CD80 on skin stem cells promotes local expansion of regulatory T cells upon injury to orchestrate repair within an inflammatory environment.

Following tissue damage, epithelial stem cells (SCs) are mobilized to enter the wound, where they confront harsh inflammatory environments that can impede their ability to repair the injury. Here, we investigated the mechanisms that protect skin SCs within this inflammatory environment. Characterization of gene expression profiles of hair follicle SCs (HFSCs) that migrated into the wound site revealed activation of an immune-modulatory program, including expression of CD80, major histocompatibility complex class II (MHCII), and CXC motif chemokine ligand 5 (CXCL5). Deletion of CD80 in HFSCs impaired re-epithelialization, reduced accumulation of peripherally generated Treg (pTreg) cells, and increased infiltration of neutrophils in wounded skin. Importantly, similar wound healing defects were also observed in mice lacking pTreg cells. Our findings suggest that upon skin injury, HFSCs establish a temporary protective network by promoting local expansion of Treg cells, thereby enabling re-epithelialization while still kindling inflammation outside this niche until the barrier is restored.

Quorum Regulation via Nested Antagonistic Feedback Circuits Mediated by the Receptors CD28 and CTLA-4 Confers Robustness to T Cell Population Dynamics.

T cell responses upon infection display a remarkably reproducible pattern of expansion, contraction, and memory formation. If the robustness of this pattern builds entirely on signals derived from other cell types or if activated T cells themselves contribute to the orchestration of these population dynamics-akin to bacterial quorum regulation-is unclear. Here, we examined this question using time-lapse microscopy, genetic perturbation, bioinformatic predictions, and mathematical modeling. We found that ICAM-1-mediated cell clustering enabled CD8+ T cells to collectively regulate the balance between proliferation and apoptosis. Mechanistically, T cell expressed CD80 and CD86 interacted with the receptors CD28 and CTLA-4 on neighboring T cells; these interactions fed two nested antagonistic feedback circuits that regulated interleukin 2 production in a manner dependent on T cell density as confirmed by in vivo modulation of this network. Thus, CD8+ T cell-population-intrinsic mechanisms regulate cellular behavior, thereby promoting robustness of population dynamics.

PD-L1:CD80 Cis-Heterodimer Triggers the Co-stimulatory Receptor CD28 While Repressing the Inhibitory PD-1 and CTLA-4 Pathways.

Combined immunotherapy targeting the immune checkpoint receptors cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death 1 (PD-1), or CTLA-4 and the PD-1 ligand (PD-L1) exhibits superior anti-tumor responses compared with single-agent therapy. Here, we examined the molecular basis for this synergy. Using reconstitution assays with fluorescence readouts, we found that PD-L1 and the CTLA-4 ligand CD80 heterodimerize in cis but not trans. Quantitative biochemistry and cell biology assays revealed that PD-L1:CD80 cis-heterodimerization inhibited both PD-L1:PD-1 and CD80:CTLA-4 interactions through distinct mechanisms but preserved the ability of CD80 to activate the T cell co-stimulatory receptor CD28. Furthermore, PD-L1 expression on antigen-presenting cells (APCs) prevented CTLA-4-mediated trans-endocytosis of CD80. Atezolizumab (anti-PD-L1), but not anti-PD-1, reduced cell surface expression of CD80 on APCs, and this effect was negated by co-blockade of CTLA-4 with ipilimumab (anti-CTLA-4). Thus, PD-L1 exerts an immunostimulatory effect by repressing the CTLA-4 axis; this has implications to the synergy of anti-PD-L1 and anti-CTLA-4 combination therapy.

The CTLA-4 immune checkpoint protein regulates PD-L1:PD-1 interaction via transendocytosis of its ligand CD80.

CTLA-4 and PD-1 are key immune checkpoint receptors that are targeted in the treatment of cancer. A recently identified physical interaction between the respective ligands, CD80 and PD-L1, has been shown to block PD-L1/PD-1 binding and to prevent PD-L1 inhibitory functions. Since CTLA-4 is known to capture and degrade its ligands via transendocytosis, we investigated the interplay between CD80 transendocytosis and CD80/PD-L1 interaction. We find that transendocytosis of CD80 results in a time-dependent recovery of PD-L1 availability that correlates with CD80 removal. Moreover, CD80 transendocytosis is highly specific in that only CD80 is internalised, while its heterodimeric PD-L1 partner remains on the plasma membrane of the antigen-presenting cell (APC). CTLA-4 interactions with CD80 do not appear to be inhibited by PD-L1, but efficient removal of CD80 requires an intact CTLA-4 cytoplasmic domain, distinguishing this process from more general trogocytosis and simple CTLA-4 binding to CD80/PD-L1 complexes. These data are consistent with CTLA-4 acting as modulator of PD-L1:PD-1 interactions via control of CD80.

Blockade of trans PD-L1 interaction with CD80 augments antitumor immunity.

PD-L1 has two receptors: PD-1 and CD80. Previous reports assumed that PD-L1 and CD80 interacted in trans, but recent reports showed that only cis PD-L1/CD80 interactions existed, and prevention of cis PD-L1/CD80 interactions on antigen-presenting cells (APCs) reduced antitumor immunity via augmenting PD-L1/PD-1 and CD80/CTLA4 interactions between T and APCs. Here, using tumor-bearing mice capable of cis and trans or trans only PD-L1/CD80 interactions, we show that trans PD-L1/CD80 interactions do exist between tumor and T cells, and the effects of trans PD-L1/CD80 interactions require tumor cell expression of MHC-I and T cell expression of CD28. The blockade of PD-L1/CD80 interactions in mice with both cis and trans interactions or with only trans interactions augments antitumor immunity by expanding IFN-γ-producing CD8+ T cells and IFN-γ-dependent NOS2-expressing tumor-associated macrophages. Our studies indicate that although cis and trans PD-L1/CD80 interactions may have opposite effects on antitumor immunity, the net effect of blocking PD-L1/CD80 interactions in vivo augments CD8+ T cell-mediated antitumor immunity.

Ox-LDL-induced CD80+ macrophages expand pro-atherosclerotic NKT cells via CD1d in atherosclerotic mice and hyperlipidemic patients.

Atherosclerosis is an inflammatory disease of blood vessels involving the immune system. Natural killer T (NKT) cells, as crucial components of the innate and acquired immune systems, play critical roles in the development of atherosclerosis. However, the mechanism and clinical relevance of NKT cells in early atherosclerosis are largely unclear. The study investigated the mechanism influencing NKT cell function in apoE deficiency-induced early atherosclerosis. Our findings demonstrated that there were higher populations of NKT cells and interferon-gamma (IFN-γ)-producing NKT cells in the peripheral blood of patients with hyperlipidemia and in the aorta, blood, spleen, and bone marrow of early atherosclerotic mice compared with the control groups. Moreover, we discovered that the infiltration of CD80+ macrophages and CD1d expression on CD80+ macrophages in atherosclerotic mice climbed remarkably. CD1d expression increased in CD80+ macrophages stimulated by oxidized low-density lipoprotein (ox-LDL) ex vivo and in vitro. Ex vivo coculture of macrophages with NKT cells revealed that ox-LDL-induced CD80+ macrophages presented lipid antigen α-Galcer (alpha-galactosylceramide) to NKT cells via CD1d, enabling NKT cells to express more IFN-γ. Furthermore, a greater proportion of CD1d+ monocytes and CD1d+CD80+ monocytes were found in peripheral blood of hyperlipidemic patients compared with that of healthy donors. Positive correlations were found between CD1d+CD80+ monocytes and NKT cells or IFN-γ+ NKT cells in hyperlipidemic patients. Our findings illustrated that CD80+ macrophages stimulated NKT cells to secrete IFN-γ via CD1d-presenting α-Galcer, which may accelerate the progression of early atherosclerosis. Inhibiting lipid antigen presentation by CD80+ macrophages to NKT cells may be a promising immune target for the treatment of early atherosclerosis.NEW & NOTEWORTHY This work proposed the ox-LDL-CD80+ monocyte/macrophage-CD1d-NKT cell-IFN-γ axis in the progression of atherosclerosis. The proinflammatory IFN-γ+ NKT cells are closely related to CD1d+CD80+ monocytes in hyperlipidemic patients. Inhibiting CD80+ macrophages to present lipid antigens to NKT cells through CD1d blocking may be a new therapeutic target for atherosclerosis.

IMMUNOREACT 7: Regular aspirin use is associated with immune surveillance activation in colorectal cancer.

BACKGROUND: Long-term daily use of aspirin reduces incidence and mortality due to colorectal cancer (CRC). This study aimed to analyze the effect of aspirin on the tumor microenvironment, systemic immunity, and on the healthy mucosa surrounding cancer. METHODS: Patients with a diagnosis of CRC operated on from 2015 to 2019 were retrospectively analyzed (METACCRE cohort). Expression of mRNA of immune surveillance-related genes (PD-L1, CD80, CD86, HLA I, and HLA II) in CRC primary cells treated with aspirin were extracted from Gene Expression Omnibus-deposited public database (GSE76583). The experiment was replicated in cell lines. The mucosal immune microenvironment of a subgroup of patients participating in the IMMUNOREACT1 (ClinicalTrials.gov NCT04915326) project was analyzed with immunohistochemistry and flow cytometry. RESULTS: In the METACCRE Cohort, 12% of 238 patients analyzed were aspirin users. Nodal metastasis was significantly less frequent (p = .008) and tumor-infiltrating lymphocyte infiltration was higher (p = .02) among aspirin users. In the CRC primary cells and selected cell lines, CD80 mRNA expression was increased following aspirin treatment (p = .001). In the healthy mucosa surrounding rectal cancer, the ratio of CD8/CD3 and epithelial cells expressing CD80 was higher in aspirin users (p = .027 and p = .034, respectively). CONCLUSIONS: These data suggested that regular aspirin use may have an active role in enhancing immunosurveillance against CRC.

The interaction between the costimulatory molecules CD80/86 and CD28 contributed to CD4+ T lymphocyte activation in flounder (Paralichthys olivaceus).

CD28 and CD80/86 are crucial co-stimulatory molecules for the T cell activation. Previous study illustrated that CD28 and CD80/86 present on T cells and antigen-presenting cells in flounder (Paralichthys olivaceus), respectively. The co-stimulatory molecules were closely associated with cell immunity. In this paper, recombinant protein of flounder CD80/86 (rCD80/86) and phytohemagglutinin (PHA) were added to peripheral blood leukocytes (PBLs) in vitro. Lymphocytes were significantly proliferated with CFSE staining, and the proportion of CD4+ and CD28+ lymphocytes significantly increased. In the meantime, genes related to the CD28-CD80/86 signaling pathway or T cell markers were significantly upregulated (p < 0.05). For further study, the interaction between CD80/86 and CD28 was confirmed. The plasmid of CD28 (pCD28-FLAG and pVN-CD28) or CD80/86 (pVC-CD80/86) was successfully constructed. In addition, pVN-ΔCD28 without the conserved motif "TFPPPF" was constructed. The results showed that bands of pCD28-FLAG bound to rCD80/86 were detected by both anti-FLAG and anti-CD80/86. pVN-CD28 complemented to pVC-CD80/86 showing positive fluorescent signals, and pVN-ΔCD28 failed to combine with pVC-CD80/86. The motif "TFPPPF" in CD28 played a crucial role in this linkage. These results indicate that CD28 and CD80/86 molecules interact with each other, and their binding may modulate T lymphocytes immune response in flounder. This study proved the existence of CD28-CD80/86 signaling pathway in flounder.

zDHHC20-driven S-palmitoylation of CD80 is required for its costimulatory function.

CD80 is a transmembrane glycoprotein belonging to the B7 family, which has emerged as a crucial molecule in T cell modulation via the CD28 or CTLA4 axes. CD80-involved regulation of immune balance is a finely tuned process and it is important to elucidate the underlying mechanism for regulating CD80 function. In this study we investigated the post-translational modification of CD80 and its biological relevance. By using a metabolic labeling strategy, we found that CD80 was S-palmitoylated on multiple cysteine residues (Cys261/262/266/271) in both the transmembrane and the cytoplasmic regions. We further identified zDHHC20 as a bona fide palmitoyl-transferase determining the S-palmitoylation level of CD80. We demonstrated that S-palmitoylation protected CD80 protein from ubiquitination degradation, regulating the protein stability, and ensured its accurate plasma membrane localization. The palmitoylation-deficient mutant (4CS) CD80 disrupted these functions, ultimately resulting in the loss of its costimulatory function upon T cell activation. Taken together, our results describe a new post-translational modification of CD80 by S-palmitoylation as a novel mechanism for the regulation of CD80 upon T cell activation.

A better understanding of the role of the CTLA-CD80/86 axis in the treatment of autoimmune diseases.

Autoimmune diseases are diseases in which the regulatory mechanisms of the immune response are disturbed. As a result, the body loses self-tolerance. Since one of the main regulatory mechanisms of the immune response is the CTLA4-CD80/86 axis, this hypothesis suggests that autoimmune diseases potentially share a similar molecular basis of pathogenesis. Hence, investigating the CTLA4-CD80/86 axis may be helpful in finding an appropriate treatment strategy. Therefore, this study aims to investigate the molecular basis of the CTLA4-CD80/86 axis in the regulation of the immune response, and then its role in developing some autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, type 1 diabetes, and multiple sclerosis. As well, the main therapeutic strategies affecting the CTLA4-CD80/86 axis have been summarized to highlight the importance of this axis in management of autoimmune diseases.

Treg-expressed CTLA-4 depletes CD80/CD86 by trogocytosis, releasing free PD-L1 on antigen-presenting cells.

Foxp3-expressing CD4+CD25+ regulatory T cells (Tregs) constitutively and highly express the immune checkpoint receptor cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4), whose Treg-specific deficiency causes severe systemic autoimmunity. As a key mechanism of Treg-mediated suppression, Treg-expressed CTLA-4 down-regulates the expression of CD80/CD86 costimulatory molecules on antigen-presenting cells (APCs). Here, we show that Treg-expressed CTLA-4 facilitated Treg-APC conjugation and immune synapse formation. The immune synapses thus formed provided a stable platform whereby Tregs were able to deplete CD80/CD86 molecules on APCs by extracting them via CTLA-4-dependent trogocytosis. The depletion occurred even with Tregs solely expressing a mutant CTLA-4 form lacking the cytoplasmic portion required for its endocytosis. The CTLA-4-dependent trogocytosis of CD80/CD86 also accelerated in vitro and in vivo passive transfer of other membrane proteins and lipid molecules from APCs to Tregs without their significant reduction on the APC surface. Furthermore, CD80 down-regulation or blockade by Treg-expressed membrane CTLA-4 or soluble CTLA-4-immunoglobulin (CTLA-4-Ig), respectively, disrupted cis-CD80/programmed death ligand-1 (PD-L1) heterodimers and increased free PD-L1 on dendritic cells (DCs), expanding a phenotypically distinct population of CD80lo free PD-L1hi DCs. Thus, Tregs are able to inhibit the T cell stimulatory activity of APCs by reducing their CD80/CD86 expression via CTLA-4-dependent trogocytosis. This CD80/CD86 reduction on APCs is able to exert dual suppressive effects on T cell immune responses by limiting CD80/CD86 costimulation to naïve T cells and by increasing free PD-L1 available for the inhibition of programmed death-1 (PD-1)-expressing effector T cells. Blockade of CTLA-4 and PD-1/PD-L1 in combination may therefore synergistically hinder Treg-mediated immune suppression, thereby effectively enhancing immune responses, including tumor immunity.

Anti-allergic effect of vitamin C through inhibiting degranulation and regulating TH1/TH2 cell polarization.

BACKGROUND: Food allergy has become a global public health problem. This study aimed to explore the possible anti-allergic effect of vitamin C (VC). A rat basophilic leukemia (RBL)-2H3 cell degranulation model was used to assess the effect of VC on degranulation in vitro, and an ovalbumin (OVA)-induced BALB/c mouse allergy model was used to assess the anti-allergy effect of VC in vivo. RESULTS: In vitro, VC significantly attenuated the release of ß-hexosaminidase, tryptase and histamine, and also reduced cytokine production (interleukins 4 and 6, tumor necrosis factor α) significantly (P < 0.05), with the inhibitory effect demonstrating a positive correlation with VC dose. In vivo, compared with the OVA group, the levels of serum immunoglobulins E and G1 of the VC low-dose (VCL) group (50 mg kg-1) and high-dose (VCH) group (200 mg·kg-1) were significantly reduced (P < 0.05). Furthermore, the plasma histamine level was also significantly decreased (P < 0.05). Moreover, TH2 cell polarization in mice of the VCL and VCH groups was significantly inhibited (P < 0.05), promoting the TH1/TH2 cell polarization balance. Additionally, VC treatment enhanced the expression of CD80 (P < 0.05) in spleen and small intestine tissues, while significantly inhibiting the expression of CD86 (P < 0.05); notably, high-dose VC treatment was more effective. CONCLUSION: VC exerted an anti-allergic effect through inhibiting degranulation and regulating TH1/TH2 cell polarization balance. © 2024 Society of Chemical Industry.

Antigenic Peptide-Thioredoxin Fusion Chimeras for In Vitro Stimulus of CD4+ TCR+ Jurkat T Cells.

Study of CD4+ T cell response and T cell receptor (TCR) specificity is crucial for understanding etiology of immune-mediated diseases and developing targeted therapies. However, solubility, accessibility, and stability of synthetic antigenic peptides used in T cell assays may be a critical point in such studies. Here we present a T cell activation reporter system using recombinant proteins containing antigenic epitopes fused with bacterial thioredoxin (trx-peptides) and obtained by bacterial expression. We report that co-incubation of CD4+ HA1.7 TCR+ reporter Jurkat 76 TRP cells with CD80+ HLA-DRB1*01:01+ HeLa cells or CD4+ Ob.1A12 TCR+ Jurkat 76 TRP with CD80+ HLA-DRB1*15:01+ HeLa cells resulted in activation of reporter Jurkat 76 TPR after addition of recombinant trx-peptide fusion proteins, containing TCR-specific epitopes. Trx-peptides were comparable with corresponding synthetic peptides in their capacity to activate Jurkat 76 TPR. These data demonstrate that thioredoxin as a carrier protein (trx) for antigenic peptides exhibits minimal interference with recognition of MHC-specific peptides by TCRs and consequent T cell activation. Our findings highlight potential feasibility of trx-peptides as a reagent for assessing the immunogenicity of antigenic fragments.

Structural and biological characterization of pAC65, a macrocyclic peptide that blocks PD-L1 with equivalent potency to the FDA-approved antibodies.

Recent advances in immuno-oncology have opened up new and impressive treatment options for cancer. Notwithstanding, overcoming the limitations of the current FDA-approved therapies with monoclonal antibodies (mAbs) that block the PD-1/PD-L1 pathway continues to lead to the testing of multiple approaches and optimizations. Recently, a series of macrocyclic peptides have been developed that exhibit binding strengths to PD-L1 ranging from sub-micromolar to micromolar. In this study, we present the most potent non-antibody-based PD-1/PD-L1 interaction inhibitor reported to date. The structural and biological characterization of this macrocyclic PD-L1 targeting peptide provides the rationale for inhibition of both PD-1/PD-L1 and CD80/PD-L1 complexes. The IC50 and EC50 values obtained in PD-L1 binding assays indicate that the pAC65 peptide has potency equivalent to the current FDA-approved mAbs and may have similar activity to the BMS986189 peptide, which entered the clinical trial and has favorable safety and pharmacokinetic data. The data presented here delineate the generation of similar peptides with improved biological activities and applications not only in the field of cancer immunotherapy but also in other disorders related to the immune system.

Hypoxia and acidity regulate immune checkpoint molecule and IFN-ß expression in non-small cell lung cancer cell lines.

PURPOSE: Non-small cell lung cancer (NSCLC) is one of the most lethal tumors in humans. Immunotherapy with immune checkpoint inhibitors (ICIs) has revolutionized the treatment of patients with advanced diseases. Tumor microenvironment conditions like hypoxia and low pH may compromise the efficacy of ICIs. MATERIALS AND METHODS: We report the effect of hypoxia and acidity on the expression levels of the major checkpoint molecules, namely PD-L1, CD80, and CD47, in the A549 and H1299 NSCLC cell lines. RESULTS: Hypoxia induces PD-L1 protein and mRNA expression, represses CD80 mRNA levels, and enhances IFNß protein expression. An opposite effect was noticed when cells were exposed to acidic conditions. Hypoxia-induced the CD47 molecule at protein and mRNA levels. It is concluded that hypoxia and acidity are important regulators of the expression of PD-L1 and CD80 immune checkpoint molecules. Acidity contributes to the suppression of the interferon type I pathway. CONCLUSIONS: These findings suggest that hypoxia and acidity assist cancer cells in the escape from immune surveillance through direct effects on cancer cells' ability to present immune checkpoint molecules and release type I interferons. Targeting hypoxia and acidity may enhance the activity of ICIs in NSCLC.

Significance of CD80 as a Prognostic and Immunotherapeutic Biomarker in Lung Adenocarcinoma.

Lung adenocarcinoma (LUAD) is the primary cause of death among pulmonary cancer patients. Upregulation of CD80 may interact with cytotoxic T lymphocyte antigen 4 (CTLA4) to promote tumor progression and provide a potential target for biological antitumor therapy. However, the role of CD80 in LUAD is still unclear. To investigate the function of CD80 in LUAD, we collected transcriptomic data from 594 lung samples from The Cancer Genome Atlas of America (TCGA) database, along with the corresponding clinical information. We systematically explored the role of CD80 in LUAD using bioinformatics methods, including GO enrichment analysis, KEGG pathway analysis, Gene Set Enrichment Analysis (GSEA), co-expression analysis, and the CIBERSORT algorithm. Finally, we investigated the differences between the two subgroups of CD80 expression in terms of some drug sensitivity, using the pRRophetic package to screen small molecular drugs for therapeutic use. A predictive model based on CD80 for LUAD patients was successfully constructed. In addition, we discovered that the CD80-based prediction model was an independent prognostic factor. Co-expression analysis revealed 10 CD80-related genes, including oncogenes and immune-related genes. Functional analysis showed that the differentially expressed genes in patients with high CD80 expression were mainly located in immune-related signaling pathways. CD80 expression was also associated with immune cell infiltration and immune checkpoints. Highly expressing patients were more sensitive to several drugs, such as rapamycin, paclitaxel, crizotinib, and bortezomib. Finally, we found evidence that 15 different small molecular drugs may benefit the treatment of LUAD patients. This study found that elevated CD80 pairs could improve the prognosis of LUAD patients. CD80 is likely to be a potential as a prognostic and therapeutic target. The future use of small molecular drugs in combination with immune checkpoint blockade to enhance antitumor therapy and improve prognosis for LUAD patients is promising.

Patients with primary focal segmental glomerulosclerosis with detectable urinary CD80 are more similar to patients with minimal change disease in clinicopathological features.

BACKGROUND: Focal segmental glomerulosclerosis (FSGS) is an important cause of refractory nephrotic syndrome (NS) in children and adults. Urinary CD80 is elevated in some patients with primary FSGS, however, its clinical value is not fully clarified. This study aims to evaluate the clinical and pathological significance of urinary CD80 in patients with primary FSGS. METHODS: Sixty-one adult patients with biopsy-proven primary FSGS, with standard treatment and long-term follow up, were enrolled retrospectively. Urinary CD80, on the day of kidney biopsy, was measured using commercial ELISA kits and adjusted by urinary creatinine excretion. Their associations with clinical and pathological parameters were investigated. RESULTS: Urinary CD80 was detectable in 30/61 (49.2%) patients, who presented with a higher level of proteinuria (10.7 vs. 5.8 g/24h; p = 0.01), a lower level of serum albumin (19.3 ± 3.9 vs. 24.2 ± 8.2 g/L; p = 0.005), a higher prevalence of hematuria (70.0 vs. 38.7%; p = 0.01), and showed a lower percentage of segmental glomerulosclerosis lesion [4.8 (3.7-14.0) vs. 9.1 (5.6-21.1) %; p = 0.06]. The cumulative relapse rate was remarkably high in these patients (log-rank, p = 0.001). Multivariate analysis identified that the elevated urinary CD80 was an independent risk factor for steroid-dependent NS (OR 8.81, 95% CI 1.41-54.89; p = 0.02) and relapse (HR, 2.87; 95% CI 1.29-6.38; p = 0.01). CONCLUSIONS: The elevated urinary CD80 is associated with mild pathological change and steroid-dependent cases of primary FSGS adults, which indicates these patients are more similar to minimal change disease (MCD) in clinicopathological features.

Clinicopathological significance of CD28 overexpression in adult T-cell leukemia/lymphoma.

CD28, one of the costimulatory molecules, has a pivotal role in T-cell activation, and its expression is strictly regulated in normal T cells. Gain-of-function genetic alterations involving CD28 have been frequently observed in adult T-cell leukemia/lymphoma (ATLL). These abnormalities, such as CD28 fusions and copy number variations, may not only confer continuous, prolonged, and enhanced CD28 signaling to downstream pathways but also induce overexpression of the CD28 protein. In this study, 120 ATLL cases were examined by immunohistochemistry for CD28 and its ligands CD80 and CD86, and their expression on tumor cells was semiquantitatively evaluated. CD28 was overexpressed in 55 (46%) cases, and CD80 or CD86 (CD80/CD86) was infrequently overexpressed in 12 (11%). Compared with non-overexpressers, CD28 overexpressers showed a higher frequency of CD28 genetic alterations and had an increased number of CD80/CD86-positive non-neoplastic cells infiltrating tumor microenvironment. In the entire ATLL patient cohort, CD28 overexpressers showed a significantly poorer overall survival (OS) compared with non-overexpressers (P = .001). The same was true for a subgroup who were treated with multidrug regimens with or without mogamulizumab. CD28 overexpression had no prognostic impact in the group who received allogeneic hematopoietic stem cell transplantation. In the multivariate analysis for OS, CD28 overexpression was selected as an independent risk factor. These results suggest ATLL patients with CD28 overexpression have more aggressive clinical course and are more refractory to treatment with multidrug chemotherapy. CD28 overexpression appears to be a novel unfavorable prognostic marker in ATLL patients, and further prospective studies are warranted to establish its prognostic significance.

Tumor-Secreted Extracellular Vesicles Regulate T-Cell Costimulation and Can Be Manipulated To Induce Tumor-Specific T-Cell Responses.

BACKGROUND & AIMS: Colorectal cancer is a major cause of cancer-related deaths worldwide. Immune checkpoint blockade therapies are effective in 30%-60% of the microsatellite instable-high subtype. Unfortunately, most patients with colorectal cancer (>85%) have microsatellite stable tumors that do not respond. In this study, we aimed to decipher the underlying tumor-intrinsic mechanisms critical for improving immunotherapy in colorectal cancer. METHODS: We used human and mouse tumor samples, cell lines, human colorectal cancer organoids, and various syngeneic orthotopic mouse models of late-stage colorectal cancer to define the effects of tumor cell-secreted extracellular vesicles (EVs) on antitumor immune response. RESULTS: Our analyses of human colorectal cancer immune profiles and tumor-immune cell interactions showed that tumor-secreted EVs containing microRNA miR-424 suppressed the CD28-CD80/86 costimulatory pathway in tumor-infiltrating T cells and dendritic cells, leading to immune checkpoint blockade resistance. Modified tumor-secreted EVs with miR-424 knocked down enhanced T-cell-mediated antitumor immune response in colorectal cancer tumor models and increased the immune checkpoint blockade response. Intravenous injections of modified tumor-secreted EVs induced tumor antigen-specific immune responses and boosted the immune checkpoint blockade efficacy in colorectal cancer models that mimic aggressively progressing, late-stage disease. CONCLUSIONS: Collectively, we show a critical role for tumor-secreted EVs in antitumor immune regulation and immunotherapy response, which could be developed as a novel treatment for immune checkpoint blockade-resistant colorectal cancer.

Immunosuppressive properties of human PD-1 + , PDL-1 + and CD80 + dendritic cells from lymph nodes aspirates of lung cancer patients.

Dendritic cells (DCs) play a pivotal role in the homeostasis of the immune system. The tumor microenvironment impairs the proper function of DCs. The immunomodulatory properties of DCs in lung cancer are of interest. In the present study, we analysed DCs subsets and immune cells with the expression of immunomodulatory molecules: PD-1 and PD-L1 and co-stimulatory molecule CD80 in metastatic, non-metastatic lymph nodes (LNs) and peripheral blood (PB). LNs aspirates were obtained during the EBUS/TBNA procedure of 29 patients with primary lung cancer. The cells were analyzed by flow cytometry. We reported a higher percentage of DCs in the metastatic than in the non-metastatic LNs and the PB (0.709% vs. 0.166% vs. 0.043%, p < 0.0001). The proportions of PD-1 + , PD-L1 + and CD80 + DCs were higher in the metastatic LNs than in the non-metastatic ones. A higher proportion of regulatory DCs (DCregs) was found in the metastatic ones than in the non-metastatic LNs (22.5% vs. 3.1%, p = 0.0189). We report that DCs cells show increased expression of PD-1, PD-L1 and CD80 molecules that can interact with T lymphocytes. It can be assumed that mature DCs infiltrating metastatic LNs can develop into DCregs, which are involved in the suppression of anti-tumor response.