An IL-4 signalling axis in bone marrow drives pro-tumorigenic myelopoiesis.

Myeloid cells are known to suppress antitumour immunity1. However, the molecular drivers of immunosuppressive myeloid cell states are not well defined. Here we used single-cell RNA sequencing of human and mouse non-small cell lung cancer (NSCLC) lesions, and found that in both species the type 2 cytokine interleukin-4 (IL-4) was predicted to be the primary driver of the tumour-infiltrating monocyte-derived macrophage phenotype. Using a panel of conditional knockout mice, we found that only deletion of the IL-4 receptor IL-4Rα in early myeloid progenitors in bone marrow reduced tumour burden, whereas deletion of IL-4Rα in downstream mature myeloid cells had no effect. Mechanistically, IL-4 derived from bone marrow basophils and eosinophils acted on granulocyte-monocyte progenitors to transcriptionally programme the development of immunosuppressive tumour-promoting myeloid cells. Consequentially, depletion of basophils profoundly reduced tumour burden and normalized myelopoiesis. We subsequently initiated a clinical trial of the IL-4Rα blocking antibody dupilumab2-5 given in conjunction with PD-1/PD-L1 checkpoint blockade in patients with relapsed or refractory NSCLC who had progressed on PD-1/PD-L1 blockade alone (ClinicalTrials.gov identifier NCT05013450 ). Dupilumab supplementation reduced circulating monocytes, expanded tumour-infiltrating CD8 T cells, and in one out of six patients, drove a near-complete clinical response two months after treatment. Our study defines a central role for IL-4 in controlling immunosuppressive myelopoiesis in cancer, identifies a novel combination therapy for immune checkpoint blockade in humans, and highlights cancer as a systemic malady that requires therapeutic strategies beyond the primary disease site.

Stellate cell-specific adhesion molecule protocadherin 7 regulates sinusoidal contraction.

BACKGROUND AND AIMS: Sustained inflammation and hepatocyte injury in chronic liver disease activate HSCs to transdifferentiate into fibrogenic, contractile myofibroblasts. We investigated the role of protocadherin 7 (PCDH7), a cadherin family member not previously characterized in the liver, whose expression is restricted to HSCs. APPROACH AND RESULTS: We created a PCDH7 fl/fl mouse line, which was crossed to lecithin retinol acyltransferase-Cre mice to generate HSC-specific PCDH7 knockout animals. HSC contraction in vivo was tested in response to the HSC-selective vasoconstrictor endothelin-1 using intravital multiphoton microscopy. To establish a PCDH7 null HSC line, cells were isolated from PCDH7 fl/fl mice and infected with adenovirus-expressing Cre. Hepatic expression of PCDH7 was strictly restricted to HSCs. Knockout of PCDH7 in vivo abrogated HSC-mediated sinusoidal contraction in response to endothelin-1. In cultured HSCs, loss of PCDH7 markedly attenuated contractility within collagen gels and led to altered gene expression in pathways governing adhesion and vasoregulation. Loss of contractility in PCDH7 knockout cells was impaired Rho-GTPase signaling, as demonstrated by altered gene expression, reduced assembly of F-actin fibers, and loss of focal adhesions. CONCLUSIONS: The stellate cell-specific cadherin, PCDH7, is a novel regulator of HSC contractility whose loss leads to cytoskeletal remodeling and sinusoidal relaxation.

Drug-Induced Liver Injury in Pregnancy: The U.S. Drug-Induced Liver Injury Network Experience.

There are limited data on the causative agents and characteristics of drug-induced liver injury in pregnant individuals. Data from patients with drug-induced liver injury enrolled in the ongoing multicenter Drug-Induced Liver Injury Network between 2004 and 2022 and occurring during pregnancy or 6 months postpartum were reviewed and compared with cases of drug-induced liver injury in nonpregnant women of childbearing age. Among 325 individuals of childbearing age in the Drug-Induced Liver Injury Network, 16 cases of drug-induced liver injury (5%) occurred during pregnancy or postpartum. Compared with drug-induced liver injury in nonpregnant women, pregnancy-related drug-induced liver injury was more severe ( P <.05). One elective termination and three miscarriages were documented; there were no maternal deaths. We recommend that isoniazid for latent tuberculosis be deferred to the postpartum period whenever feasible and that ß-blockers or calcium channel blockers rather than methyldopa be used for hypertension management during pregnancy.

Differential Immune Modulation With Carbon-Ion Versus Photon Therapy.

PURPOSE: Radiation therapy (RT) modulates the immune characteristics of the tumor microenvironment (TME). It is not known whether these effects are dependent on the type of RT used. METHODS AND MATERIALS: We evaluated the immunomodulatory effects of carbon-ion therapy (CiRT) compared with biologically equivalent doses of photon therapy (PhRT) on solid tumors. Orthotopic 4T1 mammary tumors in immunocompetent hosts were treated with CiRT or biologically equivalent doses of PhRT. Seventy-two hours after RT, tumors were harvested and the immune characteristics of the TME were quantified by flow cytometry and multiplex cytokine analyses. RESULTS: PhRT decreased the abundance of CD4+ and CD8+ T cells in the TME at all doses tested, with compensatory increases in proliferation. By contrast, CiRT did not significantly alter CD8+ T-cell infiltration. High-dose CiRT increased secretion of proinflammatory cytokines by tumor-infiltrating CD8+ T cells, including granzyme B, IL-2, and TNF-α, with no change in IFN-γ. Conversely, high-dose PhRT increased CD8+ T-cell secretion of IFN-γ only. At most of the doses studied, PhRT increased proliferation of immunosuppressive regulatory T cells; this was only seen with high-dose CiRT. Cytokine analyses of bulk dissociated tumors showed that CiRT significantly increased levels of IFN-γ, IL-2, and IL-1ß, whereas PhRT increased IL-6 levels alone. CONCLUSIONS: At low doses, lymphocytes differ in their sensitivity to CiRT compared with PhRT. Unlike PhRT, low-dose CiRT is generally lymphocyte-sparing. At higher doses, CiRT is a more potent inducer of proinflammatory cytokines and merits further study as a modulator of the immunologic characteristics of the TME.

DNMT3A haploinsufficiency causes dichotomous DNA methylation defects at enhancers in mature human immune cells.

DNMT3A encodes an enzyme that carries out de novo DNA methylation, which is essential for the acquisition of cellular identity and specialized functions during cellular differentiation. DNMT3A is the most frequently mutated gene in age-related clonal hematopoiesis. As such, mature immune cells harboring DNMT3A mutations can be readily detected in elderly persons. Most DNMT3A mutations associated with clonal hematopoiesis are heterozygous and predicted to cause loss of function, indicating that haploinsufficiency is the predominant pathogenic mechanism. Yet, the impact of DNMT3A haploinsufficiency on the function of mature immune cells is poorly understood. Here, we demonstrate that DNMT3A haploinsufficiency impairs the gain of DNA methylation at decommissioned enhancers, while simultaneously and unexpectedly impairing DNA demethylation of newly activated enhancers in mature human myeloid cells. The DNA methylation defects alter the activity of affected enhancers, leading to abnormal gene expression and impaired immune response. These findings provide insights into the mechanism of immune dysfunction associated with clonal hematopoiesis and acquired DNMT3A mutations.

Castration-mediated IL-8 promotes myeloid infiltration and prostate cancer progression.

Unlike several other tumor types, prostate cancer rarely responds to immune checkpoint blockade (ICB). To define tumor cell intrinsic factors that contribute to prostate cancer progression and resistance to ICB, we analyzed prostate cancer epithelial cells from castration-sensitive and -resistant samples using implanted tumors, cell lines, transgenic models and human tissue. We found that castration resulted in increased expression of interleukin-8 (IL-8) and its probable murine homolog Cxcl15 in prostate epithelial cells. We showed that these chemokines drove subsequent intratumoral infiltration of tumor-promoting polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs), which was largely abrogated when IL-8 signaling was blocked genetically or pharmacologically. Targeting IL-8 signaling in combination with ICB delayed the onset of castration resistance and increased the density of polyfunctional CD8 T cells in tumors. Our findings establish a novel mechanism by which castration mediates IL-8 secretion and subsequent PMN-MDSC infiltration, and highlight blockade of the IL-8/CXCR2 axis as a potential therapeutic intervention.

Immunotherapy for Prostate Cancer.

Immunotherapy with agents that block immune checkpoints is a mainstay of therapy for several common tumor types; so far, prostate cancer is not among those treated using this method. The observed lack of activity in prostate cancer is not due to a lack of testing; several agents have been evaluated both alone and in combination. Although several combination strategies show some promise, it appears likely that a greater understanding of the prostate cancer tumor microenvironment and baseline immune response will be required to optimize future treatment strategies.