Targeting the dendritic cell-secreted immunoregulatory cytokine CCL22 alleviates radioresistance.

PURPOSE: Radiation-mediated immune suppression limits efficacy and is a barrier in cancer therapy. Radiation induces negative regulators of tumor immunity including regulatory T cells (Treg). Mechanisms underlying Treg infiltration after radiotherapy (RT) are poorly defined. Given that dendritic cells (cDC) maintain Treg we sought to identify and target cDC signaling to block Treg infiltration after radiation. EXPERIMENTAL DESIGN: Transcriptomics and high dimensional flow cytometry revealed changes in murine tumor cDC that not only mediate Treg infiltration after RT, but associate with worse survival in human cancer datasets. Antibodies perturbing a cDC-CCL22-Treg axis were tested in syngeneic murine tumors. A prototype interferon-anti-epidermal growth factor receptor fusion protein (αEGFR-IFNα) was examined to block Treg infiltration and promote a CD8+ T cell response after RT. RESULTS: Radiation expands a population of mature cDC1 enriched in immunoregulatory markers that mediates Treg infiltration via the Treg-recruiting chemokine CCL22. Blocking CCL22 or Treg depletion both enhanced RT efficacy. αEGFR-IFNα blocked cDC1 CCL22 production while simultaneously inducing an antitumor CD8+ T cell response to enhance RT efficacy in multiple EGFR-expressing murine tumor models, including following systemic administration. CONCLUSIONS: We identify a previously unappreciated cDC mechanism mediating Treg tumor infiltration after RT. Our findings suggest blocking the cDC1-CCL22-Treg axis augments RT efficacy. αEGFR-IFNα added to RT provided robust antitumor responses better than systemic free interferon administration, and may overcome clinical limitations to interferon therapy. Our findings highlight the complex behavior of cDC after RT and provide novel therapeutic strategies for overcoming RT-driven immunosuppression to improve RT efficacy.

Radiotherapy Enhances Metastasis Through Immune Suppression by Inducing PD-L1 and MDSC in Distal Sites.

PURPOSE: Radiotherapy (RT) is a widely employed anticancer treatment. Emerging evidence suggests that RT can elicit both tumor-inhibiting and tumor-promoting immune effects. The purpose of this study is to investigate immune suppressive factors of radiotherapy. EXPERIMENTAL DESIGN: We used a heterologous two-tumor model in which adaptive concomitant immunity was eliminated. RESULTS: Through analysis of PD-L1 expression and myeloid-derived suppressor cells (MDSC) frequencies using patient peripheral blood mononuclear cells and murine two-tumor and metastasis models, we report that local irradiation can induce a systemic increase in MDSC, as well as PD-L1 expression on dendritic cells and myeloid cells, and thereby increase the potential for metastatic dissemination in distal, nonirradiated tissue. In a mouse model using two distinct tumors, we found that PD-L1 induction by ionizing radiation was dependent on elevated chemokine CXCL10 signaling. Inhibiting PD-L1 or MDSC can potentially abrogate RT-induced metastasis and improve clinical outcomes for patients receiving RT. CONCLUSIONS: Blockade of PD-L1/CXCL10 axis or MDSC infiltration during irradiation can enhance abscopal tumor control and reduce metastasis.

CD200+ fibroblasts form a pro-resolving mesenchymal network in arthritis.

Fibroblasts are important regulators of inflammation, but whether fibroblasts change phenotype during resolution of inflammation is not clear. Here we use positron emission tomography to detect fibroblast activation protein (FAP) as a means to visualize fibroblast activation in vivo during inflammation in humans. While tracer accumulation is high in active arthritis, it decreases after tumor necrosis factor and interleukin-17A inhibition. Biopsy-based single-cell RNA-sequencing analyses in experimental arthritis show that FAP signal reduction reflects a phenotypic switch from pro-inflammatory MMP3+/IL6+ fibroblasts (high FAP internalization) to pro-resolving CD200+DKK3+ fibroblasts (low FAP internalization). Spatial transcriptomics of human joints indicates that pro-resolving niches of CD200+DKK3+ fibroblasts cluster with type 2 innate lymphoid cells, whereas MMP3+/IL6+ fibroblasts colocalize with inflammatory immune cells. CD200+DKK3+ fibroblasts stabilized the type 2 innate lymphoid cell phenotype and induced resolution of arthritis via CD200-CD200R1 signaling. Taken together, these data suggest a dynamic molecular regulation of the mesenchymal compartment during resolution of inflammation.

Immunogenic Bifunctional Nanoparticle Suppresses Programmed Cell Death-Ligand 1 in Cancer and Dendritic Cells to Enhance Adaptive Immunity and Chemo-Immunotherapy.

Blockade of programmed cell death-1/programmed cell death-ligand 1 (PD-L1) immune checkpoints with monoclonal antibodies has shown great promise for cancer treatment, but these antibodies can cause immune-related adverse events in normal organs. Here we report a dual-cell targeted chemo-immunotherapeutic nanoscale coordination polymer (NCP), OxPt/BP, comprising oxaliplatin (OxPt) and 2-bromopalmitic acid (BP), for effective downregulation of PD-L1 expression in both cancer cells and dendritic cells (DCs) by inhibiting palmitoyl acyltransferase DHHC3. OxPt/BP efficiently promotes DC maturation by increasing intracellular oxidative stress and enhancing OxPt-induced immunostimulatory immunogenic cancer cell death. Systemic administration of OxPt/BP reduces the growth of subcutaneous and orthotopic colorectal carcinoma by facilitating the infiltration and activation of cytotoxic T lymphocytes together with reducing the population of immunosuppressive regulatory T cells. As a result, OxPt/BP significantly extends mouse survival without causing side effects. This work highlights the potential of NCPs in simultaneously reprogramming cancer cells and DCs for potent cancer treatment.

RNA m6A methylation and MDSCs: Roles and therapeutic implications for radiotherapy.

Emerging evidence suggests that local tumor radiotherapy reshapes the repertoire of circulating myeloid-derived suppressor cells (MDSCs) and leads to their infiltration into the tumor microenvironment, which poses a major obstacle for radiotherapy efficacy. Recent findings have identified RNA m6A modification at the nexus of both anti-tumor immunity and radiation response. Here, we examine the mechanisms by which this RNA modification modulates the immune milieu of the radiation-remodeled tumor microenvironment. We discuss potential therapeutic interventions targeting m6A machinery to improve radiotherapy response.

Epitranscriptional regulation of TGF-ß pseudoreceptor BAMBI by m6A/YTHDF2 drives extrinsic radioresistance.

Activation of TGF-ß signaling serves as an extrinsic resistance mechanism that limits the potential for radiotherapy. Bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) antagonizes TGF-ß signaling and is implicated in cancer progression. However, the molecular mechanisms of BAMBI regulation in immune cells and its impact on antitumor immunity after radiation have not been established. Here, we show that ionizing radiation (IR) specifically reduces BAMBI expression in immunosuppressive myeloid-derived suppressor cells (MDSCs) in both murine models and humans. Mechanistically, YTH N6-methyladenosine RNA-binding protein F2 (YTHDF2) directly binds and degrades Bambi transcripts in an N6-methyladenosine-dependent (m6A-dependent) manner, and this relies on NF-κB signaling. BAMBI suppresses the tumor-infiltrating capacity and suppression function of MDSCs via inhibiting TGF-ß signaling. Adeno-associated viral delivery of Bambi (AAV-Bambi) to the tumor microenvironment boosts the antitumor effects of radiotherapy and radioimmunotherapy combinations. Intriguingly, combination of AAV-Bambi and IR not only improves local tumor control, but also suppresses distant metastasis, further supporting its clinical translation potential. Our findings uncover a surprising role of BAMBI in myeloid cells, unveiling a potential therapeutic strategy for overcoming extrinsic radioresistance.

YTHDF2 inhibition potentiates radiotherapy antitumor efficacy.

RNA N6-methyladenosine (m6A) modification is implicated in cancer progression. However, the impact of m6A on the antitumor effects of radiotherapy and the related mechanisms are unknown. Here we show that ionizing radiation (IR) induces immunosuppressive myeloid-derived suppressor cell (MDSC) expansion and YTHDF2 expression in both murine models and humans. Following IR, loss of Ythdf2 in myeloid cells augments antitumor immunity and overcomes tumor radioresistance by altering MDSC differentiation and inhibiting MDSC infiltration and suppressive function. The remodeling of the landscape of MDSC populations by local IR is reversed by Ythdf2 deficiency. IR-induced YTHDF2 expression relies on NF-κB signaling; YTHDF2 in turn leads to NF-κB activation by directly binding and degrading transcripts encoding negative regulators of NF-κB signaling, resulting in an IR-YTHDF2-NF-κB circuit. Pharmacological inhibition of YTHDF2 overcomes MDSC-induced immunosuppression and improves combined IR and/or anti-PD-L1 treatment. Thus, YTHDF2 is a promising target to improve radiotherapy (RT) and RT/immunotherapy combinations.

Macrophages inhibit Coxiella burnetii by the ACOD1-itaconate pathway for containment of Q fever.

Infection with the intracellular bacterium Coxiella (C.) burnetii can cause chronic Q fever with severe complications and limited treatment options. Here, we identify the enzyme cis-aconitate decarboxylase 1 (ACOD1 or IRG1) and its product itaconate as protective host immune pathway in Q fever. Infection of mice with C. burnetii induced expression of several anti-microbial candidate genes, including Acod1. In macrophages, Acod1 was essential for restricting C. burnetii replication, while other antimicrobial pathways were dispensable. Intratracheal or intraperitoneal infection of Acod1-/- mice caused increased C. burnetii burden, weight loss and stronger inflammatory gene expression. Exogenously added itaconate restored pathogen control in Acod1-/- mouse macrophages and blocked replication in human macrophages. In axenic cultures, itaconate directly inhibited growth of C. burnetii. Finally, treatment of infected Acod1-/- mice with itaconate efficiently reduced the tissue pathogen load. Thus, ACOD1-derived itaconate is a key factor in the macrophage-mediated defense against C. burnetii and may be exploited for novel therapeutic approaches in chronic Q fever.

Neonatal risk factors for functional gastrointestinal disorders in preterm infants in the first year of life.

BACKGROUND: An assessment of functional gastrointestinal disorders (FGIDs) in premature infants in their first year of life and neonatal factors influencing the progression of FGIDs was conducted in this research. METHODS: Subjects selected for the retrospective study involved preterm infants being hospitalized in the neonatal department of Northern Jiangsu People`s Hospital from September 2018 to September 2021. Data on neonatal risk factors such as gestational age, gender, birth weight, mode of delivery, feeding pattern, antibiotic administration and addition of probiotics, duration of hospitalization, maternal history of smoking, and mental health status, were all collected and analyzed. FGIDs were diagnosed according to Rome IV criteria. RESULTS: This study included 988 preterm infants, with 725 (73.4%) having at least one FGID, 449 (45.4%) with infant colic, 411 (41.6%) with infant regurgitation, 237 (24.0%) with infant dyschezia, 190 (19.2%) with functional constipation, and 34 (3.4%) with functional diarrhea throughout the first year of life. In total, 263 infants (26.6%) without FGID symptoms were included in the control group. Further, a higher prevalence of FGIDs was observed in preterm infants with infant colic as well as infant regurgitation in particular as being characterized by a low gestational age ( < 32 w), low birth weight ( < 1.5 kg), Cesarean section, formula feeding, neonatal antibiotics use, hospitalization longer than 7 days, and maternal history of smoking. It was found from association analyses that infants exclusively breastfed in their first month of life were at lower risk for regurgitation than those in the control group. CONCLUSIONS: Unnecessary antibiotic use in the neonatal period, Cesarean delivery, passive smoking, lack of breastfeeding along with inappropriate probiotics usage are major risk factors for FGIDs, and their systematic control may be effective in reducing the susceptibility to and prevalence of FGIDs in preterm infants in the first year of life.

Safety and efficacy of a novel double-lumen tracheal tube in neonates with RDS: A prospective cohort study.

Background: The purpose of this study was to assess the safety and efficacy of a new double-lumen tracheal tube for neonates, with a conventional tracheal tube as a control. Method: Newborns with respiratory distress syndrome (RDS) requiring endotracheal intubation admitted to the tertiary neonatal intensive care unit (NICU) of Qujing Maternal and Child Healthcare Hospital in Yunnan Province between March 2021 and May 2022 were enrolled in this prospective cohort study. Outcome indicators related to effectiveness included mainly the number of intubations, duration of ventilation, duration of oxygenation, and length of stay; safety indicators included any clinical adverse effects during and after intubation. Appropriate stratified and subgroup analyses were performed according to the purpose of intubation, gestational age, and whether the drug was administered via endotracheal tube. Result: A total of 101 neonates were included and divided into two groups based on the choice of tracheal tube: the conventional (n = 50) and new (n = 51) tracheal tube groups. There was no statistical difference between the two groups in terms of adverse effects during and after intubation (p > 0.05). In neonates who were mechanically ventilated without endotracheal surfactant therapy or newborns receiving InSurE technique followed by non-invasive ventilation, no significant differences were found between the two groups regarding any of the efficacy indicators (p > 0.05). However, for neonates on invasive mechanical ventilation, the new tracheal tube allowed for a significant reduction in the duration of mechanical ventilation (96.50[74.00, 144.00] vs. 121.00[96.00, 196.50] hours, p = 0.037) and total ventilation (205.71 ± 80.24 vs. 277.56 ± 117.84 h, p = 0.027), when used as a route for endotracheal drug delivery. Further analysis was performed according to gestational age for newborns requiring intratracheal surfactant administration during mechanical ventilation, and the data showed that for preterm infants, the new tracheal tube not only shortened the duration of mechanical ventilation (101.75 ± 39.72 vs. 155.50 ± 51.49 h, p = 0.026) and total ventilation (216.00 ± 81.60 vs. 351.50 ± 113.79 h, p = 0.010), but also demonstrated significant advantages in reducing the duration of oxygen therapy (9.75 ± 6.02 vs. 17.33 ± 8.43 days, p = 0.042); however, there was no statistical difference in efficacy outcomes between the two groups in full-term infants (p > 0.05). Conclusion: The efficacy and safety of this new tracheal tube are promising in neonates with RDS, especially those requiring surfactant administration via a tracheal tube during mechanical ventilation. Given the limitations of this study, however, the clinical feasibility of this catheter needs to be further confirmed in prospective randomized trials with larger sample sizes. Clinical Trial Registration: http://www.chictr.org.cn/showproj.aspx?proj=122073.

Zinc cyclic di-AMP nanoparticles target and suppress tumours via endothelial STING activation and tumour-associated macrophage reinvigoration.

The clinical utility of stimulator of interferon genes (STING) agonists has been limited due to poor tumour-targeting and unwanted toxicity following systemic delivery. Here we describe a robust tumour-targeted STING agonist, ZnCDA, formed by the encapsulation of bacterial-derived cyclic dimeric adenosine monophosphate (CDA) in nanoscale coordination polymers. Intravenously injected ZnCDA prolongs CDA circulation and efficiently targets tumours, mediating robust anti-tumour effects in a diverse set of preclinical cancer models at a single dose. Our findings reveal that ZnCDA enhances tumour accumulation by disrupting endothelial cells in the tumour vasculature. ZnCDA preferentially targets tumour-associated macrophages to modulate antigen processing and presentation and subsequent priming of an anti-tumour T-cell response. ZnCDA reinvigorates the anti-tumour activity of both radiotherapy and immune checkpoint inhibitors in immunologically 'cold' pancreatic and glioma tumour models, offering a promising combination strategy for the treatment of intractable human cancers.

Tumor-Activatable Nanoparticles Target Low-Density Lipoprotein Receptor to Enhance Drug Delivery and Antitumor Efficacy.

The binding of plasma proteins to nanomedicines is widely considered detrimental to their delivery to tumors. Here, the design of OxPt/SN38 nanoparticle containing a hydrophilic oxaliplatin (OxPt) prodrug in a coordination polymer core and a hydrophobic cholesterol-conjugated SN38 prodrug on the lipid shell for active tumor targeting is reported. OxPt/SN38 hitchhikes on low-density lipoprotein (LDL) particles, concentrates in tumors via LDL receptor-mediated endocytosis, and selectively releases SN38 and OxPt in acidic, esterase-rich, and reducing tumor microenvironments, leading to 6.0- and 4.9-times higher accumulations in tumors over free drugs. By simultaneously crosslinking DNA and inhibiting topoisomerase I, OxPt/SN38 achieved 92-98% tumor growth inhibition in five colorectal cancer tumor models and prolonged mouse survival by 58-80 days compared to free drug controls in three human colorectal cancer tumor models without causing serious side effects. The study has uncovered a novel nanomedicine strategy to co-deliver combination chemotherapies to tumors via active targeting of the LDL receptor.

Synergistic checkpoint-blockade and radiotherapy-radiodynamic therapy via an immunomodulatory nanoscale metal-organic framework.

Checkpoint blockade elicits durable responses in immunogenic cancers, but it is largely ineffective in immunologically 'cold' tumours. Here we report the design, synthesis and performance of a bismuth-based nanoscale metal-organic framework that modulates the immunological and mechanical properties of the tumour microenvironment for enhanced radiotherapy-radiodynamic therapy. In mice with non-immunogenic prostate and pancreatic tumours irradiated with low X-ray doses, the intratumoural injection of the radiosensitizer mediated potent outcomes via the repolarization of immunosuppressive M2 macrophages into immunostimulatory M1 macrophages, the reduction of the concentration of intratumoural transforming growth factor beta (TGF-ß) and of collagen density, and the inactivation of cancer-associated fibroblasts. When intravenously injected in combination with checkpoint-blockade therapy, the radiosensitizer mediated the reversal of immunosuppression in primary and distant tumours via the systemic reduction of TGF-ß levels, which led to the downregulation of collagen expression, the stimulation of T-cell infiltration in the tumours and a robust abscopal effect. Nanoscale radiosensitizers that stimulate anti-tumour immunity and T-cell infiltration may enhance the therapeutic outcomes of checkpoint blockade in other tumour types.

Lactobacillus rhamnosus GG induces cGAS/STING- dependent type I interferon and improves response to immune checkpoint blockade.

OBJECTIVE: Our goals were to evaluate the antitumour efficacy of Lactobacillus rhamnosus GG (LGG) in combination with immune checkpoint blockade (ICB) immunotherapies on tumour growth and to investigate the underlying mechanisms. DESIGN: We used murine models of colorectal cancer and melanoma to evaluate whether oral administration of LGG improves the efficacy of ICB therapies. We performed the whole genome shotgun metagenome sequencing of intestinal contents and RNA sequencing of dendritic cells (DCs). In a series of in vitro and in vivo experiments, we further defined the immunological and molecular mechanisms of LGG-mediated antitumour immunity. RESULTS: We demonstrate that oral administration of live LGG augmented the antitumour activity of anti-programmed cell death 1 (PD-1) immunotherapy by increasing tumour-infiltrating DCs and T cells. Moreover, the combination treatment shifted the gut microbial community towards enrichment in Lactobacillus murinus and Bacteroides uniformis, that are known to increase DC activation and CD8+tumour recruitment. Mechanistically, treatment with live LGG alone or in combination with anti-PD-1 antibody triggered type I interferon (IFN) production in DCs, enhancing the cross-priming of antitumour CD8+ T cells. In DCs, cyclic GMP-AMP synthase (cGAS)/stimulator of IFN genes (STING) was required for IFN-ß induction in response to LGG, as evidenced by the significant decrease in IFN-ß levels in cGAS or STING-deficient DCs. LGG induces IFN-ß production via the cGAS/STING/TANK binding kinase 1/interferon regulatory factor 7 axis in DCs. CONCLUSION: Our findings have offered valuable insight into the molecular mechanisms of live LGG-mediated antitumour immunity and establish an empirical basis for developing oral administration of live LGG as a combination agent with ICB for cancer therapies.

All-trans retinoic acid overcomes solid tumor radioresistance by inducing inflammatory macrophages.

Radiotherapy (RT) is an important anti-cancer treatment modality that activates innate and adaptive immune responses. When all-trans retinoic acid (RA) was administered with radiation, we observed superior antitumor responses compared to ionizing radiation (IR) alone or RA alone. The superior antitumor effects of combination treatment were accompanied by a dramatic increase of TNF-α- and inducible nitric oxide synthase (iNOS)-producing inflammatory macrophages in local and distal non-irradiated (distal) tumors. Inflammatory macrophages are essential for the therapeutic efficacy of combination treatment by inducing effector T cell infiltration and enhancing the effector T cell to regulatory T cell ratio in local and distal tumors. T cells and T cell-derived IFN-γ are crucial for increasing inflammatory macrophage levels in IR and RA treated tumors. Notably, whereas CD8+ T cells are required for the antitumor response to IR, CD4+ T cells are required for the effectiveness of the IR and RA combination. Combination treatment with RA enhanced the abscopal response when radiation and PD-L1 blockade were used together. The synergistic positive feedback loop of inflammatory macrophages and adaptive immunity is required for the antitumor efficacy of IR plus RA combination treatment. Our findings provide a translational and relatively nontoxic strategy for enhancing the local and systemic antitumor effects of IR.

Suppression of local type I interferon by gut microbiota-derived butyrate impairs antitumor effects of ionizing radiation.

The antitumor effects of ionizing radiation (IR) are mediated in part through activation of innate and adaptive immunity. Here we report that gut microbiota influences tumor control following IR. Vancomycin decreased the abundance of butyrate-producing gut bacteria and enhanced antitumor responses to IR. Oral administration of Lachnospiraceae, a family of vancomycin-sensitive bacteria, was associated with increased systemic and intratumoral butyric acid levels and impaired the efficacy of IR in germ-free (GF) mice. Local butyrate inhibited STING-activated type I IFN expression in dendritic cells (DCs) through blockade of TBK1 and IRF3 phosphorylation, which abrogated IR-induced tumor-specific cytotoxic T cell immune responses without directly protecting tumor cells from radiation. Our findings demonstrate that the selective targeting of butyrate-producing microbiota may provide a novel therapeutic option to enhance tumor radiation sensitivity.

RIG-I-Like Receptor LGP2 Is Required for Tumor Control by Radiotherapy.

Dendritic cells (DC) play an essential role in innate immunity and radiation-elicited immune responses. LGP2 is a RIG-I-like receptor involved in cytoplasmic RNA recognition and antiviral responses. Although LGP2 has also been linked to cell survival of both tumor cells and T cells, the role of LGP2 in mediating DC function and antitumor immunity elicited by radiotherapy remains unclear. Here, we report that tumor DCs are linked to the clinical outcome of patients with breast cancer who received radiotherapy, and the presence of DC correlates with gene expression of LGP2 in the tumor microenvironment. In preclinical models, host LGP2 was essential for optimal antitumor control by ionizing radiation (IR). The absence of LGP2 in DC dampened type I IFN production and the priming capacity of DC. In the absence of LGP2, MDA5-mediated activation of type I IFN signaling was abrogated. The MDA5/LGP2 agonist high molecular weight poly I:C improved the antitumor effect of IR. This study reveals a previously undefined role of LGP2 in host immunity and provides a new strategy to improve the efficacy of radiotherapy. SIGNIFICANCE: These findings reveal an essential role of LGP2 in promoting antitumor immunity after radiotherapy and provide a new strategy to enhance radiotherapy.

Author Correction: A next-generation tumor-targeting IL-2 preferentially promotes tumor-infiltrating CD8+ T-cell response and effective tumor control.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Intratumoral accumulation of gut microbiota facilitates CD47-based immunotherapy via STING signaling.

Most studies focus on how intestinal microbiota influence cancer immunotherapy through activating gut immunity. However, immunotherapies related to innate responses such as CD47 blockade rely on the rapid immune responses within the tumor microenvironment. Using one defined anaerobic gut microbiota to track whether microbiota interact with host immunity, we observed that Bifidobacterium facilitates local anti-CD47 immunotherapy on tumor tissues through the capacity to accumulate within the tumor microenvironment. Systemic administration of Bifidobacterium leads to its accumulation within the tumor and converts the nonresponder mice into responders to anti-CD47 immunotherapy in a stimulator of interferon genes (STING)- and interferon-dependent fashion. Local delivery of Bifidobacterium potently stimulates STING signaling and increases cross-priming of dendritic cells after anti-CD47 treatment. Our study identifies the mechanism by which gut microbiota preferentially colonize in tumor sites and facilitate immunotherapy via STING signaling.