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No relevant conflicts of interest to declare.

No relevant conflicts of interest to declare.

No relevant conflicts of interest to declare.

Thirty three GD patients, followed at the Gaucher clinic of the Rambam Health Care Campus (Haifa, Israel), were enrolled. The study was approved by the local IRB. Monocyte-derived DCs were assessed to determine their functional properties.CD14+ monocytes were isolated from peripheral blood mononuclear cells (PBMCs) of untreated GD patients and healthy volunteers, using immunomagnetic bead separation (Miltenyi Biotec). Monocytes were developed into immature DCs (iDCs) with granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin-4 (IL-4) for 4 to 6 days. The iDC ability to process antigens was evaluated by an antigen uptake assay using 1mg/ml FITC-dextran. Mannose receptor-mediated endocytosis was measured by determining the cellular uptake of FITC-dextran, using FACS. iDCs were maturated with tumor necrosis factor α (TNF-α) for 48 hours. Stimulatory capacity of mature DCs (mDCs) was estimated by measuring the allogeneic T cell response, induced by stimulation with mDCs. T cell response was examined using proliferation and INF-g expression assays. Clinical data focusing on autoimmune phenomena and coexistence of hematological malignancies, mainly lymphoproliferative disorders (lymphoma, multiple myeloma and monoclonal gammopathy), were retrospectively collected from patient charts.Thirty three type I GD patients, 19 males and 14 female, with a median age at analysis of 50.5 years (range 20–74), were included in the analysis. Eight (24%) patients presented with clonal lymphoproliferative disorders, including malignant lymphoma (2), multiple myeloma (3) and monoclonal gammopathies (3). In 15/33 (45%) patients, autoimmune phenomena were revealed. In 12/15 thrombocytopenic GD patients, platelet antibodies were detected, suggesting immune etiology of their thrombocytopenia. Antiphospholipid and antiDNA antibodies were found in 3 other patients with no clinical evidence for autoimmune complications. All these complications appeared prior to the administration of enzyme replacement therapy (ERT). Immunological assessment, performed in 10 untreated patients from this cohort and compared with 10 healthy volunteers, revealed a decrease in the patient DC uptake capacity compared to that observed in DCs obtained from healthy subjects (Table 1). Additionally, GD-derived DCs exhibited impaired maturation, reflected by their limited ability to induce T cell activation, as demonstrated by decreased INF-γ secretion levels and proliferation capacity (Table 1).Forty five percent of the evaluated type I Gaucher patients exhibited autoimmune phenomena. Additionally, 24% presented with lymphoproliferative disorders. DC function analysis showed a significant impairment of both iDCs and mDCs, reflected by their decreased uptake and antigen presenting capacities. These abnormalities may adversely affect T cell polarization and functional abilities, resulting in autoimmune complications as well as hematological clonal disorders. Further studies, exploring the precise association between the existence of autoimmune/lymphoproliferative disorders, and the observed in vitro immunological impairment are required.No relevant conflicts of interest to declare.

Gaucher disease (GD) is an autosomal recessively inherited lysosomal storage disorder caused by an inborn glucocerebrosidase (GBA) deficiency. This leads to the accumulation of glycolipids in macrophages, mainly in the bone marrow, spleen and liver, resulting in organ damage. However, recent studies suggest that clinical presentation of GD is primarily attributed to the impaired inflammatory process induced by “loaded macrophages”, rather than to their physical presence. This impairment could be explained by dysfunction of circulating monocytes, normally capable of migrating into sites of vascular injury and inflammation. The current in vitro study investigated potential changes in migratory capacity of GD-derived monocytes that would contribute to the inflammatory response. Methods: CD14+ monocytes were isolated from peripheral blood mononuclear cells (PBMCs) of untreated GD patients and healthy volunteers, using immunomagnetic bead separation (Miltenyi Biotec). Monocyte migration capacity was assessed with 5μm Polycarbonate Membrane Transwell inserts which contained either stromal cell-derived factor 1 (SDF1; CXCL12) (500 and 1000 ng/ml) or serum (0.25%) at the bottom chamber. Monocytes were allowed to migrate from the upper chamber through the membrane, over 4 hours. Migrating monocytes were collected from the bottom chamber and quantified by FACS. Blockage of the CXCR4 receptor was examined using AMD3100 (10μg/ml) added to the migration assay. Serum SDF-1 levels were evaluated by ELISA (Quntikine® human CXCL12/SDF-1α R&D systems). Results: Upon exposure to SDF-1, migration capacity of GD monocytes (n=7) was significantly lower than that observed in monocytes obtained from healthy volunteers (n=6), approaching 5.7% vs. 14%, p=0.02, for SDF1of 500 ng/ml, and 8.7% vs 21.8%, p=0.013, for SDF1of 1000 ng/ml). Similar results were observed in the presence of autologous serum: migration capacity of GD monocytes (n=7) was lower than demonstrated by healthy monocytes (n=5), (18.6% vs. 45%, p=0.05). Notably, substitution of “GD serum” (n=7) with “healthy serum” (n=7) resulted in significant improvement in migration capacity of GD-derived monocytes (from 18.6% to 33.6%, p=0.038), while a reciprocal substitution of the serum caused a marked reduction in migration of monocytes derived from healthy volunteers (34% instead of 45%). Blockage of the CXCR4 receptor led to a decreased migration capacity of healthy monocytes cultured in autologous serum (from 45.2% to 39.6%) (n=4). Remarkably, this blockage had no impact on migration of both healthy and GD-derived monocytes cultured with GD serum (n=6). However, GD monocytes treated with AMD3100 in the presence of healthy serum, exhibited a reduced migration rate compared to that observed in untreated cells (22.6% vs. 33.6%; p=0.06, n=7).CXCR4 expression on GD-derived monocytes appeared to be lower than that measured on cells derived from healthy donors [64.5% (n=6) vs. 83.6% (n=3)]. Of note, serum levels of SDF-1 were significantly increased in GD subjects compared to healthy ones (2603pg/ml vs 2039 pg/ml; p=0.004, n=10). Conclusions: GD patients exhibit an impaired SDF1-dependent migration of monocytes, despite expressing a significantly increased SDF-1serum level. The impaired migration capacity is partly explained by low levels of CXCR4 on monocyte surface. Additionally, the reduced migration appears to be dependent on as yet undetermined serum-derived factors, as demonstrated by the reversibility of this impairment with substitution of the GD serum for “healthy serum”. The observed reduction in migratory capacity may significantly contribute to the abnormal inflammation accounting for GD-associated vascular and bone complications. Further studies exploring the precise mechanisms involved in this process and their direct impact on GD-related organ damage are warranted.No relevant conflicts of interest to declare.