Development Of Langerhans Cell Histiocytosis Research Articles

Detection of Immune Microenvironment Changes and Immune-Related Regulators in Langerhans Cell Histiocytosis Bone Metastasis.

The inflammation/immune response pathway is considered a key contributor to the development of Langerhans cell histiocytosis (LCH) bone metastasis. However, the dynamic changes in the immune microenvironment of LCH bone metastasis and critical regulators are still unclear. Expression profiling by arrays of GSE16395, GSE35340, and GSE122476 was applied to detect the immune microenvironment changes in the development of LCH bone metastasis. The single-cell high-throughput sequencing of GSE133704, involved in LCH bone lesions, was analyzed. The online database Metascape and gene set variation analysis (GSVA) algorithms were used to detect the gene function of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). The protein-protein interaction (PPI) network of hub regulators was constructed by the STRING database. In these results, key immune cells, such as Tem cells, NK T cells, CD8(+) T cells, and Th1 cells, were identified in LCH bone metastasis. These genes, which include LAG3, TSPAN5, LPAR5, VEGFA, CXCL16, CD74, and MARCKS, may significantly correlate with the cellular infiltration of B cells, aDCs, pDCs, cytotoxic cells, T cells, CD8+ T cells, T helper cells, and Tcm cells. In conclusion, our study constructed an atlas of the immune microenvironment of LCH bone metastasis. Genes including LAG3, TSPAN5, LPAR5, VEGFA, CXCL16, CD74, and MARCKS may be involved in the development of LCH bone metastasis. The hub gene-immune cell interactive map may be a potential prognostic biomarker for the progression of LCH bone metastasis and synergetic targets for immunotherapy in LCH patients.

BRAFV600E-induced senescence drives Langerhans cell histiocytosis pathophysiology.

Langerhans cell histiocytosis (LCH) is a potentially fatal condition characterized by granulomatous lesions with characteristic clonal mononuclear phagocytes (MNPs) harboring activating somatic mutations in mitogen-activated protein kinase (MAPK) pathway genes, most notably BRAFV600E. We recently discovered that the BRAFV600E mutation can also affect multipotent hematopoietic progenitor cells (HPCs) in multisystem LCH disease. How the BRAFV600E mutation in HPCs leads to LCH is not known. Here we show that enforced expression of the BRAFV600E mutation in early mouse and human multipotent HPCs induced a senescence program that led to HPC growth arrest, apoptosis resistance and a senescence-associated secretory phenotype (SASP). SASP, in turn, promoted HPC skewing toward the MNP lineage, leading to the accumulation of senescent MNPs in tissue and the formation of LCH lesions. Accordingly, elimination of senescent cells using INK-ATTAC transgenic mice, as well as pharmacologic blockade of SASP, improved LCH disease in mice. These results identify senescent cells as a new target for the treatment of LCH.

Disorders of Macrophages And Dendritic Cells

The mononuclear phagocytic system consists of dendritic cells (DCs) and monocytes/macrophages, historically referred to as histiocytes. The macrophages exhibit varying degrees of phagocytic activity. DCs typically have dendritic morphology. Their phagocytic activity is limited. Instead, they play a key role in antigen presentation to lymphocytes. The various populations of macrophages and DCs (such as Langerhans cells [LCs] and dermal dendrocytes) are usually distinguished based on characteristic morphology and patterns of expression of specific cell surface and intracellular markers. Abnormal accumulation and behavior of these cells may lead to the development of a spectrum of diseases collectively known as the histiocytoses. Clinically, histiocytic disorders comprise a wide variety of conditions that affect both children and adults and range from benign skin lesions to rapidly progressive life-threatening systemic disorders. LCs play a pivotal role in the development of Langerhans cell histiocytosis, dermal dendrocytes are the predominant cell population in the lesions of juvenile xanthogranuloma, and macrophages are central to the pathogenesis of hemophagocytic lymphohistiocytosis and related disorders. This review contains 5 figures, 3 tables, and 77 references. Key words: dendritic cells, dermal dendrocytes, hemophagocytic lymphohistiocytosis, histiocytes, juvenile xanthogranuloma, Langerhans cell histiocytosis, Langerhans cells, macrophage activation syndrome, macrophages

Development of Langerhans cell histiocytosis associated with chronic active Epstein–Barr virus infection

Chronic active Epstein-Barr virus (CAEBV) infection is characterized by a status of lymphoproliferative disease of EBV-infected cells, resulting in chronic or recurrent infectious mononucleosis-like symptoms. CAEBV is always accompanied by life-threatening complications. We report the case of a 2-year-old female patient with CAEBV who subsequently developed Langerhans cell histiocytosis (LCH) presenting with bilateral exophthalmos, bone, and skin involvement. In situ hybridization for EBER revealed EBV-infected B-cells present in lesional tissue implying that interactions between EBV-infected B-cells and lesional Langerhans cells may be associated with the development of LCH.