Infection perturbs Bach2- and Bach1-dependent erythroid lineage 'choice' to cause anemia.

Elucidation of how the differentiation of hematopoietic stem and progenitor cells (HSPCs) is reconfigured in response to the environment is critical for understanding the biology and disorder of hematopoiesis. Here we found that the transcription factors (TFs) Bach2 and Bach1 promoted erythropoiesis by regulating heme metabolism in committed erythroid cells to sustain erythroblast maturation and by reinforcing erythroid commitment at the erythro-myeloid bifurcation step. Bach TFs repressed expression of the gene encoding the transcription factor C/EBPß, as well as that of its target genes encoding molecules important for myelopoiesis and inflammation; they achieved the latter by binding to their regulatory regions also bound by C/EBPß. Lipopolysaccharide diminished the expression of Bach TFs in progenitor cells and promoted myeloid differentiation. Overexpression of Bach2 in HSPCs promoted erythroid development and inhibited myelopoiesis. Knockdown of BACH1 or BACH2 in human CD34+ HSPCs impaired erythroid differentiation in vitro. Thus, Bach TFs accelerate erythroid commitment by suppressing the myeloid program at steady state. Anemia of inflammation and myelodysplastic syndrome might involve reduced activity of Bach TFs.

Lactate dehydrogenase inhibition synergizes with IL-21 to promote CD8+ T cell stemness and antitumor immunity.

Interleukin (IL)-2 and IL-21 dichotomously shape CD8+ T cell differentiation. IL-2 drives terminal differentiation, generating cells that are poorly effective against tumors, whereas IL-21 promotes stem cell memory T cells (TSCM) and antitumor responses. Here we investigated the role of metabolic programming in the developmental differences induced by these cytokines. IL-2 promoted effector-like metabolism and aerobic glycolysis, robustly inducing lactate dehydrogenase (LDH) and lactate production, whereas IL-21 maintained a metabolically quiescent state dependent on oxidative phosphorylation. LDH inhibition rewired IL-2-induced effects, promoting pyruvate entry into the tricarboxylic acid cycle and inhibiting terminal effector and exhaustion programs, including mRNA expression of members of the NR4A family of nuclear receptors, as well as Prdm1 and Xbp1 While deletion of Ldha prevented development of cells with antitumor effector function, transient LDH inhibition enhanced the generation of memory cells capable of triggering robust antitumor responses after adoptive transfer. LDH inhibition did not significantly affect IL-21-induced metabolism but caused major transcriptomic changes, including the suppression of IL-21-induced exhaustion markers LAG3, PD1, 2B4, and TIM3. LDH inhibition combined with IL-21 increased the formation of TSCM cells, resulting in more profound antitumor responses and prolonged host survival. These findings indicate a pivotal role for LDH in modulating cytokine-mediated T cell differentiation and underscore the therapeutic potential of transiently inhibiting LDH during adoptive T cell-based immunotherapy, with an unanticipated cooperative antitumor effect of LDH inhibition and IL-21.

Inflammatory responses induce an identity crisis of alveolar macrophages, leading to pulmonary alveolar proteinosis.

Pulmonary alveolar proteinosis (PAP) is a severe respiratory disease characterized by dyspnea caused by accumulation of surfactant protein. Dysfunction of alveolar macrophages (AMs), which regulate the homeostasis of surfactant protein, leads to the development of PAP; for example, in mice lacking BTB and CNC homology 2 (Bach2). However, how Bach2 helps prevent PAP is unknown, and the cell-specific effects of Bach2 are undefined. Using mice lacking Bach2 in specific cell types, we found that the PAP phenotype of Bach2-deficient mice is due to Bach2 deficiency in more than two types of immune cells. Depletion of hyperactivated T cells in Bach2-deficient mice restored normal function of AMs and ameliorated PAP. We also found that, in Bach2-deficient mice, hyperactivated T cells induced gene expression patterns that are specific to other tissue-resident macrophages and dendritic cells. Moreover, Bach2-deficient AMs exhibited a reduction in cell cycle progression. IFN-γ released from T cells induced Bach2 expression in AMs, in which Bach2 then bound to regulatory regions of inflammation-associated genes in myeloid cells. Of note, in AMs, Bach2 restricted aberrant responses to excessive T cell-induced inflammation, whereas, in T cells, Bach2 puts a brake on T cell activation. Moreover, Bach2 stimulated the expression of multiple histone genes in AMs, suggesting a role of Bach2 in proper histone expression. We conclude that Bach2 is critical for the maintenance of AM identity and self-renewal in inflammatory environments. Treatments targeting T cells may offer new therapeutic strategies for managing secondary PAP.

Bach2 Controls Homeostasis of Eosinophils by Restricting the Type-2 Helper Function of T Cells.

Bach2 is a transcription factor which represses its target genes and plays important roles in the differentiation of B and T lymphoid cells. Bach2-deficient (KO) mice develop severe pulmonary alveolar proteinosis, which is associated with increased numbers of granulocytes and T cells. Bach2 is essential for the regulation of T cells, but its role in the regulation of granulocytes is not clear. Here, we observed increased numbers of eosinophils but not neutrophils in the bone marrow, spleen, peripheral blood, and bronchoalveolar lavage fluids of Bach2 KO mice compared with those of wild-type (WT) mice. Upon co-transplantation of the bone marrow cells from CD45.2 Bach2 KO and CD45.1/CD45.2 double-positive WT mice to irradiated WT CD45.1/CD45.2 mice, the reconstituted numbers of eosinophils were similar between Bach2 KO and WT cells. These results showed that the deficiency of Bach2 in eosinophils did not directly drive the differentiation of eosinophils. To investigate the effect of Bach2 KO CD4+ T cells upon eosinophils, we analyzed Rag2/Bach2-double deficient (dKO) mice which lack lymphocytes including CD4+ T cells. Rag2/Bach2 dKO mice did not show any increase in the numbers of eosinophils. Importantly, Bach2 KO mice showed an increase of interleukin-5 (Il-5) in the sera compared with WT mice. These results suggest that up-regulated functions of CD4+ T cells including secretion of Il-5 resulted in proliferation and/or migration to peripheral tissues of eosinophils in Bach2 KO mice. We propose that Bach2 controls homeostasis of eosinophils via restricting the production of Il-5 in CD4+ T cells.

Peripheral blood biomarkers associated with combination of immune checkpoint blockade plus chemotherapy in NSCLC.

BACKGROUND: Biomarkers predicting clinical outcomes of treating non-small cell lung cancer (NSCLC) with combination of immune checkpoint inhibitors (ICIs) and chemotherapy would be valuable. OBJECTIVE: This study aims to seek predictors of combination of ICI/chemotherapy response in NSCLC patients using peripheral blood samples. METHODS: Patients diagnosed with advanced NSCLC between July 2019 and May 2021 receiving combination of ICI/chemotherapy were included and assessed for partial responses (PR), stable disease (SD) or progressive disease (PD). We measured circulating immune cells, plasma cytokines and chemokines. RESULTS: Nineteen patients were enrolled. The proportions of circulating natural killer (NK) cells within CD45 + cells, programmed death 1 (PD-1) + Tim-3 + T cells within CD4 + cells, and the amount of chemokine C-X-C ligand (CXCL10) in the plasma were significantly elevated in PR relative to SD/PD patients (median 8.1%-vs-2.1%, P= 0.0032; median 1.2%-vs-0.3%, P= 0.0050; and median 122.6 pg/ml-vs-76.0 pg/ml, P= 0.0125, respectively). Patients with 2 or 3 elevated factors had longer progression-free survival than patients with 0 or only one (not reached-vs-5.6 months, P= 0.0002). CONCLUSIONS: We conclude that NK cells, CD4 + PD-1 + Tim-3 + T cells, and CXCL10 levels in pre-treatment peripheral blood may predict the efficacy of combination of ICI/chemotherapy in NSCLC.

Role of thymic stromal lymphopoietin in allergy and beyond.

Thymic stromal lymphopoietin (TSLP) is a pleiotropic cytokine that acts on multiple cell lineages, including dendritic cells, T cells, B cells, neutrophils, mast cells, eosinophils and innate lymphoid cells, affecting their maturation, survival and recruitment. It is best known for its role in promoting type 2 immune responses such as in allergic diseases and, in 2021, a monoclonal antibody targeting TSLP was approved for the treatment of severe asthma. However, it is now clear that TSLP has many other important roles in a variety of settings. Indeed, several genetic variants for TSLP are linked to disease severity, and chromosomal alterations in TSLP are common in certain cancers, indicating important roles of TSLP in disease. In this Review, we discuss recent advances in TSLP biology, highlighting how it regulates the tissue environment not only in allergic disease but also in infectious diseases, inflammatory diseases and cancer. Encouragingly, therapies targeting the TSLP pathway are being actively pursued for several diseases.

Antibody responses to second doses of COVID-19 vaccination in lung cancer patients undergoing treatment.

BACKGROUND: Several reports have revealed that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection tends to have more severe outcomes in cancer patients. Although vaccination reduces the risk of severe disease, data on antibody titers achieved by vaccination is scarce in cancer patients. METHODS: We collected 79 blood samples (69 lung cancer patients and 10 control individuals) and conducted an anti-SARS-CoV-2 antibody assay to compare the antibody titer achieved with current treatment. Sixty-eight patients (86%) received the BNT162 mRNA vaccine and 11 (14%) received the mRNA-1273 vaccine. They were categorized according to the current treatment: control individuals without cancer (cohort A), lung cancer patients who were treated with cytotoxic chemotherapy (cohort B), immunotherapy (cohort C), combination of cytotoxic chemotherapy and immunotherapy (cohort D), tyrosine kinase inhibitors (cohort E), and radiation therapy (cohort F). RESULTS: Among 69 lung cancer patients (cohort B-F), 57 (83%) had adenocarcinoma, and 66 (96%) had advanced-stage cancer. In the anti-SARS-CoV-2 antibody assay, the antibody titer was significantly lower in lung cancer patients than in control individuals (p = 0.01). The median antibody titers were 161 AU/ml in control individuals and 59.9 AU/ml in lung cancer patients. CONCLUSIONS: Antibody titers after the second vaccination were lower in cancer patients than those in healthy individuals. Our findings provide essential information for understanding the benefits and necessity of additional vaccination to prevent SARS-CoV-2 infection in lung cancer patients.

Disease control and objective responsive rates in randomized phase II trials evaluating non-first-line chemotherapy for non-small cell lung cancer: a systematic review of 74 trials.

Although objective response rate and disease control rate are commonly used as primary endpoints of lung cancer trials, it remains unclear whether objective response rate and disease control rate correctly reflect the overall survival in a non-small cell lung cancer phase II trial evaluating a non-first-line chemotherapy. Objective response rate might be easily affected by chance because the small number of patients in each trial achieved complete or partial response in the phase II non-first-line setting. This study was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (UMIN000040412). Four databases were searched for eligible trials. A Spearman's rank correlation with hazard ratio of overall survival was calculated each for odds ratio of objective response rate, difference of objective response rate (%), odds ratio of disease control rate, and difference of disease control rate (%). Of 74 eligible trials, 73 reported objective response rate and 68 reported disease control rates. Nine (12%) trials included patients with driver mutation status. Thirteen (18%) and two (3%) RCTs specifically included adenocarcinoma/non-squamous and squamous subtype of non-small cell lung cancer, respectively. The Eastern Cooperative Oncology Group performance status 0-2 (N=41, 55%) and the performance status 0-1 (N=25, 34%) were frequently used performance status criteria. The median number of patients in the two arms was 116 (interquartile range, 82-159). The correlation between trial-level odds ratio of objective response rate and hazard ratio of overall survival was weak (r=-0.29, 95% CI: -0.49 to -0.05, P=0.014). An exploratory subgroup analysis suggested that fewer responders were associated with poorer correlation. Odds ratio of disease control survival (r=-0.53, 95% CI: -0.68 to -0.32, P<0.001) had moderate rank correlations with hazard ratio of overall survival. Instead of objective response rate, disease control rate should be used as the primary endpoint in a randomized phase II trial evaluating non-first-line chemotherapy for non-small cell lung cancer.

Hydroxychloroquine and chloroquine for treatment of coronavirus disease 19 (COVID-19): a systematic review and meta-analysis of randomized and non-randomized controlled trials.

BACKGROUND: Although the US government approved hydroxychloroquine (HCQ) and chloroquine (CQ) for hospitalized coronavirus disease 19 (COVID-19) patients, some studies denied efficacy of HCQ and CQ. We aimed to evaluate HCQ/CQ treatment for COVID-19. METHODS: Five databases were searched on April 15, 2020, without publication date restriction. We followed both Preferred Reporting Items for Systematic Reviews and Meta-analyses and Meta-analysis of Observational Studies in Epidemiology statement reporting recommendations. A random-model meta-analysis was conducted to pool odds ratio (OR) and hazard ratio (HR). The quality of evidence for each outcome and the final recommendation was assessed using the GRADE guidelines of the American College of Chest Physicians. RESULTS: We identified four randomized controlled trials (RCTs) and four observational studies with 2,063 COVID-19 cases. All-cause mortality was not affected by the administration of HCQ/CQ [OR: 1.05, 95% confidence interval (CI): 0.53-2.09, P=0.89]. No improvement of viral clearance was found neither by time-to-event analysis (HR: 1.19, 95% CI: 0.74-1.94, P=0.47) nor frequency on day 7 (OR: 1.47, 95% CI: 0.33-6.63, P=0.62). HCQ/CQ treatment increased the risk of the any adverse event with OR of 3.56 (95% CI: 1.62-7.83, P=0.002). CONCLUSIONS: HCQ/CQ failed to decrease the all-cause mortality (very low quality evidence) and did not improve viral clearance (low or very low quality evidence) but increased the risk of any adverse event (moderate quality evidence). Routine administration of HCQ/CQ for COVID-19 patients is not recommended (weak recommendation, Grade 2C).