Immune Mechanisms Research Articles

Factors Predicting COVID-19 Vaccine Effectiveness and Longevity of Humoral Immune Responses

The COVID-19 pandemic, caused by SARS-CoV-2, prompted global efforts to develop vaccines to control the disease. Various vaccines, including mRNA (BNT162b2, mRNA-1273), adenoviral vector (ChAdOx1, Ad26.COV2.S), and inactivated virus platforms (BBIBP-CorV, CoronaVac), elicit high-titer, protective antibodies against the virus, but long-term antibody durability and effectiveness vary. The objective of this study is to elucidate the factors that influence vaccine effectiveness (VE) and the longevity of humoral immune responses to COVID-19 vaccines through a review of the relevant literature, including clinical and real-world studies. Here, we discuss the humoral immune response to different COVID-19 vaccines and identify factors influencing VE and antibody longevity. Despite initial robust immune responses, vaccine-induced immunity wanes over time, particularly with the emergence of variants, such as Delta and Omicron, that exhibit immune escape mechanisms. Additionally, the durability of the humoral immune responses elicited by different vaccine platforms, along with the identification of essential determinants of long-term protection—like pre-existing immunity, booster doses, hybrid immunity, and demographic factors—are critical for protecting against severe COVID-19. Booster vaccinations substantially restore neutralizing antibody levels, especially against immune-evasive variants, while individuals with hybrid immunity have a more durable and potent immune response. Importantly, comorbidities such as diabetes, cardiovascular disease, chronic kidney disease, and cancer significantly reduce the magnitude and longevity of vaccine-induced protection. Immunocompromised individuals, particularly those undergoing chemotherapy and those with hematologic malignancies, have diminished humoral responses and benefit disproportionately from booster vaccinations. Age and sex also influence immune responses, with older adults experiencing accelerated antibody decline and females generally exhibiting stronger humoral responses compared to males. Understanding the variables affecting immune protection is crucial to improving vaccine strategies and predicting VE and protection against COVID-19.

Integrative hyperspectral, transcriptomic, and metabolomic analysis reveals the mechanism of tea plants in response to sooty mold disease.

Sooty mold (SM), caused by Cladosporium species, is a pervasive threat to tea plant health, affecting both canopy structure and crop yield. Despite its significance, understanding the complex interplay between defense genes and metabolites in tea plants across various SM-infected canopy layers remains limited. Our study employed hyperspectral imaging, transcriptomic profiling, and metabolomic analysis to decipher the intricate mechanisms underlying the tea plant's response to SM infection. Our hyperspectral imaging identified three critical wavelengths (552, 673, and 800nm) inflection points associated with varying degrees of SM infection. This non-invasive method allows for the precise assessment of disease progression. Concurrently, transcriptome analysis revealed a wealth of differentially expressed genes (DEGs) enriched in metabolic pathways, secondary metabolite biosynthesis, and plant-pathogen interactions. Cluster analysis highlighted an intensified immune response in A2 and A3 samples. A comprehensive metabolomic profile identified 733 co-changed metabolites in SM-infected leaves, with alcohols, lipids (free fatty acids), hydrocarbons, and amino acids significantly accumulating in A1, while flavonoids were predominantly upregulated in A2 and A3. Weighted Gene Co-Expression Network Analysis (WGCNA) uncovered five hub genes (Dormancy-associated protein, Serine/threonine-protein phosphatase, ABC transporter, and some uncharacterized proteins) and two hub metabolites (D-Mannitol and 17-Hydroxylinolenic Acid) that exhibit significant relationships with DEGs and metabolites. Further co-expression analysis indicated that tea plants mainly employed genes and metabolites related to the biosynthesis of secondary metabolites, plant hormone signal transduction, and plant-pathogen interaction to combat SM. This study establishes a foundation for understanding the immune mechanisms of tea plants across different canopy layers in response to SM infection. It not only sheds light on the complex defense strategies employed by tea plants but also identifies candidate genes and metabolites crucial for enhancing tea plant breeding and resistance to SM.

Cannabinoid Receptor type 2 agonist GP1a attenuates macrophage activation induced by M. bovis-BCG by inhibiting NF-ĸB signaling.

Tuberculosis (TB) is one of the leading causes of death worldwide and a major public health problem. Immune evasion mechanisms and antibiotic resistance highlight the need to better understand this disease and explore alternative treatment approaches. Mycobacterial infection modulates the macrophage response and metabolism to persist and proliferate inside the cell. Cannabinoid receptor type 2 (CB2) is expressed mainly in leukocytes and modulates the course of inflammatory diseases. Therefore, our study aimed to evaluate the effects of the CB2-selective agonist GP1a on irradiated M. bovis-BCG (iBCG)-induced J774A.1 macrophage activation. We observed increased expression of CB2 in macrophages after iBCG stimulation. The pretreatment with CB2-agonists, GP1a, JWH-133, and GW-833972A (10 µM), reduced iBCG-induced TNF-α and IL-6 release by these cells. Moreover, the CB2-antagonist AM630 (200nM) treatment confirmed the activity of GP1a on CB2 by scale down its effect on cytokine production. GP1a pretreatment (10 µM) also inhibited the iBCG-induced production of inflammatory mediators as prostaglandin (PG)E2 and nitric oxide (NO) by macrophages. Additionally, GP1a pretreatment also reduced the transcription of proinflammatory genes (inos, il1b, cox2) and genes related to lipid metabolism (dgat1, acat1, plin2, atgl, cd36). Indeed, lipid droplet accumulation was reduced by GP1a treatment which was partially blockade by AM630 pretreatment. Finally, GP1a pretreatment reduced the activation of the NF-κB signaling pathway. In conclusion, the activation of CB2 by GP1a modulated the macrophage response to iBCG by reducing inflammatory mediator levels and metabolic reprogramming.

Single-cell transcriptomics unveils skin cell specific antifungal immune responses and IL-1Ra- IL-1R immune evasion strategies of emerging fungal pathogen Candida auris.

Candida auris is an emerging multidrug-resistant fungal pathogen that preferentially colonizes and persists in skin tissue, yet the host immune factors that regulate the skin colonization of C. auris in vivo are unknown. In this study, we employed unbiased single-cell transcriptomics of murine skin infected with C. auris to understand the cell type-specific immune response to C. auris. C. auris skin infection results in the accumulation of immune cells such as neutrophils, inflammatory monocytes, macrophages, dendritic cells, T cells, and NK cells at the site of infection. We identified fibroblasts as a major non-immune cell accumulated in the C. auris infected skin tissue. The comprehensive single-cell profiling revealed the transcriptomic signatures in cytokines, chemokines, host receptors (TLRs, C-type lectin receptors, NOD receptors), antimicrobial peptides, and immune signaling pathways in individual immune and non-immune cells during C. auris skin infection. Our analysis revealed that C. auris infection upregulates the expression of the IL-1RN gene (encoding IL-1R antagonist protein) in different cell types. We found IL-1Ra produced by macrophages during C. auris skin infection decreases the killing activity of neutrophils. Furthermore, C. auris uses a unique cell wall mannan outer layer to evade IL-1R-signaling mediated host defense. Collectively, our single-cell RNA seq profiling identified the transcriptomic signatures in immune and non-immune cells during C. auris skin infection. Our results demonstrate the IL-1Ra and IL-1R-mediated immune evasion mechanisms employed by C. auris to persist in the skin. These results enhance our understanding of host defense and immune evasion mechanisms during C. auris skin infection and identify potential targets for novel antifungal therapeutics.

Research Progress on the Impact of Human Chorionic Gonadotropin on Reproductive Performance in Sows

Human chorionic gonadotropin is a glycoprotein hormone produced by human or humanoid syncytiotrophoblasts that differentiate during pregnancy. Due to its superior stability and long-lasting effects compared to luteinizing hormone, it is often used to replace luteinizing hormone to regulate reproductive performance in sows. Human chorionic gonadotropin promotes oocyte maturation, follicle development, and luteinization, thereby increasing conception rates and supporting early embryonic development. In sow reproductive management, the application of human chorionic gonadotropin not only enhances ovulation synchrony but also improves the success rate of embryo implantation by regulating endometrial receptivity and immune mechanisms, significantly enhancing overall reproductive performance. This article primarily reviews the application of human chorionic gonadotropin in sow follicle development, luteal maintenance, and embryo implantation, providing theoretical support for its use in improving reproductive performance in sows.

Type I interferon signaling in dendritic cells limits direct antigen presentation and CD8+ T cell responses against an arthritogenic alphavirus.

Ross River virus (RRV) and other alphaviruses cause chronic musculoskeletal syndromes that are associated with viral persistence, which suggests deficits in immune clearance mechanisms, including CD8+ T-cell responses. Here, we used a recombinant RRV-gp33 that expresses the immunodominant CD8+ T-cell epitope of lymphocytic choriomeningitis virus (LCMV) to directly compare responses with a virus, LCMV, that strongly induces antiviral CD8+ T cells. After footpad injection, we detected fewer gp33-specific CD8+ T cells in the draining lymph node (DLN) after RRV-gp33 than LCMV infection, despite similar viral RNA levels in the foot. However, less RRV RNA was detected in the DLN compared to LCMV, with RRV localizing principally to the subcapsular region and LCMV to the paracortical T-cell zones. Single-cell RNA-sequencing analysis of adoptively transferred gp33-specific transgenic CD8+ T cells showed rapid differentiation into effector cells after LCMV but not RRV infection. This defect in RRV-specific CD8+ T effector cell maturation was corrected by local blockade of type I interferon (IFN) signaling, which also resulted in increased RRV infection in the DLN. Studies in Wdfy4-/-, CD11c-Cre B2mfl/fl, or Xcr1-Cre Ifnar1fl/fl mice that respectively lack cross-presenting capacity, MHC-I antigen presentation by dendritic cells (DCs), or type I IFN signaling in the DC1 subset show that RRV-specific CD8+ T-cell responses can be improved by enhanced direct antigen presentation by DCs. Overall, our experiments suggest that antiviral type I IFN signaling in DCs limits direct alphavirus infection and antigen presentation, which likely delays CD8+ T-cell responses.IMPORTANCEChronic arthritis and musculoskeletal disease are common outcomes of infections caused by arthritogenic alphaviruses, including Ross River virus (RRV), due to incomplete virus clearance. Unlike other viral infections that are efficiently cleared by cytotoxic CD8+ T cells, RRV infection is surprisingly unaffected by CD8+ T cells as mice lacking or having these cells show similar viral persistence in joint and lymphoid tissues. To elucidate the basis for this deficient response, we measured the RRV-specific CD8+ T-cell population size and activation state relative to another virus known to elicit a strong T-cell response. Our findings reveal that RRV induces fewer CD8+ T cells due to limited infection of immune cells in the draining lymph node. By increasing RRV susceptibility in antigen-presenting cells, we elicited a robust CD8+ T-cell response. These results highlight antigen availability and virus tropism as possible targets for intervention against RRV immune evasion and persistence.

Host Innate and Adaptive Immunity Against African Swine Fever Virus Infection

Africa swine fever virus (ASFV) is the causative agent of African swine fever (ASF), a highly contagious hemorrhagic disease that can result in up to 100% lethality in both wild and domestic swine, regardless of breed or age. The ongoing ASF pandemic poses significant threats to the pork industry and food security, with serious implications for the sanitary and socioeconomic system. Due to the limited understanding of ASFV pathogenesis and immune protection mechanisms, there are currently no safe and effective vaccines or specific treatments available, complicating efforts for prevention and control. This review summarizes the current understanding of the intricate interplay between ASFV and the host immune system, encompassing both innate and adaptive immune responses to ASFV infection, as well as insights into ASFV pathogenesis and immunosuppression. We aim to provide comprehensive information to support fundamental research on ASFV, highlighting existing gaps and suggesting future research directions. This work may serve as a theoretical foundation for the rational design of protective vaccines against this devastating viral disease.

Current vaccines, experimental immunization trials, and new perspectives to control selected vector borne blood parasites of veterinary importance

Parasite infections transmitted by vectors such as ticks and blood-sucking arthropods pose a significant threat to both human and animal health worldwide and have a substantial economic impact, particularly in the context of worsening environmental conditions. These infections can manifest in a variety of symptoms, including fever, anemia, jaundice, enlarged spleen, neurological disorders, and lymphatic issues, and can have varying mortality rates. In this review, we will focus on the current state of available vaccines, vaccine research approaches, and trials for diseases caused by vector-borne blood parasites, such as Babesia, Theileria, Anaplasma, and Trypanosoma, in farm animals. Control measures for these infections primarily rely on vector control, parasiticidal drug treatments, and vaccinations for disease prevention. However, many of these approaches have limitations, such as environmental concerns associated with the use of parasiticides, acaricides, and insecticides. Additionally, while some vaccines for blood parasites are already available, they still have several drawbacks, including practicality issues, unsuitability in non-endemic areas, and concerns about spreading other infectious agents, particularly in the case of live vaccines. This article highlights recent efforts to develop vaccines for controlling blood parasites in animals. The focus is on vaccine development approaches that show promise, including those based on recombinant antigens, vectored vaccines, and live attenuated or genetically modified parasites. Despite intensive research, developing effective subunit vaccines against blood stage parasites remains a challenge. By learning from previous vaccine development efforts and using emerging technologies to define immune mechanisms of protection, appropriate adjuvants, and protective antigens, we can expand our toolkit for controlling these burdensome diseases.

Viral infection and antiviral immunity in the oral cavity.

Individual tissues have distinct antiviral properties garnered through various mechanisms, including physical characteristics, tissue-resident immune cells and commensal organisms. Although the oral mucosa has long been appreciated as a critical barrier tissue that is exposed to a continuous barrage of pathogens, many fundamental aspects of the antiviral immune response in this tissue remain unknown. Several viral pathogens, such as herpesviruses and human papillomaviruses, have been acknowledged both historically and at present for infections in the oral cavity that result in substantial clinical burden. However, recent viral outbreaks, including those with SARS-CoV-2 and mpox, featured oral symptoms even though these viruses are not generally considered oral pathogens. Ensuing studies have shown that the oral cavity is an important locale for viral infection and potential transmission of newly emergent or re-emergent pathogens, highlighting the need for an increased understanding of the mechanisms of antiviral immunity at this site. In this Review, we provide a broad overview of antiviral immune responses in the oral cavity and discuss common viral infections and their manifestations in the oral mucosa. In addition, we present current mouse models for the study of oral viral infections.

Molecular characterization of Ebola virus, immune response, and therapeutic challenges: a narrative review

AbstractThe Ebola virus (EBOV) remains a major public health challenge due to its complex structure and the lack of appropriate and effective vaccines and therapies. This review characterizes the Ebola virus, its immune response, and its therapeutic challenges. Structural EBOV proteins include the envelope glycoprotein, nucleoprotein, RNA polymerase L, and viral proteins VP30, VP24, VP35, and VP40. The proteins play a role in the virus’s pathogenesis by evading the host's immune response. The immune system evasion mechanisms of EBOV are critical in its pathogenesis. Some vaccines, such as the recombinant vesicular stomatitis virus-Zaire Ebola virus (RVSV-ZEBOV), have proven to be very effective and have been approved by the Food and Drug Administration (FDA) additionally, four other vaccines have been approved including Gam Evac-Combi (licensed in Russia), ad5-EBOV (approved in China), Zabdeno and Mvabea (approved in Europe). However, some challenges remain in developing effective vaccines, such as the selection of immunogens, cross-protecting immunity, long-term protection, mechanism of protection, and rapid response vaccination. Despite the progress made, there is still a need for an effective vaccine that offers durable and broad protection against multiple strains of the Ebola virus. This will be achieved through the collaboration of various organizations and government and Non-Governmental Organization (NGO) agencies.

IMMU-35. TARGETING THE AHR IMMUNOMETABOLIC HUB DURING VIROIMMUNOTHERAPY OF GLIOMAS

Abstract Glioblastoma (GBM) poses a significant therapeutic challenge in oncology. Recent clinical trials have shown the feasibility of virotherapy to treat patients with GBM. Our laboratory developed an oncolytic adenovirus termed Delta-24-RGD that has been tested in clinical trials for recurrent GBM patients with encouraging results (NCT00805376, NCT02798406). These clinical studies, together with preclinical data, showed that the efficacy of Delta-24-RGD was due to direct tumor cell oncolysis and indirect activation of anti-tumor immune response. To further leverage this immune component, our group generated Delta-24-RGDOX, an armed version of Delta-24-RGD expressing the T-cell activator OX40-L, which exhibits a superior anti-cancer effect. In this project, we aim to further boost the effectiveness of Delta-24-RGDOX by targeting factors that maintain the immunosuppressive characteristic of gliomas. Specifically, we identified the environmental sensor and transcription factor Aryl Hydrocarbon Receptor (AhR) as one of the immunosuppressive factors. We show that AhR is overexpressed in GBM surgical specimens compared to healthy brain tissue, and high AhR expression correlates with poorer survival in glioma patients. Immunofluorescence staining of glioma cells treated with Delta-24-RGDOX demonstrated that AhR translocates to the nucleus, and qPCR showed that translocation resulted in the enhanced transcription of AhR-responsive elements. Additionally, bulk RNA-seq reveals that in vivo glioma models treated with Delta-24-RGDOX exhibit activation of the AhR pathway network. This unexpected and paradoxical activation may be responsible for immune suppression mechanisms, which might hinder the effect of Delta-24-RGDOX. Based on these data, we combined two innovative strategies, the oncolytic virus Delta-24-RGDOX and AhR inhibitors. Survival analysis in immunocompetent models of gliomas treated with this combined therapy showed the greatest therapeutic benefit compared to monotherapy controls. These findings highlight the critical role of AhR activation triggered by Delta-24-RGDOX and position AhR as a potential therapeutic target for enhancing the efficacy of oncolytic adenovirus therapy in GBM.

EXTH-76. REDIRECTING STROMAL CELLS TO IGNITE ANTI-TUMOR IMMUNITY AGAINST GLIOBLASTOMA

Abstract BACKGROUND The dismal prognosis of high-grade gliomas demands novel treatment approaches. Through the development of a novel mRNA lipid particle aggregate (RNA-LPA) vaccine, our lab has shown anti-tumor efficacy in preclinical murine studies and promising immunological responses in canine glioma models and human studies (Cell. 2024 May 9;187(10):2521-2535.e21). The translational potential necessitates further investigating the immune activation mechanism to allow greater applicability of this therapy in the future. OBJECTIVE We sought to unravel mechanistic cross-talk for immune initiation following intravenous administration of RNA-LPAs. METHODS We used Ai14 reporter mice to determine RNA-LPA transfected cellular subsets and dual reporter mice to assess cellular infiltration into murine glioma models. Murine gliomas were generated via implantation of K2 or KR158b-luc cell lines. RESULTS Following intravenous administration, we found fibroblastic reticular cells in secondary lymphoid organs take up RNA-LPAs. We show that FRCs have direct contact with antigen presenting cells and mediate release of full-length proteins following RNA-LPA transfection. Similar to the periphery, there is transfection of stromal cells in the brain tumor microenvironment (TME) and recruitment of infiltrating leukocytes. In response to RNA-LPAs, transfected stromal cells release type I interferon (IFN-I), which is requisite for anti-tumor efficacy. IFN-I mediates upregulation of CD69 on lymphocytes leading to sequestration following co-localization with RNA-LPAs. IFN-I is necessary for LFA-I expression on T cells, which is important for T cell trafficking across the blood-brain barrier. In preclinical models to track antigen specific immunity, we find systemic RNA administration elicits an increase in tumor reactive T cells with decreased S1P1 expression suggestive of a ‘locked-in’ response within the TME. CONCLUSION While stromal cells are regulatory niches in glioblastoma ecosystems, we show they can be leveraged for immunologic cross-talk that facilitates T cell recruitment, trafficking and sequestration in the TME critical for immunologic reprogramming and long-lasting immunotherapy.

ETIOPATHOGENETIC MECHANISMS OF IMMUNE DYSFUNCTION IN COMBATANTS WITH LOWER LIMB SOFT TISSUE INJURIES UNDER CHRONIC STRESS

Introduction. Combat injuries, including gunshot, shrapnel, and mine-explosive wounds, affect a significant number of soldiers in modern warfare. Notably, most of these injuries involve damage to the soft tissues of the extremities. Surgeons have expressed concerns regarding the unsatisfactory treatment outcomes in this group of combatants, attributing one of the primary challenges to the limited understanding of immune dysfunction pathogenesis in military trauma cases. This study aims to address this gap by examining immune system dysfunctions in combat-related injuries. The objective of this study is to thoroughly analyze and synthesize the key stages of immune dysfunction occurring over extended periods post-combat trauma, including the subsequent development of traumatic disease and various wound complications. Materials and Methods. The rising prevalence of combat trauma among soldiers has intensified interest in studying this issue, prompting surgeons and traumatologists to address its various medical aspects comprehensively. The literature search focused on recent publications, allowing for a targeted analysis of the immunological aspects relevant to military medical traumatology. Results. In the initial stages of severe or combined injuries affecting various tissues—such as tubular bones, joints, blood vessels, and peripheral nerves—systemic inflammatory response syndrome (SIRS) commonly occurs. This stage is marked by an intense activation of innate antibacterial and immune-protective responses, leading to a significant increase in inflammation. This initial response is soon replaced by a prolonged phase known as compensatory anti-inflammatory response syndrome. During this period, immune-protective responses sharply decrease, certain immunocompetent cells become inhibited, and lymphopenia develops. This phase is often accompanied by infectious contamination of wounds with pathogenic and opportunistic microorganisms, resulting in both local purulent-necrotic processes and potentially severe systemic complications, such as septic shock, sepsis, multiple organ failure, and others. The final stage, known as persistent inflammatory, immunosuppressive, catabolic syndrome, is characterized by the chronic progression of traumatic disease, accompanied by ongoing immune system dysfunction in combatants. Conclusion. In the early period of traumatic injury, the wounded experience sharp inflammatory processes and activation of immune defense mechanisms. At subsequent stages, severe disruptions in the functioning of the immune system, damage to internal organs, and the development of catabolic syndrome are recorded. These changes, especially those resulted from exposure to chronic combat stress preceding the injury, aggravate the processes of infectious decontamination of wounds, regeneration of damaged tissues, and the general process of combatant rehabilitation.

EPCO-58. INTEGRATIVE PROTEOGENOMIC ANALYSES REVEAL INSIGHTS INTO SUBTYPE-SPECIFIC GLIOMA RISK

Abstract Gliomas are heterogeneous brain tumors with prognostically-significant subtypes and few risk factors. IDH-wildtype glioblastoma, the most common subtype, carries a dismal prognosis. Using the largest GWAS dataset with histological (11,304 cases, 304,523 controls) and molecular (3,418 cases, 8,156 controls) subtypes, we analyzed the plasma and brain proteome to uncover proteins associated with glioma susceptibility. Using protein quantitative trait loci (pQTL) for 1,776 proteins in brain tissue, we identified 21 candidate proteins, including 9 associations with high probability (>70%) of colocalization (shared causal genetic variants for glioma risk and protein abundance). We confirmed known risk genes such as EGFR (p=1.9×10-35) and D2HGDH (p=1.1×10-5). We also identified novel risk proteins, including ENPP6, a choline phosphodiesterase overexpressed in glioma, for IDH-wildtype glioblastoma (OR=0.62, p=7.6×10-5), and galectin-3, a lectin encoded by a tumor fitness gene in CRISPR screens of glioma proliferation and a clinical drug target, for glioma overall (OR=1.37, p=1.3×10-5). Analyses of the plasma proteome using pQTLs for 1,362 proteins from 3 cohorts (N=88,838) identified 9 colocalized associations in whole blood. Most risk signals were subtype-specific, such as CRELD1 (p=2.5×10-5) for triple-negative glioblastoma. We found three candidate risk proteins for IDH-mutant 1p19q-intact glioma: immunoglobulin glycoprotein BCAM (p=9.6×10-8), neurotrophin receptor SorCS2 (p=3.6×10-5) and immune checkpoint PD-1 (p=1.1×10-5). Interestingly, genetically-predicted PD-1 levels had a larger effect on IDH-mutant 1p19q-intact (OR=2.75, 95% CI=1.61-4.69) than IDH-wildtype (OR=0.73, 95% CI=0.51-1.05) tumors, suggesting germline differences in immune checkpoint mechanisms among subtypes. For all colocalized candidates, genetically-predicted protein abundance was correlated with cis-regulated transcriptional activity in brain tissue. For example, genetically-predicted SORCS2 gene expression in brain tissue was associated with plasma SorCS2 levels (Z=16.1, p=1.1×10-68). Our analysis identified candidate proteins involved in immune response and neuronal proliferation, which may enable prioritization of drug targets and provide insight into disease mechanisms for glioma.

TMIC-49. TUMOR-DERIVED SPERMIDINE DRIVES IMMUNE SUPPRESSION IN THE GLIOBLASTOMA MICROENVIRONMENT VIA CD8 T CELL DEPLETION AND FUNCTIONAL ATTENUATION

Abstract A hallmark of glioblastoma (GBM) is an immunosuppressive microenvironment that is partially driven by tumor cell-derived secreted factors, highlighting the need for a more complete understanding of local immune suppressive mechanism. Altered secreted metabolite levels are observed in the GBM microenvironment; specifically, spermidine (a polyamine), which functions to drive cell proliferation, apoptosis, T cell lineage commitment, and myeloid cell-mediated suppression. However, the direct link between GBM cell-derived spermidine and the tumor microenvironment has yet to be determined. In syngeneic mouse GBM models, spermidine levels were increased in the tumor microenvironment and exogenous administration of spermidine accelerated tumor aggressiveness in an immune dependent-manner. Mechanistically, spermidine administration increased apoptosis of CD8+ T-cells and generated an exhausted phenotype. When ornithine decarboxylase (ODC1, the rate limiting enzyme in spermidine synthesis), was knocked down in tumor cells, no direct effect was observed on tumor cell growth. However, there was an increase in time to tumor succumbence and a concomitant increase in CD8+ T-cells and decrease in CD8+ T cell exhaustion. In GBM patients, there was a negative correlation between ODC1 expression and CD8+ T-cells present near the tumor. Additionally, patients with a favorable prognosis had significantly lower intratumoral levels of spermidine compared to patients with a poor prognosis. Taken together, these results demonstrate that spermidine functions as a tumor cell-derived metabolite that drives tumor progression through reducing CD8+T cell number and altering their phenotype. These findings have clinical implications as clinical trials using a polyamine biosynthesis inhibitor alone have not been very effective in GBM patients, suggesting the need for additional combination immunotherapies. Finally, spermidine is also produced at prominent levels by commensal gut microbes as well as absorbed from consumption of foods such as mushrooms; investigation into how these distal spermidine sources impact GBM growth via the gut-brain axis is actively ongoing.

TMIC-37. GEMISTOCYTIC TUMOR CELLS AND IMMUNE REACTIVE MICROGLIA PROGRAMMED FOR GLIAL SCARRING CHARACTERIZE T CELL CONTAINMENT IN IDH-MUTANT ASTROCYTOMA

Abstract Isocitrate dehydrogenase 1/2 mutant (IDHmt) astrocytoma is considered a T cell-deprived tumor, yet little is known regarding the phenotype that relates to T cell exclusion. To aid better understanding of this mechanism, we systematically characterized the IDHmt astrocytoma immune microenvironment in a large cohort by multiplex immunofluorescence (IF) (n=75), bulk RNA sequencing (n=158), single nucleus RNA sequencing (n=7) and spatial RNA and protein profiling (n=12). We integrated and analyzed all datasets to acquire a robust characterization of the microenvironment organization and validated our results using IF stainings. We demonstrated that in IDHmt astrocytomas, T cells were contained in the perivascular space (i.e., T cell cuffs). In the tumor stroma surrounding T cell cuffs, we found a dense accumulation of gemistocytic tumor cells (GTCs), a histologically distinct tumor cell subtype. GTC-high tumors demonstrated enhanced expression of immune cell migration and activation pathways that were reliably expressed by TAMs and T cells. Notably, we found that GTCs formed a unique transcriptional cell sub-cluster that expressed markers including CD44, TNC and CRYAB, which are specific for glial scarring, a central nervous system specific mechanism for immune exclusion. Surrounding T cell cuffs, GTCs co-localized with immune-reactive microglia that expressed the chemoattractants CCL3 and CCL4. Together, co-localizing GTCs and reactive microglia expressed receptor-ligand pairs that take part in reactive astrogliosis and glial scarring, including Osteopontin – CD44 and IL-1β – IL1R1. Validation whole-slide multiplex IF stainings for this spatial relationship showed specific local accumulation of CD44 positive GTCs and TAMs around T cell cuffs in GTC-high tumors, which was absent in GTC-low tumors. Together, we show that IDHmt astrocytomas organize a network of tumor cells and leukocytes that mimics glial scarring and can aid T cell exclusion. Elucidating such specific immune exclusion mechanisms is vital for more appropriate target selection in novel immune therapies.

Delineating MYC-Mediated Escape Mechanisms from Conventional and T Cell-Redirecting Therapeutic Antibodies

In B-cell malignancies, the overexpression of MYC is associated with poor prognosis, but its mechanism underlying resistance to immunochemotherapy remains less clear. In further investigations of this issue, we show here that the pharmacological inhibition of MYC in various lymphoma and multiple myeloma cell lines, as well as patient-derived primary tumor cells, enhances their susceptibility to NK cell-mediated cytotoxicity induced by conventional antibodies targeting CD20 (rituximab) and CD38 (daratumumab), as well as T cell-mediated cytotoxicity induced by the CD19-targeting bispecific T-cell engager blinatumomab. This was associated with upregulation of the target antigen only for rituximab, suggesting additional escape mechanisms. To investigate these mechanisms, we targeted the MYC gene in OCI-LY18 cells using CRISPR-Cas9 gene-editing technology. CRISPR-Cas9-mediated MYC targeting not only upregulated CD20 but also triggered broader apoptotic pathways, upregulating pro-apoptotic PUMA and downregulating anti-apoptotic proteins BCL-2, XIAP, survivin and MCL-1, thereby rendering tumor cells more prone to apoptosis, a key tumor-lysis mechanism employed by T-cells and NK-cells. Moreover, MYC downregulation boosted T-cell activation and cytokine release in response to blinatumomab, revealing a MYC-mediated T-cell suppression mechanism. In conclusion, MYC overexpressing tumor cells mitigated the efficacy of therapeutic antibodies through several non-overlapping mechanisms. Given the challenges associated with direct MYC inhibition due to toxicity, successful modulation of MYC-mediated immune evasion mechanisms may improve the outcome of immunotherapeutic approaches in B-cell malignancies.

Unraveling the Immune Web: Advances in SMI Capsular Fibrosis from Molecular Insights to Preclinical Breakthroughs

Breast implant surgery has evolved significantly, yet challenges such as capsular contracture remain a persistent concern. This review presents an in-depth analysis of recent advancements in understanding the immune mechanisms and clinical implications associated with silicone mammary implants (SMIs). The article systematically examines the complex interplay between immune responses and capsular fibrosis, emphasizing the pathophysiological mechanisms of inflammation in the etiology of this fibrotic response. It discusses innovations in biomaterial science, including the development of novel anti-biofilm coatings and immunomodulatory surfaces designed to enhance implant integration and minimize complications. Emphasis is placed on personalized risk assessment strategies, leveraging molecular insights to tailor interventions and improve patient outcomes. Emerging therapeutic targets, advancements in surgical techniques, and the refinement of post-operative care are also explored. Despite notable progress, challenges such as the variability in immune responses, the long-term efficacy of new interventions, and ethical considerations remain. Future research directions are identified, focusing on personalized medicine, advanced biomaterials, and bridging preclinical findings with clinical applications. As we advance from bench to bedside, this review illuminates the path forward, where interdisciplinary collaboration and continued inquiry weave together to enhance the art and science of breast implant surgery, transforming patient care into a realm of precision and excellence.

An Actual Insight into the Pathogenic Pathways of Ankylosing Spondylitis

Spondyloarthritis refers to a broad group of conditions that include ankylosing spondylitis, psoriatic arthritis, reactive arthritis, and enteropathic arthritis associated with Crohn’s disease or ulcerative colitis. They have been classified by the ASAS group (ASsessment in Ankylosing Spondylitis) into axial spondyloarthritis and peripheral spondyloarthritis. Common features include the absence of autoantibodies, genetic predisposition, and clinical aspects such as axial joint involvement, peripheral manifestations, and extra-articular involvement. However, the pathogenic mechanisms remain complex and incompletely elucidated, despite the fact that the specialized literature has described several pathways that act in synergy: genetic predisposition, environmental factors (infections and mechanical stress), or innate and acquired immune mechanisms. Finally, an inflammatory response is triggered by the recruitment of a large number of inflammatory cells and the release of innate cytokines in the affected areas: joints or periarticular or extraarticular tissues. The current article aims to update and systematize the knowledge accumulated so far on this topic, focusing on the mechanisms that have been involved in the onset, progression, and severity of ankylosing spondylitis.

IMMU-11. GUARDIANS OF INNATE IMMUNE ACTIVATION: CRUCIAL ROLES OF NONO AND CGAMP IN GLIOMA VIROTHERAPY

Abstract Despite aggressive therapeutic interventions, glioblastoma patients face a median survival of seven months after tumor recurrence. Alarmingly, there has been no improvement to the standard of care for two decades, and patients still receive toxic doses of radiation and chemotherapy, rendering many unable to perform daily functions. An emerging approach, oncolytic virotherapy (OV) using Delta-24-RGD, is gaining traction due to recent clinical trials (NCT00805376, NCT03178032, and NCT02798406) exhibiting robust responses in subsets of patients. While these studies demonstrated the therapeutic potential of OV, findings also indicate the early clearance of the virus, hindering the establishment of an effective anti-tumor immune response in most patients. We propose that mitigating the innate immune response against the therapeutic virus should result in improved intratumoral persistence, increasing the window of opportunity for developing an anti-tumor immune response. RNA-sequencing identified the non-POU domain containing octamer-binding (NONO) pathway as highly upregulated in syngenic glioma models and further amplified by OV treatment. In-vitro RNA sequencing and comparative analysis complemented these results to define a unique transcriptomic profile induced by adenovirus infection. LC-MS/MS identified host cGAS and adenoviral capsid proteins as candidate binding partners of NONO, which were validated using co-immunoprecipitation. Although the type I interferon cluster is deleted in most gliomas, tumor cells have a profound influence on their microenvironment through the secretion of the second messenger cGAMP. We show that NONO is required for cGAMP production, providing a mechanism to modulate antiviral responses in the tumor microenvironment during OV. Our findings underscore the significance of cGAMP shed from tumor cells in response to OV, and how NONO interacts with cGAS in the nucleus to sensor adenovirus infection. These findings uncover novel innate immunity mechanisms in gliomas and will inform the design of more efficacious oncolytic adenoviruses for glioma therapy.