Intranasal administration of octavalent next-generation influenza vaccine elicits protective immune responses against seasonal and pre-pandemic viruses.

Development of next-generation influenza virus vaccines is crucial to improve protection against circulating and emerging viruses. Current vaccine formulations have to be updated annually due to mutations in seasonal strains and do not offer protection against strains with pandemic potential. Computationally optimized broadly reactive antigen (COBRA) methodology has been utilized by our group to generate broadly reactive immunogens for individual influenza subtypes, which elicit protective immune responses against a broad range of strains over numerous seasons. Octavalent mixtures of COBRA hemagglutinin (HA) (H1, H2, H3, H5, H7, and influenza B virus) plus neuraminidase (NA) (N1 and N2) recombinant proteins mixed with c-di-AMP adjuvant were administered intranasally to naive or pre-immune ferrets in prime-boost fashion. Four weeks after final vaccination, collected sera were analyzed for breadth of antibody response, and the animals were challenged with seasonal or pre-pandemic strains. The octavalent COBRA vaccine elicited antibodies that recognized a broad panel of strains representing different subtypes, and these vaccinated animals were protected against influenza virus challenges. Overall, this study demonstrated that the mixture of eight COBRA HA/NA proteins mixed with an intranasal adjuvant is a promising candidate for a universal influenza vaccine. IMPORTANCE: Influenza is a respiratory virus which infects around a billion people globally every year, with millions experiencing severe illness. Commercial vaccine efficacy varies year to year and can be low due to mismatch of circulating virus strains. Thus, the formulation of current vaccines has to be adapted accordingly every year. The development of a broadly reactive influenza vaccine would lessen the global economic and public health burden caused by the different types of influenza viruses. The significance of our research is producing a promising universal vaccine candidate which provides protection against a wider range of virus strains over a wider range of time.

Bifunctional black phosphorus quantum dots platform: Delivery and remarkable immunotherapy enhancement of STING agonist.

Cancer immunotherapy has been developed to improve therapeutic effects for patients by activating the innate immune stimulator of interferon gene (STING) pathway. However, most patients cannot benefit from this therapy, mainly due to the problems of excessively low immune responses and lack of tumor specificity. Herein, we report a solution to these two problems by developing a bifunctional platform of black phosphorus quantum dots (BPQDs) for STING agonists. Specifically, BPQDs could connect targeted functional groups and regulate surface zeta potential by coordinating metal ions to increase loading (over 5 times) while maintaining high universality (7 STING agonists). The controlled release of STING agonists enabled specific interactions with their proteins, activating the STING pathway and stimulating the secretion release of immunosuppressive factors by phosphorylating TBK1 and IFN-IRF3 and secreting high levels of immunostimulatory cytokines, including IL-6, IFN-α, and IFN-ß. Moreover, the immunotherapy was enhanced was enhanced mild photothermal therapy (PTT) of BPQDs platform, producing enough T cells to eliminate tumors and prevent tumor recurrence. This work facilitates further research on targeted delivery of small-molecule immune drugs to enhance the development of clinical immunotherapy.

STING activation increases the efficiency of temozolomide in PTEN harbouring glioblastoma cells.

Background/aim: Glioblastoma is one of the most aggressive tumours, resistant to all applied therapy regiments and prone to relapse. Median survival rates are therefore only expressed as months. STING agonists are immunomodulatory molecules that activate type I interferon expression, making them potentially useful in regulating the tumour microenvironment. Since PTEN serves as a critical phosphatase in activating interferon-regulating transcription factors and is frequently mutated in glioblastoma cells, this study aimed to investigate STING activation in glioblastoma cell lines, examining whether they harbour the PTEN protein or not.°. Materials and methods: T98G and U118MG glioblastoma cell lines were treated with the 2'3'-c-di-AM(PS)2(Rp,Rp) STING agonist together with or without the chemotherapeutic agent temozolomide. cGAS/STING pathway components were subsequently analysed using qRT-PCR, western blot, and ELISA methods. Results: Our results showed that PTEN-harbouring T98G cells responded well to STING activation, leading to increased temozolomide efficacy. In contrast, STING activation in U118MG cells did not affect the response to temozolomide. mRNA expression levels of STING, IRF3, NF-KB, and RELA genes were significantly increased at the combined treatment groups in T98G cell line. Conversely, combined treatment with STING agonist and temozolomide did not affect mRNA expression levels of cGAS/STING pathway genes in U118MG cells. Conclusion: Our data offers new evidence suggesting that STING agonists can effectively be used to increase temozolomide response in the presence of PTEN protein. Therefore, increased GBM therapy success rates can be achieved by employing the PTEN expression status as a predictive biomarker before treating patients with a chemotherapeutic agent in combination with STING agonist.

Spatiotemporal release of non-nucleotide STING agonist and AKT inhibitor from implantable 3D-printed scaffold for amplified cancer immunotherapy.

Immunotherapy through the activation of the stimulator of interferon genes (STING) signaling pathway is increasingly recognized for its robust anti-tumor efficacy. However, the effectiveness of STING activation is often compromised by inadequate anti-tumor immunity and a scarcity of primed immune cells in the tumor microenvironment. Herein, we design and fabricate a co-axial 3D-printed scaffold integrating a non-nucleotide STING agonist, SR-717, and an AKT inhibitor, MK-2206, in its respective shell and core layers, to synergistically enhance STING activation, thereby suppressing tumor recurrence and growth. SR-717 initiates the STING activation to enhance the phosphorylation of the factors along the STING pathway, while MK-2206 concurrently inhibits the AKT phosphorylation to facilitate the TBK1 phosphorylation of the STING pathway. The sequential and sustained release of SR-717 and MK-2206 from the scaffold results in a synergistic STING activation, demonstrating substantial anti-tumor efficacy across multiple tumor models. Furthermore, the scaffold promotes the recruitment and enrichment of activated dendritic cells and M1 macrophages, subsequently stimulating anti-tumor T cell activity, thereby amplifying the immunotherapeutic effect. This precise and synergistic activation of STING by the scaffold offers promising potential in tumor immunotherapy.

STING agonist-conjugated metal-organic framework induces artificial leukocytoid structures and immune hotspots for systemic antitumor responses.

Radiotherapy is widely used for cancer treatment, but its clinical utility is limited by radioresistance and its inability to target metastases. Nanoscale metal-organic frameworks (MOFs) have shown promise as high-Z nanoradiosensitizers to enhance radiotherapy and induce immunostimulatory regulation of the tumor microenvironment. We hypothesized that MOFs could deliver small-molecule therapeutics to synergize with radiotherapy for enhanced antitumor efficacy. Herein, we develop a robust nanoradiosensitizer, GA-MOF, by conjugating a STING agonist, 2',3'-cyclic guanosine monophosphate-adenosine monophosphate (GA), on MOFs for synergistic radiosensitization and STING activation. GA-MOF demonstrated strong anticancer efficacy by forming immune-cell-rich nodules (artificial leukocytoid structures) and transforming them into immunostimulatory hotspots with radiotherapy. Further combination with an immune checkpoint blockade suppressed distant tumors through systemic immune activation. Our work not only demonstrates the potent radiosensitization of GA-MOF, but also provides detailed mechanisms regarding MOF distribution, immune regulatory pathways and long-term immune effects.

Improving STING agonist-based cancer therapy by inhibiting the autophagy-related protein VPS34.

We have recently demonstrated that inhibiting VPS34 enhances T-cell-recruiting chemokines through the activation of the cGAS/STING pathway using the STING agonist ADU-S100. Combining VPS34 inhibitors with ADU-S100 increased cytokine release and improved tumor control in mouse models, suggesting a potential synergy between VPS34 inhibition and therapies based on STING agonists.

The multiple faces of cGAS-STING in antitumor immunity: prospects and challenges.

As a key sensor of double-stranded DNA (dsDNA), cyclic GMP-AMP synthase (cGAS) detects cytosolic dsDNA and initiates the synthesis of 2'3' cyclic GMP-AMP (cGAMP) that activates the stimulator of interferon genes (STING). This finally promotes the production of type I interferons (IFN-I) that is crucial for bridging innate and adaptive immunity. Recent evidence show that several antitumor therapies, including radiotherapy (RT), chemotherapy, targeted therapies and immunotherapies, activate the cGAS-STING pathway to provoke the antitumor immunity. In the last decade, the development of STING agonists has been a major focus in both basic research and the pharmaceutical industry. However, up to now, none of STING agonists have been approved for clinical use. Considering the broad expression of STING in whole body and the direct lethal effect of STING agonists on immune cells in the draining lymph node (dLN), research on the optimal way to activate STING in tumor microenvironment (TME) appears to be a promising direction. Moreover, besides enhancing IFN-I signaling, the cGAS-STING pathway also plays roles in senescence, autophagy, apoptosis, mitotic arrest, and DNA repair, contributing to tumor development and metastasis. In this review, we summarize the recent advances on cGAS-STING pathway's response to antitumor therapies and the strategies involving this pathway for tumor treatment.

Delivery of mRNA Encoding Interleukin-12 and a Stimulator of Interferon Genes Agonist Potentiates Antitumor Efficacy through Reversing T Cell Exhaustion.

T cell exhaustion has emerged as a major hurdle that impedes the clinical translation of stimulator of interferon genes (STING) agonists. It is crucial to explore innovative strategies to rejuvenate exhausted T cells and potentiate the antitumor efficacy. Here, we propose an approach utilizing MSA-2 as a STING agonist, along with nanoparticle-mediated delivery of mRNA encoding interleukin-12 (IL-12) to restore the function of T cells. We developed a lipid nanoparticle (DMT7-IL12 LNP) that encapsulated IL12 mRNA. Our findings convincingly demonstrated that the combination of MSA-2 and DMT7-IL12 LNP can effectively reverse the exhausted T cell phenotype, as evidenced by the enhanced secretion of cytokines, such as tumor necrosis factor alpha, interferon gamma, and Granzyme B, coupled with reduced levels of inhibitory molecules such as T cell immunoglobulin and mucin domain-3 and programmed cell death protein-1 on CD8+ T cells. Furthermore, this approach led to improved survival and tumor regression without causing any systemic toxicity in melanoma and lung metastasis models. These findings suggest that mRNA encoding IL-12 in conjunction with STING agonists has the potential to confer superior clinical outcomes, representing a promising advancement in cancer immunotherapy.

2',4'-LNA-Functionalized 5'-S-Phosphorothioester CDNs as STING Agonists.

Cyclic dinucleotides (CDNs) have garnered popularity over the last decade as immunotherapeutic agents, which activate the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway to trigger an immune response. Many analogs of 2'3'-cGAMP, c-di-GMP, and c-di-AMP have been developed and shown as effective cancer vaccines and immunomodulators for the induction of both the adaptive and innate immune systems. Unfortunately, the effectiveness of these CDNs is limited by their chemical and enzymatic instability. We recently introduced 5'-endo-phosphorothoiate 2'3'-cGAMP analogs as potent STING agonist with improved resistance to cleavage by clinically relevant phosphodiesterases. We herein report the synthesis of locked nucleic acid-functionalized (LNA) endo-S-CDNs and evaluate their ability to activate STING in THP1 monocytes. Interestingly, some of our synthesized LNA 3'3'-endo-S-CDNs can moderately activate hSTING REF haplotype (R232H), which exhibit diminished response to both 2'3'-cGAMP and ADU-S100. Also, we show that one of our most potent endo-S-CDNs has remarkable chemical (oxidants I2 and H2O2) and phosphodiesterase stability.

STING agonist, SMA-2, inhibits clear cell renal cell carcinoma through improving tumor microenvironment.

Clear cell renal cell carcinoma (ccRCC) is the most prevalent and lethal subtype of kidney cancer, patients with ccRCC usually have very poor prognosis and short survival. Therefore, it is urgent to develop more effective therapeutics or medications to suppress ccRCC progression. Here, we demonstrated that STING agonist, MSA-2 significantly inhibits tumor progress and prolongs the survival of ccRCC mice by promoting cytokines secretion. Moreover, MSA-2 triggered the trafficking and infiltration of CD8+ T cells, supported by the generation of a chemokine milieu that promoted recruitment and modulation of the immunosuppressive TME in ccRCC. These findings suggest that MSA-2 potentially serves an effective and preferable adjuvant immunotherapy of ccRCC.

STING agonist inflames the cervical cancer immune microenvironment and overcomes anti-PD-1 therapy resistance.

Background: Cervical cancer poses a significant global threat to women's health. However, current therapeutic interventions, such as radiotherapy, chemotherapy, surgical resection, and immune checkpoint inhibitors, face limitations in the advanced stages of the disease. Given the immunosuppressive microenvironment in cervical cancer, it is imperative to explore novel perspectives. In this regard, STING agonists have emerged as promising candidates. Methods: The expression profiles and clinicopathological data were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets. Prognostic analysis of STING downstream genes (CCL5, CXCL9, CXCL10) and immune infiltration analysis were conducted using Kaplan-Meier Plotter, ESTIMATE, and deconvo_CIBERSOR. Single-cell RNA-seq (scRNA-seq) analysis was conducted to evaluate the potential of MSA-2 in cervical cancer treatment employing SingleR, chi-squared test, and Gene Set Enrichment Analysis (GSEA). Cellular interaction analysis utilized the CellChat package to assess the potentiation of cellular interaction following MSA-2 administration. Murine tumor models involving U14 and TC-1, were conducted, and the IF of tissue was subsequently conducted to assess the tumor microenvironment status after treatment. Results: Prognosis in cervical cancer correlated with elevated expression of STING downstream genes, indicating prolonged survival and reduced recurrence. These genes positively correlated with immune infiltration, influencing stromal scores, immune scores, and estimate scores. Specific immune cell populations, including CD8+ T cells, M1-type macrophages, NK cells, and T follicular helper cells, were associated with STING downstream genes. scRNA-seq in a classic immune-excluded model revealed that MSA-2 exerts priming and activating functions on vital components within TME, and intensifies their intercellular communications. The in vivo assay ultimately demonstrated that MSA-2, either as a standalone treatment or in combination with anti-PD-1, effectively suppressed the growth of subcutaneous cervical tumors. Moreover, the combination strategy significantly augmented efficacy compared to anti-PD-1 monotherapy by eliciting a robust antitumor immune response. Conclusion: This study highlights the pivotal role of the STING pathway and the potential of MSA-2 in reshaping the immune microenvironment in cervical cancer. Combining MSA-2 with immune checkpoint inhibitors presents a transformative approach, holding promise for improved prognosis. Further investigations are warranted to explore the broader immune landscape and potential long-term effects of MSA-2 in cervical cancer treatment.

Neutralization of SARS-CoV-2 BA.2.86 and JN.1 by CF501 adjuvant-enhanced immune responses targeting the conserved epitopes in ancestral RBD.

The emerged severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron subvariants BA.2.86 and JN.1 raise concerns regarding their potential to evade immune surveillance and spread globally. Here, we test sera from rhesus macaques immunized with 3 doses of wild-type SARS-CoV-2 receptor-binding domain (RBD)-Fc adjuvanted with the STING agonist CF501. We find that the sera can potently neutralize pseudotyped XBB.1.5, XBB.1.16, CH.1.1, EG.5, BA.2.86, and JN.1, with 50% neutralization titers ranging from 3,494 to 7,424. We also demonstrate that CF501, but not Alum, can enhance immunogenicity of the RBD from wild-type SARS-CoV-2 to improve induction of broadly neutralizing antibodies (bnAbs) with binding specificity and activity similar to those of SA55, BN03, and S309, thus exhibiting extraordinary broad-spectrum neutralizing activity. Overall, the RBD from wild-type SARS-CoV-2 also contains conservative epitopes. The RBD-Fc adjuvanted by CF501 can elicit potent bnAbs against JN.1, BA.2.86, and other XBB subvariants. This strategy can be adopted to develop broad-spectrum vaccines to combat future emerging and reemerging viral infectious diseases.

Vaccination with a combination of STING agonist-loaded lipid nanoparticles and CpG-ODNs protects against lung metastasis via the induction of CD11bhighCD27low memory-like NK cells.

BACKGROUND: Natural killer (NK) cells are effective in attacking tumor cells that escape T cell attack. Memory NK cells are believed to function as potent effector cells in cancer immunotherapy. However, knowledge of their induction, identification, and potential in vivo is limited. Herein, we report on the induction and identification of memory-like NK cells via the action of a combination of a stimulator of interferon genes (STING) agonist loaded into lipid nanoparticles (STING-LNPs) and cytosine-phosphorothioate-guanine oligodeoxynucleotides (CpG-ODNs), and the potential of the inducted memory-like NK cells to prevent melanoma lung metastasis. METHODS: The antitumor effects of either the STING-LNPs, CpG-ODNs, or the combination therapy were evaluated using a B16-F10 lung metastasis model. The effect of the combined treatment was evaluated by measuring cytokine production. The induction of memory-like NK cells was demonstrated via flow cytometry and confirmed through their preventative effect. RESULTS: The combination of STING-LNPs and CpG-ODNs tended to enhance the production of interleukin 12 (IL-12) and IL-18, and exerted a therapeutic effect against B16-F10 lung metastasis. The combination therapy increased the population of CD11bhighCD27low NK cells. Although monotherapies failed to show preventative effects, the combination therapy induced a surprisingly strong preventative effect, which indicates that CD11bhighCD27low cells could be a phenotype of memory-like NK cells. CONCLUSION: As far as could be ascertained, this is the first report of the in vivo induction, identification, and confirmation of a phenotype of the memory-like NK cells through a prophylactic effect via the use of an immunotherapeutic drug. Our findings provide novel insights into the in vivo induction of CD11bhighCD27low memory-like NK cells thus paving the way for the development of efficient immunotherapies.

STING-activating cyclic dinucleotide-manganese nanoparticles evoke robust immunity against acute myeloid leukemia.

Acute myeloid leukemia (AML) is one of the most common types of leukemia in adults with a 5-year survival rate of 30.5%. These poor patient outcomes are attributed to tumor relapse, stemming from ineffective innate immune activation, T cell tolerance, and a lack of immunological memory. Thus, new strategies are needed to activate innate and effector immune cells and evoke long-term immunity against AML. One approach to address these issues is through Stimulator of Interferon Genes (STING) pathway activation, which produces Type I Interferons (Type I IFN) critical for innate and adaptive immune activation. Here, we report that systemic immunotherapy with a lipid-based nanoparticle platform (CMP) carrying Mn2+ and STING agonist c-di-AMP (CDA) exhibited robust anti-tumor efficacy in a mouse model of disseminated AML. Moreover, CMP immunotherapy combined with immune checkpoint blockade against cytotoxic T-lymphocyte-associated protein 4 (anti-CTLA-4) elicited robust innate and adaptive immune activation with enhanced cytotoxic potential against AML, leading to extended animal survival after re-challenge with AML. Overall, this CMP combination immunotherapy may be a promising approach against AML and other disseminated cancer.

cGAS-STING pathway agonists are promising vaccine adjuvants.

Adjuvants are of critical value in vaccine development as they act on enhancing immunogenicity of antigen and inducing long-lasting immunity. However, there are only a few adjuvants that have been approved for clinical use, which highlights the need for exploring and developing new adjuvants to meet the growing demand for vaccination. Recently, emerging evidence demonstrates that the cGAS-STING pathway orchestrates innate and adaptive immunity by generating type I interferon responses. Many cGAS-STING pathway agonists have been developed and tested in preclinical research for the treatment of cancer or infectious diseases with promising results. As adjuvants, cGAS-STING agonists have demonstrated their potential to activate robust defense immunity in various diseases, including COVID-19 infection. This review summarized the current developments in the field of cGAS-STING agonists with a special focus on the latest applications of cGAS-STING agonists as adjuvants in vaccination. Potential challenges were also discussed in the hope of sparking future research interests to further the development of cGAS-STING as vaccine adjuvants.

STING agonist-based hydrogel enhances immune activation in synergy with radiofrequency ablation for hepatocellular carcinoma treatment.

Immunosuppression caused by incomplete radiofrequency ablation (iRFA) is a crucial factor affecting the effectiveness of RFA for solid tumors. However, little is known about the changes iRFA induces in the tumor immune microenvironment (TIME) of hepatocellular carcinoma (HCC), the primary application area for RFA. In this study, we found iRFA promotes a suppressive TIME in residual HCC tumors, characterized by M2 macrophage polarization, inhibited antigen presentation by dendritic cells (DCs), and reduced infiltration of cytotoxic T lymphocytes (CTLs). Interestingly, the STING agonist MSA-2 was able to reorganize M2-like tumor-promoting macrophages into M1-like anti-tumor states and enhance antigen presentation by DCs. To optimize the therapeutic effect of MSA-2, we used a calcium ion (Ca2+) responsive sodium alginate (ALG) as a carrier, forming an injectable hydrogel named ALG@MSA-2. This hydrogel can change from liquid to gel, maintaining continuous drug release in situ. Our results suggested that ALG@MSA-2 effectively activated anti-tumor immunity, as manifested by increased M1-like macrophage polarization, enhanced antigen presentation by DCs, increased CTL infiltration, and inhibited residual tumor growth. ALG@MSA-2 also resulted in a complete regression of contralateral tumors and widespread liver metastases in vivo. In addition, the excellent biosafety of ALG@MSA-2 was also proved by blood biochemical analysis and body weight changes in mice. In summary, this study demonstrated that the immune cascade of ALG@MSA-2 mediated the STING pathway activation and promoted a favorable TIME which might provide novel insights for the RFA treatment of HCC.

Combining cisplatin and a STING agonist into one molecule for metalloimmunotherapy of cancer.

Mounting evidence suggests that strategies combining DNA-damaging agents and stimulator of interferon genes (STING) agonists are promising cancer therapeutic regimens because they can amplify STING activation and remodel the immunosuppressive tumor microenvironment. However, a single molecular entity comprising both agents has not yet been developed. Herein, we designed two PtIV-MSA-2 conjugates (I and II) containing the DNA-damaging chemotherapeutic drug cisplatin and the innate immune-activating STING agonist MSA-2; these conjugates showed great potential as multispecific small-molecule drugs against pancreatic cancer. Mechanistic studies revealed that conjugate I upregulated the expression of transcripts associated with innate immunity and metabolism in cancer cells, significantly differing from cisplatin and MSA-2. An analysis of the tumor microenvironment demonstrated that conjugate I could enhance the infiltration of natural killer (NK) cells into tumors and promote the activation of T cells, NK cells and dendritic cells in tumor tissues. These findings indicated that conjugate I, which was created by incorporating a Pt chemotherapeutic drug and STING agonist into one molecule, is a promising and potent anticancer drug candidate, opening new avenues for small-molecule-based cancer metalloimmunotherapy.

A Thermosensitive Bi-Adjuvant Hydrogel Triggers Epitope Spreading to Promote the Anti-Tumor Efficacy of Frameshift Neoantigens.

Tumor-specific frameshift mutations encoding peptides (FSPs) are highly immunogenic neoantigens for personalized cancer immunotherapy, while their clinical efficacy is limited by immunosuppressive tumor microenvironment (TME) and self-tolerance. Here, a thermosensitive hydrogel (FSP-RZ-BPH) delivering dual adjuvants R848 (TLR7/8 agonist) + Zn2+ (cGAS-STING agonist) is designed to promote the efficacy of FSPs on murine forestomach cancer (MFC). After peritumoral injection, FSP-RZ-BPH behaves as pH-responsive sustained drug release at sites near the tumor to effectively transform the immunosuppressive TME into an inflammatory type. FSP-RZ-BPH orchestrates innate and adaptive immunity to activate dendritic cells in tumor-draining lymph nodes and increase the number of FSPs-reactive effector memory T cells (TEM) in tumor by 2.9 folds. More importantly, these TEM also exhibit memory responses to nonvaccinated neoantigens on MFC. This epitope spreading effect contributes to reduce self-tolerance to maintain long-lasting anti-tumor immunity. In MFC suppressive model, FSP-RZ-BPH achieves 84.8% tumor inhibition rate and prolongs the survival of tumor-bearing mice with 57.1% complete response rate. As a preventive tumor vaccine, FSP-RZ-BPH can also significantly delay tumor growth. Overall, the work identifies frameshift MFC neoantigens for the first time and demonstrates the thermosensitive bi-adjuvant hydrogel as an effective strategy to boost bystander anti-tumor responses of frameshift neoantigens.

Exosome co-delivery of a STING agonist augments immunogenicity elicited by CVB3 VP1 vaccine via promoting antigen cross-presentation of CD8 + DCs.

The induction of a robust CD8+ T cell response is critical for the success of an antiviral vaccine. In this study, we incorporated a STING agonist (SA) 2'3'-cGAMP into a previously developed exosome-based CVB3 viral myocarditis vaccine (Exo-VP1) to enhance its ability to induce CD8+ T cell responses and immunoprotection. Our results showed that compared to free SA adjuvant, exosome-mediated co-delivery (ExoSA-VP1) significantly enhanced SA uptake by dendritic cells (DCs) and more potently stimulated DC maturation. Immunization of mice showed that the ExoSA-VP1 vaccine-induced higher levels of CVB3-specific T cell proliferation and cytotoxicity, significantly increased the percentage of IFN-γ+CD8+ rather than CD4+ T cells, effectively reduced cardiac viral loads, attenuated myocarditis and improved survival in mice compared to the previous Exo-VP1 vaccine. Further investigation showed that ExoSA-VP1 significantly increased both the percentage and antigen cross-presentation capacity of splenic CD8+ DCs. Depletion of these CD8+ DCs by cytochrome C administration nearly abolished the advantage of ExoSA-VP1 in dominantly inducing IFN-γ+CD8+ cytotoxic T lymphocyte (CTL) production in immunized mice. Taken together, our results demonstrated the potential of ExoSA-VP1 as a promising candidate for anti-CVB3 vaccines and provide insights into immune-enhancing strategies aiming at augmenting antigen cross-presentation by DCs and enhancing potent CTL responses.

Emerging mechanisms and implications of cGAS-STING signaling in cancer immunotherapy strategies.

The intricate interplay between the human immune system and cancer development underscores the central role of immunotherapy in cancer treatment. Within this landscape, the innate immune system, a critical sentinel protecting against tumor incursion, is a key player. The cyclic GMP-AMP synthase (cGAS) and stimulator of interferon genes (STING) pathway has been found to be a linchpin of innate immunity: activation of this signaling pathway orchestrates the production of type I interferon (IFN-α/ß), thus fostering the maturation, differentiation, and mobilization of immune effectors in the tumor microenvironment. Furthermore, STING activation facilitates the release and presentation of tumor antigens, and therefore is an attractive target for cancer immunotherapy. Current strategies to activate the STING pathway, including use of pharmacological agonists, have made substantial advancements, particularly when combined with immune checkpoint inhibitors. These approaches have shown promise in preclinical and clinical settings, by enhancing patient survival rates. This review describes the evolving understanding of the cGAS-STING pathway's involvement in tumor biology and therapy. Moreover, this review explores classical and non-classical STING agonists, providing insights into their mechanisms of action and potential for optimizing immunotherapy strategies. Despite challenges and complexities, the cGAS-STING pathway, a promising avenue for enhancing cancer treatment efficacy, has the potential to revolutionize patient outcomes.