Mechanisms Of Immune Resistance Research Articles

Epidermolysis-Bullosa-Associated Squamous Cell Carcinomas Support an Immunosuppressive Tumor Microenvironment: Prospects for Immunotherapy.

Cutaneous squamous cell carcinomas (SCCs) are a major complication of some subtypes of epidermolysis bullosa (EB), with high morbidity and mortality rates and unmet therapeutic needs. The high rate of endogenous mutations and the fibrotic stroma are considered to contribute to the pathogenesis. Patients with dystrophic EB (DEB) and Kindler EB (KEB) have the highest propensity for developing SCCs. Another patient group that develops high-risk SCCs is immunosuppressed (IS) patients, especially after organ transplantation. Herein, we interrogate whether immune checkpoint proteins and immunosuppressive enzymes are dysregulated in EB-associated SCCs as an immune resistance mechanism and compare the expression patterns with those in SCCs from IS patients, who frequently develop high-risk tumors and sporadic SCCs, and immunocompetent (IC) individuals. The expression of indoleamine 2,3-dioxygenase (IDO), programmed cell death protein-1 (PD-1), programmed cell death ligand-1 (PD-L1), T cell immunoglobulin and mucin-domain-containing protein-3 (TIM-3), lymphocyte activation gene-3 (LAG-3), and inflammatory infiltrates (CD4, CD8, and CD68) was assessed via immunohistochemistry and semi-quantitative analysis in 30 DEB-SCCs, 22 KEB-SCCs, 106 IS-SCCs, and 100 sporadic IC-SCCs. DEB-SCCs expressed significantly higher levels of IDO and PD-L1 in tumor cells and PD-1 in the tumor microenvironment (TME) compared with SCCs from IC and IS individuals. The number of CD4-positive T cells per mm2 was significantly lower in DEB-SCCs compared with IC-SCCs. KEB-SCCs showed the lowest expression of the exhaustion markers TIM-3 and LAG-3 compared with all other groups. These findings identify IDO, PD-1, and PD-L1 to be increased in EB-SCCs and candidate targets for combinatory treatments, especially in DEB-SCCs.

Tissue biomarkers of immune checkpoint inhibitor therapy.

Cancer immunotherapy has been rejuvenated by the growing understanding of the immune system's role in tumor activity over the past two decades. During cancer initiation and progression, tumor cells employ various mechanisms that resemble peripheral immune tolerance to evade the antitumor responses of the immune system. Immune checkpoint molecules are the major mechanism of immune resistance that are exploited by tumor cells to inhibit T-cell activation and suppress immune responses. The targeting of immune checkpoint pathways has led to substantial improvements in survival rates in a number of solid cancers. However, a lack of understanding of the heterogeneity of the tumor microenvironment (TME) has resulted in inefficient therapy responses. A greater understanding of the TME is needed to identify patients likely to respond, and those that will have resistance to immune checkpoint inhibitors (ICIs). Advancement in spatial single-cell technologies has allowed deeper insight into the phenotypic and functional diversities of cells in the TME. In this review, we provide an overview of ICI biomarkers and highlight how high-dimensional spatially resolved, single-cell approaches provide deep molecular insights into the TME and allow for the discovery of biomarkers of clinical benefit.

Glycolysis-associated lncRNAs in cancer energy metabolism and immune microenvironment: a magic key.

The dependence of tumor cells on glycolysis provides essential energy and raw materials for their survival and growth. Recent research findings have indicated that long chain non-coding RNAs (LncRNAs) have a key regulatory function in the tumor glycolytic pathway and offer new opportunities for cancer therapy. LncRNAs are analogous to a regulatory key during glycolysis. In this paper, we review the mechanisms of LncRNA in the tumor glycolytic pathway and their potential therapeutic strategies, including current alterations in cancer-related energy metabolism with lncRNA mediating the expression of key enzymes, lactate production and transport, and the mechanism of interaction with transcription factors, miRNAs, and other molecules. Studies targeting LncRNA-regulated tumor glycolytic pathways also offer the possibility of developing new therapeutic strategies. By regulating LncRNA expression, the metabolic pathways of tumor cells can be interfered with to inhibit tumor growth and metastasis, thus affecting the immune and drug resistance mechanisms of tumor cells. In addition, lncRNAs have the capacity to function as molecular markers and target therapies, thereby contributing novel strategies and approaches to the field of personalized cancer therapy and prognosis evaluation. In conclusion, LncRNA, as key molecules regulating the tumor glycolysis pathway, reveals a new mechanism of abnormal metabolism in cancer cells. Future research will more thoroughly investigate the specific mechanisms of LncRNA glycolysis regulation and develop corresponding therapeutic strategies, thereby fostering new optimism for the realization of precision medicine.

Immune Evasion in Cancer Is Regulated by Tumor-Asociated Macrophages (TAMs): Targeting TAMs.

Recent advancements in cancer treatment have explored a variety of approaches to address the needs of patients. Recently, immunotherapy has evolved as an efficacious treatment for various cancers resistant to conventional therapies. Hence, significant milestones in immunotherapy were achieved clinically in a large subset of cancer patients. Unfortunately, some cancer types do not respond to treatment, and among the responsive cancers, some patients remain unresponsive to treatment. Consequently, there is a critical need to examine the mechanisms of immune resistance and devise strategies to target immune suppressor cells or factors, thereby allowing for tumor sensitivity to immune cytotoxic cells. M2 macrophages, also known as tumor-associated macrophages (TAMs), are of interest due to their role in suppressing the immune system and influencing antitumor immune responses through modulating T cell activity and immune checkpoint expression. TAMs are associated with signaling pathways that modulate the tumor microenvironment (TME), contributing to immune evasion. One approach targets TAMs, focusing on preventing the polarization of M1 macrophages into the protumoral M2 phenotype. Other strategies focus on direct or indirect targeting of M2 macrophages through understanding the interaction of TAMs with immune factors or signaling pathways. Clinically, biomarkers associated with TAMs' immune resistance in cancer patients have been identified, opening avenues for intervention using pharmacological agents or immunotherapeutic approaches. Ultimately, these multifaceted approaches are promising in overcoming immune resistance and improving cancer treatment outcomes.

A Large-Scale Meta-Analysis Reveals Positive Feedback between Macrophages and T Cells That Sensitizes Tumors to Immunotherapy.

Identification of robust immunogenomic connections, particularly macrophage T-cell interactions, in a large-scale pan-cancer meta-analysis and development of a predictive model for immunotherapy response that outperformed existing models could facilitate clinical decision-making.

Overcoming Resistance Mechanisms to Immune Checkpoint Inhibitors: Leveraging the Anti-Tumor Immune Response.

As far back as 3000 years ago, the immune system was observed to play a role in mediating tumor regression. Since then, many strategies have been developed to leverage the anti-tumor immune response. However, while many patients respond to ICIs up front some do not, and many of those that do eventually experience tumor progression. Currently, there are several predictive biomarkers of the immune checkpoint inhibitor response; however, no one test appears to be universally predictive and their application varies by disease site. There are many ways in which cancer cells develop primary or acquired resistance to immune checkpoint inhibitors. Efforts to reverse resistance include ways to combat T cell exhaustion, reprogram the tumor microenvironment, increase the availability of tumor neo-antigens, target alternative immune checkpoints, restore a normal/healthy patient gut microbiome, oncolytic viruses and tumor vaccines. The most studied and most promising methods include combining ICIs with therapies targeting alternative immune checkpoints and restoring a normal/healthy patient gut microbiome. This review will discuss T cell-mediated immunity, how this is leveraged by modern immunotherapy to treat cancer and mechanisms of immune checkpoint inhibitor resistance, while highlighting strategies to overcome primary and secondary resistance mechanisms.

The dynamics of the content of immunoglobulins in the blood serum of piglets according to the actions of immunostimulating agents

Inconsistency in housing and feeding conditions, production stress, a combination of environmental factors, and technological solutions reduce the protective properties of the animal body, which often leads to a decrease in their productive properties. The work aimed to investigate changes in indicators of the humoral protection factor, in particular, the quantitative composition of immunoglobulins M, G, and A in the body of young pigs under the influence of immunostimulating agents Globigen® Pig Doser and Globigen® Jump Start, which include specific Ig Y. To perform this task in the conditions of the private farm of FG PE "Glynyany Agro" of Lviv region, Zolochiv district, which uses a single-phase method of raising pigs, a study was conducted with the involvement of 36 piglets-analogues of crossbreeds of the Great White and Landrace breeds, which were formed into three groups of 12 animals each. Piglets of the control group were fed feed of a standard diet. The piglets of the first experimental group were orally administered 2 ml/g of Globigen®Pig Doser during the first three days after birth. Then, according to the technology, they consumed the feed prescribed in the diet. The piglets of the second experimental group were given Globigen®Jump Start, which was mixed with the feed of the basic ration in the amount of 2 kg per ton of feed and, starting from the age of 7 days, was fed to the piglets according to the technology. It was established that the use of immunostimulating agents was characterized by an increase in Ig G and Ig A in the blood serum of piglets in the most critical period of their lives. Thus, in the blood serum of 30-day-old piglets under the influence of Globigen® Pig Doser, with a high level of probability (Р < 0.01), an increase of this class of antibodies to the level of 13.47 mg/ml was detected, with the use of Globigen® Jump Start, this indicator reached the mark 12.51 mg/ml. Since this period, colostral immunity, represented by placental immunoglobulins of class G and colostrum immunoglobulins of class A, is already exhausted; we assume that the formation of the body's immune response of young pigs has begun. We believe that the increase in the content of class A immunoglobulins, most likely the secretory form of the piglets themselves, when using Globigen® Jump Start, which reached the mark of 1.48 mg/ml, indicates the formation of immune resistance mechanisms. The effectiveness, specificity, and mechanism of action of these agents is based on the ability of their components, particularly Ig Y, to bind to pathogens or their fragments, to neutralize and safely remove them from the body, which helps to increase the barrier function of the intestinal mucosa. The obtained research results confirm the practicality of using Globigen® Pig Doser and Globigen® Jump Start immunostimulants during single-phase rearing of piglets to increase the level of non-specific resistance and obtain healthy young animals with a high level of viability.

Abstract IA009: Antibody-lectin chimeras for glyco-immune checkpoint blockade

Abstract Despite the curative potential of checkpoint blockade immunotherapy, a majority of patients remain unresponsive to existing treatments. Glyco-immune checkpoints – interactions of cell-surface glycans with lectin, or glycan binding, immunoreceptors – have emerged as prominent mechanisms of immune evasion and therapeutic resistance in cancer. Here, we describe antibody-lectin chimeras (AbLecs), a modular platform for glyco-immune checkpoint blockade. AbLecs are bispecific antibody-like molecules comprising a tumor-targeting arm as well as a lectin “decoy receptor” domain that directly binds tumor glycans and blocks their ability to engage lectin receptors on immune cells. AbLecs enhanced cancer cell killing in vitro via macrophage phagocytosis and NK cell and granulocyte cytotoxicity compared to their parent monoclonal antibodies. AbLec treatment reduced tumor burden in vivo compared to treatment with the parent antibody in a humanized model of metastatic HER2+ cancer. Furthermore, AbLecs synergized with blockade of the “don’t eat me” signal CD47 for enhanced tumor killing. AbLecs can be readily designed to target numerous tumor-associated antigens and glyco-immune checkpoint ligands, and therefore represent a new modality of cancer immunotherapy. Citation Format: Jessica Stark. Antibody-lectin chimeras for glyco-immune checkpoint blockade [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr IA009.

Abstract B014: Spatial genomics identifies cancer cell cytokines regulating ovarian cancer immunity

Abstract Ovarian cancer (OvCa) is among the most aggressive and lethal cancers with a poor response to immune checkpoint blockade (ICB) despite its modest tumor mutational burden and expression of known cancer antigens. Consequently, it is critical to understand the molecular mechanisms of tumor immune escape and resistance to immunotherapies. Intercellular signaling between cancer cells and the tumor microenvironment (TME) is a crucial determinant of tumor immunity and given the immunosuppressive nature of OvCa TME, it is of utmost importance to dissect how this immunosuppressed TME is established. To begin to determine which cancer-cell genes may function cell externally in controlling of OvCa immunity, we employed a first-of-its-kind spatial functional genomics approach we developed, called Perturb-map, which enables dozens of CRISPR gene knock-out (KO) cells to be resolved in a tissue/tumor by imaging, along with cells in the local TME. We used Perturb-map to determine how 35 different genes, identified through ligand-receptor analysis of ovarian tumors, influenced tumor response to anti-PD-1 treatment in an OvCa mouse model. Strikingly, Il4 KO tumors were unique amongst the 35 gene KOs making the tumors significantly more responsive to anti-PD-1 treatment despite not impacting tumor growth in the absence of immunotherapy. Further experiments with single CRISPR KO tumors validated the Perturb-map finding, where Il4 KO combined with anti-PD-1 treatment resulted in a major reduction in tumor growth and a significant increase in survival. Cyclic immunofluorescence (CyCIF) multiplex imaging revealed that loss of cancer cell-derived IL-4 led to a significant reduction in pro-tumor macrophages and an increase in dendritic cell (DC) subsets as well as both progenitor and terminally exhausted CD8 T cells. Upon anti-PD-1 treatment, Il4 KO tumors had significant enrichment for activated CD8 T cells and B cells. Importantly, spatial analysis of the tumor samples identified enrichment of T follicular helper cells, B cells, and DCs in tertiary lymphoid structures in tumors with combined IL-4 loss and PD-1 inhibition. Further, we analyzed a human OvCa single-cell transcriptomics dataset and demonstrated that an IL-4 response signature is expressed in tumor-associated macrophages, indicating active IL-4 signaling in human ovarian tumors. Importantly, we employed a CRISPR-knock-in expression reporter in mouse tumors as well as immunohistochemistry of both human and mouse tumor samples to confirm that IL-4 is expressed by cancer cells. Thus, we identified cancer cell-secreted IL-4 as a potent regulator of OvCa TME and response to ICB. Given that an anti-IL-4-receptor antibody is already in clinical use to treat immune diseases, our findings have the potential to be translated to the clinical management of this dreadful disease. Citation Format: Gurkan Mollaoglu, Alexander Tepper, Hunter Potak, Luisanna Pia, Angelo Amabile, Chiara Falcomata, Jaime Mateus-Tique, Noam Rabinovich, Rachel Brody, Lindsay Browning, Jia-Ren Lin, Peter Sorger, Sandro Santagata, Miriam Merad, Alessia Baccarini, Brian Brown. Spatial genomics identifies cancer cell cytokines regulating ovarian cancer immunity [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr B014.

Resistance to immune checkpoint inhibitors in gastric cancer.

Gastric cancer (GC) is one of the most common gastrointestinal malignancies worldwide. In the past decade, with the development of early diagnostic techniques, a clear decline in GC incidence has been observed, but its mortality remains high. The emergence of new immunotherapies such as immune checkpoint inhibitors (ICIs) has changed the treatment of GC patients to some extent. However, only a small number of patients with advanced GC have a durable response to ICI treatment, and the efficacy of ICIs is very limited. Existing studies have shown that the failure of immunotherapy is mainly related to the development of ICI resistance in patients, but the understanding of the resistance mechanism is still insufficient. Therefore, clarifying the mechanism of GC immune resistance is critical to improve its treatment and clinical benefit. In this review, we focus on summarizing the mechanisms of primary or acquired resistance to ICI immunotherapy in GC from both internal and external aspects of the tumor. At the same time, we also briefly discuss some other possible resistance mechanisms in light of current studies.

The Yin Yang of Complement and Cancer.

Cancer-related inflammation is a crucial component of the tumor microenvironment (TME). Complement activation occurs in cancer and supports the development of an inflammatory microenvironment. Complement has traditionally been considered a mechanism of immune resistance against cancer, and its activation is known to contribute to the cytolytic effects of antibody-based immunotherapeutic treatments. However, several studies have recently revealed that complement activation may exert protumoral functions by sustaining cancer-related inflammation and immunosuppression through different molecular mechanisms, targeting both the TME and cancer cells. These new discoveries have revealed that complement manipulation can be considered a new strategy for cancer therapies. Here we summarize our current understanding of the mechanisms by which the different elements of the complement system exert antitumor or protumor functions, both in preclinical studies and in human tumorigenesis. Complement components can serve as disease biomarkers for cancer stratification and prognosis and be exploited for tumor treatment.

A new prognostic risk model for acute myeloid leukemia patients based on telomere-related genes

Telomere maintenance is critical to ensure unlimited cancer cell proliferation, but the role of telomere-related genes in acute myeloid leukemia (AML) has not yet been thoroughly discussed. This study aims to develop a new prognostic risk model based on telomere-related genes and analyze potential mechanisms and targets. Cox regression analyses were used to build the prognostic risk model. Kaplan-Meier (KM) survival analysis and receiver operating characteristic (ROC) curve were used to assess the model performance. At the same time, we analyzed the relationship between the risk score and chemotherapy and immunotherapy and preliminarily explored possible mechanisms of immune resistance. The real-time polymerase chain reaction (PCR) was used to detect the prognosis gene expression levels. Finally, a prognostic signature of six telomere-related genes (TGPS6) including ALDH2, CDK18, DNMT3B, FRAT2, LGALSL, and RBL2 was constructed. The TGPS6 score was confirmed as an independent prognostic factor (HR 2.74, CI [2.13–3.53], p < 0.001) in AML and the five-year area under the ROC curve (AUC) value of the score in the training and validation set reached 0.74, 0.81 respectively. In addition, the TGPS6 perfected the European LeukemiaNet (ELN) 2017 prognosis risk stratification and performed well in both AML and cytogenetically normal AML (CN-AML) cohorts. The TGPS6 score also provided a reference for chemotherapy and immunotherapy in patients with AML.

Thermoelectric Nanofluidics Probing Thermal Heterogeneity inside Single Cells.

Accurate temperature measurement in one living cell is of great significance for understanding biological functions and regulation. Here, a nanopipet electric thermometer (NET) is established for real-time intracellular temperature measurement. Based on the temperature-controlled ion migration, the temperature change in solution results in altered ion mobilities and ion distributions, which can be converted to the thermoelectric responses of NET in a galvanostatic configuration. The exponential relationship between the voltage and the temperature promises highly sensitive thermoelectric responses up to 11.1 mV K-1, which is over an order of magnitude higher than previous thermoelectric thermometry. Moreover, the NET exhibits superior thermal resolution of 25 mK and spatiotemporal resolution of 100 nm and 0.9 ms as well as excellent stability and reproducibility. Benefiting from these unique features, both thermal fluctuations in steady-state cells and heat generation and dissipation upon drug administration can be successfully monitored, which are hardly achieved by current methods. By using NET, thermal heterogeneities of single cancer cells during immunotherapy were reported first in this work, in which the increased intracellular temperature was demonstrated to be associated with the survival benefit and resistance of cancer cells in immunotherapy. This work not only provides a reliable method for microscopic temperature monitoring but also gains new insights to elucidate the mechanism of immune evasion and therapeutic resistance.

Non-Redundant Mechanisms of Immune Resistance to Radiotherapy Converge on Innate Immunity

Despite evidence of preclinical synergy between radiotherapy (RT) and immune checkpoint blockade (ICB), randomized trials of RT/ICB have demonstrated limited benefit in solid tumors. We performed single-cell RNA sequencing (scRNA-seq) and CITE-seq (cellular indexing of transcriptomes and epitopes) to address the discordance between preclinical and clinical data. We hypothesized that multiple orthogonal inhibitory immune pathways restrain the local and systemic efficacy of RT beyond T-cell oriented immune checkpoints. We used the EO771 syngeneic murine model of breast cancer to characterize the immune tumor microenvironment following RT with or without ICB. RT (16 Gy x 1) was delivered using the X-RAD SmART platform with CT image guidance. Neutralizing antibodies (anti-PD-1/Ly6G/Gr-1/CD47) were delivered by intraperitoneal injections. scRNA-seq analysis were performed by Seurat and BBrowser (BioTuring). We found that adaptive ICB (anti-PD-1) reprogrammed the immune response to RT by promoting an M1-like interferon-primed state (ISG15, CXCL10) in tumor associated macrophages (TAMs) and by increasing the late recruitment of intratumoral neutrophils. Given that neutrophils may drive resistance to RT in other models, we evaluated the effect of intratumoral neutrophil depletion using anti-Ly6G or anti-Gr-1 on the antitumor efficacy of RT/ICB. Both neutrophil depletion strategies led to enhanced tumor control and improved survival in advanced EO771 tumors compared to RT/ICB alone (P<0.001). In parallel to this approach, we found that TAMs upregulated several innate immune checkpoints including SIRPα in response to RT. Disruption of the SIRPα-CD47 interaction by anti-CD47 antibodies similarly enhanced the antitumor efficacy of RT/ICB by improving tumor control and survival (P<0.001). Using scRNA-seq and unbiased clustering, we found that anti-CD47 eliminated an entire cluster of chronically inflamed TAMs, characterized by pro-inflammatory markers (IL1A, NOS2) and chemokines (CCL3, CXCL1/2/3). Anti-CD47 also reduced intratumoral neutrophils by eliminating a cluster of pathologically activated neutrophils, termed myeloid-derived suppressor cells (PMN-MDSCs) that expressed several markers of ferroptosis (TFRC, PTGS2, SLC3A2). Consistent with the potent immunosuppressive capacity of PMN-MDSCs, we found that anti-CD47 increased tumor-infiltrating lymphocytes including central memory TCF7+ T cells and CD19+ B cells. Lastly, by inference and analysis of cell-cell communication (CellChat), we found that anti-CD47 strengthened the interactions between TAMs and CD8+ T cells compared to RT/ICB alone. Our data collectively indicate that resistance to RT/ICB in the EO771 model Is driven by innate immune cells including neutrophils and chronically inflamed TAMs. Targeted disruption of the CD47-SIRPα axis is a promising approach to overcoming immune resistance by reprogramming TAMs and eliminating PMN-MDSCs.

Tumor microenvironment and CAR-T cell immunotherapy in B-cell lymphoma.

Chimeric receptor antigen T cell (CAR-T cell) therapy has demonstrated effectiveness and therapeutic potential in the immunotherapy of hematological malignancies, representing a promising breakthrough in cancer treatment. Despite the efficacy of CAR-T cell therapy in B-cell lymphoma, response variability, resistance, and side effects remain persistent challenges. The tumor microenvironment (TME) plays an intricate role in CAR-T cell therapy of B-cell lymphoma. The TME is a complex and dynamic environment that includes various cell types, cytokines, and extracellular matrix components, all of which can influence CAR-T cell function and behavior. This review discusses the design principles of CAR-T cells, TME in B-cell lymphoma, and the mechanisms by which TME influences CAR-T cell function. We discuss emerging strategies aimed at modulating the TME, targeting immunosuppressive cells, overcoming inhibitory signaling, and improving CAR-T cell infiltration and persistence. Therefore, these processes enhance the efficacy of CAR-T cell therapy and improve patient outcomes in B-cell lymphoma. Further research will be needed to investigate the molecular and cellular events that occur post-infusion, including changes in TME composition, immune cell interactions, cytokine signaling, and potential resistance mechanisms. Understanding these processes will contribute to the development of more effective CAR-T cell therapies and strategies to mitigate treatment-related toxicities.

BSBM-16 HLA CLASS-I ANTIGEN PRESENTATION MACHINERY AND IFN-γ PATHWAY ALTERATIONS IN LUNG CANCER BRAIN METASTASES

Abstract BACKGROUND Immune checkpoint inhibitors (ICI) can have activity in lung cancer brain metastases (LBM). However, the duration of responses is limited and most patients with LBM do not benefit from these therapies. Alterations in HLA class-I antigen presentation machinery via beta-2 microglobulin (B2M) downregulation and disruption of IFN-γ sensing were identified as mechanisms of immune evasion and ICI resistance in solid tumors. However, the expression and clinical significance of these pathways in LBM are poorly understood. METHODS Using multiplex quantitative immunofluorescence we measured the localized expression of B2M protein; and the IFN-γ pathway markers phospho-STAT1 (pSTAT1), and Interferon Regulatory Factor 1 (IRF-1) in 67 immunotherapy naïve LBM and 45 primary lung tumors (PLT), including 15 patients with paired samples represented in a tissue microarray. The markers were selectively measured in cytokeratin + tumor cells and in cytokeratin- stromal cells. Associations between the markers, PD-L1, TILs and clinicopathologic variables were compared between LBM and PLT. RESULTS LBM showed lower levels of B2M in both tumor and stroma compartments compared to PLT. In contrast, high tumor and stromal levels of pSTAT1 were observed in LBM and comparable levels of IRF-1 were found between both tumor sites. Consistently across LBM and PLT samples, pSTAT1 and IRF1 were strongly correlated, and a positive but weaker association was observed with B2M and TILs. Only in PLT high tumor-cell PD-L1 expression was associated with high levels of IRF-1. No statistically significant association was observed between the markers and clinicopathologic variables. Tumor B2M downregulation in PLT was associated with worse survival. CONCLUSION LBM show distinct immunomodulatory properties relative to PLT, characterized by reduced HLA class-I antigen presentation machinery, elevated IFN-γ signaling and reduced local adaptive immune responses. These results support differences in immune evasion mechanisms in LBM compared with the PLT, which may have biological and clinical implications.

Comprehensive analysis of the immunological differences in the intestinal barrier of improved grass carp and their parents

Disease-resistant grass carp (DR-GGC) was an improved grass carp developed by backcrossing gynogenetic grass carp (GGC, female) with grass carp (Ctenopharyngodon iIdella, GC, male), which had better disease resistance advantages than GC in aquaculture. However, little was known about the immune mechanism of disease resistance advantages of DR-GGC compared with GC. This study aimed to investigate the differences in molecular mechanisms of disease resistance among DR-GGC, GGC and GC by comparing intestinal histopathology, antioxidant activity in the liver and spleen, tight junction protein gene expression, intestinal microbiota structure, intestinal transcriptome and metabolomics following intestinal inflammation induced by Aeromonas hydrophila. The histopathological results showed that the intestinal villi of DR-GGC, GGC and GC were damaged with shedding and fusion, the intestinal damage of GC being the most severe. Tight junction protein gene expression in the intestine and antioxidant enzyme activity in the liver and spleen were significantly higher in DR-GGC than in GC (P < 0.05), whereas serum creatinine (CRE) and plasma free hemoglobin (FHB) were significantly below that in GC (P < 0.05). Meanwhile, the transcriptome results showed that the differentially expressed genes (DEGs) were significantly enriched in immune response-related pathways in DR-GGC and GGC compared with GC (P < 0.05). The DEGs were also enriched in cellular and molecular processes in DR-GGC and GC compared with GGC (P < 0.05). The metabolomics results revealed lipid and oxidative metabolism-related differential metabolites (DMs) among the three grass carp groups. Furthermore, twenty amino acids and their metabolites were up-regulated in DR-GGC compared with GC, including aspartic acid, arginine, ornithine and others, and cloud significantly reduces intestinal inflammation by regulating the immune and oxidative responses. And the combined analysis of the transcriptome and metabolome revealed that the DEGs and DMs in these pathways were significantly correlated and regulated. Additionally, the intestinal microbiota analysis showed that DR-GGC had an increased abundance of probiotic Fusobacteriota at the phylum level and Cetobacterium at the genus level. Conversely, GC had an increased abundance of pathogenic Bacteroidetes at the phylum level and Aeromonas at the genus level. In conclusion, this study comprehensively confirmed the greater disease resistance of DR-GGC and further elucidated the potential molecular mechanism of better intestinal immune barrier resistance than that of GC, which is of significant value for the development of the GC.

Staphylococcal Enterotoxin C2 Mutant-Induced Antitumor Immune Response Is Controlled by CDC42/MLC2-Mediated Tumor Cell Stiffness.

As a biological macromolecule, the superantigen staphylococcal enterotoxin C2 (SEC2) is one of the most potent known T-cell activators, and it induces massive cytotoxic granule production. With this property, SEC2 and its mutants are widely regarded as immunomodulating agents for cancer therapy. In a previous study, we constructed an MHC-II-independent mutant of SEC2, named ST-4, which exhibits enhanced immunocyte stimulation and antitumor activity. However, tumor cells have different degrees of sensitivity to SEC2/ST-4. The mechanisms of immune resistance to SEs in cancer cells have not been investigated. Herein, we show that ST-4 could activate more powerful human lymphocyte granule-based cytotoxicity than SEC2. The results of RNA-seq and atomic force microscopy (AFM) analysis showed that, compared with SKOV3 cells, the softer ES-2 cells could escape from SEC2/ST-4-induced cytotoxic T-cell-mediated apoptosis by regulating cell softness through the CDC42/MLC2 pathway. Conversely, after enhancing the stiffness of cancer cells by a nonmuscle myosin-II-specific inhibitor, SEC2/ST-4 exhibited a significant antitumor effect against ES-2 cells by promoting perforin-dependent apoptosis and the S-phase arrest. Taken together, these data suggest that cell stiffness could be a key factor of resistance to SEs in ovarian cancer, and our findings may provide new insight for SE-based tumor immunotherapy.

Immunomodulatory effects of CDK4/6 inhibitors.

The dysregulation of the cell cycle is one of the hallmarks of cancer. Cyclin-dependent kinase 4 (CDK4) and CDK6 play crucial roles in regulating cell cycle and other cellular functions. CDK4/6 inhibitors have achieved great success in treating breast cancers and are currently being tested extensively in other tumor types as well. Accumulating evidence suggests that CDK4/6 inhibitors exert antitumor effects through immunomodulation aside from cell cycle arrest. Here we outline the immunomodulatory activities of CDK4/6 inhibitors, discuss the immune mechanisms of drug resistance and explore avenues to harness their immunotherapeutic potential when combined with immune checkpoint inhibitors (ICIs) or chimeric antigen receptor (CAR) T-cell therapy to improve the clinical outcomes.

Cooperation between physiological defenses and immune resistance produces asymptomatic carriage of a lethal bacterial pathogen.

Animals evolved two defense strategies to survive infections. Antagonistic strategies include immune resistance mechanisms that operate to kill invading pathogens. Cooperative or physiological defenses mediate host adaptation to the infected state, limiting physiological damage and disease, without killing the pathogen, and have been shown to cause asymptomatic carriage and transmission of lethal pathogens. Here, we demonstrate that physiological defenses cooperate with the adaptive immune response to generate long-term asymptomatic carriage of the lethal enteric murine pathogen, Citrobacter rodentium. Asymptomatic carriage of genetically virulent C. rodentium provided immune resistance against subsequent infections. Immune protection was dependent on systemic antibody responses and pathogen virulence behavior rather than the recognition of specific virulent antigens. Last, we demonstrate that an avirulent strain of C. rodentium in the field has background mutations in genes that are important for LPS structure. Our work reveals insight into how asymptomatic infections can arise mechanistically with immune resistance, mediating exclusion of phenotypically virulent enteric pathogen to promote asymptomatic carriage.