PD-1 signaling negatively regulates the common cytokine receptor γ chain via MARCH5-mediated ubiquitination and degradation to suppress anti-tumor immunity.

Combination therapy with PD-1 blockade and IL-2 substantially improves anti-tumor efficacy comparing to monotherapy. The underlying mechanisms responsible for the synergistic effects of the combination therapy remain enigmatic. Here we show that PD-1 ligation results in BATF-dependent transcriptional induction of the membrane-associated E3 ubiquitin ligase MARCH5, which mediates K27-linked polyubiquitination and lysosomal degradation of the common cytokine receptor γ chain (γc). PD-1 ligation also activates SHP2, which dephosphorylates γcY357, leading to impairment of γc family cytokine-triggered signaling. Conversely, PD-1 blockade restores γc level and activity, thereby sensitizing CD8+ T cells to IL-2. We also identified Pitavastatin Calcium as an inhibitor of MARCH5, which combined with PD-1 blockade and IL-2 significantly improves the efficacy of anti-tumor immunotherapy in mice. Our findings uncover the mechanisms by which PD-1 signaling antagonizes γc family cytokine-triggered immune activation and demonstrate that the underlying mechanisms can be exploited for increased efficacy of combination immunotherapy of cancer.

Phenotype Analysis of 78 Cases of Abnormal Hemoglobin E Homozygotes / 中国实验血液学杂志

OBJECTIVE@#To analyze the hematological characteristics of HbE homozygotes.@*METHODS@#Complete blood cells count and hemoglobin electrophoresis were used for phenotypic analysis of 78 cases with HbE homozygotes from Yunnan province, China. The PCR-fluorescence hybridization was used to detect the common gene mutation of thalassemia. The hematological indexes, including MCV, MCH, Hb, HbA2, HbF and HbE were statistically analyzed between groups with different sex, ages and compound α thalassemia status.@*RESULTS@#In HbE homozygotes (HbEE), 89.5% (17/19) children presented mild to moderate microcytic hypochromic anemia, and 10.5% of them presented moderate anemia. 39.6% (19/48) of women with HbEE developed mild anemia ,while 11 cases of male with HbE homozygotes were asymptomatic. The levels of MCV and MCH in HbE homozygotes increased by co-inheritance of α thalassemia mutation.@*CONCLUSION@#The clinical phenotype of HbE homozygote shows highly heterogeneous, which is relates with age, sex and co-inheriting α-globin genotypes. In Hb EE women and children are more likely to develop mild to moderate anemia. The microcytic hypochromic anemia degree is relieved when HbEE combined with α- thalassemia.