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Objective: To delineate the clinical feature and genetic basis of four patients with congenital neutropenia., Methods: All patients were subjected to whole exome sequencing (WES). Suspected variants were verified by Sanger sequencing., Results: The patients (two boys and two girls), aged 7 to 15 months, suffered from neutropenia and recurrent infections. Bone marrow smears showed a significant decrease in the proportion of rod-shaped and lobulated granulocytes, which suggested impaired development and maturation of bone marrow neutrophils. WES has discovered heterozygous variants (c.496G>A, c.58C>G, c.391G>A and IVS1+5T>A) of the ELANE gene in the patients. Among these, c.58C>G and IVS1+5T>A were unreported previously. Follow up revealed patients 1 and 3 had periodic neutropenia, while patients 2 and 4 had severe congenital neutropenia. After attaining the definite diagnosis, the patients were treated symptomatically., Conclusion: The main clinical feature of congenital neutropenia is refractory recurrent bacterial infections, for which mutations of the ELANE gene are a common cause. Two novel pathogenic ELANE variants have been discovered in this study.

Objective: To explore the clinical characteristics of congenital neutropenia caused by ELANE gene mutations., Methods: Clinical manifestations, absolute blood neutrophil count, high-throughput exome sequencing for mutation screening, suspected locus Sanger sequencing verification, processes of diagnosis and treatment of two patients with congenital neutropenia caused by ELANE gene mutation were retrospectively analyzed., Results: High-throughput sequencing has found that proband 1 has carried a heterozygous c.170C>T (p.Ala57Val) missense mutation in exon 2 of the ELANE gene, which was known to be pathological, and a heterozygous c.251T>G (p.Leu84Arg) mutation in exon 3 of proband 2, which was unreported previously. Sanger sequencing confirmed that neither mutation was inherited from their parents., Conclusion: ELANE mutation is an important cause for congenital neutropenia. Detection of new pathogenic variants has enriched the mutation spectrum of the ELANE gene.

Objective: To establish recombinant adenovirus carrying human neutrophil elastase (NE) gene using AdEasy system, over-express NE in K562 cell line and observe the effects of NE on K562 cell proliferation and apoptosis., Methods: NE gene was amplified with RNA extracted from acute premyelocytic leukemia (APL) HL-60 cells as a template using reverse transcription-PCR. The coding sequence was cloned into shuttle plasmid pAdTrack-CMV to obtain the recombinant plasmid named pAd-NE. After digested with HindIII and EcoRV and sequenced, the pAd-NE was transformed to competent E.coli BJ5183 containing adenovirus backbone plasmid pAdEasy-1. The obtained recombinant adenovirus plasmid Ad-NE was digested with PacI and transfected into AD293 cells for packaging. Fourteen days later, primary recombinant adenovirus Ad-NE was harvested, and then subjected to five cycles of amplification, titer determination and PCR identification. K562 cells were infected by the recombinant adenovirus. The infection efficiency was observed under a fluorescence microscope and detected by flow cytometry. Western blotting was used to detect NE expression. The proliferation of K562 cells was detected by CCK-8 assay. Cell cycle and apoptosis was measured by annexin V/PI accompanied by flow cytometry., Results: HindIII and EcoRV digestion and sequencing suggested that the recombinant vector Ad-NE was successfully constructed. The recombinant plasmid Ad-NE was packaged in AD293 cells as expected. Following five-cycle amplification, the viral titer was up to 1.64 × 10¹² pfu/mL. GFP expression observed by fluorescence microscopy and flow cytometry implied that the infection efficiency of Ad-NE in K562 cells reached about 80%. Western blotting showed that NE expression was up-regulated in K562 cells. CCK-8 assay revealed that the proliferation of K562 cells over-expressing NE was enhanced. Meanwhile, flow cytometry indicated that the K562 cells were arrested in S phase and the apoptosis rate was highly reduced., Conclusion: Over-expressed NE in K562 leukemia cells could promote cell proliferation, inhibit apoptosis and block cell cycle in S phase.

Objective: To prepare a purified recombinant human neutrophil elastase (HNE) using genetic engineering technology, and pave the way for the preparation of the antibody to HNE and establishment of semen HNE detection methods., Methods: HNE mRNA was obtained from human peripheral blood granulocytes with specific HNE primers, and the cDNA of HNE was cloned into the plasmid pGEX-2T to derive a recombinant plasmid pGEX-2T/HNE. After PCR identification, double-enzyme digestion and gene sequencing, the recombinant plasmid was transferred into competent Escherichia coli DH5alpha and further induced to express the recombinant fusion protein GST/HNE by isopropyl beta-D-thiosulfate galactosidase (IPTG). The recombinant fusion protein was cleaved by thrombin and further purified with glutathione agarose beads to obtain purified recombinant HNE., Results: The recombinant plasmid pGEX-2T/HNE was successfully prepared and transferred into E. coli DH5o; the expression of the recombinant fusion protein GST/ HNE was successfully induced by IPTG at 18 degrees C overnight; and the purified recombinant protein HNE was successfully obtained by thrombin cleavage and purification of glutathione agarose beads., Conclusion: The acquirement of purified recombinant HNE has prepared the ground for the preparation of the antibody to HNE and establishment of semen HNE detection methods.