Cathepsin D promotes polarization of tumor-associated macrophages and metastasis through TGFBI-CCL20 signaling.

M2-like tumor-associated macrophages (TAMs) are risk factors for cancer progression and metastasis. However, the mechanisms underlying their polarization are still not fully understood. Although cathepsin D (Cat D) has been reported as a procarcinogenic factor, little is known about the functional role of Cat D in the tumor microenvironment (TME). This study aimed to explore the effect and molecular mechanisms of Cat D in the TME. Cat D knockout (KO) altered the cytokine secretion pattern and induced TAM reprogramming from the M2 to M1 subtype, thereby preventing epithelial-mesenchymal transition and tumor metastasis. Mechanistically, we identified transforming growth factor beta-induced protein (TGFBI) as a Cat D target protein that is specifically associated with TAM polarization. Elevated TGFBI expression in Cat D KO cancer cells resulted in a decline in M2-like TAM polarization. Our RNA-sequencing results indicated that the cancer cell-secreted chemokine CCL20 is a major secretory chemokine for Cat D-TGFBI-mediated TAM polarization. In contrast, Cat D overexpression accelerated TAM polarization into M2-like cells by suppressing TGFBI expression. In addition, the double Cat D and TGFBI KO rescued the inhibitory effects of Cat D KO on tumor metastasis by controlling TAM and T-cell activation. These findings indicated that Cat D contributes to cancer metastasis through TGFBI-mediated TAM reprogramming. Cat D deletion inhibits M2-like TAM polarization through TGFBI-mediated CCL20 expression, reprogramming the immunosuppressive TME. Our results open a potential new avenue for therapy focused on eliminating tumor metastasis.

Modification of immune cell-derived exosomes for enhanced cancer immunotherapy: current advances and therapeutic applications.

Cancer immunotherapy has revolutionized the approach to cancer treatment of malignant tumors by harnessing the body's immune system to selectively target cancer cells. Despite remarkable advances, there are still challenges in achieving successful clinical responses. Recent evidence suggests that immune cell-derived exosomes modulate the immune system to generate effective antitumor immune responses, making them a cutting-edge therapeutic strategy. However, natural exosomes are limited in clinical application due to their low drug delivery efficiency and insufficient antitumor capacity. Technological advancements have allowed exosome modifications to magnify their intrinsic functions, load different therapeutic cargoes, and preferentially target tumor sites. These engineered exosomes exert potent antitumor effects and have great potential for cancer immunotherapy. In this review, we describe ingenious modification strategies to attain the desired performance. Moreover, we systematically summarize the tumor-controlling properties of engineered immune cell-derived exosomes in innate and adaptive immunity. Collectively, this review provides a comprehensive and intuitive guide for harnessing the potential of modified immune cell-derived exosome-based approaches, offering valuable strategies to enhance and optimize cancer immunotherapy.

Ellagic Acid Prevented Dextran-Sodium-Sulfate-Induced Colitis, Liver, and Brain Injury through Gut Microbiome Changes.

Inflammatory bowel disease (IBD) affects millions of people worldwide and is considered a significant risk factor for colorectal cancer. Recent in vivo and in vitro studies reported that ellagic acid (EA) exhibits important antioxidant and anti-inflammatory properties. In this study, we investigated the preventive effects of EA against dextran sulfate sodium (DSS)-induced acute colitis, liver, and brain injury in mice through the gut-liver-brain axis. Acute colitis, liver, and brain injury were induced by treatment with 5% (w/v) DSS in the drinking water for 7 days. Freshly prepared EA (60 mg/kg/day) was orally administered, while control (CON) group mice were treated similarly by daily oral administrations with a vehicle (water). All the mice were euthanized 24 h after the final treatment with EA. The blood, liver, colon, and brain samples were collected for further histological and biochemical analyses. Co-treatment with a physiologically relevant dose (60 mg/kg/day) of EA for 7 days significantly reduced the DSS-induced gut barrier dysfunction; endotoxemia; and inflammatory gut, liver, and brain injury in mice by modulating gut microbiota composition and inhibiting the elevated oxidative and nitrative stress marker proteins. Our results further demonstrated that the preventive effect of EA on the DSS-induced IBD mouse model was mediated by blocking the NF-κB and mitogen-activated protein kinase (MAPK) pathway. Therefore, EA co-treatment significantly attenuated the pro-inflammatory and oxidative stress markers by suppressing the activation of NF-κB/MAPK pathways in gut, liver, and brain injury. These results suggest that EA, effective in attenuating IBD in a mouse model, deserves further consideration as a potential therapeutic for the treatment of inflammatory diseases.

Plum-Derived Exosome-like Nanovesicles Induce Differentiation of Osteoblasts and Reduction of Osteoclast Activation.

Osteoblasts and osteoclasts play crucial roles in bone formation and bone resorption. We found that plum-derived exosome-like nanovesicles (PENVs) suppressed osteoclast activation and modulated osteoblast differentiation. PENVs increased the proliferation, differentiation, and mineralization of osteoblastic MC3T3-E1 cells and osteoblasts from mouse bone marrow cultures. Notably, PENVs elevated the expression of osteoblastic transcription factors and osteoblast differentiation marker proteins in MC3T3-E1 cells. Higher levels of phosphorylated BMP-2, p38, JNK, and smad1 proteins were detected in PENV-treated MC3T3-E1 cells. Additionally, the number of TRAP-positive cells was significantly decreased in PENV-treated osteoclasts isolated from osteoblasts from mouse bone marrow cultures. Importantly, osteoclastogenesis of marker proteins such as PPAR-gamma, NFATc1, and c-Fos were suppressed by treatment with PENVs (50 µg/mL). Taken together, these results demonstrate that PENVs can be used as therapeutic targets for treating bone-related diseases by improving osteoblast differentiation and inhibiting osteoclast activation for the first time.

Engineered CD8+ T cell-derived extracellular vesicles induce enhanced anti-cancer efficacy and targeting to lung cancer cells.

Lung cancer is a common and highly malignant tumor. Although lung cancer treatments continue to advance, conventional therapies are limited and the response rate of patients to immuno-oncology drugs is low. This phenomenon raises an urgent need to develop effective therapeutic strategies for lung cancer. In this study, we genetically modified human primary CD8+ T cells and obtained antitumor extracellular vesicles (EVs) from them. The engineered EVs, containing interlekin-2 and the anti-epidermal growth factor receptor (EGFR) antibody cetuximab on their surfaces, exhibited direct cytotoxicity against A549 human lung cancer cells and increased cancer cell susceptibility to human peripheral blood mononuclear cell-mediated cytotoxicity. In addition, the engineered EVs specifically targeted the lung cancer cells in an EGFR-dependent manner. Taken together, these findings show that surface engineering of cytokines and antibodies on CD8+ T cell-derived EVs not only enhances their antitumor effects but also confers target specificity, suggesting a potential of modifying the immune cell-derived EVs in cancer treatment.

GDNF family receptor alpha-like antagonist antibody alleviates chemotherapy-induced cachexia in melanoma-bearing mice.

BACKGROUND: Patients with cancer undergoing chemotherapy experience cachexia with anorexia, body weight loss, and the depletion of skeletal muscles and adipose tissues. Effective treatment strategies for chemotherapy-induced cachexia are scarce. The growth differentiation factor 15 (GDF15)/GDNF family receptor alpha-like (GFRAL)/rearranged during transfection (RET) axis is a critical signalling pathway in chemotherapy-induced cachexia. In this study, we developed a fully human GFRAL antagonist antibody and investigated whether it inhibits the GDF15/GFRAL/RET axis, thereby alleviating chemotherapy-induced cachexia in tumour-bearing mice. METHODS: Anti-GFRAL antibodies were selected via biopanning, using a human combinatorial antibody phage library. The potent GFRAL antagonist antibody A11 was selected via a reporter cell assay and its inhibitory activity of GDF15-induced signalling was evaluated using western blotting. To investigate the in vivo function of A11, a tumour-bearing mouse model was established by inoculating 8-week-old male C57BL/6 mice with B16F10 cells (n = 10-16 mice per group). A11 was administered subcutaneously (10 mg/kg) 1 day before intraperitoneal treatment with cisplatin (10 mg/kg). Animals were assessed for changes in food intake, body weight, and tumour volume. Plasma and key metabolic tissues such as skeletal muscles and adipose tissues were collected for protein and mRNA expression analysis. RESULTS: A11 reduced serum response element-luciferase reporter activity up to 74% (P < 0.005) in a dose-dependent manner and blocked RET phosphorylation up to 87% (P = 0.0593), AKT phosphorylation up to 28% (P = 0.0593) and extracellular signal regulatory kinase phosphorylation up to 75% (P = 0.0636). A11 inhibited the action of cisplatin-induced GDF15 on the brainstem and decreased GFRAL-positive neuron population expressing c-Fos in the area postrema and nucleus of the solitary tract by 62% in vivo (P < 0.05). In a melanoma mouse model treated with cisplatin, A11 recovered anorexia by 21% (P < 0.05) and tumour-free body weight loss by 13% (P < 0.05). A11 significantly improved the cisplatin-induced loss of skeletal muscles (quadriceps: 21%, gastrocnemius: 9%, soleus: 13%, P < 0.05) and adipose tissues (epididymal white adipose tissue: 37%, inguinal white adipose tissue: 51%, P < 0.05). CONCLUSIONS: Our study suggests that GFRAL antagonist antibody may alleviate chemotherapy-induced cachexia, providing a novel therapeutic approach for patients with cancer experiencing chemotherapy-induced cachexia.

Yam-derived exosome-like nanovesicles stimulate osteoblast formation and prevent osteoporosis in mice.

Plants-releasing exosome-like nanovesicles (PENs) contain miRNA, bioactive lipids, mRNAs, and proteins to exert antioxidant, anti-inflammatory, and regenerative activity. Substances extracted from yams have been reported to promote osteoblast growth in bone regeneration, which prevent weak and brittle bones in osteoporosis. Herein, we describe the beneficial effects of yam-derived exosome-like nanovesicles (YNVs) on promoting differentiation and mineralization of osteoblasts for bone regeneration in ovariectomized (OVX)-induced osteoporotic mice. YNVs were successfully isolated and characterized. YNVs stimulate the proliferation, differentiation, and mineralization of osteoblasts with increased bone differentiation markers (OPN, ALP, and COLI). Interestingly, YNVs do not contain saponins including diosgenin and dioscin known to mainly exert osteogenic activity of yams. Instead, the osteogenic activity of YNVs was revealed to be resulted from activation of the BMP-2/p-p38-dependent Runx2 pathway. As a result, YNVs promote longitudinal bone growth and mineral density of the tibia in the OVX-induced osteoporotic mice in vivo, and these results positively correlate the significant increases in osteoblast-related parameters. In addition, the orally administered YNVs were transported through the GI tract and absorbed through the small intestine. These results showed an excellent systemic biosafety determined by histological analysis and liver/kidney toxicity tests. Taken together, YNVs can serve as a safe and orally effective agent in the treatment of osteoporosis.

The Effect of Apple-Derived Nanovesicles on the Osteoblastogenesis of Osteoblastic MC3T3-E1 Cells.

Osteoporosis is characterized by low bone mass and elevated structural deterioration of the bone tissue, resulting in bone weakness with an increased risk of fracture. Considering biological activities of various phytochemicals extracted from apples, we herein demonstrated the potential antiosteoporotic effects of apple-derived nanovesicles (apple NVs) using osteoblastic MC3T3-E1 cells. Apple NVs significantly stimulated the growth of MC3T3-E1 cells. The cellular alkaline phosphatase (ALP) activity was significantly upregulated in the 5 µg/mL apple NVs-treated group. In addition, the concentrarion of mineralized nodules was significantly increased in the apple NVs-treated groups. Furthermore, apple NVs increased the expression of the genes and proteins associated with osteoblast growth and differentiation, such as Runx2, ALP, OPN, and BMP2/4, which further activated ERK- and JNK-related mitogen-activated protein kinase signaling. These results demonstrate that apple NVs have a potential to prevent osteoporosis by promoting osteoblastogenesis in osteoblastic MC3T3-E1 cells through regulating the BMP2/Smad1 pathways.

Dissecting exosome inhibitors: therapeutic insights into small-molecule chemicals against cancer.

Intensive research in the field of cancer biology has revealed unique methods of communication between cells through extracellular vesicles called exosomes. Exosomes are released from a broad spectrum of cell types and serve as functional mediators under physiological or pathological conditions. Hence, blocking the release of exosome bio carriers may prove useful for slowing the progression of certain types of cancers. Therefore, efforts are being made to develop exosome inhibitors to be used both as research tools and as therapies in clinical trials. Thus, studies on exosomes may lead to a breakthrough in cancer research, for which new clinical targets for different types of cancers are urgently needed. In this review, we briefly outline exosome inhibitors and discuss their modes of action and potential for use as therapeutic tools for cancer.

Reprogramming of T cell-derived small extracellular vesicles using IL2 surface engineering induces potent anti-cancer effects through miRNA delivery.

T cell-derived small extracellular vesicles (sEVs) exhibit anti-cancer effects. However, their anti-cancer potential should be reinforced to enhance clinical applicability. Herein, we generated interleukin-2-tethered sEVs (IL2-sEVs) from engineered Jurkat T cells expressing IL2 at the plasma membrane via a flexible linker to induce an autocrine effect. IL2-sEVs increased the anti-cancer ability of CD8+ T cells without affecting regulatory T (Treg ) cells and down-regulated cellular and exosomal PD-L1 expression in melanoma cells, causing their increased sensitivity to CD8+ T cell-mediated cytotoxicity. Its effect on CD8+ T and melanoma cells was mediated by several IL2-sEV-resident microRNAs (miRNAs), whose expressions were upregulated by the autocrine effects of IL2. Among the miRNAs, miR-181a-3p and miR-223-3p notably reduced the PD-L1 protein levels in melanoma cells. Interestingly, miR-181a-3p increased the activity of CD8+ T cells while suppressing Treg cell activity. IL2-sEVs inhibited tumour progression in melanoma-bearing immunocompetent mice, but not in immunodeficient mice. The combination of IL2-sEVs and existing anti-cancer drugs significantly improved anti-cancer efficacy by decreasing PD-L1 expression in vivo. Thus, IL2-sEVs are potential cancer immunotherapeutic agents that regulate both immune and cancer cells by reprogramming miRNA levels.

Temsirolimus Enhances Anti-Cancer Immunity by Inducing Autophagy-Mediated Degradation of the Secretion of Small Extracellular Vesicle PD-L1.

Tumor-derived small extracellular vesicle (sEV) programmed death-ligand 1 (PD-L1) contributes to the low reactivity of cells to immune checkpoint blockade therapy (ICBT), because sEV PD-L1 binds to programmed death 1 (PD-1) in immune cells. However, there are no commercially available anti-cancer drugs that activate immune cells by inhibiting tumor-derived sEV PD-L1 secretion and cellular PD-L1. Here, we aimed to investigate if temsirolimus (TEM) inhibits both sEV PD-L1 and cellular PD-L1 levels in MDA-MB-231 cells. In cancer cell autophagy activated by TEM, multivesicular bodies (MVBs) associated with the secretion of sEV are degraded through colocalization with autophagosomes or lysosomes. TEM promotes CD8+ T cell-mediated anti-cancer immunity in co-cultures of CD8+ T cells and tumor cells. Furthermore, the combination therapy of TEM and anti-PD-L1 antibodies enhanced anti-cancer immunity by increasing both the number and activity of CD4+ and CD8+ T cells in the tumor and draining lymph nodes (DLNs) of breast cancer-bearing immunocompetent mice. In contrast, the anti-cancer effect of the combination therapy with TEM and anti-PD-L1 antibodies was reversed by the injection of exogenous sEV PD-L1. These findings suggest that TEM, previously known as a targeted anti-cancer drug, can overcome the low reactivity of ICBT by inhibiting sEV PD-L1 and cellular PD-L1 levels.

Novel antitumor therapeutic strategy using CD4+ T cell-derived extracellular vesicles.

Extracellular vesicles (EVs) mediate cell-cell crosstalk by carrying bioactive molecules derived from cells. Recently, immune cell-derived EVs have been reported to regulate key biological functions such as tumor progression. CD4+ T cells orchestrate overall immunity; however, the biological role of their EVs is unclear. This study reveals that EVs derived from CD4+ T cells increase the antitumor response of CD8+ T cells by enhancing their proliferation and activity without affecting regulatory T cells (Tregs). Moreover, EVs derived from interleukin-2 (IL2)-stimulated CD4+ T cells induce a more enhanced antitumor response of CD8+ T cells compared with that of IL2-unstimulated CD4+ T cell-derived EVs. Mechanistically, miR-25-3p, miR-155-5p, miR-215-5p, and miR-375 within CD4+ T cell-derived EVs are responsible for the induction of CD8+ T cell-mediated antitumor responses. In a melanoma mouse model, the EVs potently suppress tumor growth through CD8+ T cell activation. This study demonstrates that the EVs, in addition to IL2, are important mediators between CD4+ and CD8+ T cells. Furthermore, unlike IL2, clinically used as an antitumor agent, CD4+ T cell-derived EVs stimulate CD8+ T cells without activating Tregs. Therefore, CD4+ T cell-derived EVs may provide a novel direction for cancer immunotherapy by inducing a CD8+ T cell-mediated antitumor response.

Hemp-Derived Nanovesicles Protect Leaky Gut and Liver Injury in Dextran Sodium Sulfate-Induced Colitis.

Hemp (Cannabis sativa L.) is used for medicinal purposes owing to its anti-inflammatory and antioxidant activities. We evaluated the protective effect of nanovesicles isolated from hemp plant parts (root, seed, hemp sprout, and leaf) in dextran sulfate sodium (DSS)-induced colitis in mice. The particle sizes of root-derived nanovesicles (RNVs), seed-derived nanovesicles (SNVs), hemp sprout-derived nanovesicles (HSNVs), and leaf-derived nanovesicles (LNVs) were within the range of 100-200 nm as measured by nanoparticle tracking analysis. Acute colitis was induced in C57BL/N mice by 5% DSS in water provided for 7 days. RNVs were administered orally once a day, leading to the recovery of both the small intestine and colon lengths. RNVs, SNVs, and HSNVs restored the tight (ZO-1, claudin-4, occludin) and adherent junctions (E-cadherin and α-tubulin) in DSS-induced small intestine and colon injury. Additionally, RNVs markedly reduced NF-κB activation and oxidative stress proteins in DSS-induced small intestine and colon injury. Tight junction protein expression and epithelial cell permeability were elevated in RNV-, SNV-, and HSNV-treated T84 colon cells exposed to 2% DSS. Interestedly, RNVs, SNVs, HSNVs, and LNVs reduced ALT activity and liver regeneration marker proteins in DSS-induced liver injury. These results showed for the first time that hemp-derived nanovesicles (HNVs) exhibited a protective effect on DSS-induced gut leaky and liver injury through the gut-liver axis by inhibiting oxidative stress marker proteins.

Atorvastatin Enhances the Efficacy of Immune Checkpoint Therapy and Suppresses the Cellular and Extracellular Vesicle PD-L1.

According to clinical studies, statins improve the efficacy of programmed death-1/programmed death-ligand 1 (PD-1/PD-L1) blockade therapy for breast cancer; however, the underlying mechanisms are unclear. Herein, we showed that atorvastatin (ATO) decreased the content of PD-L1 in extracellular vesicles (EVs) by reducing cellular PD-L1 expression and inhibiting EV secretion in breast cancer cells, thereby enhancing the efficacy of anti-PD-L1 therapy. ATO reduced EV secretion by regulating the Rab proteins involved in EV biogenesis and secretion. ATO-mediated inhibition of the Ras-activated MAPK signaling pathway downregulated PD-L1 expression. In addition, ATO strongly promoted antitumor efficacy by inducing T cell-mediated tumor destruction when combined with an anti-PD-L1 antibody. Moreover, suppression of EV PD-L1 by ATO improved the reactivity of anti-PD-L1 therapy by enhancing T-cell activity in draining lymph nodes of EMT6-bearing immunocompetent mice. Therefore, ATO is a potential therapeutic drug that improves antitumor immunity by inhibiting EV PD-L1, particularly in response to immune escape during cancer.

Plum Prevents Intestinal and Hepatic Inflammation in the Acute and Chronic Models of Dextran Sulfate Sodium-Induced Mouse Colitis.

SCOPE: Inflammatory bowel disease (IBD), including ulcerative colitis (UC), is a chronic recurrent inflammatory disease of the digestive tract and increases the risk of colon cancer. METHOD AND RESULTS: This study evaluates the effects of dietary intervention with freeze-dried plum (FDP), a natural antioxidant and anti-inflammatory fruit with no toxicity on dextran sulfate sodium (DSS)-induced acute and chronic experimental colitis in a mouse model and studies the molecular mechanisms of protection through the gut-liver axis. The results show that FDP decreases the levels of inflammatory mediators, which is a nitrative stress biomarker in both acute and chronic models. FDP markedly reduces DSS-induced injury to the colonic epithelium in both acute and chronic models. In addition, FDP significantly decreases the levels of pro-oxidant markers such as CYP2E1, iNOS, and nitrated proteins (detected by anti-3-NT antibody) in DSS-induced acute and chronic colonic injury models. Furthermore, FDP markedly reduces markers of liver injury such as serum ALT/AST, antioxidant markers, and inflammatory mediators in DSS-induced acute and chronic colonic injury. CONCLUSION: These results demonstrate that the FDP exhibits a protective effect on DSS-induced acute and chronic colonic and liver injury through the gut-liver axis via antioxidant and anti-inflammatory properties.

Macitentan improves antitumor immune responses by inhibiting the secretion of tumor-derived extracellular vesicle PD-L1.

Extracellular vesicles (EVs) carrying tumor cell-derived programmed death-ligand 1 (PD-L1) interact with programmed death 1 (PD-1)-producing T cells, thus significantly lowering a patient's response to immune checkpoint blockade drugs. No drug that reinvigorates CD8+ T cells by suppressing EV PD-L1 has been approved for clinical usage. Here we have identified macitentan (MAC), an FDA-approved oral drug, as a robust booster of antitumor responses in CD8+ T cells by suppressing tumor cell-derived EV PD-L1. Methods: EV was analyzed by the data from nanoparticle tracking, immunoblotting analyses, and nano-flow cytometry. Antitumor immunity was evaluated by luciferase assay and immune phenotyping using flow cytometry. Clinical relevance was analyzed using the cancer genome atlas database. Results: MAC inhibited secretion of tumor-derived EV PD-L1 by targeting the endothelin receptor A (ETA) in breast cancer cells and xenograft models. MAC enhanced CD8+ T cell-mediated tumor killing by decreasing the binding of PD-1 to the EV PD-L1 and thus synergizing the effects of the anti-PD-L1 antibody. MAC also showed an anticancer effect in triple-negative breast cancer (TNBC)-bearing immunocompetent mice but not in nude mice. The combination therapy of MAC and anti-PD-L1 antibody significantly improved antitumor efficacy by increasing CD8+ T cell number and activity with decreasing Treg number in the tumors and draining lymph nodes in TNBC, colon, and lung syngeneic tumor models. The antitumor effect of MAC was reversed by injecting exogenous EV PD-L1. Notably, ETA level was strongly associated with the innate anti-PD-1 resistance gene signature and the low response to the PD-1/PD-L1 blockade. Conclusion: These findings strongly demonstrate that MAC, already approved for clinical applications, can be used to improve and/or overcome the inadequate response to PD-1/PD-L1 blockade therapy.

Immune cell-derived small extracellular vesicles in cancer treatment.

Small extracellular vesicles (sEVs) secreted by most cells carry bioactive macromolecules including proteins, lipids, and nucleic acids for intercellular communication. Given that some immune cell-derived sEVs exhibit anti-cancer properties, these sEVs have received scientific attention for the development of novel anticancer immunotherapeutic agents. In this paper, we reviewed the latest advances concerning the biological roles of immune cell-derived sEVs for cancer therapy. sEVs derived from immune cells including dendritic cells (DCs), T cells, natural-killer (NK) cells, and macrophages are good candidates for sEV-based cancer therapy. Besides their role of cancer vaccines, DC-shed sEVs activated cytotoxic lymphocytes and killed tumor cells. sEVs isolated from NK cells and chimeric antigen receptor (CAR) T cells exhibited cytotoxicity against cancer cells. sEVs derived from CD8+ T and CD4+ T cells inhibited cancer-associated cells in tumor microenvironment (TME) and activated B cells, respectively. M1-macrophage-derived sEVs induced M2 to M1 repolarization and also created a pro-inflammatory environment. Hence, these sEVs, via mono or combination therapy, could be considered in the treatment of cancer patients in the future. In addition, sEVs derived from cytokine-stimulated immune cells or sEV engineering could improve their anti-tumor potency. [BMB Reports 2022; 55(1): 48-56].

Sulfisoxazole Elicits Robust Antitumour Immune Response Along with Immune Checkpoint Therapy by Inhibiting Exosomal PD-L1.

Despite their potent antitumor activity, clinical application of immune checkpoint inhibitors has been significantly limited by their poor response rates (<30%) in cancer patients, primarily due to immunosuppressive tumor microenvironments. As a representative immune escape mechanism, cancer-derived exosomes have recently been demonstrated to exhaust CD8+ cytotoxic T cells. Here, it is reported that sulfisoxazole, a sulfonamide antibacterial, significantly decreases the exosomal PD-L1 level in blood when orally administered to the tumor-bearing mice. Consequently, sulfisoxazole effectively reinvigorates exhausted T cells, thereby eliciting robust antitumor effects in combination with anti-PD-1 antibody. Overall, sulfisoxazole regulates immunosuppression through the inhibition of exosomal PD-L1, implying its potential to improve the response rate of anti-PD-1 antibodies.

Ellagic Acid Prevents Binge Alcohol-Induced Leaky Gut and Liver Injury through Inhibiting Gut Dysbiosis and Oxidative Stress.

Alcoholic liver disease (ALD) is a major liver disease worldwide and can range from simple steatosis or inflammation to fibrosis/cirrhosis, possibly through leaky gut and systemic endotoxemia. Many patients with alcoholic steatohepatitis (ASH) die within 60 days after clinical diagnosis due to the lack of an approved drug, and thus, synthetic and/or dietary agents to prevent ASH and premature deaths are urgently needed. We recently reported that a pharmacologically high dose of pomegranate extract prevented binge alcohol-induced gut leakiness and hepatic inflammation by suppressing oxidative and nitrative stress. Herein, we investigate whether a dietary antioxidant ellagic acid (EA) contained in many fruits, including pomegranate and vegetables, can protect against binge alcohol-induced leaky gut, endotoxemia, and liver inflammation. Pretreatment with a physiologically-relevant dose of EA for 14 days significantly reduced the binge alcohol-induced gut barrier dysfunction, endotoxemia, and inflammatory liver injury in mice by inhibiting gut dysbiosis and the elevated oxidative stress and apoptosis marker proteins. Pretreatment with EA significantly prevented the decreased amounts of gut tight junction/adherent junction proteins and the elevated gut leakiness in alcohol-exposed mice. Taken together, our results suggest that EA could be used as a dietary supplement for alcoholic hepatitis patients.

M1 macrophage exosomes engineered to foster M1 polarization and target the IL-4 receptor inhibit tumor growth by reprogramming tumor-associated macrophages into M1-like macrophages.

M2-polarized, pro-tumoral tumor-associated macrophages (TAMs) express the interleukin-4 receptor (IL4R) at higher levels compared with M1-polarized, anti-tumoral macrophages. In this study, we harnessed M1 macrophage-derived exosomes engineered to foster M1 polarization and target IL4R for the inhibition of tumor growth by reprogramming TAMs into M1-like macrophages. M1 exosomes were transfected with NF-κB p50 siRNA and miR-511-3p to enhance M1 polarization and were surface-modified with IL4RPep-1, an IL4R-binding peptide, to target the IL4 receptor of TAMs (named IL4R-Exo(si/mi). IL4R-Exo(si/mi) were internalized and downregulated target gens in M2 macrophages and decreased M2 markers, while increasing M1 markers, more efficiently compared with untargeted and control peptide-labeled exosomes and exosomes from non-immune, normal cells. Whole-body fluorescence imaging showed that IL4R-Exo(si/mi) homed to tumors at higher levels compared with the liver, unlike untargeted and control peptide-labeled exosomes. Systemic administration of IL4R-Exo(si/mi) inhibited tumor growth, downregulated target genes, and decreased the levels of M2 cytokines and immune-suppressive cells, while increasing the levels of M1 cytokines and immune-stimulatory cells, more efficiently than untargeted and control peptide-labeled exosomes. These results suggest that IL4R-Exo(si/mi) inhibits tumor growth by reprogramming TAMs into M1-like macrophages and increasing anti-tumor immunity, thus representing a novel cancer immunotherapy.