The Protective Effect of Chronic Intermittent Hypobaric Hypoxia on Preventing the Destruction of CD34+ Haematopoietic Stem Cells in Aplastic Anaemia by Modulating the Th1/Th2 Balance.

Aplastic anaemia (AA) is a haematopoietic disorder caused by immune-mediated attack on haematopoietic stem cells (HSCs). Stem cell transplantation and immunosuppressive therapy remain the major treatment choice for AA patients but have limited benefits and undesired side effects. The aim of our study was to clarify the protective role of immunity of chronic intermittent hypobaric hypoxia (CIHH) and the underlying mechanism in AA. Our integrative analysis demonstrated that CIHH pre-treatment significantly improved haematopoiesis and survival in an AA rat model. We further confirmed that CIHH pre-treatment was closely associated with the Th1/Th2 balance and a large number of negative regulatory haematopoietic factors, such as TNF-α and IFN-γ, produced by hyperactive Th1 lymphocytes released in AA rats, which induced the death program in a large number of CD34+ HSCs by activating the Fas/FasL apoptosis pathway, while CIHH pre-treatment effectively downregulated the expression of TNF-α and IFN-γ, resulting in a reduction in Fas antigen expression in CD34+ HSCs. In summary, this study provides evidence that CIHH has good protective effect against AA by modulating immune balance in Th1/Th2 cells and may provide a new therapeutic strategy.

mTOR regulates GPVI-mediated platelet activation.

BACKGROUND: Due to mTOR (mammalian/mechanistic target of rapamycin) gene-loss mice die during embryonic development, the role of mTOR in platelets has not been evaluated using gene knockout technology. METHODS: A mouse model with megakaryocyte/platelet-specific deletion of mTOR was established, and be used to evaluate the role of mTOR in platelet activation and thrombus formation. RESULTS: mTOR-/- platelets were deficient in thrombus formation when grown on low-concentration collagen-coated surfaces; however, no deficiency in thrombus formation was observed when mTOR-/- platelets were perfused on higher concentration collagen-coated surfaces. In FeCl3-induced mouse mesenteric arteriole thrombosis models, wild-type (WT) and mTOR-/- mice displayed significantly different responses to low-extent injury with respect to the ratio of occluded mice, especially within the first 40 min. Additionally, mTOR-/- platelets displayed reduced aggregation and dense granule secretion (ATP release) in response to low doses of the glycoprotein VI (GPVI) agonist collagen related peptide (CRP) and the protease-activated receptor-4 (PAR4) agonist GYPGKF-NH2; these deficiencies were overcame by stimulation with higher concentration agonists, suggesting dose dependence of the response. At low doses of GPVI or PAR agonist, the activation of αIIbß3 in mTOR-/- platelets was reduced. Moreover, stimulation of mTOR-/- platelets with low-dose CRP attenuated the phosphorylation of S6K1, S6 and Akt Ser473, and increased the phosphorylation of PKCδ Thr505 and PKCε Ser729. Using isoform-specific inhibitors of PKCs (δ, ɛ, and α/ß), we established that PKCδ/ɛ, and especially PKCδ but not PKCα/ß or PKCθ, may be involved in low-dose GPVI-mediated/mTOR-dependent signaling. CONCLUSION: These observations indicate that mTOR plays an important role in GPVI-dependent platelet activation and thrombus formation.

The influence of PD-L1 genetic variation on the prognosis of R0 resection colorectal cancer patients received capecitabine-based adjuvant chemotherapy: a long-term follow-up, real-world retrospective study.

PURPOSE: This study investigated the influence of PD-L1 genetic variation on the prognosis of R0 resection colorectal cancer (CRC) patients who received capecitabine-based adjuvant chemotherapy in real world. METHODS: A total of 315 CRC patients underwent R0 surgical resection and received capecitabine-based adjuvant chemotherapy were included. Clinical characteristics were collected from the hospital record system, prognosis was obtained by telephone follow-up. Peripheral blood and peripheral blood mononuclear cell (PBMC) specimen of CRC patients were performed for the genotyping of polymorphism and mRNA expression of PD-L1, respectively. Analysis on the association between genotypes and prognosis was conducted. RESULTS: The median disease-free survival (DFS) of the 315 CRC patients was 5.1 years, the median overall survival (OS) was 6.0 years. Regarding the PD-L1 gene polymorphism analysis, the prevalence of 901T>C among the CRC patients was as follows: TT genotype 221 cases (70.16%), TC genotype 86 cases (27.30%), CC genotype 8 cases (2.54%), the minor allele frequency was 0.16, the distribution of three genotypes was in accordance with Hardy-Weinberg equilibrium (P = 0.915). Moreover, the prognosis analysis indicated that the median DFS of patients with TT and TC/CC genotype was 5.4 and 4.0 years, respectively (P = 0.008). The median OS of patients with the two genotypes was 6.4 and 5.0 years (P = 0.007). The multivariate Cox regression analysis showed that the TC/CC genotypes were an independent factor for DFS (odds ratio = 1.56, P = 0.018). Furthermore, the mRNA expression results indicated that the mRNA expression of PD-L1 in PBMC of the patients with TC/CC genotype was significantly higher than patients with TT genotype (P < 0.001). CONCLUSION: The prognosis of R0 resection CRC patients received capecitabine-based adjuvant chemotherapy in real world may be influenced by PD-L1 901T>C polymorphism through mediation of the mRNA expression of PD-L1.

XPG Asp1104His polymorphism increases colorectal cancer risk especially in Asians.

Xeroderma pigmentosum group G (XPG) protein is a pivotal element of the nucleotide excision repair pathway. XPG gene single nucleotide polymorphisms (SNPs) have been shown to confer colorectal cancer (CRC) susceptibility. In this study, we further investigated the role of Asp1104His (rs17655 G > C) in XPG on CRC risk. We genotyped the rs17655 G > C polymorphism in Chinese population comprising 1019 CRC cases and 1036 cancer-free controls. We also performed a meta-analysis to further assess the association. Overall, no significant association was detected between the rs17655 G > C and the risk of CRC. Stratified analysis also revealed no significant association. To further elucidate the association of the rs17655 with CRC susceptibility, we conducted a meta-analysis by including qualified publications and the current study. The meta-analysis results demonstrated that rs17655 G > C was associated with an increased CRC risk (CG vs. GG: OR = 1.14, 95% CI = 1.01-1.28; CC/CG vs. GG: OR = 1.12, 95% CI = 1.01-1.24; C vs. G: OR = 1.06, 95% CI = 1.01-1.11). In subgroup analysis, the significant association between the rs17655 C allele and CRC risk was found in Asians and hospital-based subgroups. Taken together, our results suggested that the XPG rs17655 G > C polymorphism is a low-penetrance susceptibility locus for CRC. Further studies are warranted to validate these findings.

Integrin-αIIbß3-mediated outside-in signalling activates a negative feedback pathway to suppress platelet activation.

Integrin-αIIbß3-mediated outside-in signalling is widely accepted as an amplifier of platelet activation; accumulating evidence suggests that outside-in signalling can, under certain conditions, also function as an inhibitor of platelet activation. The role of integrin-αIIbß3-mediated outside-in signalling in platelet activation is disputable. We employed flow cytometry, aggregometry, immunoprecipitation, and immunoblotting to investigate the role of integrin-αIIbß3-mediated outside-in signalling in platelet activation. Integrin αIIbß3 inhibition enhances agonist-induced platelet ATP secretion. Human platelets lacking expression of αIIbß3 exhibited more platelet ATP secretion than their wild-type counterparts. Moreover, integrin-αIIbß3-mediated outside-in signals activate SHIP-1, which in turn mediates p-Akt dephosphorylation, leading to inactivation of PI3K/Akt signalling. Furthermore, 3AC (SHIP-1 inhibitor) inhibits platelet disaggregation, and promotes platelet ATP secretion. Upon ADP stimulation, Talin is recruited to αIIbß3, and it is dissociated from αIIbß3 when platelets disaggregate. In addition, treatment with RUC2, an inhibitor of αIIbß3, which blocks αIIbß3-mediated outside-in signalling, can markedly prevent the dissociation of talin from integrin. SHIP1 Inhibitor 3AC inhibits the dissociation of talin from integrin-ß3. These results suggest that integrin-αIIbß3-mediated outside-in signalling can serve as a brake to restrict unnecessary platelet activation by activated SHIP-1, which mediated the disassociation of talin from ß3, leading to integrin inactivation and blocking of PI3K/Akt signalling to restrict platelet ATP secretion.