輕鏈型類澱粉沉積症：骨髓與心臟組織之臨床特徵與免疫微環境特性分析

Abstract

輕鏈類澱粉沉積症（AL amyloidosis）是一種系統性類澱粉蛋白沉積症，其病因為單株漿細胞分泌錯誤摺疊的輕鏈，形成澱粉樣纖維沉積於全身器官中，導致器官功能損傷。由於其臨床表現多樣且症狀不具特異性，早期診斷極具挑戰性。 本研究為回溯性研究，納入自2004年至今於台大醫院及台大癌醫中心分院新診斷之原發性輕鏈類澱粉沉積症病患共50人，系統性分析其臨床特徵、治療模式與預後，並進一步以骨髓與心臟組織標本進行bulk RNA定序與PD-1免疫組織化學染色，深入探討其腫瘤微環境的免疫特性。 本研究比較三種相似的漿細胞疾病（輕鏈類澱粉沉積症、意義不明單株蛋白血症與多發性骨髓瘤）間的骨髓RNA表現差異，並對其中與免疫功能相關的轉錄體進行富集分析。 研究結果顯示，如之前已經被驗證過的分期系統，此群病患的心臟分期能有效預測病患存活，而腎臟分期則與是否會進展到洗腎顯著相關。 在RNA定序分析中，輕鏈類澱粉沉積症病患骨髓和多發性骨髓瘤相較，具有細胞外結構變化訊號的上升，此發現可能反應輕鏈類澱粉蛋白與骨髓內細胞的之間的互動。在免疫功能相關的轉錄體分析中，輕鏈類澱粉沉積症病患有HIF-1 signaling pathway、PD-L1 expression and PD-1 checkpoint pathway in cancer、JAK-STAT signaling pathway等訊息傳遞路徑的上升，在這些免疫相關訊息傳遞路徑中，我們對於PD-1/PD-L1訊息傳遞特別有興趣，並在受類澱粉沉積症影響的心臟組織及骨髓檢體中做驗證，我們確認PD-1染色分數在輕鏈類澱粉沉積症病患的心臟組織中明顯較ATTR類澱粉沉積症者高，顯示輕鏈類澱粉蛋白可能誘發抑制性的免疫微環境。另外我們發現，骨髓中PD-1染色分數較高者有比較差的預後，暗示抑制性的免疫微環境可能有負面的影響。 當輕鏈類澱粉沉積症病患骨髓和意義不明單株蛋白血症相較，在RNA分析中則顯示肌肉與心肌相關訊號顯著上升，此發現非常特別，因為骨髓細胞中應該不會表現肌肉的轉錄體，我們推測此一發現可能和輕鏈類澱粉沉積症常合併心肌細胞的受損，此受損訊號會回饋骨髓，造成骨髓內的漿細胞或免疫細胞做出轉譯體上的調適或變化，此一發現待後續研究做進一步驗證。 本研究綜合臨床資料、轉錄體與免疫化學染色分析，同時呈現輕鏈類澱粉沉積症的臨床預後因子、骨髓免疫微環境差異與心肌免疫抑制性微環境。在未來的研究，我們希望進一步藉由單細胞RNA定序與多重螢光染色，進一步釐清輕鏈類澱粉蛋白沉積與骨髓及受影響器官免疫系統間之交互作用，並探討免疫檢查點抑制劑於此疾病之潛在治療角色。

Light chain (AL) amyloidosis is a systemic amyloid disease caused by the secretion of misfolded monoclonal light chains by abnormal plasma cells, forming amyloid fibrils that deposit in multiple organs and lead to progressive organ dysfunction. Due to its highly variable and non-specific clinical manifestations, early diagnosis remains a major challenge. In this retrospective study, we enrolled 50 newly diagnosed primary AL amyloidosis patients from National Taiwan University Hospital and National Taiwan University Cancer Center since 2004. We systematically analyzed their clinical features, treatment strategies, and outcomes. In addition, bulk RNA sequencing and PD-1 immunohistochemical (IHC) staining were performed on bone marrow and cardiac tissue specimens to explore the immune characteristics of the tumor microenvironment. Transcriptomic profiles of AL amyloidosis were compared with two related plasma cell disorders: monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM). Immune-related gene expression and pathway enrichment analyses were conducted across cohorts. Consistent with prior findings, cardiac staging effectively predicted survival, while renal staging was significantly associated with dialysis progression. RNA sequencing analysis revealed that AL bone marrow, compared to MM, exhibited upregulation of pathways associated with extracellular structural remodeling, possibly reflecting interaction between amyloid protein and the marrow microenvironment. Immune-related transcriptome analyses further identified enrichment in the HIF-1, PD-1/PD-L1 checkpoint, and JAK-STAT signaling pathways. Given the prominence of the PD-1/PD-L1 axis, we validated its relevance by PD-1 IHC staining in cardiac and bone marrow tissue. We found that there was significantly higher PD-1 expression in AL amyloidosis cardiac tissues compared to ATTR amyloidosis, supporting an immunosuppressive microenvironment in AL-affected hearts. In addition, patients with a higher PD-1 expression in bone marrow had worse outcomes than those with low PD-1 expression, suggesting a negative impact of an immunosuppressive microenvironment. When comparing AL to MGUS, AL samples unexpectedly showed enrichment of muscle and cardiomyocyte-related transcriptional signals in the bone marrow. This surprising finding may reflect cardiac injury related feedback signals that influence transcriptional reprogramming in bone marrow plasma or immune cells, and warrants further investigation. This study integrates clinical data, transcriptomic analysis, and tissue-level immunohistochemistry to elucidate the prognostic factors, immune microenvironment, and potential immunosuppressive signatures in AL amyloidosis. Future studies utilizing single-cell RNA sequencing and multiplex tissue flow cytometry imaging are planned to further dissect the crosstalk between amyloid protein deposition and immune modulation in both the marrow and affected organs, and to evaluate the therapeutic potential of immune checkpoint blockade in this disease.