TIMP1 Mediates Astrocyte-Dependent Local Immunosuppression in Brain Metastasis Acting on Infiltrating CD8+ T Cells

Hormonal and neuronal interactions shaping the brain metastatic microenvironment

Metastatic progression drives the majority of cancer-related fatalities, and involvement of the central nervous system (CNS) poses especially formidable challenges to patients and clinicians. Brain metastases (BrM), commonly originate from lung, breast and melanoma cancers, and carry disproportionately poor outcomes. Although therapeutic advances have extended survival for many extracranial tumors, BrM incidence continues to climb-underscoring critical knowledge gaps in understanding the unique biology of tumor colonization in the CNS. While definitive evidence remains limited, a growing focus on cancer neuroscience-especially regarding hormone dependent cancer cells in the brain-has begun to reveal that factors normally regulated by sex steroids and neurosteroids may similarly influence the specialized metastatic microenvironment in the CNS. Steroid hormones can permeate the blood-brain barrier (BBB) or be synthesized de novo by astrocytes and other CNS-resident cells, potentially influencing processes such as inflammation, synaptic plasticity, and immune surveillance. However, how these hormonal pathways are co-opted by disseminated cancer cells remains unclear. Here, we review the complex hormonal landscape of the adult brain and examine how neuroendocrine-immune interactions, often regulated by sex hormones, may support metastatic growth. We discuss the interplay between systemic hormones, local steroidogenesis, and tumor adaptation to identify novel therapeutic opportunities.

Deciphering the Dialogue between Brain Tumors, Neurons, and Astrocytes

Glioblastoma (GB) and brain metastases (BM) from peripheral tumors account for most cases of tumors in the central nervous system (CNS) while also being the deadliest. From a structural point of view, malignant brain tumors are classically characterized by hypercellularity of glioma and vascular endothelial cells. Given these atypical histologic features, GB and BM have long been considered as "foreign" entities with few to no connections to the brain parenchyma. The identification of intricate connections established between GB cells and the brain parenchyma paired with the ability of peripheral metastatic cells to form functional synapses with neurons challenged the concept of brain tumors disconnected from the CNS. Tumor cell integration to the CNS alters brain functionality in patients and accelerates cancer progression. Next-generation precision medicine should therefore attempt to disconnect brain cancer cells from the brain. This review encompasses recent discoveries on the mechanisms underlying these relationships and discusses the impact of these connections on tumor progression. It also summarizes the therapeutic opportunities of interrupting the dialogue between healthy and neoplastic brains.

Shared genetic association between inflammatory bowel disease and acute myeloid leukemia: insights from mendelian randomization and transcriptomic analyses

BACKGROUND

Observational studies suggest that a history of inflammatory bowel disease (IBD) is associated with the onset of acute myeloid leukemia (AML), often attributed to drug use. However, these findings are inconsistent. This study aimed to assess the causal relationship between IBD and AML, identify shared pathogenesis, and discover diagnostic and prognostic markers and potential therapeutic drugs.

METHODS

Two-sample Mendelian randomization (MR) was employed to analyze genetic associations between IBD [ulcerative colitis (UC) and Crohn's disease (CD)] and AML. Transcriptomic data from gene expression omnibus (GEO) identified differentially expressed genes (DEGs) in UC, AML, and controls. Weighted Gene Co-expression Network Analysis (WGCNA) and enrichment analyses [Gene Multiple Association Network Integration Algorithm (GeneMANIA), Kyoto Encyclopedia of Genes and Genomes (KEGG), Ractom pathway] and Gene Ontology (GO) explored shared genetic pathways. Receiver Operating Characteristic (ROC) curve and survival analyses screened diagnostic and prognostic markers. Cibersort and GSVA were employed to analyze the proportion of immune cells in UC and AML datasets, as well as to assess the association of specific genes with immune infiltration. The Drug Signatures Database (DSigDB) and Autodock molecular docking identified potential therapeutic small molecules.

RESULTS

MR analysis revealed a causal association between UC and the onset of AML. Differential expression and WGCNA analyses identified 23 co-driver genes regulated by Signal Transducer and Activator of Transcription 3 (STAT3) and Activating Transcription Factor 4 (AFT4), enriched in immune, inflammatory, and cell proliferation pathways. Tissue Inhibitor of Metalloproteinases 1 (TIMP1) and F2R-Like Trypsin Receptor 1 (F2RL1) were identified as practical diagnostic and prognostic markers for AML, with high TIMP1 and low F2RL1 expression promoting an immunosuppressive and inflammatory tumor microenvironment. Quercetin was identified as a promising candidate for UC-associated AML.

CONCLUSIONS

UC is a risk factor for AML pathogenesis. TIMP1 and F2RL1 are diagnostic and prognostic markers for UC-associated AML, potentially facilitating AML development through sustained inflammation and an immunosuppressive tumor microenvironment. Quercetin, a potential TIMP1 and F2RL1 inhibitor, may mitigate UC-AML transformation, providing insights into UC management, AML monitoring, and preventive therapy development.

Single-cell and spatial transcriptomic analysis reveals tumor cell heterogeneity and underlying molecular program in colorectal cancer

Background

Colorectal cancer (CRC) is a highly heterogeneous tumor, with significant variation in malignant cells, posing challenges for treatment and prognosis. However, this heterogeneity offers opportunities for personalized therapy.

Methods

The consensus non-negative matrix factorization algorithm was employed to analyze single-cell transcriptomic data from CRC, which helped identify malignant cell expression programs (MCEPs). Subsequently, a crosstalk network linking MCEPs with immune/stromal cell trajectory development was constructed using Monocle3 and NicheNet. Additionally, bulk RNA-seq data were utilized to systematically explore the relationships between MCEPs, clinical features, and genetic mutations. A prognostic model was then established through Lasso and Cox regression analyses, integrating clinical data into a nomogram for personalized risk prediction. Furthermore, key genes associated with MCEPs and their potential therapeutic targets were identified using protein-protein interaction networks, followed by molecular docking to predict drug-binding affinity.

Results

We classified CRC malignant cell transcriptional states into eight distinct MCEPs and successfully constructed crosstalk networks between these MCEPs and immune or stromal cells. A prognostic model containing 15 genes was developed, demonstrating an AUC greater than 0.8 for prognostic evaluation over 1 to 10 years when combined with clinical features. A key drug target gene TIMP1 was identified, and several potential targeted drugs were discovered.

Conclusion

This study demonstrated that characterization of the malignant cell transcriptional programs could effectively reveal the biological features of highly heterogeneous tumors like CRC and exhibit significant potential in tumor prognosis assessment. Our research provides new theoretical and practical directions for CRC prognosis and targeted therapy.

PDGFRα-positive cell-derived TIMP-1 modulates adaptive immune responses to influenza A viral infection

Tissue inhibitor of metalloproteinases-1 (TIMP-1) is a physiologic inhibitor of the matrix metalloproteinases (MMPs), but little is known about the role of TIMP-1 in regulating the pathogenesis of influenza A virus (IAV) infection. Here, we performed both in vivo and in vitro experiments to investigate the regulation and function of TIMP-1 during IAV infection. Specifically, plasma levels of TIMP-1 are significantly increased in human subjects and wild-type (WT) mice infected with 2009 H1N1 IAV compared with levels in uninfected controls. Also, TIMP-1 is strikingly upregulated in PDGFRα positive (PDGFRα+) cells in IAV-infected murine lungs as demonstrated using conditional KO (cKO) mice with a specific deletion of Timp-1 in PDGFRα+ cells. Our in vitro data indicated that TIMP-1 is induced by transforming growth factor-β (TGF-β) during lipofibroblasts (lipoFBs)-to-myofibroblast (myoFB) transdifferentiation. Timp-1 deficiency protects mice from H1N1 IAV-induced weight loss, mortality, and lung injury. IAV-infected Timp-1-deficient mice showed increased macrophages, and B and T cell counts in bronchoalveolar lavage (BAL) on day 7 postinfection (p.i.), but reduced BAL neutrophil counts. Increased Cxcl12 levels were detected in both BAL cells and lungs from Timp-1-deficient mice on day 3 p.i. Taken together, our data strongly link TIMP-1 to IAV pathogenesis. We identified that PDGFRα-lineage cells are the main cellular source of elevated TIMP-1 during IAV infection. Loss of Timp-1 attenuates IAV-induced mortality and promotes T and B cell recruitment. Thus, TIMP-1 may be a novel therapeutic target for IAV infection.NEW & NOTEWORTHY Our data strongly link tissue inhibitor of metalloproteinases-1 (TIMP-1) to influenza A virus (IAV) pathogenesis. TIMP-1 is highly increased in PDGFRα-lineage cells during IAV infection. Transforming growth factor-β (TGF-β) induces TIMP-1 during lipofibroblast (lipoFB)-to- myofibroblast (myoFB) transdifferentiation. Timp-1 deficiency protects mice from H1N1 IAV-induced weight loss, mortality, and lung injury. TIMP-1 may be a novel therapeutic target for IAV infection.

Immune checkpoint inhibitors as first-line treatment for brain metastases in stage IV NSCLC patients without driver mutations

Immune checkpoint inhibitors (ICI) therapy with or without chemotherapy has been established as the first-line treatment for patients with non-oncogene addicted advanced Non-Small Cell Lung Cancer (NSCLC). Yet some clinical settings, such as the treatment sequence in patients with brain metastases, have barely been evidenced. Although ICIs cannot directly cross the blood-brain barrier (BBB), evidence suggests that BBB damage could allow ICIs into the central nervous system, or that they can have an indirect effect on the tumor immune microenvironment (TIME) and cause an anti-tumor response. Pivotal phase III trials have included a highly selected population but offer few data on these patients. Here we first review how ICIs can indirectly shape the brain metastases microenvironment through different mechanisms, and some possible causes of ICIs resistance. We also analyze the evidence reported in pivotal phase III trials and phase II trials focused on NSCLC brain metastases for first-line treatment, and the evidence for upfront or delayed local brain therapy. Finally, we discuss the best evidence-based approach to treat NSCLC patients with brain metastases and propose future research.