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INTRODUCTION: Cardiac hypertrophy is an important contributor of heart failure, and the mechanisms remain unclear. Leucine zipper protein 1 (LUZP1) is essential for the development and function of cardiovascular system; however, its role in cardiac hypertrophy is elusive. OBJECTIVES: This study aims to investigate the molecular basis of LUZP1 in cardiac hypertrophy and to provide a rational therapeutic approach. METHODS: Cardiac-specific Luzp1 knockout (cKO) and transgenic mice were established, and transverse aortic constriction (TAC) was used to induce pressure overload-induced cardiac hypertrophy. The possible molecular basis of LUZP1 in regulating cardiac hypertrophy was determined by transcriptome analysis. Neonatal rat cardiomyocytes were cultured to elucidate the role and mechanism of LUZP1 in vitro. RESULTS: LUZP1 expression was progressively increased in hypertrophic hearts after TAC surgery. Gain- and loss-of-function methods revealed that cardiac-specific LUZP1 deficiency aggravated, while cardiac-specific LUZP1 overexpression attenuated pressure overload-elicited hypertrophic growth and cardiac dysfunction in vivo and in vitro. Mechanistically, the transcriptome data identified Stat3 pathway as a key downstream target of LUZP1 in regulating pathological cardiac hypertrophy. Cardiac-specific Stat3 deletion abolished the pro-hypertrophic role in LUZP1 cKO mice after TAC surgery. Further findings suggested that LUZP1 elevated the expression of Src homology region 2 domain-containing phosphatase 1 (SHP1) to inactivate Stat3 pathway, and SHP1 silence blocked the anti-hypertrophic effects of LUZP1 in vivo and in vitro. CONCLUSION: We demonstrate that LUZP1 attenuates pressure overload-induced cardiac hypertrophy through inhibiting Stat3 signaling, and targeting LUZP1 may develop novel approaches to treat pathological cardiac hypertrophy.
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OBJECTIVE: To investigate the changes in function of CD8+ T cell subsets, and explore its significance in pathogenesis of secondary hemophagocytic lymphohistiocytosis (sHLH). METHODS: Flow cytometry was used to detect the expressions of PD-1, TIM-3, and LAG-3, which were the markers of exhausted CD8+ T cell, as well as the secretion levels of interferon γ (IFN-γ) and expression of ΔCD107a after the stimulation; the numbers of effector-memory CD8+ T cells, regulatory T cells and double negative T cells were also detected. RESULTS: The expressions of inhibitory receptors (PD-1, TIM3 and LAG-3) on CD8+ T cells of sHLH patients were 40.73±22.64, 15.97±14.45 and 0.73 (0-37.41), respectively, which were significantly higher than those of the control group (P<0.001). In contrast, the expression of ΔCD107a (4.49±2.71 vs 6.07±2.14, P=0.035) and secretion level of IFN-γ (37.30±24.46 vs 55.17±22.23, P=0.034) were significantly lower. The number of effector-memory CD8+ T cells in sHLH patients was also lower as compared with that in control group (14.35±10.37 vs 22.92±11.12, P=0.016). But there was no significant difference in the number of regulatory T cell and double negative T cell. In addition, the expressions of PD-1, TIM3 and LAG-3 in active stage of sHLH were 38.09±21.87, 14.35±13.70 and 0.82 (0-13.22), respectively, which were significant higher than those in remission stage [24.27±17.23 (P=0.03), 8.64±5.60 (P=0.014) and 0.13 (0-3.69)]. CONCLUSION: The exhausted CD8+ T lymphocytes may play a critical role in the development of sHLH.