Alpha1-antitrypsin and the maintenance of hemostatic balance

[α1-antitrypsin Pittsburg mutations: report of two cases in the same family]

目的

分析2例α1抗胰蛋白酶（α1-AT）Pittsburg突变患者的临床和实验室特点。

方法

采用凝固法或发色底物法分别检测凝血时间及凝血因子活性；比浊法测定血小板聚集功能；采用毛细管电泳法测定血清蛋白；PCR扩增目的DNA片段并测序检测突变。

结果

先证者，女，34岁，多次术后出血及黄体破裂出血；女儿，10岁，无出血表现。两例患者APTT、凝血酶时间均明显延长且正常人混和血浆1∶1不能纠正，凝血因子Ⅸ、Ⅹ、Ⅺ、Ⅻ活性明显降低，蛋白C、蛋白S活性均为0，1 U/ml凝血酶诱导的血小板聚集降低，4 U/ml凝血酶诱导的血小板聚集为48%；血清α1球蛋白电泳条带异常；DNA测序结果显示两例患者的α1-AT基因（NG_008290.1）均存在g.T17132G（p.Met358Arg）杂合突变。

结论

α1-AT Pittsburg突变患者表现出明显的凝血异常，临床出血表现有较大的差异性，黄体破裂出血可能是女性患者的一个明显特征。

[Recurrent bleeding tendency in a school-aged boy]

The study reports a boy with alpha1-antitrypsin Pittsburgh mutation. The boy was admitted into the hospital because of recurrent joint hematoma. The laboratory examinations revealed that prothrombin time and activated partial thromboplastin time were prolonged and cannot be corrected by 1:1 fresh plasma. The inhibitor of factor VIII, anticardiolipin antibody and lupus anticoagulant were all negative. Platelet aggregation test indicated the existence of the inhibitor of thrombin. Alpha1-antitrypsin Pittsburgh mutation was confirmed by genomic sequencing. The clinical manifestations, diagnosis and treatment of this disorder are discussed in this paper.

Revascularization of pancreatic islet allografts is enhanced by α-1-antitrypsin under anti-inflammatory conditions

Pancreatic islets are a highly vascularized entity, and their transplantation into diabetic individuals requires optimal revascularization. In addition, β-cells in islets are extremely sensitive to inflammation. α-1-Antitrypsin (AAT), a circulating serine-protease inhibitor that is available for clinical use as an affinity-purified human product, has been shown to protect islets from graft failure in mouse transplantation models and to achieve readily vascularized islet grafts. AAT is known to induce vascular endothelial growth factor (VEGF) expression and release, as well as protect from proteolytic cleavage of VEGF by elastase, promote viability of endothelial cells, and enhance migration of myocytes. Our aim was to examine whether AAT enhances vasculogenesis toward islet grafts. We employed Matrigel-islet plugs as means to introduce islets in an explantable isolated compartment and examined vessel formation, vessel maturation, and inflammatory profile of explants 9 days after implantation. Also, we examined primary epithelial cell grafts that were prepared from lungs of mice that are transgenic for human AAT. In addition, aortic ring sprouting assay was performed, and HUVEC tube formation assays were studied in the presence of AAT. Our findings indicate that islet grafts exhibit mature vessels in the presence of AAT, as demonstrated by morphology, as well as expression of endothelial CD31, smooth muscle actin (SMA), and von Willebrand factor (vWF). Epithelial cells that express human AAT achieved a similar positive outcome. Aortic ring sprouting was enhanced in AAT-treated cultures and also in cultures that contained primary epithelial cells from human AAT transgenic animals in the absence of added AAT. According to the tube formation assay, HUVECs exhibited superior responses in the presence of AAT. We conclude that vasculogenesis toward islet grafts is enhanced in the presence of AAT. Together with the remarkable safety profile of AAT, the study supports its use in the relevant clinical setups.

Lentivirus-mediated expression of human α1-antitrypsin in mice

AIM: To construct a recombinant lentiviral vector carrying the human α1-antitrypsin (hAAT) gene，then express the hAAT in fibroblasts and mice.

METHODS: The coding sequence of the hAAT gene was amplified by RT-PCR and ligated into a lentiviral vector to construct a recombinant lentiviral vector (pLVX-ser). Lentiviral particles were packaged in vitro and used to infect fibroblasts and mice. GFP expression was detected by fluorescence microscopy. The supernatants of infected cells and liver samples from infected mice were used to detect the expression of hAAT by Western blot and ELISA.

RESULTS: The recombinant hAAT lentiviral vector pLVX-ser was successfully constructed. The titer of lentiviral particles reached 8×10⁶ TU/mL after viral packaging. Fluorescence microscopic analysis showed that hAAT was successfully expressed in fibroblasts. Western blot analysis suggested that hAAT was expressed well in mice, and ELISA assay showed that the mean expression level amounted to 190 μg/L. The expression of hAAT in mice could even last for several months.

CONCLUSION: The recombinant lentiviral vector carrying the hAAT gene allows efficient and persistent expression of hAAT in mice, which paves the way to producing hAAT in industry and gene therapy for AATD disease.