人類胎盤絨毛膜蛻膜間葉細胞在酯多糖誘發急性肺損傷動物模式療效之評估

Abstract

急性肺損傷（ALI）與嚴重程度更高的急性呼吸窘迫綜合徵（ARDS）為臨床公衛統計上高發病率和死亡率的疾病，佔醫院重症照護患者的26％至58％。在其的眾多危險因素中，細菌性肺炎和敗血症為構成死亡的主要原因。儘管已有許多研究探討急性肺損傷的病理機轉試圖發展最佳治療方法，目前臨床上治療選擇仍然有限：其用藥主要為抗發炎藥物，同時給病患接上呼吸器避免呼吸衰竭。這些支持性治療雖有助於降低死亡率，但對肺部組織受損和纖維化仍未能有效治癒。近年來，間葉幹細胞（MSCs）被報導具有免疫調控的特性，且已被運用在發炎與退化性疾病的基礎研究及臨床試驗中。本實驗室成功分離並鑑定人類胎盤絨毛膜蛻膜間葉幹細胞（placenta-choriodecidual derived mesenchymal stromal cells, pcMSCs），以體外無血清培養基進行繼代培養。由於先前已經證實pcMSCs在實驗性自體免疫腦脊髓炎（EAE）模式中具治療潛力，便假設其同樣可做為急性肺損傷的細胞治療來源。我們透過脂多醣（LPS）誘導的急性肺損傷動物模式及體外pcMSCs/骨髓來源巨噬細胞（BMDM）共同培養系統，探討pcMSCs的治療潛力與機制。首先於體內實驗，證實尾靜脈給予pcMSCs可降低ALI小鼠的死亡率、免疫細胞浸潤和發炎性細胞激素的產生，使CD11c+肺泡巨噬細胞的活化程度受到抑制，且治療組小鼠亦觀察到肺組織損傷降低和肺功能回升；體外系統結果亦呈現相同趨勢：pcMSCs可能透過本身的COX-2表現量上升，抑制BMDM受LPS刺激而大量分泌的細胞激素，並進一步調控骨髓前驅細胞分化為BMDM的過程。雖然pcMSCs並未顯著促使CD86+/M1轉變為CD206+/M2表型，卻能使活化巨噬細胞內染的TNF-α降低並伴隨IL-10上升。另一方面，經過TNF-α和IFN-γ預處理之pcMSCs則可觀察到免疫抑制能力的提升。本實驗從pcMSC/巨噬細胞互動的角度證明其在發炎性疾病急性肺損傷的治療成效，期望可以作為具應用潛力的細胞治療產品。

Acute lung injury (ALI) and its most devastating form, the acute respiratory distress syndrome (ARDS), caused morbidity and mortality ranging from 26 to 58% of patients in critical care. Among the associated risk factors, pneumonia and sepsis constitute the leading cause of death. Although intensive studies have been made to reveal optimal treatment for this disease, the clinically adopted therapeutic options are still limited: pharmacological cares which mainly include anti-inflammatory agents and non-pharmacological ventilators are utilized. These supportive treatments contributed to the decrease in mortality, but protection of damaged pulmonary tissue and end-staged fibrosis remain incurable. Mesenchymal stem cells (MSCs) have been reported to be potentiate in immunomodulation and regenerative abilities. Recently, we have successfully identified a novel type of MSCs derived from placenta-choriodecidual membrane abbreviated in pcMSCs. The cells were established in an in vitro serum-free culture condition which could be applied for clinical use. As pcMSCs have previously been confirmed to exert therapeutic potential in mice experimental autoimmune encephalomyelitis (EAE) model, we subsequently hypothesized that pcMSCs will also be a promising cell therapy source for ALI. In this study, we conducted in vivo lipopolysaccharide (LPS)-induced ALI and in vitro pcMSC/bone marrow-derived monocyte (BMDM) co-culture system to reveal the therapeutic efficacies. The results first showed that pcMSC treatment reduced mortality, infiltration and cytokine production in ALI mice, with further flow cytometry analysis demonstrated that CD11c+ alveolar macrophages activation were regulated. pcMSCs therapy also rescued tissue damage and lung function after LPS challenge. In vitro co-culture presented similar trend that pro-inflammatory cytokines secreted by LPS-induced BMDM were also down-regulated with an upregulation of anti-inflammatory COX-2 in pcMSCs. Furthermore, pcMSCs were able to suppress differentiation from bone marrow progenitors to BMDMs. However, the co-culture of pcMSCs and LPS-induced BMDMs failed to promote significant population shifting from CD86+/M1 to CD206+/M2 phenotype, while intracellular staining indicated the downregulation of TNF-α accompanied by the upregulation in IL-10. On the other hand, pretreatment of pcMSCs with TNF-α and IFN-γ increased the immunosuppressive capacity. Taken together, the results indicated that pcMSCs provide therapeutic potentials by programming macrophages to an anti-inflammatory state and eventually resulting in the protection of pulmonary tissue. In conclusion, we demonstrated the modulation of ALI from a perspective of pcMSC/macrophage interaction, and that pcMSCs may serve as a promising cell therapy product for ALI.