STAT5 promotes PD-L1 expression by facilitating histone lactylation to drive immunosuppression in acute myeloid leukemia.

Immunotherapy is a revolutionized therapeutic strategy for tumor treatment attributing to the rapid development of genomics and immunology, and immune checkpoint inhibitors have successfully achieved responses in numbers of tumor types, including hematopoietic malignancy. However, acute myeloid leukemia (AML) is a heterogeneous disease and there is still a lack of systematic demonstration to apply immunotherapy in AML based on PD-1/PD-L1 blockage. Thus, the identification of molecules that drive tumor immunosuppression and stratify patients according to the benefit from immune checkpoint inhibitors is urgently needed. Here, we reported that STAT5 was highly expressed in the AML cohort and activated the promoter of glycolytic genes to promote glycolysis in AML cells. As a result, the increased-lactate accumulation promoted E3BP nuclear translocation and facilitated histone lactylation, ultimately inducing PD-L1 transcription. Immune checkpoint inhibitor could block the interaction of PD-1/PD-L1 and reactive CD8+ T cells in the microenvironment when co-culture with STAT5 constitutively activated AML cells. Clinically, lactate accumulation in bone marrow was positively correlated with STAT5 as well as PD-L1 expression in newly diagnosed AML patients. Therefore, we have illustrated a STAT5-lactate-PD-L1 network in AML progression, which demonstrates that AML patients with STAT5 induced-exuberant glycolysis and lactate accumulation may be benefited from PD-1/PD-L-1-based immunotherapy.

Disruption of mitochondrial oxidative phosphorylation by chidamide eradicates leukemic cells in AML.

PURPOSE: Nowadays, the oxidative phosphorylation (OXPHOS) correlated with leukemogenesis and treatment response is extensive. Thus, exploration of novel approaches in disrupting OXPHOS in AML is urgently needed. MATERIALS AND METHODS: Bioinformatical analysis of TCGA AML dataset was performed to identify the molecular signaling of OXPHOS. The OXPHOS level was measured through a Seahorse XFe96 cell metabolic analyzer. Flow cytometry was applied to measure mitochondrial status. Real-time qPCR and western blot were used to analyze the expression of mitochondrial or inflammatory factors. MLL-AF9-induced leukemic mice were conducted to measure the anti-leukemia effect of chidamide. RESULTS: Here, we reported that AML patients with high OXPHOS level were in a poor prognosis, which was associated with high expression of HDAC1/3 (TCGA). Inhibition of HDAC1/3 by chidamide inhibited cell proliferation and induced apoptotic cell death in AML cells. Intriguingly, chidamide could disrupt mitochondrial OXPHOS as assessed by inducing mitochondrial superoxide and reducing oxygen consumption rate, as well as decreasing mitochondrial ATP production. We also observed that chidamide augmented HK1 expression, while glycolysis inhibitor 2-DG could reduce the elevation of HK1 and improve the sensitivity of AML cells exposed to chidamide. Furthermore, HDAC3 was correlated with hyperinflammatory status, while chidamide could downregulate the inflammatory signaling in AML. Notably, chidamide eradicated leukemic cells in vivo and prolonged the survival time of MLL-AF9-induced AML mice. CONCLUSION: Chidamide disrupted mitochondrial OXPHOS, promoted cell apoptosis and reduced inflammation in AML cells. These findings exhibited a novel mechanism that targeting OXPHOS would be a novel strategy for AML treatment.

Mutant C/EBPα p30 alleviates immunosuppression of CD8+ T cells by inhibiting autophagy-associated secretion of IL-1ß in AML.

OBJECTIVES: Mutant C/EBPα p30 (mp30), the product of C/EBPα double mutations (DM), lacks transactivation domain 1 and has C-terminal loss-of-function mutation. Acute myeloid leukaemia (AML) patients harbouring C/EBPα DM could be classified as a distinct subgroup with favourable prognosis. However, the underlying mechanism remains elusive. MATERIALS AND METHODS: Autophagy regulated by mp30 was detected by western blot and immunofluorescence. Immune infiltration analysis and GSEA were performed to investigate autophagic and inflammatory status of AML patients from the GSE14468 cohort. Flow cytometry was applied to analyse T cell activation. RESULTS: Mp30 inhibited autophagy by suppressing nucleus translocation of NF-κB. Autophagy-associated secretion of IL-1ß was decreased in mp30-overexpressed AML cells. Bioinformatic analysis revealed that inflammatory status was attenuated, while CD8+ T cell infiltration was upregulated in C/EBPα DM AML patients. Consistently, the proportion of CD8+ CD69+ T cells in peripheral blood mononuclear cells (PBMCs) was upregulated after co-culture with mp30 AML cell conditional culture medium. Knock-out of IL-1ß in AML cells also enhanced CD8+ T cell activation. Accordingly, IL-1ß expression was significantly reduced in the bone marrow (BM) cells of C/EBPα DM AML patients compared to the wildtype, while the CD8+ CD69+ T cell proportion was specifically elevated. CONCLUSIONS: C/EBPα DM alleviates immunosuppression of CD8+ T cells by inhibiting the autophagy-associated secretion of IL-1ß, which elucidated that repression of autophagy-related inflammatory response in AML patients might achieve a favourable clinical benefit.

cGAS/STING cross-talks with cell cycle and potentiates cancer immunotherapy.

The correct duplication and transfer of genetic material to daughter cells is the major event of cell division. Dysfunction of DNA replication or chromosome segregation presents challenges in cancer initiation and development as well as opportunities for cancer treatment. Cyclic GMP-AMP synthase (cGAS) of the innate immune system detects cytoplasmic DNA and mediates downstream immune responses through the molecule stimulator of interferon genes (STING). However, how cytosolic DNA sensor cGAS participates in guaranteeing accurate cell division and preventing tumorigenesis is still unclear. Recent evidence indicates malfunction of cGAS/STING pathway in cancer progression. Cell cycle-targeted therapy synergizes with immunotherapy via cGAS/STING activation, leading to promising therapeutic benefit. Here, we review the interactions between cell cycle regulation and cGAS/STING signaling, thus enabling us to understand the role of cGAS/STING in cancer initiation, development, and treatment.

Antibacterial effect of porcine PTX3 against Streptococcus suis type 2 infection.

Pentraxin 3 (PTX3), a soluble pattern recognition receptor, plays an important role in innate immunity and has been implicated to be a candidate resistance gene against Streptococcus suis 2 infection. To discover the antibacterial effect of porcine PTX3 against S. suis 2, the 42-kDa PTX3 protein was expressed by Chinese hamster ovary cells (CHO), and an additional eukaryotic expression vector pVAX-ptx3 was constructed. The expressed porcine PTX3 mediated a range of antibacterial activities including increasing phagocytic capacity of primary porcine alveolar macrophages (PAM) against S. suis 2 and inhibiting adhesion of S. suis 2 to human epidermoid cancer cells (Hep-2). In mouse model, pre-intramuscular injecting with pVAX-ptx3 reduced mortality and reduced bacteria loads in blood, spleen, lung and brain compared with that of control group during 2-12 h following intraperitoneal injection (i.p.) with S. suis 2. Meanwhile, the expressions of IL-6 and IL-8 in blood were increased in pVAX-ptx3 group, whereas no obvious changes about IL-10. In piglet model, bacteria load in blood of pVAX-ptx3 group was significantly lower than that of control group after i.p. with S. suis 2, correspondingly, expression of IL-6 and IL-8 were significantly increased in pVAX-ptx3 group. In contrast, white blood cell (WBC) and neutrophil cell (NEU) count of peripheral blood in pVAX-ptx3 group were lower than that of control group. These studies described a novel antibacterial role for porcine PTX3 against S. suis 2 both in vitro and in vivo and suggested that porcine PTX3 may be a potential biological agent against S. suis 2 in pig and be used for the clinical prevention and treatment of streptococcosis caused by S. suis 2.

Virulence genotyping and population analysis of Streptococcus suis serotype 2 isolates from China.

Streptococcus suis is one of the most important swine pathogens worldwide. In this study, a total of 22 virulence-related genes in 101 strains of S. suis serotype 2 (SS2) were detected by PCR, namely, mrp, epf, sly, fbps, rgg, ofs, srtA, pgdA, gapdh, iga, endoD, ciaRH, salKR, manN, purD, rgg, DppIV, neuB, dltA, SMU_61-like, SpyM3_0908 (Permease) and the SspA gene. The distribution of virulence-related genes among isolates was visualized using BioNumerics software to study similarities among the isolates. Two clusters of SS2 were apparent on the phylogenetic tree, namely, Clusters A and B. Both mouse and zebrafish infection models revealed that strains in Cluster B were more virulent than those in Cluster A. Statistical comparison between the two clusters was performed, and structure analysis demonstrated that epf, sly, rgg, endoD, SMU_61-like and SpyM3_0908 were possible predictive markers for SS2 virulence. The transcription levels of highly prevalent genes in both clusters were detected by qRT-PCR in representative strains. For Cluster A isolates, the transcription levels of neuB, dltA, fbps and pgdA were significantly lower, but the transcription level of iga was significantly higher than that in Cluster B isolates. Although encoded in the genomes of the selected Cluster A isolates, DppIV and mrp genes were not expressed. These results revealed the genetic differences between virulent and low-virulence SS2 isolates from China and provide a better understanding of the SS2 pathogenic mechanism.