关键词: 念珠菌病, 侵袭性, 白色念珠菌, 颈部淋巴结炎, CARD9, 基因突变, 免疫缺陷

Abstract: 【Abstract】 Objective To explore genetic etiology and antifungal immunity in a patient with recurrent cervical lymphadenitis caused by Candida albicans. Methods Next-generation sequencing was performed to screen susceptibility genes for mycosis in a patient with recurrent cervical lymphadenitis caused by Candida albicans and his parents. Peripheral blood mononuclear cells （PBMCs） and neutrophils were extracted from the patient and 6 healthy controls, and subjected to in vitro co-culture with Candida albicans. Western blot analysis was performed to determine the expression of caspase recruitment domain-containing protein 9 （CARD9） in PBMCs of the patient, enzyme-linked immunosorbent assay to detect levels of tumor necrosis factor-α （TNF-α）, interleukin （IL）-6, IL-17A, IL-1β and granulocyte-macrophage colony-stimulating factor （GM-CSF） in the co-culture medium, and a colony-counting method was used to detect the survival rate of Candida albicans after treatment with neutrophils. Statistical analysis was carried out by using t test for comparisons between two groups. Results Two compound heterozygous mutations were identified in the CARD9 gene of the patient, including c.68C>A （p.S23X） in exon 2 inherited from his father and c.820dupG （p.D274Gfs*61） in exon 6 inherited from his mother. Western blot analysis showed that the relative expression level of CARD9 protein in the PBMCs was 0.41 ± 0.07 in the healthy control group, but CARD9 expression was absent in the patient. After stimulation with heat-inactivated Candida albicans spores, the levels of TNF-α, IL-6, IL-17A, IL-1β and GM-CSF secreted by PBMCs of the patient were significantly lower than those by PBMCs of the healthy controls （all P < 0.001）. After 30- and 120-minute in vitro co-culture with neutrophils, the survival rates of Candida albicans were significantly higher in the patient （78.00%, 74.00%, respectively） than in the healthy controls （70.91% ± 1.75%, 34.55% ± 5.35%, t = 3.743, 6.988, respectively, both P < 0.05）. Conclusion Compound heterozygous mutations were identified in the CARD9 gene of the patient with recurrent cervical lymphadenitis caused by Candida albicans, leading to the absence of CARD9 protein expression, and the deficiency in the immunity against Candida albicans.

Key words: Candidiasis, invasive, Candida albicans, Cervical lymphadenitis, CARD9, Gene mutation, Immunodeficiency