Mucosal co-immunization with AIM2 enhances protective SIgA response and increases prophylactic efficacy of chitosan-DNA vaccine against coxsackievirus B3-induced myocarditis

An intranasal attenuated Coxsackievirus B3 vaccine induces strong systemic and mucosal immunity against CVB3 lethal challenge

Coxsackievirus B3 (CVB3) triggers viral myocarditis, with no effective vaccine yet. This fecal-oral transmitted pathogen has prompted interest in mucosal immunization strategies to impede CVB3 spread. We developed a new attenuated vaccine strain, named CVB3(mu). The potential of CVB3(mu) to stimulate mucosal immune protection remains to be elucidated. This study evaluates the attenuation characteristics of CVB3(mu) via a rapid evolution cellular model and RNA sequencing. Its temperature sensitivity and safety were evaluated through in vitro and in vivo experiments. The mucosal immunity protection of CVB3(mu) was assessed via intranasal immunization in Balb/c mice. The results indicate that CVB3(mu) exhibits temperature sensitivity and forms smaller plaques. It sustains fewer genetic mutations and still possesses certain attenuated traits up to the 25th passage, in comparison to CVB3(WT). Intranasal immunization elicited a significant serum neutralizing antibodies, and a substantial sIgA response in nasal washes. In vivo trials revealed CVB3(mu) protection in adult mice and passive protection in suckling mice against lethal CVB3(WT) challenges. In conclusion, CVB3(mu), a live attenuated intranasal vaccine, provides protection involving humoral and mucosal immunity, making it a promising candidate to control CVB3 spread and infection.

The cytoplasmic sensor, the AIM2 inflammasome: A precise therapeutic target in vascular and metabolic diseases

Cardio-cerebrovascular diseases encompass pathological changes in the heart, brain and vascular system, which pose a great threat to health and well-being worldwide. Moreover, metabolic diseases contribute to and exacerbate the impact of vascular diseases. Inflammation is a complex process that protects against noxious stimuli but is also dysregulated in numerous so-called inflammatory diseases, one of which is atherosclerosis. Inflammation involves multiple organ systems and a complex cascade of molecular and cellular events. Numerous studies have shown that inflammation plays a vital role in cardio-cerebrovascular diseases and metabolic diseases. The absent in melanoma 2 (AIM2) inflammasome detects and is subsequently activated by double-stranded DNA in damaged cells and pathogens. With the assistance of the mature effector molecule caspase-1, the AIM2 inflammasome performs crucial biological functions that underpin its involvement in cardio-cerebrovascular diseases and related metabolic diseases: The production of interleukin-1 beta (IL-1β), interleukin-18 (IL-18) and N-terminal pore-forming Gasdermin D fragment (GSDMD-N) mediates a series of inflammatory responses and programmed cell death (pyroptosis and PANoptosis). Currently, several agents have been reported to inhibit the activity of the AIM2 inflammasome and have the potential to be evaluated for use in clinical settings. In this review, we systemically elucidate the assembly, biological functions, regulation and mechanisms of the AIM2 inflammasome in cardio-cerebrovascular diseases and related metabolic diseases and outline the inhibitory agents of the AIM2 inflammasome as potential therapeutic drugs.

Impact of COVID-19 vaccination on saliva immune barriers: IgA, lysozyme, and lactoferrin

Understanding the role of salivary constituents, such as lactoferrin, lysozyme, and secretory immunoglobulin A (sIgA), in immune protection and defense mechanisms against microbial invasion and colonization of the airways is important in light of the ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. The salivary immune barrier in individuals affected by COVID-19 may contribute to disease prognosis. Thus, the aim of the present review is to evaluate the effect of COVID-19 vaccines on the immunological composition of saliva. IgA antibodies generated by vaccination can neutralize the virus at mucosal surfaces, whereas antimicrobial peptides, such as lysozyme and lactoferrin, have broad-spectrum antimicrobial activity. Collectively, these components contribute to the protective immune response of the oral cavity and may help minimize viral transmission as well as the severity of COVID-19. Measuring the levels of these components in the saliva of COVID-19-vaccinated individuals can help in evaluating the vaccine's ability to induce mucosal immunity, and it might also provide insights into whether saliva can be used in diagnostics or surveillance for monitoring immune responses following vaccination. This also has implications for viral transmission.

Roles of inflammasomes in viral myocarditis

Viral myocarditis (VMC), characterized by viral infection-induced inflammation, is a life-threatening disease associated with dilated cardiomyopathy or heart failure. Innate immunity plays a crucial role in the progression of inflammation, in which inflammasomes provide a platform for the secretion of cytokines and mediate pyroptosis. Inflammasomes are rising stars gaining increasing attention. The nucleotide oligomerization domain-, leucine-rich repeat-, and pyrin domain-containing protein 3 (NLRP3) inflammasome, the caspase recruitment domain-containing protein 8 (CARD8) inflammasome, and the caspase-11 inflammasome are three inflammasomes that were reported to affect the process and prognosis of VMC. These inflammasomes can be activated by a wide range of cellular events. Accumulating evidence has suggested that inflammasomes are involved in different stages of VMC, including the trigger and progression of myocardial injury and remodeling after infection. In this review, we summarized the pathways involving inflammasomes in VMC and discussed the potential therapies targeting inflammasomes and related pathways.

Vaccines against Group B Coxsackieviruses and Their Importance

The group B coxsackieviruses (CVBs) exist in six serotypes (CVB1 to CVB6). Disease associations have been reported for most serotypes, and multiple serotypes can cause similar diseases. For example, CVB1, CVB3, and CVB5 are generally implicated in the causation of myocarditis, whereas CVB1 and CVB4 could accelerate the development of type 1 diabetes (T1D). Yet, no vaccines against these viruses are currently available. In this review, we have analyzed the attributes of experimentally tested vaccines and discussed their merits and demerits or limitations, as well as their impact in preventing infections, most importantly myocarditis and T1D.

The AIM2 inflammasome: A novel biomarker and target in cardiovascular disease

Absent in melanoma 2 (AIM2) is a cytoplasmic sensor that recognises the double-strand DNA. AIM2 inflammasome is a protein platform in the cell that initiates innate immune responses by cleaving pro-caspase-1 and converting IL-1β and IL-18 to their mature forms. Additionally, AIM2 inflammasome promotes pyroptosis by converting Gasdermin-D (GSDMD) to GSDMD-N fragments. An increasing number of studies have indicated the important and decisive roles of the AIM2 inflammasome, IL-1β, and pyroptosis in cardiovascular diseases, such as coronary atherosclerosis, myocardial infarction, ischaemia/reperfusion injury, heart failure, aortic aneurysm and ischaemic stroke. Here, we review the molecular mechanism of the activation and effect of the AIM2 inflammasome in cardiovascular disease, revealing new insights into pathogenic factors that may be targeted to treat cardiovascular disease and related dysfunctions.

Infectious Inflammatory Processes and the Role of Bioactive Agent Released from Imino-Chitosan Derivatives Experimental and Theoretical Aspects

The paper focuses on the development of a multifractal theoretical model for explaining drug release dynamics (drug release laws and drug release mechanisms of cellular and channel-type) through scale transitions in scale space correlated with experimental data. The mathematical model has been developed for a hydrogel system prepared from chitosan and an antimicrobial aldehyde via covalent imine bonds. The reversible nature of the imine linkage points for a progressive release of the antimicrobial aldehyde is controlled by the reaction equilibrium shifting to the reagents, which in turn is triggered by aldehyde consumption in the inhibition of the microbial growth. The development of the mathematical model considers the release dynamic of the aldehyde in the scale space. Because the release behavior is dictated by the intrinsic properties of the polymer–drug complex system, they were explained in scale space, showing that various drug release dynamics laws can be associated with scale transitions. Moreover, the functionality of a Schrödinger-type differential equation in the same scale space reveals drug release mechanisms of channels and cellular types. These mechanisms are conditioned by the intensity of the polymer–drug interactions. It was demonstrated that the proposed mathematical model confirmed a prolonged release of the aldehyde, respecting the trend established by in vitro release experiments. At the same time, the properties of the hydrogel recommend its application in patients with intrauterine adhesions (IUAs) complicated by chronic endometritis as an alternative to the traditional antibiotics or antifungals.

Aim2 and Nlrp3 Are Dispensable for Vaccine-Induced Immunity against Francisella tularensis Live Vaccine Strain

Francisella tularensis is a facultative, intracellular, Gram-negative bacterium that causes a fatal disease known as tularemia. Due to its extremely high virulence, ease of spread by aerosolization, and potential to be used as a bioterror agent, F. tularensis is classified by the CDC as a tier 1 category A select agent. Previous studies have demonstrated the roles of the inflammasome sensors absent in melanoma 2 (AIM2) and NLRP3 in the generation of innate immune responses to F. tularensis infection. However, contributions of both the AIM2 and NLRP3 to the development of vaccine-induced adaptive immune responses against F. tularensis are not known. This study determined the contributions of Aim2 and Nlrp3 inflammasome sensors to vaccine-induced immune responses in a mouse model of respiratory tularemia. We developed a model to vaccinate Aim2- and Nlrp3-deficient (Aim2^-/- and Nlrp3^-/-) mice using the emrA1 mutant of the F. tularensis live vaccine strain (LVS). The results demonstrate that the innate immune responses in Aim2^-/- and Nlrp3^-/- mice vaccinated with the emrA1 mutant differ from those of their wild-type counterparts. However, despite these differences in the innate immune responses, both Aim2^-/- and Nlrp3^-/- mice are fully protected against an intranasal lethal challenge dose of F. tularensis LVS. Moreover, the lack of both Aim2 and Nlrp3 inflammasome sensors does not affect the production of vaccination-induced antibody and cell-mediated responses. Overall, this study reports a novel finding that both Aim2 and Nlrp3 are dispensable for vaccination-induced immunity against respiratory tularemia caused by F. tularensis.

Characterization of dendritic cells in human and experimental myocarditis

Aims

Dendritic cells (DCs) are central mediators of adaptive immunity, and there is growing evidence of their role in myocardial inflammatory disease. We hypothesized that plasmacytoid and myeloid DCs are involved in the mechanisms of myocarditis and analysed these two main subtypes in human myocarditis subjects, as well as in a murine model of experimental autoimmune myocarditis (EAM).

Methods and results

Circulating DCs were analysed by flow cytometry in patients with acute myocarditis, dilated cardiomyopathy, and controls. Myocardial biopsies were immunostained for the presence of DCs and compared with non‐diseased controls. In a mouse model of acute myocarditis induced through synthetic cardiac myosine peptide injection, effects of immunomodulation including DC inhibition through MCS‐18 versus placebo treatment were tested at the peak of inflammation (Day 21), as well as 1 week later (partial recovery). Circulatory pDCs and mDCs were significantly reduced in myocarditis patients compared with controls (P < 0.01 for both) and remained so even after 6 months of follow‐up. Human myocarditis biopsies showed accumulation of pDCs (two‐fold CD304+/three‐fold CD123+, all P < 0.05) compared with controls. Myocardial pDCs and mDCs accumulated in EAM (P for both <0.0001). MCS‐18 treatment reduced pDC levels (P = 0.009), reduced myocardial inflammation (myocarditis score reduction from 2.6 to 1.8, P = 0.026), and improved ejection fraction (P = 0.03) in EAM at Day 21 (peak of inflammation). This effect was not observed during the partial recovery of inflammation on Day 28.

Conclusions

Circulating DCs are reduced in human myocarditis and accumulate in the inflamed myocardium. MCS‐18 treatment reduces DCs in EAM, leading to amelioration of inflammation and left ventricular remodelling during the acute phase of myocarditis. Our data further elucidate the role of DCs and their specific subsets in acute inflammatory cardiomyopathies.

Calpain regulates CVB3 induced viral myocarditis by promoting autophagic flux upon infection

Calpains are calcium-activated neutral cysteine proteases. The dysregulation of calpain activity has been found to be related to cardiovascular diseases, for which calpain inhibition is used as a treatment. Viral myocarditis (VMC) is primarily caused by Coxsackievirus group B3 virus infection (CVB3). CVB3 virus infection induces autophagy and hijacks this process to facilitate its replication. In this study, we found that calpain was significantly activated in hearts affected by VMC. However, pharmacologically inhibiting calpain aggravated VMC symptoms in mice due to myocardial inflammation and cardiac dysfunction. The inhibition of calpain activity in vitro led to the accumulation of LC3-II and increased levels of p62/SQSTM1 protein expression, suggesting that autophagic flux was impaired by calpain inhibition. These effects of calpain inhibition were also observed in capn4-specific myocardial knockout mice in vivo. Furthermore, our results provided evidence that calpain inhibition in VMC, unlike other cardiovascular diseases, exacerbated the disease symptom by impairing CVB3-induced autophagic flux, which may subsequently reduce virus autolysosome degradation. Our findings indicated that calpain inhibition may not be a good treatment for VMC disease in a clinical setting.

Dpep2 Emerging as a Modulator of Macrophage Inflammation Confers Protection Against CVB3-Induced Viral Myocarditis

Overwhelming cardiac inflammation has been reported to be the pathogenic mechanism of Coxsackievirus B3 (CVB3)-induced viral myocarditis (VMC), while the detailed molecular mechanisms remain unknown. Membrane-bound dipeptidases (MBD, also known as Dpep) have been shown to be involved in inflammatory diseases. However, the clear and direct evidence of their impacts on inflammation is still lacking. In this study, our results revealed that Dpep2 expression was remarkably increased during CVB3 infection, and primarily produced by the cardiac tissue-infiltrating macrophages instead of constitutive cardiomyocytes. Macrophages have been reported to play an important pathological role in driving VMC. Interestingly, macrophage-specific Dpep2 deletion robustly aggravated CVB3-induced cardiac inflammation, evidenced by augmented expression of TNF-α, IL-6, and MCP-1 in heart tissue. In addition, Dpep2-deficient bone-marrow derived macrophages (BMDMs) generated more TNF-α, IL-6, and MCP-1 after CVB3 stimulation compared with the control BMDMs. Moreover, this suppressive effect of Dpep2 on macrophages relied on its repression on NF-κB signaling pathway, but not on its conventional hydrolysate LTE4. Taken together, this study revealed that Dpep2 could protect against CVB3-induced VMC by acting as a suppressor of macrophage inflammation. Better understanding how macrophage Dpep2 dampened the cardiac inflammation would provide us with insights for the efficient control of CVB3-induced VMC.

Glycyrrhizin Attenuates Salmonella enterica Serovar Typhimurium Infection: New Insights Into Its Protective Mechanism

Glycyrrhizin (GL), a triterpenoid glycoside, serves important functions in various biological activities, including antiviral and antitumor immune responses. However, the anti-inflammatory effects of GL on Salmonella enterica serovar Typhimurium (ST)-induced injury in mice and the mechanisms underlying the protection of GL are poorly understood. Here, we investigated the effects of GL on host immune responses against ST infection in mice. A phenotypic analysis using hematoxylin and eosin (H&E) staining and transmission electron microscopy showed that GL relieved ST-induced weight loss and intestinal mucosal injury. A colonization assay showed that GL significantly reduced ST colonization in the ileum and colon and translocation to the liver and spleen. An antibacterial activity assay and real-time PCR revealed that GL had no direct inhibitory impact on ST growth or virulence gene expression. ELISA showed that GL pretreatment significantly decreased proinflammatory cytokine (IFN-γ, TNF-α, IL-6) secretion and increased anti-inflammatory cytokine (IL-10) secretion in the ileum, colon and serum of ST-infected mice. Moreover, flora analysis showed that GL reduced Akkermansia, Sutterella, Prevotella and Coprococcus but enriched Parabacteroides and Anaerotruncus in the cecum of ST-infected mice. These results suggest that GL promotes the secretion of immune factors and modulates intestinal flora to prevent further ST infection. We also analyzed the effect of GL on immunocytes and found that GL promoted the phenotypic and functional maturation of murine bone marrow-derived dendritic cells (BMDCs). Flow cytometry and western blotting demonstrated that NF-κB, ERK, and p38 MAPK were required for GL-induced BMDC maturation. The above findings indicate that GL attenuates ST infection by modulating immune function and intestinal flora. This study enriches our current knowledge of GL-mediated immunological function and provides a new perspective on the prevention of Salmonella infection in animals and humans.

AIM2 Co-immunization with VP1 Is Associated with Increased Memory CD8 T Cells and Mounts Long Lasting Protection against Coxsackievirus B3 Challenge

The recurrent Coxsackievirus B3 (CVB3) infection is the most important cause of intractable myocarditis which often leads to chronic myocarditis and even dilated cardiomyopathy. Therefore, enhanced DNA vaccines capable of memory CD8 T cells are essential for long-lasting immunological protection against CVB3 infection. In this study, absent in melanoma 2 (AIM2) was used as an adjuvant to enhance the induction of memory CD8 T cells elicited by VP1 (viral capsid protein 1) vaccine. Mice were intramuscularly injected with 50 μg AIM2 plasmid and equal amount of VP1 plasmid (pAIM2/pVP1) vaccine 4 times at 2 week-intervals. We observed that the protection of pAIM2/pVP1 vaccine against CVB3 challenge was evidenced by significantly improved cardiac function, reduced myocardial injuries, and increased survival rate when compared with immunization with pVP1. Co-immunization with pAIM2/pVP1 robustly augmented T lymphocytes proliferation and CVB3-specific cytotoxic T lymphocyte responses. Importantly, 16 weeks after the last immunization, pAIM2/pVP1 co-immunization significantly enhanced the expression of Bcl-6, SOCS3, and Sca-1 which are critical for memory CD8 T cells as compared with pVP1 immunization. Notably, CD8 T cells that are likely vaccine-induced memory T cells were responsible for the protective efficacy of pAIM2/pVP1 vaccine by abolition of a CD8 T cell immune response following a lethal dose of CVB3 infection. Our results indicate that AIM2-adjuvanted vaccine could be a potential and promising approach to promote a long-lasting protection against CVB3-induced myocarditis.

Transmissible endoplasmic reticulum stress from myocardiocytes to macrophages is pivotal for the pathogenesis of CVB3-induced viral myocarditis

Infiltrating macrophages have been proven as a pivotal pathological inflammatory cell subset in coxsackievirus B3 (CVB3) induced viral myocarditis. However, the mechanisms underlying the initiation and promotion of macrophage pro-inflammatory responses are still blur. We previously reported that cardiac ER stress contributed to CVB3-induced myocarditis by augmenting inflammation. In this study, we focused on the influence of ER stress on the macrophage inflammatory responses in the viral myocarditis. We found that ER stress was robustly induced in the cardiac infiltrating macrophages from CVB3-infected mice, and robustly facilitated the production of pro-inflammatory cytokines (IL-6, IL-12, MCP-1 and IP-10). Consistently, adoptive transfer of ER stressed macrophages significantly worsened the viral myocarditis; while transfer of ER stress-inhibited macrophages obviously alleviated the myocarditis. To our surprise, this significantly activated ER stress was not directly caused by the virus stimulation, but was transferred from the CVB3-infected, ER stressed myocardiocytes via soluble molecules in a TLR2, 4-independent way. In the present study, we reported that the transmissible ER stress from the infected myocardiocytes to macrophages could augment the pro-inflammatory responses and promoted the pathogenesis of viral myocarditis. Blocking ER stress transmission, instead of inhibiting its initiation, may represent novel therapeutic strategies against viral myocarditis.

Review Article. Absent in melanoma 2 (AIM2) in the intestine: diverging actions with converging consequences

The intestinal mucosa is a difficult environment to maintain homeostasis as it is constantly challenged by microbial and food antigens. Maintaining an intact epithelial barrier, a continuous turnover of intestinal epithelial cells and normobiosis of the gut microbiota are essential components to prevent intestinal diseases such as inflammatory bowel diseases (IBD) and colorectal cancer (CRC). Inflammasomes are critical immune regulators that are involved in all of these processes. They are multiprotein complexes able to assemble upon interaction with a noxious stimulus that will subsequently lead to caspase-1 activation. Activated caspase-1 will orchestrate the maturation and release of proinflammatory cytokines IL-1β and IL-18, and induce pyroptosis, an inflammatory form of cell death. Both cytokine release and pyroptosis are initiated after detection of molecular patterns by a distinct inflammasome sensor protein. Absent in melanoma 2 (AIM2) is such an inflammasome sensor that specifically responds to the presence of double stranded DNA (dsDNA) in the cytoplasm, leading to the recruitment and activation of caspase-1. Recent studies revealed additional roles of AIM2 in controlling epithelial cell proliferation, tight junction expression and the microbiome. Therefore, AIM2 plays a significant role in maintaining intestinal homeostasis. This review focuses on the multifunctional role of AIM2 in intestinal homeostasis by regulating intestinal immunity and preventing colorectal cancer development.

Micro- and nanoparticulates for DNA vaccine delivery

DNA vaccination has emerged as a promising alternative to traditional protein-based vaccines for the induction of protective immune responses. DNA vaccines offer several advantages over traditional vaccines, including increased stability, rapid and inexpensive production, and flexibility to produce vaccines for a wide variety of infectious diseases. However, the immunogenicity of DNA vaccines delivered as naked plasmid DNA is often weak due to degradation of the DNA by nucleases and inefficient delivery to immune cells. Therefore, biomaterial-based delivery systems based on micro- and nanoparticles that encapsulate plasmid DNA represent the most promising strategy for DNA vaccine delivery. Microparticulate delivery systems allow for passive targeting to antigen presenting cells through size exclusion and can allow for sustained presentation of DNA to cells through degradation and release of encapsulated vaccines. In contrast, nanoparticle encapsulation leads to increased internalization, overall greater transfection efficiency, and the ability to increase uptake across mucosal surfaces. Moreover, selection of the appropriate biomaterial can lead to increased immune stimulation and activation through triggering innate immune response receptors and target DNA to professional antigen presenting cells. Finally, the selection of materials with the appropriate properties to achieve efficient delivery through administration routes conducive to high patient compliance and capable of generating systemic and local (i.e. mucosal) immunity can lead to more effective humoral and cellular protective immune responses. In this review, we discuss the development of novel biomaterial-based delivery systems to enhance the delivery of DNA vaccines through various routes of administration and their implications for generating immune responses.

Biopanel identifies expression status of targetable proteins in sinonasal melanoma

BACKGROUND

Advanced stage at presentation, lack of BRAF mutations and overall rarity pose unique challenges to the therapy and trial design in sinonasal melanoma.

METHODS

Here, we assessed the expression status of 12 proteins in two independent cohorts of sinonasal melanoma (n = 20).

RESULTS

Each case showed expression of at least one protein (KIT, TP53, MYC, HER2, EGFR, MET, VEGFR, BRAF V600E and/or MDM2), whereas lack of ALK, FLI1 and PDGFRα expression underscores differences to cutaneous melanoma. Comparison of marker frequencies to a metareview of the literature indicates that MYC, HER2, EGFR and MET had not been previously assessed.

CONCLUSION

Expression of at least one potentially targetable protein per case illustrates proteome pathway profiling as one starting point for marker stratified trial design.

Methods for Testing Immunological Factors

Hypersensitivity reactions can be elicited by various factors: either immunologically induced, i.e., allergic reactions to natural or synthetic compounds mediated by IgE, or non-immunologically induced, i.e., activation of mediator release from cells through direct contact, without the induction of, or the mediation through immune responses. Mediators responsible for hypersensitivity reactions are released from mast cells. An important preformed mediator of allergic reactions found in these cells is histamine. Specific allergens or the calcium ionophore 48/80 induce release of histamine from mast cells. The histamine concentration can be determined with the o-phthalaldehyde reaction.

AIM2 co-immunization favors specific multifunctional CD8(+) T cell induction and ameliorates coxsackievirus B3-induced chronic myocarditis

Coxsackievirus B3 (CVB3) infection can cause acute myocarditis and chronic myocarditis, leading to dilated cardiomyopathy (DCM) with no effective therapeutic strategy. Therefore, we investigated the potential of absent in melanoma 2 (AIM2) to enhance the therapeutic efficacy of DNA vaccine against CVB3-induced chronic myocarditis. Mice were infected with CVB3 and then intranasally immunized with chitosan-pcDNA3.1 (mock), chitosan-pAIM2 (CS-pAIM2), chitosan-pVP1 (CS-pVP1), or chitosan-pAIM2 plus chitosan-pVP1 (CS-pAIM2/CS-pVP1) at 7, 21, and 35d. Therapeutic efficacies of various vaccines were evaluated at day 56d. Compared with CS-pVP1 immunization, CS-pAIM2/CS-pVP1 co-immunization significantly increased survival rate, improved cardiac function, as well as decreased myocardial injury and fibrosis, this result indicated that CVB3-induced chronic myocarditis was alleviated. CVB3-specific T lymphocyte proliferation and cytotoxic T lymphocyte responses of the CS-pAIM2/CS-pVP1 co-immunization group were also increased. More interestingly, CS-pAIM2/CS-pVP1 co-immunization could facilitate CVB3-specific multifunctional CD8(+) T cell induction in the intestinal mucosa, and this induction was closely correlated with myocardial scores, this result indicated that CS-pAIM2/CS-pVP1 vaccine exhibits therapeutic efficacy by enhancing multifunctional CD8(+) T cells. This study may represent a novel therapy for CVB3-induced chronic myocarditis.

Endoplasmic Reticulum Stress Aggravates Viral Myocarditis by Raising Inflammation Through the IRE1-Associated NF-κB Pathway

BACKGROUND

Viral myocarditis, which is mostly caused by coxsackievirus infection, is characterized by myocardial inflammation. Abnormal endoplasmic reticulum (ER) stress participates in many heart diseases, but its role in viral myocarditis remains unsolved.

METHODS

We investigated the influence of ER stress in coxsackievirus B3 (CVB3)-induced viral myocarditis by dynamically detecting its activation in CVB3-infected hearts, analyzing its association with myocarditis severity, and exploring its impact on disease development by modulating the strength of ER stress with the chemical activator tunicamycin (Tm) or the inhibitor tauroursodeoxycholic acid (TUDCA). The underlying signal pathway of ER stress in CVB3-induced myocarditis was also deciphered.

RESULTS

We found that myocardial expression of Grp78 and Grp94, 2 ER stress markers, was significantly increased after CVB3 infection and positively correlated with myocarditis severity. Consistently, Tm-augmented ER stress obviously aggravated myocarditis, as shown by more severe myocardial inflammation, reduced cardiac function, and a lower survival rate, whereas TUDCA decreased ER stress and obviously alleviated myocarditis. This pathologic effect of ER stress could be attributed to increased levels of proinflammatory cytokine (interleukin [IL]-6, IL-12, tumor necrosis factor-alpha, and monocyte chemoattractant protein-1) production through the IRE1-associated nuclear factor-κB (NF-kB) pathway.

CONCLUSIONS

ER stress accentuated CVB3-induced myocardial inflammation through the IRE1-associated NF-κB pathway. This study may help us understand the role of ER stress in viral myocarditis and promote the development of corresponding therapeutic strategies based on manipulating ER stress.