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Checkpoint blockade therapies have improved cancer treatment, but such immunotherapy regimens fail in a large subset of patients. Conventional type 1 dendritic cells (DC1s) control the response to checkpoint blockade in preclinical models and are associated with better overall survival in patients with cancer, reflecting the specialized ability of these cells to prime the responses of CD8 + T cells 1 – 3 . Paradoxically, however, DC1s can be found in tumours that resist checkpoint blockade, suggesting that the functions of these cells may be altered in some lesions. Here, using single-cell RNA sequencing in human and mouse non-small-cell lung cancers, we identify a cluster of dendritic cells (DCs) that we name ‘mature DCs enriched in immunoregulatory molecules’ (mregDCs), owing to their coexpression of immunoregulatory genes ( Cd274 , Pdcd1lg2 and Cd200 ) and maturation genes ( C d40 , C cr7 and Il12b ). We find that the mregDC program is expressed by canonical DC1s and DC2s upon uptake of tumour antigens. We further find that upregulation of the programmed death ligand 1 protein—a key checkpoint molecule—in mregDCs is induced by the receptor tyrosine kinase AXL, while upregulation of interleukin (IL)-12 depends strictly on interferon-γ and is controlled negatively by IL-4 signalling. Blocking IL-4 enhances IL-12 production by tumour-antigen-bearing mregDC1s, expands the pool of tumour-infiltrating effector T cells and reduces tumour burden. We have therefore uncovered a regulatory module associated with tumour-antigen uptake that reduces DC1 functionality in human and mouse cancers. After taking up tumour-associated antigens, dendritic cells in mouse and human tumours upregulate a regulatory gene program that limits dendritic cell immunostimulatory function, and modulating this program can rescue antitumor immunity in mice.

Personalized immunotherapy targeting tumor-specific antigens (TSAs) could generate efficient and safe antitumor immune response without damaging normal tissues. Although neoantigen vaccines have shown therapeutic effect in clinic trials, precise prediction of neoantigens from tumor mutations is still challenging. The host antitumor immune response selects and activates T cells recognizing tumor antigens. Hence, T cells engineered with T-cell receptors (TCRs) from these naturally occurring tumor antigen-specific T (Tas) cells in a patient will target personal TSAs in his/her tumor. To establish such a personalized TCR-T cell therapy, we comprehensively characterized T cells in tumor and its adjacent tissues by single-cell mRNA sequencing (scRNA-seq), TCR sequencing (TCR-seq) and in vitro neoantigen stimulation. Compared to bystander T cells circulating among tissues, Tas cells were characterized by tumor enrichment, tumor-specific clonal expansion and neoantigen specificity. We found that CXCL13 is a unique marker for both CD4 + and CD8 + Tas cells. Importantly, TCR-T cells expressing TCRs from Tas cells showed significant therapeutic effects on autologous patient-derived xenograft (PDX) tumors. Intratumoral Tas cell levels measured by CXCL13 expression precisely predicted the response to immune checkpoint blockade, indicating a critical role of Tas cells in the antitumor immunity. We further identified CD200 and ENTPD1 as surface markers for CD4 + and CD8 + Tas cells respectively, which enabled the isolation of Tas cells from tumor by Fluorescence Activating Cell Sorter (FACS) sorting. Overall, our results suggest that TCR-T cells engineered with Tas TCRs are a promising agent for personalized immunotherapy, and intratumoral Tas cell levels determine the response to immunotherapy.

The main function of the lung is to perform gas exchange while maintaining lung homeostasis despite environmental pathogenic and non-pathogenic elements contained in inhaled air. Resident cells must keep lung homeostasis and eliminate pathogens by inducing protective immune response and silently remove innocuous particles. Which lung cell type is crucial for this function is still subject to debate, with reports favoring either alveolar macrophages (AMs) or lung epithelial cells (ECs) including airway and alveolar ECs. AMs are the main immune cells in the lung in steady-state and their function is mainly to dampen inflammatory responses. In addition, they phagocytose inhaled particles and apoptotic cells and can initiate and resolve inflammatory responses to pathogens. Although AMs release a plethora of mediators that modulate immune responses, ECs also play an essential role as they are more than just a physical barrier. They produce anti-microbial peptides and can secrete a variety of mediators that can modulate immune responses and AM functions. Furthermore, ECs can maintain AMs in a quiescent state by expressing anti-inflammatory membrane proteins such as CD200. Thus, AMs and ECs are both very important to maintain lung homeostasis and have to coordinate their action to protect the organism against infection. Thus, AMs and lung ECs communicate with each other using different mechanisms including mediators, membrane glycoproteins and their receptors, gap junction channels, and extracellular vesicles. This review will revisit characteristics and functions of AMs and lung ECs as well as different communication mechanisms these cells utilize to maintain lung immune balance and response to pathogens. A better understanding of the cross-talk between AMs and lung ECs may help develop new therapeutic strategies for lung pathogenesis.

Immunotherapy, with an increasing number of therapeutic dimensions, is becoming an important mode of treatment for cancer patients. The inhibition of immune checkpoints, which are the source of immune escape for various cancers, is one such immunotherapeutic dimension. It has mainly been aimed at T cells in the past, but NK cells are a newly emerging target. Simultaneously, the number of checkpoints identified has been increasing in recent times. In addition to the classical NK cell receptors KIRs, LIRs, and NKG2A, several other immune checkpoints have also been shown to cause dysfunction of NK cells in various cancers and chronic infections. These checkpoints include the revolutionized CTLA-4, PD-1, and recently identified B7-H3, as well as LAG-3, TIGIT & CD96, TIM-3, and the most recently acknowledged checkpoint-members of the Siglecs family (Siglec-7/9), CD200 and CD47. An interesting dimension of immune checkpoints is their candidacy for dual-checkpoint inhibition, resulting in therapeutic synergism. Furthermore, the combination of immune checkpoint inhibition with other NK cell cytotoxicity restoration strategies could also strengthen its efficacy as an antitumor therapy. Here, we have undertaken a comprehensive review of the literature to date regarding NK cell-based immune checkpoints.

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. Here the authors use positron emission tomography to visualize fibroblasts in patients with arthritis and combined with spatial transcriptomic data show that these cells undergo a phenotypic shift upon resolution of inflammation. A CD200 + DKK3 + fibroblast subset promotes this resolution by inhibiting tumor necrosis factor and interleukin-17A.

Ibrutinib has been shown to have immunomodulatory effects by inhibiting Bruton's tyrosine kinase (BTK) and IL-2-inducible T cell kinase (ITK). The relative importance of inhibiting these 2 kinases has not been examined despite its relevance to immune-based therapies. Peripheral blood mononuclear cells from chronic lymphocytic leukemia (CLL) patients on clinical trials of ibrutinib (BTK/ITK inhibitor; n = 19) or acalabrutinib (selective BTK inhibitor; n = 13) were collected serially. T cell phenotype, immune function, and CLL cell immunosuppressive capacity were evaluated. Ibrutinib markedly increased CD4+ and CD8+ T cell numbers in CLL patients. This effect was more prominent in effector/effector memory subsets and was not observed with acalabrutinib. Ex vivo studies demonstrated that this may be due to diminished activation-induced cell death through ITK inhibition. PD-1 and CTLA-4 expression was significantly markedly reduced in T cells by both agents. While the number of Treg cells remained unchanged, the ratio of these to conventional CD4+ T cells was reduced with ibrutinib, but not acalabrutinib. Both agents reduced expression of the immunosuppressive molecules CD200 and BTLA as well as IL-10 production by CLL cells. Ibrutinib treatment increased the in vivo persistence of activated T cells, decreased the Treg/CD4+ T cell ratio, and diminished the immune-suppressive properties of CLL cells through BTK-dependent and -independent mechanisms. These features provide a strong rationale for combination immunotherapy approaches with ibrutinib in CLL and other cancers. ClinicalTrials.gov NCT01589302 and NCT02029443. Samples described here were collected per OSU-0025. The National Cancer Institute.

To evaluate the validity of CHAC1 for predicting the prognosis of kidney renal clear cell carcinoma (KIRC) and to explore its therapeutic potential for KIRC, we conducted several bioinformatic analyses using the sequencing data and clinical information derived from online databases. We found CHAC1 is down‐regulated in KIRC samples when compared with normal samples but up‐regulated in KIRC samples with relatively higher malignancy and later stages. Univariate cox analysis and multivariate cox regression analysis were conducted and the results revealed up‐regulated CHAC1 is an independent risk factor for poor prognosis of KIRC. Further, the nomogram model based on the result of multivariate cox regression analysis was constructed and effectively predicted patients' 1‐year, 3‐year and 5‐year survival respectively. The correlation analyses showed CHAC1 is associated with the immune pathway markers of memory B cell, natural killer cell and type1 T helper cell as well as the checkpoint genes like ADORA2A, CD200, CD44, CD70, HHLA2, NRP1, PDCD1LG2 and TNFRSF18. Furthermore, experiments in vitro indicated CHAC1 could induce cell death in KIRC cell lines but had limited influence on cell migration and cell invasion. In conclusion, CHAC1 is found a valid indicator for poor prognosis of kidney renal clear cell carcinoma.

Purpose Despite the revealed role of immunological dysfunctions in the development and progression of Alzheimer’s disease (AD) through animal and postmortem investigations, direct evidence regarding the impact of genetic factors on microglia response and amyloid-β (Aβ) deposition in AD individuals is lacking. This study aims to elucidate this mechanism by integrating transcriptomics and TSPO, Aβ PET imaging in clinical AD cohort. Methods We analyzed 85 patients with PET/MR imaging for microglial activation (TSPO, [ 18 F]DPA-714) and Aβ ([ 18 F]AV-45) within the prospective Alzheimer’s Disease Immunization and Microbiota Initiative Study Cohort (ADIMIC). Immune-related differentially expressed genes (IREDGs), identified based on AlzData, were screened and verified using blood samples from ADIMIC. Correlation and mediation analyses were applied to investigate the relationships between immune-related genes expression, TSPO and Aβ PET imaging. Results TSPO uptake increased significantly both in aMCI ( P  < 0.05) and AD participants ( P  < 0.01) and showed a positive correlation with Aβ deposition (r = 0.42, P  < 0.001). Decreased expression of TGFBR3, FABP3, CXCR4 and CD200 was observed in AD group. CD200 expression was significantly negatively associated with TSPO PET uptake (r =—0.33, P  = 0.013). Mediation analysis indicated that CD200 acted as a significant mediator between TSPO uptake and Aβ deposition (total effect B = 1.92, P  = 0.004) and MMSE score (total effect B =—54.01, P  = 0.003). Conclusion By integrating transcriptomics and TSPO PET imaging in the same clinical AD cohort, this study revealed CD200 played an important role in regulating neuroinflammation, Aβ deposition and cognitive dysfunction.

Mesenchymal stem cells (MSCs), which are pluripotent cells with immunomodulatory properties, have been considered good candidates for the therapy of several immune disorders, such as inflammatory bowel diseases, concanavalin A-induced liver injury, and graft-versus-host disease. The embryo is a natural allograft to the maternal immune system. A successful pregnancy depends on the timely extinction of the inflammatory response induced by embryo implantation, followed by the switch to a tolerant immune microenvironment in both the uterus and the system. Excessive infiltration of immune cells and serious inflammatory responses are triggers for embryo rejection, which results in miscarriage. Here, we demonstrated that adoptive transfer of MSCs could prevent fetal loss in a lipopolysaccharide (LPS)-induced abortion model and immune response-mediated spontaneous abortion model. The immunosuppressive MSCs alleviated excessive inflammation by inhibiting CD4 + T cell proliferation and promoting the decidual macrophage switch to M2 in a tumor necrosis factor-stimulated gene-6 (TSG-6)-dependent manner. Cell-to-cell contact with proinflammatory macrophages increased the TSG-6 production by the MSCs, thereby enhancing the suppressive regulation of T cells and macrophages. Moreover, proinflammatory macrophages in contact with the MSCs upregulated the expression of CD200 on the stem cells and facilitated the reprogramming of macrophages towards an anti-inflammatory skew through the interaction of CD200 with CD200R on proinflammatory macrophages. Therefore, the results demonstrate that a TSG-6-mediated paracrine effect, reinforced by cell-to-cell contact between MSCs and proinflammatory macrophages, is involved in the mechanism of MSC-mediated abortion relief through the induction of immune tolerance. Our study also indicates the potential application of MSCs in clinical recurrent miscarriages.