登革熱是由登革熱病毒感染所引起的疾病，其臨床表現很廣泛，從一般病毒感染症狀至登革出血熱和登革休克症候群，但有些感染者也會有無症狀的現象。先前的研究指出，登革病毒可以感染造血幹細胞及前驅細胞並導致血液相關疾病，如血小板低下症、白血病和非典型淋巴細胞增多等。然而，登革病毒與血液相關疾病之間的機轉還沒有很詳盡的了解。造血作用是由許多轉錄因子共同作用所才能進行，而造血轉錄因子GATA，其中包括GATA-1、GATA-2和GATA-3，它們對於造血作用中的細胞的譜系訂定非常重要。GATA-1和GATA-2與骨髓細胞譜系定型相配合，GATA-1和GATA-2之間的平衡在造血細胞的增殖和分化中是重要的；GATA-3主要表現在T淋巴細胞中。因此，本篇主要想藉由登革病毒感染臍帶血比照沒有感染組，去研究登革病毒感染造血幹細胞後所導致造血作用異常的機制。我們利用登革病毒去感染臍帶血細胞，並在特定時間點收取細胞，然後利用帶有螢光訊號的抗體去染色，再以流式細胞儀去檢測。結果顯示，表達GATA-1和GATA-2的造血幹細胞增加，然而巨核細胞及前驅細胞卻減少，這表明登革病毒感染可能透過改變GATA-1和GATA-2之間的平衡來促使造血幹細胞的增殖，但抑制其分化。再以細胞集落形成法(一種透過幹細胞形成細胞集落的能力去測試幹細胞增殖和分化能力)去檢測，證實登革病毒感染後，髓樣前驅細胞會減少。另一方面，在病毒複製時，表現GATA-3的造血幹細胞也高度增加，這表明在登革病毒感染期間，非典型淋巴細胞增生是可能的現象。從先前的研究報告也指出，儘管在血液中偵測到非典型淋巴細胞並不是登革病毒造成的經典症狀之一，但其濃度卻在登革重症患者體內高度增加。對於登革病毒感染而出現的非典型淋巴細胞的定義仍然不清，因此我們進一步評估了在登革病毒感染後，非典型淋巴細胞在臍帶血細胞中表現的比率，並試圖去定義這群表現在臍帶血細胞中的非典型淋巴細胞的特徵。結果顯示，在登革病毒感染後主要表現出源自未成熟B細胞非典型淋巴細胞，而這群細胞會同時表現出病毒的NS1蛋白及CD117這個幹細胞的細胞表現標記物。另外也有文獻指出說，非典型淋巴細胞可能是源自於T細胞，但是對於這類細胞的表行尚未有人定義出來。因此我們也去檢測病毒的NS1蛋白表現在未成熟T細胞上的情況，發現登革病毒也可去感染未成熟的幹細胞尤其在感染後期，表現出NS1的未成熟T細胞的量有突然增加的現象。總結以上，登革病毒可以透過調控不同造血轉錄因子的平衡來改變細胞族群，同時會抑制巨核細胞譜系細胞的分化，並在感染後增加臍帶血細胞中的非典型淋巴細胞的表現。

Dengue fever which is caused by dengue virus (DENV) infection results in asymptomatic or with a wide spectrum of clinical manifestations as normal viral infection to severe dengue. Previous study has reported that DENV can infect hematopoietic stem and progenitor cell (HSPC) and lead to hematological diseases, like thrombocytopenia, leukemia, and increased atypical lymphocyte. Hematopoiesis, the formation of blood cellular components, is supported by many transcription factors cooperatively functioning. Hematopoietic GATA factors, including GATA-1, GATA-2 and GATA-3, are essential for hematopoietic lineages determination. GATA-1 and GATA-2 cooperate with myeloid cell lineage commitment, the balance between GATA-1 and GATA-2 is important in proliferation and differentiation of hematopoietic cells, while GATA-3 dictates the production of T lymphocytes. However, the relationship between DENV and hematological diseases is yet to be explored. To investigate the mechanism of DENV infected HSCs leading to abnormal hematopoiesis. Umbilical cord blood (UCB) cells, enriched with HSCs, were challenged with or without DENV. The cells were harvested at specific time points and analyzed by flow cytometry after staining with fluorescence antibodies. GATA-1 and GATA-2 expressing HSCs were increased during DENV infection, while megakaryocytic progenitors were decreased, indicated DENV infection may promote HSC proliferation, but inhibit differentiation by affecting the balance of GATA-1 and GATA-2. Myeloid progenitors were decreased after DENV infection was further confirmed by colony forming assay which is used to test the proliferation and differentiation pattern of hematopoietic progenitors. GATA-3 expressing HSCs were also highly increased during DENV infection, suggesting a likely event of the abnormal lymphocytic cells production. Previous study has reported that atypical lymphocytes (ATLs) are increased in dengue patients, especially in severe forms. We observed that the ATLs were elevated in the early stage of DENV infection, and these cells co-expressed DENV viral protein NS1 and stem cells markers, suggesting DENV could infect immature T cells. In conclusion, DENV infection can alter cell populations through affecting the balance of different transcription factors to suppress megakaryocytic lineage cells differentiation as well as increase ATLs in UCB cells.

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