement Induced by Immunization with Suboptimal Doses of Respiratory Syncytial Virus Fusion Protein in the Mouse Model

Respiratory syncytial virus (RSV) infection of seronegative children previously immunized with formalin-inactivated (FI) RSV has been associated with serious enhanced respiratory disease (ERD). The phenomenon was reproduced in the cotton rat and the mouse, and both preclinical models have been routinely used to evaluate the safety of new RSV vaccine candidates. More recently, we demonstrated that immunizations with suboptimal doses of the RSV fusion (F) antigen, in its post- or prefusion conformation, and in the presence of a Th1-biasing adjuvant, unexpectedly led to ERD in the cotton rat model. To assess if those observations are specific to the cotton rat and to elucidate the mechanism by which vaccination with low antigen doses can drive ERD post-RSV challenge, we evaluated RSV post-F antigen dose de-escalation in BALB/c mice in the presence of a Th1-biasing adjuvant. While decreasing antigen doses, we observed an increase in lung inflammation associated with an upregulation of proinflammatory cytokines. The amplitude of the lung histopathology was comparable to that of FI-RSV-induced ERD, confirming the observations made in the cotton rat. Importantly, depletion of CD4+ T cells prior to viral challenge completely abrogated ERD, preventing proinflammatory cytokine upregulation and the infiltration of T cells, neutrophils, eosinophils, and macrophages into the lung. Overall, low-antigen-dose-induced ERD resembles FI-RSV-induced ERD, except that the former appears in the absence of detectable levels of viral replication and in the context of a Th1-biased immune response. Taken together, our observations reinforce the recent concept that vaccines developed for RSV-naïve individuals should be systematically tested under suboptimal dosing conditions.IMPORTANCE RSV poses a significant health care burden and is the leading cause of serious lower-respiratory-tract infections in young children. A formalin-inactivated RSV vaccine developed in the 1960s not only showed a complete lack of efficacy against RSV infection but also induced severe lung disease enhancement in vaccinated children. Since then, establishing safety in preclinical models has been one of the major challenges to RSV vaccine development. We recently observed in the cotton rat model that suboptimal immunizations with RSV fusion protein could induce lung disease enhancement. In the present study, we extended suboptimal dosing evaluation to the mouse model. We confirmed the induction of lung disease enhancement by vaccinations with low antigen doses and dissected the associated immune mechanisms. Our results stress the need to evaluate suboptimal dosing for any new RSV vaccine candidate developed for seronegative infants.

Lipopolysaccharide Inhibits FI-RSV Vaccine-enhanced Inflammation Through Regulating Th Responses

Respiratory syncytial virus (RSV) infection is the primary cause of respiratory disease in infants. The formalin-inactivated RSV (FI-RSV) vaccine resulted in an enhanced respiratory disease (ERD) in infants upon natural RSV infection, which is a major obstacle for development of safe and efficacious vaccines. Excessive and uncontrolled Th immune responses could be involved in the ERD. Agonists of TLRs are used as adjuvants to guide the type of immune response induced by vaccines. We evaluated the impact of lipopolysaccharide (LPS), the agonist of TLR4, on ERD as the adjuvant of FI-RSV. The results showed that LPS remarkably inhibited FI-RSV-enhanced lung inflammation, mucus production, airway inflammatory cell infiltration, and inflammatory cytokines following RSV challenge. Interestingly, LPS inhibited both Th2 and Th17 type cytokines in lungs of FI-RSV-immunized mice following RSV challenge, without an increase in the Th1 type cytokines, suggesting a controlled immune response. In contrast, Pam3Cys and Poly(I:C), the agonist of TLR1/2 or TLR3, partly inhibited FI-RSV-enhanced lung inflammation. Pam3Cys inhibited Th17 type cytokine IL-17, but promoted both Th1 and Th2 type cytokines. Poly(I:C) inhibited Th2 and Th17 type cytokines, but promoted Th1 type cytokines. In addition, LPS promoted IgG and IgG2a antibody production, which might provide protection from RSV challenge. These results suggest that LPS inhibits ERD without impairment in antibody production and protection, and the mechanism appears to be related with regulation of Th responses induced by FI-RSV.

A unique combination adjuvant modulates immune responses preventing vaccine-enhanced pulmonary histopathology after a single dose vaccination with fusion protein and challenge with respiratory syncytial virus

Alum adjuvanted formalin-inactivated respiratory syncytial virus (RSV) vaccination resulted in enhanced respiratory disease in young children upon natural infection. Here, we investigated the adjuvant effects of monophosphoryl lipid A (MPL) and oligodeoxynucleotide CpG (CpG) on vaccine-enhanced respiratory disease after fusion (F) protein prime vaccination and RSV challenge in infant and adult mouse models. Combination CpG + MPL adjuvant in RSV F protein single dose priming of infant and adult age mice was found to promote the induction of IgG2a isotype antibodies and neutralizing activity, and lung viral clearance after challenge. CpG + MPL adjuvanted F protein (Fp) priming of infant and adult age mice was effective in avoiding lung histopathology, in reducing interleukin-4⁺ CD4 T cells and cellular infiltration of monocytes and neutrophils after RSV challenge. This study suggests that combination CpG and MPL adjuvant in RSV subunit vaccination might contribute to priming protective immune responses and preventing inflammatory RSV disease after infection.

RSV recombinant candidate vaccine G1F/M2 with CpG as an adjuvant prevents vaccine-associated lung inflammation, which may be associated with the appropriate types of immune memory in spleens and lungs

Respiratory syncytial virus (RSV) is a major respiratory pathogen in infants. The early formalin-inactivated RSV not only failed to protect infants against infection, but also was associated with enhanced pulmonary inflammatory disease upon natural infection. A safe and effective vaccine should prevent the inflammatory disease and provide protection. Immune memory is the cornerstone of vaccines. In this study, we evaluated three types of immune memory T cells, antibodies, and lung inflammation of a vaccine candidate G1F/M2, which includes a neutralizing epitope fragment of RSV G protein and a cytotoxic T lymphocyte epitope of M2 protein, with toll-like receptor 9 agonist CpG2006 as an adjuvant by intranasal (i.n.) and intraperitoneal (i.p.) immunization protocols. The results indicated that immunization of mice with G1F/M2 + CpG i.p. induced significantly higher level of CD4⁺ or CD8⁺ central memory (TCM), Th1-type effector memory (TEM), and balanced ratio of IgG1/IgG2a, but lower level of lung tissue-resident memory (TRM), compared with immunization with G1F/M2 + CpG i.n., G1F/M2 i.n., or G1F/M2 i.p. Following RSV challenge, the mice immunized with G1F/M2 + CpG i.p. showed higher level of Th1-type responses, remarkably suppressed inflammatory cytokines and histopathology in lungs, compared with mice immunized with G1F/M2 + CpG i.n., G1F/M2 i.n., or G1F/M2 i.p. These results suggested that high level of TCM and Th1 type of TEM in spleens may contribute to inhibition of lung inflammation, while high level of TRM in lungs and lack of or weak Th1-type immune memory in spleens may promote lung inflammation following RSV challenge.

Oral vaccination with influenza hemagglutinin combined with human pulmonary surfactant-mimicking synthetic adjuvant SF-10 induces efficient local and systemic immunity compared with nasal and subcutaneous vaccination and provides protective immunity in mice

We reported previously that a synthetic mucosal adjuvant SF-10, which mimics human pulmonary surfactant, delivers antigen to mucosal dendritic cells in the nasal cavity and promotes induction of humoral and cellular immunity. The aim of the present study was to determine the effects of oral administration of antigen combined with SF-10 (antigen-SF-10) on systemic and local immunity. Oral administration of ovalbumin, a model antigen, combined with SF-10 enhanced ovalbumin uptake into intestinal antigen presenting MHC II⁺CD11c⁺ cells and their CD11b⁺CD103⁺ and CD11b⁺CD103^- subtype dendritic cells, which are the major antigen presenting subsets of the intestinal tract, more efficiently compared to without SF-10. Oral vaccination with influenza hemagglutinin vaccine (HAv)-SF-10 induced HAv-specific IgA and IgG in the serum, and HAv-specific secretory IgA and IgG in bronchoalveolar lavage fluid, nasal washes, gastric extracts and fecal material; their levels were significantly higher than those induced by subcutaneous HAv or intranasal HAv and HAv-SF-10 vaccinations. Enzyme-linked immunospot assay showed high numbers of HAv-specific IgA and IgG antibody secreting cells in the gastrointestinal and respiratory mucosal lymphoid tissues after oral vaccination with HAv-SF-10, but no or very low induction following oral vaccination with HAv alone. Oral vaccination with HAv-SF-10 provided protective immunity against severe influenza A virus infection, which was significantly higher than that induced by HAv combined with cholera toxin. Oral vaccination with HAv-SF-10 was associated with unique cytokine production patterns in the spleen after HAv stimulation; including marked induction of HAv-responsive Th17 cytokines (e.g., IL-17A and IL-22), high induction of Th1 cytokines (e.g., IL-2 and IFN-γ) and moderate induction of Th2 cytokines (e.g., IL-4 and IL-5). These results indicate that oral vaccination with HAv-SF-10 induces more efficient systemic and local immunity than nasal or subcutaneous vaccination with characteristically high levels of secretory HAv-specific IgA in various mucosal organs and protective immunity.

Small Animal Models of Respiratory Viral Infection Related to Asthma

Respiratory viral infections are strongly associated with asthma exacerbations. Rhinovirus is most frequently-detected pathogen; followed by respiratory syncytial virus; metapneumovirus; parainfluenza virus; enterovirus and coronavirus. In addition; viral infection; in combination with genetics; allergen exposure; microbiome and other pathogens; may play a role in asthma development. In particular; asthma development has been linked to wheezing-associated respiratory viral infections in early life. To understand underlying mechanisms of viral-induced airways disease; investigators have studied respiratory viral infections in small animals. This report reviews animal models of human respiratory viral infection employing mice; rats; guinea pigs; hamsters and ferrets. Investigators have modeled asthma exacerbations by infecting mice with allergic airways disease. Asthma development has been modeled by administration of virus to immature animals. Small animal models of respiratory viral infection will identify cell and molecular targets for the treatment of asthma.

High-Throughput Sequencing of Putative Novel microRNAs in Rhesus Monkey Peripheral Blood Mononuclear Cells following EV71 and CA16 Infection

OBJECTIVES

Enterovirus 71 (EV71) and Coxsackievirus A16 (CA16) remain the major pathogens in hand, foot, and mouth disease (HFMD) cases, but the mechanisms of the different pathogeneses that follow EV71 and CA16 infection remain largely unknown.

METHODS

Herein, we utilized microRNA (miRNA) deep sequencing to investigate the roles of novel differentially expressed miRNAs in peripheral blood mononuclear cells (PBMCs) infected with EV71 and CA16.

RESULTS

The results identified 13 novel differentially expressed miRNAs in each group. Additionally, the target genes were predicted by the miRanda and RNAhybrid programs, and a total of 2,501 targets were found in the two databases. Then, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed that these targets were mainly involved in cell development and were associated with nervous system development, system development, multicellular organism development, the Wnt signaling pathway, the PDGF signaling pathway, and the EGF receptor signaling pathway. Finally, a coexpression regulatory network was built with the key targets to further extrapolate the functional interactions of the targets and their coexpressed genes.

CONCLUSION

Our results not only revealed potential biomarkers or targets for the diagnosis and treatment of HFMD, but also provided new insights to explore the mechanisms of EV71 and CA16 pathogenesis.

CD8+ Resident Memory T Cells and Viral Infection

Tissue-resident memory T (Trm) cells are a subset of recently identified memory T cells that mainly reside and serve as sentinels in non-lymphoid peripheral tissues. Unlike the well-characterized circulating central memory T (Tcm) cells and effector memory T (Tem) cells, Trm cells persist in the tissues, do not recirculate into blood, and offer immediate protection against pathogens upon reinfection. In this review, we focus on CD8⁺ Trm cells and briefly introduce their characteristics, development, maintenance, and function during viral infection. We also discuss some unresolved problems, such as how CD8⁺ Trm cells adapt to the local tissue microenvironment, how Trm cells interact with other immune cells during their development and maintenance, and the mechanisms by which CD8⁺ Trm cells confer immune protection. We believe that a better understanding of these problems is of great clinical and therapeutic value and may contribute to more effective vaccination and treatments against viral infection.

Targeting Resident Memory T Cells for Cancer Immunotherapy

A novel population of memory CD8⁺ T cells called resident memory T cells (T_RM) has been identified based on their phenotype (CD103, CD69) and on their local tissue residency without recirculating in the blood. These cells have been implicated in protective immune response against pathogens in both animal models and humans. Their role in cancer is just emerging as a key player in tumor immunosurveillance. Many properties of these cells suggest that they could control tumor growth: (i) they respond much faster to reexposure to cognate antigen than circulating memory cells, (ii) they express high levels of cytotoxic molecules, and (iii) they are enriched in tumor-specific T cells in close contact with tumor cells. T_RM are present in many human cancers and are associated with a good clinical outcome independently of the infiltration of CD8⁺ T cells. It has been recently shown that the efficacy of cancer vaccines depends on their ability to elicit T_RM. In adoptive cell therapy, the transfer of cells with the ability to establish T_RM at the tumor site correlates with the potency of this approach. Interestingly, T_RM express immune checkpoint molecules and preliminary data showed that they could expand early during anti-PD-1 treatment, and thus be considered as a surrogate marker of response to immunotherapy. Some cues to better expand these cells in vivo and improve the success of cancer immunotherapy include using mucosal routes of immunization, targeting subpopulations of dendritic cells as well as local signal at the mucosal site to recruit them in mucosal tissue.

A Systematic Review: The Role of Resident Memory T Cells in Infectious Diseases and Their Relevance for Vaccine Development

Background

Resident memory T cells have emerged as key players in the immune response generated against a number of pathogens. Their ability to take residence in non-lymphoid peripheral tissues allows for the rapid deployment of secondary effector responses at the site of pathogen entry. This ability to provide enhanced regional immunity has gathered much attention, with the generation of resident memory T cells being the goal of many novel vaccines.

Objectives

This review aimed to systematically analyze published literature investigating the role of resident memory T cells in human infectious diseases. Known effector responses mounted by these cells are summarized and key strategies that are potentially influential in the rational design of resident memory T cell inducing vaccines have also been highlighted.

Methods

A Boolean search was applied to Medline, SCOPUS, and Web of Science. Studies that investigated the effector response generated by resident memory T cells and/or evaluated strategies for inducing these cells were included irrespective of published date. Studies must have utilized an established technique for identifying resident memory T cells such as T cell phenotyping.

Results

While over 600 publications were revealed by the search, 147 articles were eligible for inclusion. The reference lists of included articles were also screened for other eligible publications. This resulted in the inclusion of publications that studied resident memory T cells in the context of over 25 human pathogens. The vast majority of studies were conducted in mouse models and demonstrated that resident memory T cells mount protective immune responses.

Conclusion

Although the role resident memory T cells play in providing immunity varies depending on the pathogen and anatomical location they resided in, the evidence overall suggests that these cells are vital for the timely and optimal protection against a number of infectious diseases. The induction of resident memory T cells should be further investigated and seriously considered when designing new vaccines.