Therapeutics that target the T cell inhibitory checkpoint proteins CTLA-4 and PD(L)1 are efficacious across a broad range of cancers, resulting in reductions in tumor burden and increased long-term ...survival in subsets of patients. The significant and wide-ranging effects of these immunotherapies have prompted the clinical investigation of additional therapies that modulate anti-tumor immunity through effects on T cells, myeloid cells, and other cell types within the tumor microenvironment. The clinical activity of these newer investigational therapies has been mixed, with some therapeutics showing promise but others not exhibiting appreciable efficacy. In this review, we summarize the results of select recent clinical studies of cancer immunotherapies beyond anti-CTLA-4 and anti-PD(L)1 and discuss how these results are providing new insights into the regulation of human anti-tumor immunity.
Wu, Ouyang, and Egen review recent clinical studies of cancer immunotherapies beyond anti-CTLA-4 and anti-PD(L)1 and discuss therapeutic avenues that are showing promise and ones that do not seem to be working. In this context, they outline emerging insights into anti-tumor immunity with relevance both to the clinic and to our basic understanding of the interactions between tumors and the immune system.
After an infection, the immune system generates long-lived memory lymphocytes whose increased frequency and altered state of differentiation enhance host defense against reinfection. Recently, the ...spatial distribution of memory cells was found to contribute to their protective function. Effector memory CD8+ T cells reside in peripheral tissue sites of initial pathogen encounter, in apparent anticipation of reinfection. Here we show that within lymph nodes (LNs), memory CD8+ T cells were concentrated near peripheral entry portals of lymph-borne pathogens, promoting rapid engagement of infected sentinel macrophages. A feed-forward CXCL9-dependent circuit provided additional chemotactic cues that further increase local memory cell density. Memory CD8+ T cells also produced effector responses to local cytokine triggers, but their dynamic behavior differed from that seen after antigen recognition. These data reveal the distinct localization and dynamic behavior of naive versus memory T cells within LNs and how these differences contribute to host defense.
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► CM CD8+ T cells reside in the cortical ridge and near the LN capsule ► Naive and CM CD8+ T cells largely engage distinct APCs upon LN infection ► CXCL9-dependent feed-forward circuit recruits local CM CD8+ T cells ► TCR versus cytokine stimulation leads to distinct CM CD8+ T cell dynamics
Cell-mediated adaptive immunity is critical for host defense, but little is known about T cell behavior during delivery of effector function. Here we investigate relationships among antigen ...presentation, T cell motility, and local production of effector cytokines by CD4
+ T cells within hepatic granulomas triggered by Bacille Calmette-Guérin or
Mycobacterium tuberculosis. At steady-state, only small fractions of mycobacteria-specific T cells showed antigen-induced migration arrest within granulomas, resulting in low-level, polarized secretion of cytokines. However, exogenous antigen elicited rapid arrest and robust cytokine production by the vast majority of effector T cells. These findings suggest that limited antigen presentation and/or recognition within granulomas evoke a muted T cell response drawing on only a fraction of the host's potential effector capacity. Our results provide new insights into the regulation of host-protective functions, especially how antigen availability influences T cell dynamics and, in turn, effector T cell function during chronic infection.
► Effector T cells within mycobacterial granulomas show limited antigen activation ► Effector T cells within granulomas have submaximal responses ► Low frequency of arrested effector T cells display polarized cytokine secretion ► Effector T cell motility and cytokine production have an inverse relationship
Activated T cells must mediate effector responses sufficiently to clear pathogens while avoiding excessive tissue damage. Here we have combined dynamic intravital microscopy with ex vivo assessments ...of T cell cytokine responses to generate a detailed spatiotemporal picture of CD4+ T cell effector regulation in the skin. In response to antigen, effector T cells arrested transiently on antigen-presenting cells, briefly producing cytokine and then resuming migration. Antigen recognition led to upregulation of the programmed death-1 (PD-1) glycoprotein by T cells and blocking its canonical ligand, programmed death-ligand 1 (PD-L1), lengthened the duration of migration arrest and cytokine production, showing that PD-1 interaction with PD-L1 is a major negative feedback regulator of antigen responsiveness. We speculate that the immune system employs T cell recruitment, transient activation, and rapid desensitization to allow the T cell response to rapidly adjust to changes in antigen presentation and minimize collateral injury to the host.
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•Effector CD4+ T cell function and motility inversely correlate in inflamed tissue•Antigen sensitivity tuning limits the duration of effector T cell activity in vivo•PD-1 upregulation contributes to sensitivity loss and cessation of effector function•Feedback regulation of effector activity helps balance host defense and tissue damage
Single-cell RNA sequencing (scRNA-seq) is a powerful tool for defining cellular diversity in tumors, but its application toward dissecting mechanisms underlying immune-modulating therapies is scarce. ...We performed scRNA-seq analyses on immune and stromal populations from colorectal cancer patients, identifying specific macrophage and conventional dendritic cell (cDC) subsets as key mediators of cellular cross-talk in the tumor microenvironment. Defining comparable myeloid populations in mouse tumors enabled characterization of their response to myeloid-targeted immunotherapy. Treatment with anti-CSF1R preferentially depleted macrophages with an inflammatory signature but spared macrophage populations that in mouse and human expresses pro-angiogenic/tumorigenic genes. Treatment with a CD40 agonist antibody preferentially activated a cDC population and increased Bhlhe40+ Th1-like cells and CD8+ memory T cells. Our comprehensive analysis of key myeloid subsets in human and mouse identifies critical cellular interactions regulating tumor immunity and defines mechanisms underlying myeloid-targeted immunotherapies currently undergoing clinical testing.
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•scRNA-seq analyses highlight conserved myeloid subsets in human and murine CRC•Two distinct TAM subsets show inflammatory and angiogenic signatures, respectively•Two distinct TAM subsets show differential sensitivity to CSF1R blockade•Anti-CD40 activates specific cDC1s and expands Th1-like and CD8+ memory T cells
Combined scRNA-seq analyses on the tumor microenvironment in colorectal cancer and murine tumor models identify distinct myeloid populations that convey differential sensitivity to CSF1R blockade and define concerted immune responses involving dendric cells and T cells upon anti-CD40 treatment.
After entry into lymph nodes (LNs), B cells migrate to follicles, whereas T cells remain in the paracortex, with each lymphocyte type showing apparently random migration within these distinct areas. ...Other than chemokines, the factors contributing to this spatial segregation and to the observed patterns of lymphocyte movement are poorly characterized. By combining confocal, electron, and intravital microscopy, we showed that the fibroblastic reticular cell network regulated naive T cell access to the paracortex and also supported and defined the limits of T cell movement within this domain, whereas a distinct follicular dendritic cell network similarly served as the substratum for movement of follicular B cells. These results highlight the central role of stromal microanatomy in orchestrating cell migration within the LN.
Tumor-associated macrophages (TAMs) are abundant in solid tumors where they exhibit immunosuppressive and pro-tumorigenic functions. Inhibition of TAM proliferation and survival through CSF1R ...blockade has been widely explored as a cancer immunotherapy. To further define mechanisms regulating CSF1R-targeted therapies, we systematically evaluated the effect of anti-CSF1R treatment on tumor growth and tumor microenvironment (TME) inflammation across multiple murine models. Despite substantial macrophage depletion, anti-CSF1R had minimal effects on the anti-tumor immune response in mice bearing established tumors. In contrast, anti-CSF1R treatment concurrent with tumor implantation resulted in more robust tumor growth inhibition and evidence of enhanced anti-tumor immunity. Our findings suggest only minor contributions of CSF1R-dependent TAMs to the inflammatory state of the TME in established tumors, that immune landscape heterogeneity across different tumor models can influence anti-CSF1R activity, and that alternative treatment schedules and/or TAM depletion strategies may be needed to maximize the clinical benefit of this approach.
Infection with the obligate intracellular protozoan Leishmania is thought to be initiated by direct parasitization of macrophages, but the early events following transmission to the skin by vector ...sand flies have been difficult to examine directly. Using dynamic intravital microscopy and flow cytometry, we observed a rapid and sustained neutrophilic infiltrate at localized sand fly bite sites. Invading neutrophils efficiently captured Leishmania major (L.m.) parasites early after sand fly transmission or needle inoculation, but phagocytosed L.m. remained viable and infected neutrophils efficiently initiated infection. Furthermore, neutrophil depletion reduced, rather than enhanced, the ability of parasites to establish productive infections. Thus, L.m. appears to have evolved to both evade and exploit the innate host response to sand fly bite in order to establish and promote disease.
Osteoclasts are the only somatic cells with bone-resorbing capacity and, as such, they have a critical role not only in normal bone homeostasis (called 'bone remodelling') but also in the ...pathogenesis of bone destructive disorders such as rheumatoid arthritis and osteoporosis. A major focus of research in the field has been on gene regulation by osteoclastogenic cytokines such as receptor activator of NF- B-ligand (RANKL, also known as TNFSF11) and TNF- , both of which have been well documented to contribute to osteoclast terminal differentiation. A crucial process that has been less well studied is the trafficking of osteoclast precursors to and from the bone surface, where they undergo cell fusion to form the fully differentiated multinucleated cells that mediate bone resorption. Here we report that sphingosine-1-phosphate (S1P), a lipid mediator enriched in blood, induces chemotaxis and regulates the migration of osteoclast precursors not only in culture but also in vivo, contributing to the dynamic control of bone mineral homeostasis. Cells with the properties of osteoclast precursors express functional S1P1 receptors and exhibit positive chemotaxis along an S1P gradient in vitro. Intravital two-photon imaging of bone tissues showed that a potent S1P1 agonist, SEW2871, stimulated motility of osteoclast precursor-containing monocytoid populations in vivo. Osteoclast/monocyte (CD11b, also known as ITGAM) lineage-specific conditional S1P1 knockout mice showed osteoporotic changes due to increased osteoclast attachment to the bone surface. Furthermore, treatment with the S1P1 agonist FTY720 relieved ovariectomy-induced osteoporosis in mice by reducing the number of mature osteoclasts attached to the bone surface. Together, these data provide evidence that S1P controls the migratory behaviour of osteoclast precursors, dynamically regulating bone mineral homeostasis, and identifies a critical control point in osteoclastogenesis that may have potential as a therapeutic target.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The examination of tissue histology by light microscopy is a fundamental tool for investigating the structure and function of organs under normal and disease states. Many current techniques for ...tissue sectioning, imaging and analysis are time-consuming, and they present major limitations for 3D tissue reconstruction. The introduction of methods to achieve the optical clearing and subsequent light-sheet laser scanning of entire transparent organs without sectioning represents a major advance in the field. We recently developed a highly reproducible and versatile clearing procedure called 3D imaging of solvent-cleared organs, or 3DISCO, which is applicable to diverse tissues including brain, spinal cord, immune organs and tumors. Here we describe a detailed protocol for performing 3DISCO and present its application to various microscopy techniques, including example results from various mouse tissues. The tissue clearing takes as little as 3 h, and imaging can be completed in ∼45 min. 3DISCO is a powerful technique that offers 3D histological views of tissues in a fraction of the time and labor required to complete standard histology studies.
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